Document And Entity Information - USD ($)	12 Months Ended
Document And Entity Information - USD ($)	Dec. 31, 2020	Jan. 31, 2021	Jun. 30, 2020
Document and Entity Information [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	0-19341
Entity Registrant Name	BOK FINANCIAL CORP
Entity Incorporation, State or Country Code	OK
Entity Tax Identification Number	73-1373454
Entity Address, Address Line One	Boston Avenue at Second Street
Entity Address, City or Town	Tulsa,
Entity Address, State or Province	OK
Entity Address, Postal Zip Code	74172
City Area Code	918
Local Phone Number	588-6000
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
ICFR Auditor Attestation Flag	true
Entity Common Stock, Shares Outstanding		69,577,615
Entity Central Index Key	0000875357
Current Fiscal Year End Date	--12-31
Entity Public Float			$ 1,800,000,000
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Statements of Earnings - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest and dividend revenue [Abstract]
Loans	$ 889,507	$ 1,123,791	$ 891,587
Residential mortgage loans held for sale	6,397	7,105	8,123
Trading securities	67,689	61,595	57,531
Investment securities	11,943	13,426	14,775
Available for sale securities	261,196	254,031	197,317
Fair value option securities	18,475	32,936	15,205
Restricted equity securities	10,963	26,860	21,555
Interest-bearing cash and cash equivalents	2,830	12,214	22,333
Total interest revenue	1,269,000	1,531,958	1,228,426
Interest Expense [Abstract]
Deposits	89,996	175,538	95,517
Borrowed funds	56,616	228,428	138,215
Subordinated debentures	13,944	15,113	9,827
Total interest expense	160,556	419,079	243,559
Net interest and dividend revenue	1,108,444	1,112,879	984,867
Provision for credit losses	222,592	44,000	8,000
Net interest and dividend revenue after provision for credit losses	885,852	1,068,879	976,867
Total fees and commissions	810,320	702,201	643,176
Other gains (losses), net	7,675	9,351	(2,265)
Gain (loss) on derivatives, net	42,320	14,951	(422)
Gain (loss) on fair value option securities, net	53,248	15,787	(25,572)
Change in fair value of mortgage servicing rights	(79,524)	(53,517)	4,668
Gain (loss) on available for sale securities, net	9,910	5,597	(2,801)
Total other operating revenue	843,949	694,370	616,784
Other operating expense [Abstract]
Personnel	688,474	660,565	583,131
Business promotion	14,511	35,662	30,523
Charitable contributions to BOKF Foundation	9,000	3,000	2,846
Professional fees and services	53,437	54,861	59,099
Net occupancy and equipment	112,722	110,275	97,981
Insurance	19,990	20,906	23,318
Data processing and communications	135,497	124,983	114,796
Printing, postage and supplies	15,061	16,517	17,169
Net losses and operating expenses of repossessed assets	10,709	6,707	17,052
Amortization of intangible assets	20,443	20,618	9,620
Mortgage banking costs	56,711	50,685	46,298
Other expense	29,382	27,602	26,333
Total other operating expense	1,165,937	1,132,381	1,028,166
Net income before taxes	563,864	630,868	565,485
Federal and state income taxes	128,793	130,183	119,061
Net income	435,071	500,685	446,424
Net income (loss) attributable to Non-controlling interests	41	(73)	778
Net income attributable to BOK Financial Corporation shareholders	$ 435,030	$ 500,758	$ 445,646
Earnings per share: [Abstract]
Basic (in dollars per share)	$ 6.19	$ 7.03	$ 6.63
Diluted (in dollars per share)	$ 6.19	$ 7.03	$ 6.63
Average shares used in computation: [Abstract]
Basic (in shares)	69,840,977	70,787,700	66,628,640
Diluted (in shares)	69,844,172	70,802,612	66,662,273
Dividends declared per share (in dollars per share)	$ 2.05	$ 2.01	$ 1.90
Brokerage and trading revenue [Member]
Total fees and commissions	$ 221,833	$ 159,826	$ 108,323
Transaction card revenue [Member]
Total fees and commissions	90,182	87,216	84,025
Fiduciary and asset management revenue [Member]
Total fees and commissions	167,445	177,025	184,703
Deposit service charges and fees [Member]
Total fees and commissions	96,805	112,485	112,153
Mortgage banking revenue [Member]
Total fees and commissions	182,360	107,541	97,787
Other revenue [Member]
Total fees and commissions	$ 51,695	$ 58,108	$ 56,185

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 435,071	$ 500,685	$ 446,424
Other comprehensive income (loss), before income taxes: [Abstract]
Net change in unrealized gain (loss)	313,796	241,047	(48,010)
Reclassification adjustments included in earnings: [Abstract]
Loss (gain) on available for sale securities, net	(9,910)	(5,597)	2,801
Other comprehensive gain (loss), before income taxes	303,886	235,450	(45,209)
Federal and state income taxes	72,941	57,942	(11,507)
Other comprehensive gain (loss), net of income taxes	230,945	177,508	(33,702)
Comprehensive income	666,016	678,193	412,722
Comprehensive income (loss) attributable to non-controlling interests	41	(73)	778
Comprehensive income attributable to BOK Financial Corp. shareholders	$ 665,975	$ 678,266	$ 411,944

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets [Abstract]
Cash and due from banks	$ 798,757	$ 735,836
Interest-bearing cash and cash equivalents	381,816	522,985
Trading securities	4,707,975	1,623,921
Investment securities	244,843	293,418
Available for sale securities	13,050,665	11,269,643
Fair value option securities	114,982	1,098,577
Restricted equity securities	171,391	460,552
Residential mortgage loans held for sale	252,316	182,271
Loans	23,007,520	21,750,987
Allowance for loan losses	(388,640)	(210,759)
Loans, net of allowance	22,618,880	21,540,228
Premises and equipment, net	551,308	535,519
Receivables	245,880	231,811
Goodwill	1,048,091	1,048,091
Intangible assets, net	113,436	125,271
Mortgage servicing rights	101,172	201,886
Real estate and other repossessed assets, net of allowance	90,526	20,359
Derivative contracts, net	810,688	323,375
Cash surrender value of bank-owned life insurance	398,758	389,879
Receivable on unsettled securities sales	62,386	1,020,404
Other assets	907,218	547,995
Total assets	46,671,088	42,172,021
Deposits [Abstract]
Noninterest-bearing demand deposits	12,266,338	9,461,291
Interest-bearing Deposit Liabilities [Abstract]
Transaction	21,158,422	15,391,752
Savings	751,992	550,276
Time	1,967,128	2,217,849
Total deposits	36,143,880	27,621,168
Funds purchased and repurchase agreements	1,662,386	3,818,350
Other borrowings	1,882,970	4,527,055
Subordinated debentures	276,005	275,923
Accrued interest, taxes and expense	323,667	259,701
Derivative contracts, net	405,779	251,128
Due on unsettled securities purchases	257,627	182,547
Other liabilities	427,213	372,230
Total liabilities	41,379,527	37,308,102
Shareholders' equity: [Abstract]
Common stock	5	5
Capital surplus	1,368,062	1,350,995
Retained earnings	3,973,675	3,729,778
Treasury stock	(411,344)	(329,906)
Accumulated other comprehensive income (loss)	335,868	104,923
Total shareholders’ equity	5,266,266	4,855,795
Non-controlling interests	25,295	8,124
Total equity	5,291,561	4,863,919
Total liabilities and equity	$ 46,671,088	$ 42,172,021

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Investment securities [Abstract]
Investment securities, fair value	$ 272,431	$ 314,402
Real estate and other repossessed assets, allowance	$ 15,060	$ 11,013
Shareholders' equity: [Abstract]
Common stock, par value (in dollars per share)	$ 0.00006	$ 0.00006
Common stock, shares authorized (in shares)	2,500,000,000	2,500,000,000
Common stock, shares issued (in shares)	75,995,205	75,758,597
Common stock, shares outstanding (in shares)	75,995,205	75,758,597
Treasury stock, shares at cost (in shares)	6,357,605	5,178,999

Consolidated Statements of Changes in Equity - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjusted Balance	Common Stock [Member]	Common Stock [Member] Cumulative Effect, Period of Adoption, Adjusted Balance	Capital Surplus [Member]	Capital Surplus [Member] Cumulative Effect, Period of Adoption, Adjusted Balance	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjusted Balance	Treasury Stock [Member]	Treasury Stock [Member] Cumulative Effect, Period of Adoption, Adjusted Balance	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Other Comprehensive Income (Loss) [Member] Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss) [Member] Cumulative Effect, Period of Adoption, Adjusted Balance	Total Shareholders' Equity [Member]	Total Shareholders' Equity [Member] Cumulative Effect, Period of Adoption, Adjustment	Total Shareholders' Equity [Member] Cumulative Effect, Period of Adoption, Adjusted Balance	Non-Controlling Interests [Member]	Non-Controlling Interests [Member] Cumulative Effect, Period of Adoption, Adjusted Balance
Balance, beginning of period (in shares) at Dec. 31, 2017				75,148	75,148						9,753	9,753
Balance, beginning of period at Dec. 31, 2017	$ 3,518,334	$ (2,709)	$ 3,518,334	$ 4	$ 4	$ 1,035,895	$ 1,035,895	$ 3,048,487		$ 3,051,196	$ (552,845)	$ (552,845)	$ (36,174)		$ (38,883)	$ 3,495,367		$ 3,495,367	$ 22,967	$ 22,967
Balance, beginning of period (Accounting Standards Update 2016-01) at Dec. 31, 2017									$ 2,709					$ (2,709)
Net income	446,424							445,646								445,646			778
Other comprehensive income (loss), net	(33,702)												(33,702)			(33,702)
Repurchase of common stock (in shares)											616
Repurchase of common stock	(53,465)										$ (53,465)					(53,465)
Stock options exercised (in shares)				54
Stock options exercised	2,781					2,781										2,781
Non-vested shares awarded, net (in shares)				109
Vesting of non-vested shares (in shares)											31
Vesting of non-vested shares	(2,870)										$ (2,870)					(2,870)
Share-based compensation	4,229					4,229										4,229
Cash dividends on common stock	(127,188)							(127,188)								(127,188)
Capital calls and distributions, net	12,809																		12,809
Issuance of shares for CoBiz acquisition (in shares)				400							(6,811)
Issuance of shares for CoBiz acquisition	701,311			$ 1		291,125					$ 410,185					701,311
Balance, end of period (in shares) at Dec. 31, 2018				75,711	75,711						3,589	3,589
Balance, end of period at Dec. 31, 2018	4,443,045		4,445,907	$ 5	$ 5	1,334,030	1,334,030	3,369,654		3,372,516	$ (198,995)	$ (198,995)	(72,585)		(72,585)	4,432,109		4,434,971	10,936	10,936
Balance, end of period (Accounting Standards Update 2016-02) at Dec. 31, 2018		2,862							2,862								$ 2,862
Net income	500,685							500,758								500,758			(73)
Other comprehensive income (loss), net	177,508												177,508			177,508
Repurchase of common stock (in shares)											1,572
Repurchase of common stock	(129,483)										$ (129,483)					(129,483)
Stock options exercised (in shares)				27
Stock options exercised	1,421					1,421										1,421
Non-vested shares awarded, net (in shares)				21
Vesting of non-vested shares (in shares)											18
Vesting of non-vested shares	(1,428)										$ (1,428)					(1,428)
Share-based compensation	15,544					15,544										15,544
Cash dividends on common stock	(143,496)							(143,496)								(143,496)
Capital calls and distributions, net	2,739																		2,739
Balance, end of period (in shares) at Dec. 31, 2019				75,759	75,759						5,179	5,179
Balance, end of period at Dec. 31, 2019	4,863,919		$ 4,817,223	$ 5	$ 5	1,350,995	$ 1,350,995	3,729,778		$ 3,683,082	$ (329,906)	$ (329,906)	104,923		$ 104,923	4,855,795		$ 4,809,099	8,124	$ 8,124
Balance, end of period (Accounting Standards Update 2016-13) at Dec. 31, 2019		$ (46,696)							$ (46,696)								$ (46,696)
Net income	435,071							435,030								435,030			41
Other comprehensive income (loss), net	230,945												230,945			230,945
Repurchase of common stock (in shares)											1,107
Repurchase of common stock	(75,830)										$ (75,830)					(75,830)
Stock options exercised (in shares)				12
Stock options exercised	675					675										675
Non-vested shares awarded, net (in shares)				224
Vesting of non-vested shares (in shares)											72
Vesting of non-vested shares	(5,608)										$ (5,608)					(5,608)
Share-based compensation	16,392					16,392										16,392
Cash dividends on common stock	(144,437)							(144,437)								(144,437)
Capital calls and distributions, net	17,130																		17,130
Balance, end of period (in shares) at Dec. 31, 2020				75,995							6,358
Balance, end of period at Dec. 31, 2020	$ 5,291,561			$ 5		$ 1,368,062		$ 3,973,675			$ (411,344)		$ 335,868			$ 5,266,266			$ 25,295

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows From Operating Activities: [Abstract]
Net income	$ 435,071	$ 500,685	$ 446,424
Adjustments to reconcile net income to net cash provided by (used in) operating activities: [Abstract]
Provision for credit losses	222,592	44,000	8,000
Change in fair value of mortgage servicing rights due to market changes	79,524	53,517	(4,668)
Change in fair value of mortgage servicing rights due to principal payments	41,598	38,979	33,528
Net unrealized losses (gains) from derivative contracts	(59,253)	(25,936)	4,686
Share-based compensation	16,392	15,544	4,229
Depreciation and amortization	99,013	95,416	60,843
Net amortization of discounts and premiums	5,357	(16,984)	30,945
Net losses (gains) on financial instruments and other losses (gains), net	(15,949)	(583)	9,585
Net gain on mortgage loans held for sale	(114,545)	(40,402)	(35,705)
Mortgage loans originated for sale	(3,764,112)	(3,025,930)	(2,587,297)
Proceeds from sale of mortgage loans held for sale	3,817,475	3,035,600	2,691,144
Capitalized mortgage servicing rights	(31,209)	(35,128)	(35,247)
Change in trading and fair value option securities	(2,103,931)	(483,007)	(1,023,097)
Change in receivables	945,087	(740,868)	(38,346)
Change in other assets	1,739	18,955	27,507
Change in other liabilities	8,895	92,463	(144,537)
Net cash provided by (used in) operating activities	(416,256)	(473,679)	(552,006)
Cash Flows From Investing Activities: [Abstract]
Proceeds from maturities or redemptions of investment securities	46,992	60,128	124,864
Proceeds from maturities or redemptions of available for sale securities	2,695,067	1,841,069	1,122,680
Purchases of investment securities	0	0	(4,468)
Purchases of available for sale securities	(4,575,324)	(5,245,256)	(1,955,172)
Proceeds from sales of available for sale securities	384,507	1,211,718	745,643
Change in amount receivable on unsettled available for sale securities transactions	(6,357)	25,410	38,347
Loans originated, net of principal collected	(1,103,752)	(44,414)	(1,553,033)
Net payments on derivative asset contracts	(121,130)	33,566	(114,417)
Acquisitions, net of cash acquired	0	0	(175,755)
Net change in restricted equity securities	289,161	116,105	18,997
Proceeds from disposition of assets	73,135	62,576	289,765
Purchases of assets	(141,134)	(384,639)	(345,082)
Net cash provided by (used in) investing activities	(2,458,835)	(2,323,737)	(1,807,631)
Cash Flows From Financing Activities: [Abstract]
Net change in demand deposits, transaction deposits and savings accounts	8,773,433	2,252,936	(13,870)
Net change in time deposits	(250,721)	104,288	(73,089)
Net change in other borrowed funds	(5,091,026)	1,110,970	1,295,484
Change in amount due on unsettled security purchases	63,521	(41,651)	(41,319)
Issuance of common and treasury stock, net	(4,933)	(7)	(88)
Net change in derivative margin accounts	(600,218)	(207,122)	85,466
Net payments or proceeds on derivative liability contracts	127,054	(33,622)	114,076
Repurchase of common stock	(75,830)	(129,483)	(53,465)
Dividends paid	(144,437)	(143,496)	(127,188)
Net cash provided by (used in) financing activities	2,796,843	2,912,813	1,186,007
Net increase (decrease) in cash and cash equivalents	(78,248)	115,397	(1,173,630)
Cash and cash equivalents at beginning of period	1,258,821	1,143,424	2,317,054
Cash and cash equivalents at end of period	1,180,573	1,258,821	1,143,424
Supplemental Cash Flow Information: [Abstract]
Cash paid for interest	160,288	417,070	243,121
Cash paid for taxes	136,181	87,361	92,291
Net loans and bank premises transferred to repossessed real estate and other assets	85,323	10,665	9,880
Increase in U.S. government guaranteed loans eligible for repurchase	290,977	91,634	100,238
Increase in receivables from conveyance of GNMA OREO	11,322	28,669	38,216
Right-of-use assets obtained in exchange for operating lease liabilities	$ 16,177	$ 62,755	$ 0

Mortgage Banking Activities Mortgage Banking Activities

12 Months Ended

Dec. 31, 2020

Mortgage Banking [Abstract]

Mortgage Banking Activities [Text Block]

Mortgage Banking Activities

Residential Mortgage Loan Production

The Company originates, markets and services conventional and government-sponsored residential mortgage loans. Generally, conforming fixed rate residential mortgage loans are held for sale in the secondary market and non-conforming and adjustable-rate residential mortgage loans are held for investment. The volume of mortgage loans originated for sale and secondary market prices are the primary drivers of originating and marketing revenue.

Residential mortgage loan commitments are generally outstanding for 60 to 90 days, which represents the typical period from commitment to originate a residential mortgage loan to when the closed loan is sold to an investor. Residential mortgage loan commitments are subject to both credit and interest rate risk. Credit risk is managed through underwriting policies and procedures, including collateral requirements, which are generally accepted by the secondary loan markets. Exposure to interest rate fluctuations is partially managed through forward sales of residential mortgage-backed securities and forward sales contracts. These latter contracts set the price for loans that will be delivered in the next 60 to 90 days.

The unpaid principal balance of residential mortgage loans held for sale, notional amounts of derivative contracts related to residential mortgage loan commitments and forward contract sales and their related fair values included in Mortgage loans held for sale on the Consolidated Balance Sheets were (in thousands):


	December 31, 2020				December 31, 2019
	Unpaid Principal Balance/ Notional		Fair Value		Unpaid Principal Balance/ Notional		Fair Value
Residential mortgage loans held for sale	$	227,161	$	236,444	$	175,117	$	177,703
Residential mortgage loan commitments	380,637		20,435		158,460		5,233
Forward sales contracts	549,414		(4,563)		315,203		(665)
			$	252,316			$	182,271

No residential mortgage loans held for sale were 90 days or more past due or considered impaired as of December 31, 2020 or December 31, 2019. No credit losses were recognized on residential mortgage loans held for sale for the years ended December 31, 2020, 2019 and 2018.

Mortgage banking revenue was as follows (in thousands):


	Year Ended
	2020		2019		2018
Production revenue:
Net realized gains on sales of mortgage loans	$	107,847	$	39,730	$	36,379
Net change in unrealized gain on mortgage loans held for sale	6,697		672		(674)
Net change in the fair value of mortgage loan commitments	15,202		(145)		(1,145)
Net change in the fair value of forward sales contracts	(3,898)		2,463		(2,870)
Total mortgage production revenue	125,848		42,720		31,690
Servicing revenue	56,512		64,821		66,097
Total mortgage banking revenue	$	182,360	$	107,541	$	97,787

Mortgage production revenue includes gain (loss) on residential mortgage loans held for sale and changes in the fair value of derivative contracts not designated as hedging instruments related to residential mortgage loan commitments and forward sales contracts. Servicing revenue includes servicing fee income and late charges on loans serviced for others.

Residential Mortgage Servicing

The Company generally retains the right to service residential mortgage loans sold and may purchase mortgage servicing rights. The unpaid principal balance of loans serviced for others is the primary driver of servicing revenue.

The following represents a summary of mortgage servicing rights (Dollars in thousands):


	December 31,
	2020			2019			2018
Number of residential mortgage loans serviced for others	106,201			126,828			132,463
Outstanding principal balance of residential mortgage loans serviced for others	$	16,228,449		$	20,727,106		$	21,658,335
Weighted average interest rate	3.84		%	3.98		%	3.99		%
Remaining contractual term (in months)	280			289			293

Activity in capitalized mortgage servicing rights during the three years ended December 31, 2020 is as follows (in thousands):



Balance, December 31, 2017	$	252,867
Additions, net	35,247
Change in fair value due to loan runoff	(33,528)
Change in fair value due to market changes	4,668
Balance, December 31, 2018	259,254
Additions, net	35,128
Change in fair value due to loan runoff	(38,979)
Change in fair value due to market changes	(53,517)
Balance, December 31, 2019	201,886
Additions	31,209
Disposals	(10,801)
Change in fair value due to loan runoff	(41,598)
Change in fair value due to market changes	(79,524)
Balance, December 31, 2020	$	101,172

Changes in the fair value of mortgage servicing rights due to market changes are included in Other operating revenue in the Consolidated Statements of Earnings. Changes in fair value due to loan runoff are included in Mortgage banking costs.

Mortgage servicing rights are not traded in active markets. Fair value is determined by discounting the projected net cash flows. Significant assumptions used to determine fair value considered to be significant unobservable inputs were as follows:


	December 31,
	2020	2019
Discount rate – risk-free rate plus a market premium	9.14%	9.81%
Prepayment rate - based upon loan interest rate, original term and loan type	9.41% - 21.87%	8.28% - 16.05%
Loan servicing costs – annually per loan based upon loan type:
Performing loans	$69 - $94	$68 - $94
Delinquent loans	$150 - $500	$150 - $500
Loans in foreclosure	$1,000 - $4,000	$1,000 - $4,000
Primary/secondary mortgage rate spread	105 bps	104 bps
Escrow earnings rate – indexed to rates paid on deposit accounts with comparable average life	0.43%	1.73%
Delinquency rate	3.54%	2.73%

Changes in primary residential mortgage interest rates directly affect the prepayment speeds used in valuing our mortgage servicing rights. A separate third party model is used to estimate prepayment speeds based on interest rates, housing turnover rates, estimated loan curtailment, anticipated defaults and other relevant factors. The prepayment model is updated periodically for changes in market conditions and adjusted to better correlate with actual performance of BOK Financial’s servicing portfolio.

Significant Accounting Policies	12 Months Ended
Significant Accounting Policies	Dec. 31, 2020
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Significant Accounting Policies Basis of Presentation The Consolidated Financial Statements of BOK Financial Corporation (“BOK Financial” or “the Company”) have been prepared in conformity with accounting principles generally accepted in the United States ("U.S. GAAP"), including interpretations of U.S. GAAP issued by federal banking regulators and general practices of the banking industry. The Consolidated Financial Statements include the accounts of BOK Financial and its subsidiaries, principally BOKF, NA, BOK Financial Securities, Inc., BOK Financial Private Wealth, Inc., BOK Financial Insurance, Inc. and Cavanal Hill Distributors, Inc. All significant intercompany transactions are eliminated in consolidation. The Consolidated Financial Statements include the assets, liabilities, non-controlling interests and results of operations of variable interest entities (“VIEs”) when BOK Financial is determined to be the primary beneficiary. Variable interest entities are generally defined as entities that either do not have sufficient equity to finance their activities without support from other parties or whose equity investors lack a controlling financial interest. Determination that the Company is the primary beneficiary considers the power to direct the activities that most significantly impact the variable interest's economic performance and the obligation to absorb losses of the variable interest or the right to receive benefits of the variable interest that could be significant to the variable interest. Certain prior year amounts have been reclassified to conform to current year presentation. Nature of Operations BOK Financial, through its subsidiaries, provides a wide range of financial services to commercial and industrial customers, other financial institutions, municipalities, and consumers. These services include depository and cash management; lending and lease financing; mortgage banking; securities brokerage, trading and underwriting; and personal and corporate trust. BOKF, NA operates as Bank of Oklahoma primarily in the Tulsa and Oklahoma City metropolitan areas of the state of Oklahoma and Bank of Texas primarily in the Dallas, Fort Worth and Houston metropolitan areas of the state of Texas. In addition, BOKF, NA does business as BOK Financial in the metropolitan areas of Phoenix, Arizona; Northwest Arkansas; Denver, Colorado; Kansas City, Missouri/Kansas; and as Bank of Albuquerque in Albuquerque, New Mexico. BOKF, NA also operates the TransFund electronic funds network, Cavanal Hill Investment Management, and BOK Financial Asset Management, Inc. Use of Estimates Preparation of BOK Financial's Consolidated Financial Statements requires management to make estimates of future economic activities, including loan collectability, loss contingencies, prepayments and cash flows from customer accounts. These estimates are based upon current conditions and information available to management. Actual results may differ significantly from these estimates. Acquisitions Assets and liabilities acquired, including identifiable intangible assets, are recorded at fair value on the acquisition date. The purchase price includes consideration paid at closing and the estimated fair value of contingent consideration that will be paid in the future, subject to achieving defined performance criteria. Premiums and discounts assigned to interest-earning assets and interest-bearing liabilities are amortized over the lives of the acquired assets and liabilities on either an individual instrument or pool basis. Provision for credit losses is recognized for changes in credit quality after the acquisition date. Goodwill is recognized as the excess of the purchase price over the net fair value of assets acquired and liabilities assumed. The Consolidated Statements of Earnings include the results of operations from the acquisition date. Goodwill and Intangible Assets Goodwill and intangible assets generally result from business combinations and are evaluated for each of BOK Financial's reporting units for impairment annually or more frequently if conditions indicate impairment. The evaluation of possible impairment of goodwill and intangible assets involves significant judgment based upon short-term and long-term projections of future performance. Reporting units are defined by the Company as significant lines of business within each operating segment. This definition is consistent with the manner in which the chief operating decision maker assesses the performance of the Company and makes decisions concerning the allocation of resources. The Company qualitatively assesses whether it is more likely than not that the fair value of the reporting units are less than their carrying value, including goodwill. Reporting unit carrying value includes sufficient capital to exceed regulatory requirements. This assessment includes consideration of relevant events and circumstances including but not limited to macroeconomic conditions, industry and market conditions, the financial and stock performance of the Company and other relevant factors. If the Company concludes based on the qualitative assessment that goodwill may be impaired, a quantitative one-step impairment test will be applied to goodwill at all reporting units. The quantitative analysis compares the fair value of the reporting unit with its carrying value, including goodwill. The fair value of each reporting unit is estimated by the discounted future earnings method. Goodwill is considered impaired if the fair value of the reporting unit is less than the carrying value of the reporting unit, including goodwill. Intangible assets are generally composed of customer relationships, naming rights, non-compete agreements and core deposit premiums. They are amortized using accelerated or straight-line methods, as appropriate, over the estimated benefit periods. These periods range from 3 years to 20 years. The net book values of identifiable intangible assets are evaluated for impairment when economic conditions indicate impairment may exist. Cash Equivalents Due from banks, funds sold (generally federal funds sold for one day), resell agreements (which generally mature within one day to 30 days) and investments in money market funds are considered cash equivalents. Securities Securities are identified as trading, investment (held to maturity) or available for sale at the time of purchase based upon the intent of management, liquidity and capital requirements, regulatory limitations and other relevant factors. Trading securities, which are acquired for profit through resale, are carried at fair value with unrealized gains and losses included in current period earnings. Investment securities are carried at amortized cost. Amortization is computed by methods that approximate level yield and is adjusted for changes in prepayment estimates. Securities identified as available for sale are carried at fair value. Unrealized gains and losses are recorded, net of deferred income taxes, as accumulated other comprehensive income in shareholders' equity. Available for sale securities are separately identified as pledged to creditors if the creditor has the right to sell or re-pledge the collateral. The purchase or sale of securities is recognized on a trade date basis. Realized gains and losses on sales of securities are based upon specific identification of the security sold. A receivable or payable is recognized for subsequent transaction settlement. On a quarterly basis, the Company performs separate evaluations of debt investment and available for sale securities for the presence of impairment. We assess whether impairment is present on an individual security basis when the fair value of a debt security is less than the amortized cost. Management determines whether it intends to sell or if it is more likely than not that it will be required to sell impaired securities. This determination considers current and forecasted liquidity requirements and securities portfolio management. If the Company intends to sell or it is more likely than not that it will be required to sell the impaired debt security, a charge is recognized against earnings for the entire unrealized loss. For all impaired debt securities for which there is no intent or expected requirement to sell, the evaluation considers all available evidence to assess whether it is more likely than not that all amounts due would not be collected according to the security's contractual terms and whether there is any impairment attributable to credit-related factors. If an impairment exists, the amount attributed to credit-related factors is measured and an allowance for credit loss is recognized. Declines in fair value that are not recorded in the allowance are recorded in other comprehensive income, net of taxes. BOK Financial may elect to carry certain securities that are not held for trading purposes at fair value with changes in fair value recognized in current period income. These securities are held with the intent that gains or losses will offset changes in the fair value of mortgage servicing rights or other financial instruments. Restricted equity securities represent equity interests the Company is required to hold in the Federal Reserve Banks and Federal Home Loan Banks. Restricted equity securities are carried at cost as these securities do not have a readily determined fair value because ownership of these shares is restricted and they lack a market. The fair value of our securities portfolio is generally based on a single price for each financial instrument provided to us by a third-party pricing service determined by one or more of the following: •Quoted prices for similar, but not identical, assets or liabilities in active markets; •Quoted prices for identical or similar assets or liabilities in inactive markets; •Inputs other than quoted prices that are observable, such as interest rate and yield curves, volatilities, prepayment speeds, loss severities, credit risks and default rates; and •Other inputs derived from or corroborated by observable market inputs. The underlying methods used by the third-party pricing services are considered in determining the primary inputs used to determine fair values. We evaluate the methodologies employed by the third-party pricing services by comparing the price provided by the pricing service with other sources, including brokers' quotes, sales or purchases of similar instruments and discounted cash flows to establish a basis for reliance on the pricing service values. Significant differences between the pricing service provided value and other sources are discussed with the pricing service to understand the basis for their values. Based on all observable inputs, management may adjust prices obtained from third-party pricing services to more appropriately reflect the prices that would be received to sell assets or paid to transfer liabilities in orderly transactions in the current market. Derivative Instruments Derivative instruments may be used by the Company as part of its internal risk management programs or may be offered to customers. All derivative instruments are carried at fair value and changes in fair value are generally reported in income as they occur. The determination of fair value of derivative instruments considers changes in interest rates, commodity prices and foreign exchange rates. Fair values for exchange-traded contracts are based on quoted prices in an active market for identical instruments. Fair values for over-the-counter contracts are generated internally using third-party valuation models. Inputs used in third-party valuation models to determine fair values are considered significant other observable inputs. Credit risk is also considered in determining fair value. Deterioration in the credit rating of customers or other counterparties reduces the fair value of asset contracts. Deterioration of our credit rating could decrease the fair value of our derivative liabilities. When bilateral netting agreements or similar agreements exist between the Company and its counterparties that create a single legal claim or obligation to pay or receive the net amount in settlement of the individual derivative contracts, the Company reports derivative assets and liabilities on a net by derivative contract by counterparty basis. Derivative contracts may also require the Company to provide or receive cash margin as collateral for derivative assets and liabilities. Derivative assets and liabilities are reported net of cash margin when certain conditions are met. In addition, derivative contracts executed with customers under Customer Risk Management Programs may be secured by non-cash collateral in conjunction with a credit agreement with that customer. Access to collateral in the event of default is reasonably assured. BOK Financial offers programs that permit its customers to manage various risks, including fluctuations in energy, cattle and other agricultural products, interest rates and foreign exchange rates with derivative contracts. Customers may also manage interest rate risk through interest rate swaps used by the borrower to modify interest rate terms of their loans. Derivative contracts are executed between the customers and BOK Financial. Offsetting contracts are executed between BOK Financial and other selected counterparties to minimize market risk from changes in commodity prices, interest rates or foreign exchange rates. The counterparty contracts are identical to customer contracts, except for a fixed pricing spread or fee paid to BOK Financial as profit and compensation for administrative costs and credit risk which is recognized over the life of the contracts and included in Other Operating Revenue - Brokerage and trading revenue in the Consolidated Statements of Earnings. BOK Financial may offer derivative instruments such as to-be-announced U.S. agency residential mortgage-backed securities to mortgage banking customers to enable them to manage their market risk or to mitigate the Company's market risk of holding trading securities. Changes in the fair value of derivative instruments for trading purposes or used to mitigate the market risk of holding trading securities are included in Other Operating Revenue - Brokerage and trading revenue. BOK Financial may use derivative instruments in managing its interest rate sensitivity, as part of its economic hedge of the changes in the fair value of mortgage servicing rights. Changes in the fair value of derivative instruments used in managing interest rate sensitivity and as part of its economic hedge of changes in the fair value of mortgage servicing rights are included in Other Operating Revenue - Gain (loss) on derivatives, net in the Consolidated Statements of Earnings. BOK Financial also enters into mortgage loan commitments that are considered derivative contracts. Forward sales contracts that have not been designated as hedging instruments are used to economically hedge these mortgage loan commitments as well as mortgage loans held for sale. Mortgage loan commitments, forward sales contracts, and residential mortgage loans held for sale are carried at fair value. Changes in the fair value are reported in Other Operating Revenue - Mortgage banking revenue. Loans Loans are either secured or unsecured based on the type of loan and the financial condition of the borrower. Repayment is generally expected from cash flow or proceeds from the sale of selected assets of the borrower. BOK Financial is exposed to risk of loss on loans due to the borrower's financial difficulties, which may arise from any number of factors, including problems within the respective industry or local economic conditions. Access to collateral, in the event of borrower default, is reasonably assured through adherence to applicable lending laws and through sound lending standards and credit review procedures. Accounting policies for all loans, excluding residential mortgage loans guaranteed by U.S. government agencies, are as follows. Interest is accrued at the applicable interest rate on the outstanding principal amount. Loans are placed on nonaccruing status when, in the opinion of management, full collection of principal or interest is uncertain. Internally risk graded loans are individually evaluated for nonaccruing status quarterly. Non-risk graded loans are generally placed on nonaccruing status when 90 days or more past due or within 60 days of being notified of the borrower's bankruptcy filing. Interest previously accrued but not collected is charged against interest income when the loan is placed on nonaccruing status. Payments received on nonaccruing loans are applied to principal or recognized as interest income, according to management's judgment as to the collectability of principal. Loans may be returned to accruing status when, in the opinion of management, full collection of principal and interest, including principal previously charged off, is probable based on improvements in the borrower's financial condition or a sustained period of performance. For loans acquired with no evidence of credit deterioration, discounts are accreted on either an individual basis for loans with unique characteristics or on a pool basis for groups of homogeneous loans. Accretion is discontinued when a loan with an individually attributed discount is placed on nonaccruing status. Loans to borrowers experiencing financial difficulties may be modified in troubled debt restructurings ("TDRs"). TDRs are generally classified as nonaccruing, excluding loans guaranteed by U.S. government agencies. Modifications generally consist of extension of payment terms or interest rate concessions and may result either voluntarily through negotiations with the borrower or involuntarily through court order. Payment deferrals of up to six months are generally considered to be short-term modifications. Generally, principal and accrued but unpaid interest is not voluntarily forgiven. Performing loans may be renewed under the then current collateral, debt service ratio and other underwriting standards. Nonaccruing loans may also be renewed and will remain classified as nonaccruing. Occasionally, loans, other than residential mortgage loans, may be held for sale in order to manage credit concentration. These loans are carried at the lower of cost or fair value with gains or losses recognized in gain (loss) on assets. All loans are charged-off when the loan balance or a portion of the loan balance is no longer supported by the paying capacity of the borrower or when the required cash flow is reduced in a TDR. The charge-off amount is determined through an evaluation of available cash resources and collateral value. Internally risk graded loans are evaluated quarterly and charge-offs are taken in the quarter in which the loss is identified. Non-risk graded loans that are past due between 60 days and 180 days, based on the loan product type, are charged off. Loans to borrowers whose personal obligation has been discharged through Chapter 7 bankruptcy proceedings are charged off within 60 days of notice of the bankruptcy filing, regardless of payment status. Loan origination and commitment fees and direct loan acquisition and origination costs are deferred and amortized as an adjustment to yield over the life of the loan or over the commitment period, as applicable. Amortization does not anticipate loan prepayments. Net unamortized fees are recognized in full at time of payoff. Qualifying residential mortgage loans guaranteed by U.S. government agencies have been sold into GNMA pools. Under certain performance conditions specified in government programs, the Company has the right, but not the obligation to repurchase loans from GNMA pools. These loans no longer qualify for sale accounting and are recognized in the Consolidated Balance Sheets. Guaranteed loans are considered to be impaired because we do not expect to receive all principal and interest based on the loan's contractual terms. A portion of the principal balance continues to be guaranteed; however, interest accrues at a curtailed rate as specified in the programs. The carrying value of these loans is reduced based on an estimate of expected cash flows discounted at the original note rate plus a liquidity spread. Guaranteed loans may be modified in TDRs in accordance with U.S. government agency guidelines. Interest continues to accrue at the modified rate. Guaranteed loans may either be resold into GNMA pools after a performance period specified by the programs or foreclosed and conveyed to the guarantors. Loans are disaggregated into portfolio segments and further disaggregated into classes. The portfolio segment is the level at which the Company develops and documents a systematic method for determining its Allowance for Credit Losses. Classes are based on the risk characteristics of the loans and the Company's method for monitoring and assessing credit risk. Allowances for Credit Losses and Accrual for Off-balance Sheet Credit Risk from Unfunded Loans Commitments BOK Financial’s accounting policies have changed significantly with the adoption of CECL as of January 1, 2020. Prior periods are not restated. Prior to January 1, 2020, general allowances and nonspecific allowances were based on incurred credit losses in accordance with accounting policies disclosed in Note 1 of the Consolidated Financial Statements included in the 2019 Form 10-K. The allowance for loan losses and accrual for off-balance sheet credit risk from unfunded loan commitments represent the portion of the amortized cost basis of loans that we do not expect to collect over the asset’s contractual life, considering past events, current conditions, and reasonable and supportable forecasts of future economic conditions. The appropriateness of the allowance for credit losses, including industry and product adjustments, is assessed quarterly by a senior management Allowance Committee. This review is based on an on-going evaluation of the estimated expected credit losses in the portfolio and on unused commitments to provide financing. A well-documented methodology has been developed and is applied by an independent Credit Administration department to assure consistency across the Company. The allowance for loan losses consists of specific allowances attributed to certain individual loans, generally nonaccruing loans, with dissimilar risk characteristics that have not yet been charged down to amounts we expect to recover and general allowances for estimated credit losses on pools of loans that share similar risk characteristics. When full collection of principal or interest is uncertain, the loan’s risk characteristics have changed, and we exclude the loan from the general allowance pool, typically designating it as nonaccruing. For these loans, a specific allowance reflects the expected credit loss. We measure specific allowances for loans excluded from the general allowance pool by an evaluation of estimated future cash flows discounted at the loans initial effective interest rate or the fair value of collateral for certain collateral dependent loans. For a non-collateral dependent loan, the specific allowance is the amount by which the loan’s amortized cost basis exceeds its net realizable value. We measure the specific allowance for collateral dependent loans as the amount by which the loan’s amortized cost basis exceeds its fair value. When repayment is expected to be provided substantially through the sale of collateral, we deduct estimated selling costs from the collateral’s fair value. Generally, third party appraisals that conform to Uniform Standards of Professional Appraisal Practice serve as the basis for the fair value of real property held as collateral. These appraised values are on an “as-is” basis and generally are not adjusted by the Company. We obtain updated appraisals at least annually or more frequently if market conditions indicate collateral values may have declined. For energy loans, our internal staff of engineers generally determines collateral value of mineral rights based on projected cash flows from proven oil and gas reserves under existing economic and operating conditions. For real property held as collateral for other loans, third party appraisals that conform to Uniform Standards of Professional Appraisal Practice generally serve as the basis for the fair value. These appraised values are on an “as-is” basis and generally are not adjusted by the Company. We obtain updated appraisals at least annually or more frequently if market conditions indicate collateral values may have declined. Our special assets staff generally determines the value of other collateral based on projected liquidation cash flows under current market conditions. We evaluate collateral values and available cash resources quarterly. Historical statistics may be used to estimate specific allowances in limited situations, such as when a collateral dependent loan is removed from the general allowance pool near the end of a reporting period until an appraisal of collateral value is received or a full assessment of future cash flows is completed. General allowances estimate expected credit losses on pools of loans sharing similar risk characteristics that are expected to occur over the loan’s estimated remaining life. The loan’s estimated remaining life represents the contractual term adjusted for amortization, estimates of prepayments, and borrower-owned extension options. Approximately 90 percent of the committed dollars in the loan portfolio is risk graded loans with general allowance model inputs that include probability of default, loss given default, and exposure at default. Probability of default is based on the migration of loans from performing to nonperforming using historical life of loan analysis periods. Loss given default is based on the aggregate losses incurred, net of estimated recoveries. Exposure at default represents an estimate of the outstanding amount of credit exposure at the time a default may occur. Charge-off migration is used to calculate the general allowance for the majority of non-risk graded loans to individuals. The expected credit loss on less than 10 percent of the committed dollars in the portfolio is calculated using charge-off migration. The expected credit loss on approximately 1 percent of the committed dollars in the portfolio is calculated using a non-modeled approach. Specifically, the calculation applies a long-term net charge-off rate to the loan balances, adjusted for the weighted average remaining maturity of each portfolio. In estimating the expected credit losses for general allowances on performing risk-graded loans, each portfolio class is assigned relevant economic loss drivers which best explain variations in portfolio net loss rates. The probability of default estimates for each portfolio class are adjusted for current and forecasted economic conditions. The result is applied to the exposure at default and loss given default to calculate the lifetime expected credit loss estimate. Selection of relevant economic loss drivers is re-evaluated periodically and involves statistical analysis as well as management judgment. The unemployment rate factors significantly in the allowance for loan losses calculation, affecting commercial and loans to individuals segments. Other primary factors impacting the commercial portfolio include BBB corporate spreads, real gross domestic product growth rate, and energy commodity prices. The primary commercial real estate variables are vacancy rate and BBB corporate spreads. In addition to the unemployment rate, the forecast for loans to individuals is tied to home price index. The forecasts may include regional economic factors when localized conditions diverge from national conditions. An Economic Forecast Committee, consisting of senior management with members largely independent of the allowance process develops a twelve-month forward-looking forecast for the relevant economic loss drivers. Management develops these forecasts based on external data as well as a view of future economic conditions, which may include adjustments for regional conditions. The forecast includes three economic scenarios and probability weights for each scenario. The base forecast represents management's view of the most likely outcome, while the downside forecast reflects reasonably possible worsening economic conditions, and the upside forecast projects reasonably possible improving conditions. At the end of the one-year reasonable and supportable forecast period, we transition from shorter-term expected losses to long-term loss averages for the loan’s estimated remaining life. The difference between short-term loss forecasts and long-term loss averages is run-off over the reversion horizon, up to three years, depending on the forecasted economic scenarios. General allowances also consider the estimated impact of factors that are not captured in the modeled results or historical experience. These factors may increase or decrease modeled results by amounts determined by the Allowance Committee. Factors not captured in modeled results or historical experience may include for example, new lines of business, market conditions that have not been previously encountered, observed changes in credit risk that are not yet reflected in macro-economic factors, or economic conditions that impact loss given default assumptions. The accrual for off-balance sheet credit risk is maintained at a level that is appropriate to cover estimated losses associated with credit instruments that are not currently recognized as assets such as loan commitments, standby letters of credit or guarantees that are not unconditionally cancellable by the bank. This accrual is included in other liabilities in the Consolidated Balance Sheets. The appropriateness of the accrual is determined in the same manner as the allowance for loan losses, with the added consideration of commitment usage over the remaining life for those loans that the bank can not unconditionally cancel. A provision for credit losses is charged against or credited to earnings in amounts necessary to maintain an appropriate Allowance for Credit Losses. Recoveries of loans previously charged off are added to the allowance when received. Real Estate and Other Repossessed Assets Real estate and other repossessed assets are acquired in partial or total forgiveness of loans. These assets are initially recognized at cost, which is determined by fair value at date of foreclosure less estimated disposal costs. They are subsequently carried at the lower of cost or current fair value less estimated disposal costs. Decreases in fair value below cost are recognized as asset-specific valuation allowances which may be reversed when supported by future increases in fair value. Subsequent increases in fair value may be used to reduce the allowance but not below zero. Fair values of real estate are based on “as is” appraisals which are updated at least annually or more frequently for certain asset types or assets located in certain distressed markets. Fair values based on appraisals are generally considered to be based on significant other observable inputs. The Company also considers decreases in listing price and other relevant information in quarterly evaluations and reduces the carrying value of real estate and other repossessed assets when necessary. Fair values based on list prices and other relevant information are generally considered to be based on significant unobservable inputs. Additional costs incurred to complete real estate and other repossessed assets may increase the carrying value, up to current fair value based on “as completed” appraisals. The fair value of mineral rights included in repossessed assets is generally determined by our internal staff of engineers based on projected cash flows from proven oil and gas reserves under existing economic and operating conditions. The value of other repossessed assets is generally determined by our special assets staff based on projected liquidation cash flows under current market conditions. Income generated by these assets is recognized as received. Operating expenses are recognized as incurred. Gains or losses on sales of real estate and other repossessed assets are based on the cash proceeds received less the cost basis of the asset, net of any valuation allowances. The estimated disposal costs of real estate and other repossessed assets are evaluated by the Company on an annual basis based on actual results. Transfers of Financial Assets BOK Financial regularly transfers financial assets as part of its mortgage banking activities and periodically may transfer other financial assets. Transfers are recorded as sales when the criteria for surrender of control are met. The Company has elected to carry certain residential mortgage loans held for sale at fair value under the fair value option. Changes in fair value are recognized in net income as they occur. These loans are reported separately in the Consolidated Balance Sheets and changes in fair value are recorded in Other Operating Revenue - Mortgage banking revenue in the Consolidated Statements of Earnings. Fair value of conforming residential mortgage loans that will be sold to U.S. government agencies is based on sales commitments or market quotes considered Level 2 inputs. Fair value of mortgage loans that are unable to be sold to U.S. government agencies is based on Level 3 inputs using quoted prices of loans that are sold in securitization transactions with a liquidity discount applied. The fair value is corroborated with an independent third party on at least an annual basis. BOK Financial retains a repurchase obligation under underwriting representations and warranties related to residential mortgage loans transferred and generally retains the right to service the loans. These are not credit obligations. The Company may incur a recourse obligation in limited circumstances. Separate accruals are recognized in Other liabilities in the Consolidated Balance Sheets for repurchase and recourse obligations. These reserves reflect the estimated amount of probable loss the Company will incur as a result of repurchasing a loan, indemnifications, and other settlement resolutions. Repurchases of loans with an origination defect that are also credit impaired are considered collateral dependent and are initially recognized at net realizable value (appraised value less the cost to sell). The difference between unpaid principal balance and net realizable value is not accreted. Repurchases of loans with an origination defect that are not credit impaired are carried at fair value as of the repurchase date. Interest income continues to accrue on these loans and the discount is accreted over the estimated life of the loan. The Company may also choose to purchase GNMA loans once certain mandated delinquency criteria are met. The loans that are eligible and are chosen to be repurchased are initially recognized at fair value based on expected cash flows discounted using the average agency guaranteed debenture rates, average actual principal loss rates and liquidity premium. Mortgage Servicing Rights Mortgage servicing rights may be purchased or may be recognized when mortgage loans are originated and sold with servicing rights retained. All mortgage servicing rights are carried at fair value. Changes in the fair value are recognized in earnings as they occur. Mortgage servicing rights are not traded in active markets. A cash flow model is used to determine fair value. Key assumptions and estimates, including projected prepayment speeds and assumed servicing costs, earnings on escrow deposits, ancillary income and discount rates, used by this model are based on current market sources. Assumptions used to value mortgage servicing rights are considered significant unobservable inputs. A separate third-party model is used to estimate prepayment speeds based on interest rates, housing turnover rates, estimated loan curtailment, anticipated defaults and other relevant factors. The prepayment model is updated daily for changes in market conditions and adjusted to better correlate with actual performance of BOK Financial's servicing portfolio. Fair value estimates from outside sources are received at least annually to corroborate the results of the valuation model. Premises and Equipment Premises and equipment are carried at cost, including capitalized interest when appropriate, less accumulated depreciation and amortization. Depreciation and amortization are computed on a straight-line basis over the estimated useful lives of the assets or, for leasehold improvements, over the shorter of the estimated useful lives or remaining lease terms. Useful lives range from 5 years to 40 years for buildings and improvements, 3 years to 10 years for software and related implementation costs, and 3 years to 10 years for furniture and equipment. Construction in progress represents facilities construction and data processing systems projects underway that have not yet been placed into service. Depreciation and amortization begin once the assets are placed into service. Repair and maintenance costs, including software maintenance and enhancement costs, are charged to expense as incurred. Software licensing costs are generally charged to expense as incurred. Software licensing costs are capitalized if the contractual right to take possession of the software exists and it is feasible to take possession without significant penalty. Capitalized costs are amortized over the shorter of the estimated useful life of the software or remaining contractual life of the license. Premises no longer used by the Company are transferred to real estate and other repossessed assets. The transferred amount is the lower of cost less accumulated depreciation or fair value less estimated disposal costs as of the transfer date. Premises and equipment includes rights to use leased facilities and equipment. Right of use assets are initially measured by the present value of future rent payments over lease terms, adjusted for rent concessions. Rent payments exclude both payments made for non-lease components such as services and variable lease payments other than payments dependent on an index at lease commencement. Lease term includes options reasonably certain to be exercised. The right of use assets and lease liabilities are amortized to achieve straight-line expense over the lease term. Upon lease modification, the right of use asset and liability are reassessed and remeasured. Right of use assets are evaluated for impairment when facts and circumstances change that indicate an impairment may be necessary. Leases less than twelve months are excluded from capitalization. Ongoing technology projects of significant size or length are reviewed at least annually for impairment. Accumulated costs are reviewed for projects or components of projects that do not support the value of the asset being developed. Findings of obsolescence, duplicate effort or other conditions that do not support the recorded value are impaired, with the cost of the impaired components being charged to current-year earnings. Federal and State Income Taxes BOK Financial and its subsidiaries file consolidated tax returns. The subsidiaries provide for income taxes on a separate return basis and remit to BOK Financial amounts determined to be currently payable. BOK Financial is an agent for its subsidiaries under the Company's tax sharing agreements and has no ownership rights to any refunds received for the benefit of its subsidiaries. Current income tax expense or benefit is based on an evaluation that considers estimated taxable income, tax credits, and statutory federal and state income tax rates. The amount of current income tax expense or benefit recognized in any period may differ from amounts reported to taxing authorities. Annually, tax returns are filed with each jurisdiction where the Company conducts business and recognized current income tax expense or benefit is adjusted to the filed tax returns. Deferred tax assets and liabilities are based upon the temporary differences between the values of assets and liabilities as recognized in the financial statements and their related tax basis using enacted tax rates in effect for the year in which the differences are expected to be recovered or settled. The effect of changes in statutory tax rates on the measurement of deferred tax assets and liabilities is recognized through income tax expense in the period the change is enacted. A valuation allowance is provided when it is more likely than not that some portion of the entire deferred tax asset may not be realized. BOK Financial has unrecognized tax benefits, which are included in accrued current income taxes payable, for the uncertain portion of recorded tax benefits and related interest. These uncertainties result from the application of complex tax laws, rules, regulations and interpretations, primarily in state taxing jurisdictions. Unrecognized tax benefits are assessed quarterly and may be adjusted through current income tax expense in future periods based on changing facts and circumstances, completion of examinations by taxing authorities or expiration of a statute of limitations. Estimated penalties and interest on uncertain tax positions are recognized in income tax expense. Employee Benefit Plans BOK Financial sponsors a defined contribution plan (“Thrift Plan”) and a defined benefit cash balance pension plan (“Pension Plan”). Employer contributions to the Thrift Plan, which matches employee contributions subject to percentage and years of service limits, are expensed when incurred. Pension Plan costs, which are based upon actuarial computations of current costs, are expensed annually. Pension Plan benefits were curtailed as of April 1, 2006. No participants may be added to the Pension Plan and no additional service benefits will be accrued. BOK Financial recognizes the funded status of its employee benefit plans. Adjustments required to recognize the Pension Plan's net funded status are made through accumulated other comprehensive income, net of deferred income taxes. Share-Based Compensation Plans BOK Financial awards non-vested common shares and stock options as compensation to certain officers. The grant date fair value of non-vested shares is based on the then-current market value of BOK Financial common stock. Non-vested shares generally cliff vest in 3 years and are subject to a holding period after vesting of 2 years. The grant date fair value of stock options is based on the Black-Scholes option pricing model. Stock options generally have graded vesting over 7 years. Each tranche is considered a separate award for valuation and compensation cost recognition. Compensation cost is initially based on the grant date fair value of the award and recognized as expense over the service period, which is generally the vesting period. Expense is reduced for estimated forfeitures over the vesting period and adjusted for actual forfeitures as they occur. Share-based compensation awarded to certain officers has performance conditions that affect the number of awards granted. Compensation cost is adjusted based on the probable outcome of the performance conditions. Restricted stock units ("RSUs") may also be awarded for certain executives who have elected to defer income recognition upon vesting of their awards. RSUs are subject to the same vesting criteria as non-vested shares. The value of the awards will vary in amounts equal to changes in the fair value of an equal number of BOK Financial common shares. Tax effects of share-based payments are recognized through tax expense. Dividends on non-vested shares are charged to retained earnings. Dividend equivalents on RSUs are charged to expense. Other Operating Revenue Fees and commissions revenue is generated through the sales of products, consisting primarily of financial instruments, and the performance of services for customers under contractual obligations. Revenue from providing services for customers is recognized at the time services are provided in an amount that reflects the consideration we expect to be entitled to for those services. Revenue is recognized based on the application of five steps: •Identify the contract with a customer •Identify the performance obligations in the contract •Determine the transaction price •Allocate the transaction price to the performance obligations in the contract •Recognize revenue when (or as) the Company satisfies a performance obligation For contracts with multiple performance obligations, individual performance obligations are accounted for separately if the customer can benefit from the good or service on its own or with other resources readily available to the customer and the promise to transfer goods and services to the customer is separately identifiable in the contract. The transaction price is allocated to the performance obligations based on relative standalone selling prices. Revenue is recognized on a gross basis whenever we have primary responsibility and risk in providing the services or products to our customers and have discretion in establishing the price for the services or products. Revenue is recognized on a net basis whenever we act as an agent for products or services of others. Brokerage and trading revenue includes revenues from trading, customer hedging, retail brokerage, investment banking and insurance brokerage. Trading revenue includes net realized and unrealized gains primarily related to sales of securities to institutional customers and related derivative contracts. Customer hedging revenue includes realized and unrealized changes in the fair value of derivative contracts held for customer risk management programs including credit valuation adjustments, as necessary. We offer commodity, interest rate, foreign exchange and equity derivatives to our customers. These customer contracts are offset with contracts with selected counterparties and exchanges to minimize changes in market risk from changes in commodity prices, interest rates or foreign exchange rates. Retail brokerage revenue represents fees and commissions earned on sales of fixed income securities, annuities, mutual funds and other financial instruments to retail customers. Investment banking revenue includes fees earned upon completion of underwriting and financial advisory services. Investment banking revenue also includes fees earned in conjunction with loan syndications. Insurance brokerage revenues represent fees and commissions earned on placement of insurance products with carriers for property and casualty and health coverage. Transaction card revenue includes merchant discount fees and electronic funds transfer network fees, net of interchange fees paid to card issuers and assessments paid to card networks. Merchant discount fees represent fees paid by customers for account management and electronic processing of card transactions. Merchant discount fees are recognized at the time the customer’s transactions are processed or other services are performed. The Company also maintains the TransFund electronic funds transfer network for the benefit of its members, which includes BOKF, NA. Electronic funds transfer fees are recognized as electronic transactions are processed on behalf of its members. Fiduciary and asset management revenue includes fees from asset management, custody, recordkeeping, investment advisory and administration services. Revenue is recognized on an accrual basis at the time the services are performed and may be based on either the fair value of the account or the service provided. Deposit service charges and fees include commercial account service charges, overdraft fees, check card fee revenue and automated service charge and other deposit service fees. Fees are recognized at least quarterly in accordance with published deposit account agreements and disclosure statements for retail accounts or contractual agreements for commercial accounts. Item charges for overdraft or non-sufficient funds items are recognized as items are presented for payment. Account balance charges and activity fees are accrued monthly and collected in arrears. Commercial account activity fees may be offset by an earnings credit based on account balances. Check card fees represent interchange fees paid by a merchant bank for transactions processed from cards issued by the Company. Check card fees are recognized when transactions are processed. Mortgage banking revenue includes revenues recognized in conjunction with the origination, marketing and servicing of conventional and government-sponsored residential mortgage loans. Mortgage production revenue includes net realized gains (losses) on sales of residential mortgage loans in the secondary market and the net change in unrealized gains (losses) on residential mortgage loans held for sale. Mortgage production revenue also includes changes in the fair value of derivative contracts not designated as hedging instruments related to residential mortgage loan commitments and forward sales contracts. Mortgage servicing revenue includes servicing fee income and late charges on loans serviced for others. Newly Adopted and Pending Accounting Pronouncements The following is a summary of newly adopted and pending accounting pronouncements that may have a more than insignificant effect on the Company's financial statements. Financial Accounting Standards Board ("FASB") FASB Accounting Standards Update No. 2016-02, Leases (Topic 842) ("ASU 2016-02") On February 25, 2016, the FASB issued ASU 2016-02 to increase transparency and comparability by recognizing lease assets and liabilities on the balance sheet and disclosing key information about leasing arrangements. The Company adopted the new standard January 1, 2019 through a cumulative effect adjustment to retained earnings. The implementation of ASU 2016-02 increased the reported right-of-use asset and lease liability by $137 million. The effect on retained earnings was immaterial. FASB Accounting Standards Update No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Assets Measured at Amortized Cost ("ASU 2016-13") On June 16, 2016, the FASB issued ASU 2016-13 to provide more timely recording of credit losses on loans and other financial assets measured at amortized cost. The Company adopted the new standard January 1, 2020, through a cumulative effect adjustment to retained earnings. Prior periods were not restated. Under ASU 2016-13, acquired loans must be reserved in a manner consistent with originated loans while the incurred loss model excluded purchased loans because the loans had been marked to fair value at acquisition. Under ASU 2016-13, the fair value discount will remain in place and be accreted into interest income over the life of any acquired loans in the portfolio. Another transition adjustment component is related to expected credit losses for residential mortgage loans sold that exceed amounts guaranteed by the U.S. Department of Veterans Affairs as we retain the credit risk for any amounts exceeding the guarantee as well as for recourse loans. Prior to ASU 2016-13, held-to-maturity non-agency securities carried no reserve for credit losses. Note 4 disaggregates the transition adjustment for loans and unfunded loan commitments among portfolio segments as well as on-and off-balance sheet reserves. FASB Accounting Standards Update No. 2019-04, Codification Improvements to Topic 326, Financial Instruments-Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments ("ASU 2019-04") On April 25, 2019, the FASB issued ASU 2019-04 which clarifies certain aspects of the accounting for credit losses, hedging activities, and financial instruments addressed by ASUs 2016-13, 2017-12, and 2016-01, respectively. Significant amendments made to the provisions of ASU 2016-13 by ASU 2019-04 include providing certain alternatives for the measurement of the allowance for credit losses on accrued interest receivable and clarifying steps entities should take when recording the transfer of loans or debt securities between measurement classification or categories. ASU 2019-04 further clarifies the expectation that entities include recoveries of financial assets in the calculation of the current expected credit losses allowance for both pools of financial assets and individual financial assets. Significant amendments made to the provisions of ASU 2017-12 by ASU 2019-04 include clarification on partial-term fair value hedges of interest rate risk, amortization of fair value hedge basis adjustments and disclosure of fair value hedge basis adjustments. Significant amendments made to provisions of ASU 2016-01 include clarification of the measurement alternative practice for equity securities and remeasurement of equity securities at historical exchange rates. ASU 2019-04 includes other amendments which clarify various provisions within the codification. The Company adopted ASU 2019-04 in the first quarter of 2020. Adoption of ASU 2019-04 did not have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2019-05, Financial Instruments-Credit Losses (Topic 326): Targeted Transition Relief ("ASU 2019-05") On May 15, 2019, the FASB issued ASU 2019-05 which provides transition relief for entities adopting the Board's credit losses standard, ASU 2016-13. ASU 2019-05 amends ASU 2016-13 to allow companies to irrevocably elect, upon adoption of ASU 2016-13, the fair value option for financial instruments that meet specific requirements and is effective for the Company for annual reporting periods beginning after December 15, 2019. The Company did not elect the fair value option for additional financial instruments. FASB Accounting Standards Update No. 2019-11, Codification Improvements to Topic 326: Financial Instruments-Credit Losses ("ASU 2019-11") On November 27, 2019, the FASB issued ASU 2019-11 which revises certain aspects of new guidance on credit losses. Topics addressed include purchased credit-deteriorated assets, transition relief for troubled debt restructurings, disclosure relief for accrued interest receivable, and financial assets secured by collateral maintenance provisions. ASU 2019-11 is effective for the Company for annual reporting periods beginning after December 15, 2019. The Company adopted ASU 2019-11 in the first quarter of 2020. Adoption of ASU 2019-11 did not have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ("ASU 2019-12") On December 18, 2019, the FASB issued ASU 2019-12 which simplifies the accounting for income taxes by eliminating certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The ASU also simplifies aspects of accounting for franchise taxes and enacted changes in tax laws or rates and clarifies accounting for transactions that result in a step-up in the tax basis of goodwill. ASU 2019-12 is effective for the Company for annual reporting periods beginning after December 15, 2020, and interim periods within; however, early adoption is permitted. The Company adopted ASU 2019-12 in the first quarter of 2020. Adoption of ASU 2019-12 did not have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting ("ASU 2020-04") On March 12, 2020, the FASB issued ASU 2020-04 which provides optional expedients and exceptions for applying U.S. GAAP to contract modifications and hedging relationships that reference LIBOR or another reference rate expected to be discontinued, subject to meeting certain criteria. Under the new guidance, an entity can elect by accounting topic or industry subtopic to account for the modification of a contract affected by reference rate reform as a continuation of the existing contract, if certain conditions are met. In addition, the new guidance allows an entity to elect on a hedge-by-hedge basis to continue to apply hedge accounting for hedging relationships in which the critical terms change due to reference rate reform, if certain conditions are met. A one-time election to sell and/or transfer held-to-maturity debt securities that reference a rate affected by reference rate reform is also allowed. ASU 2020-04 became effective for all entities as of March 12, 2020 and will apply to all LIBOR reference rate modifications through December 31, 2022. Management is currently evaluating the impact of ASU 2020-04 on the Company's financial statements. FASB Accounting Standards Update No. 2021-01, Reference Rate Reform (Topic 848): Scope ("ASU 2021-01") On January 7, 2021, the FASB issued ASU 2021-01 which clarifies that certain optional expedients and exceptions in Topic 848 for contract modifications and hedge accounting apply to derivatives that are affected by the discounting transition. The amendments in this update are elective and apply to all entities that have derivative instruments that use an interest rate for margining, discounting, or contract price alignment that is modified as a result of reference rate reform. The amendments also optionally apply to all entities that designate receive-variable rate, pay-variable-rate cross-currency interest rate swaps as hedging instruments in net investment hedges that are modified as a result of reference rate reform. ASU 2021-01 is effective immediately for all entities and amendments may be applied on a full retrospective basis as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020. Management is currently evaluating the impact of ASU 2021-01 on the Company's financial statements.

Securities

12 Months Ended

Dec. 31, 2020

Marketable Securities [Abstract]

Securities [Text Block]

Securities

Trading Securities

The fair value and net unrealized gain (loss) included in trading securities is as follows (in thousands):


	December 31, 2020				December 31, 2019
	Fair Value		Net Unrealized Gain (Loss)		Fair Value		Net Unrealized Gain (Loss)
U.S. government securities	$	9,183	$	—	$	44,264	$	6
Residential agency mortgage-backed securities	4,669,148		(3,624)		1,504,651		2,293
Municipal securities	19,172		42		26,196		60
Asset-backed securities	—		—		14,084		(21)
Other debt securities	10,472		22		34,726		21
Total trading securities	$	4,707,975	$	(3,560)	$	1,623,921	$	2,359

Investment Securities

The amortized cost and fair values of investment securities are as follows (in thousands):


	December 31, 2020
	Amortized		Fair		Gross Unrealized
	Cost		Value		Gain		Loss
Municipal securities	$	229,245	$	255,270	$	26,169	$	(144)
Residential agency mortgage-backed securities	8,913		9,790		877		—
Other debt securities	7,373		7,371		—		(2)
Total investment securities	$	245,531	$	272,431	$	27,046	$	(146)
Allowance for credit losses1	(688)
Investment securities, net of allowance	$	244,843	$	272,431	$	27,046	$	(146)

1 Effective with the adoption of FASB ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326) on January 1, 2020.


	December 31, 2019
	Amortized		Fair		Gross Unrealized
	Cost		Value		Gain		Loss
Municipal securities	$	274,535	$	295,032	$	20,797	$	(300)
Residential agency mortgage-backed securities	10,676		11,164		488		—
Other debt securities	8,207		8,206		—		(1)
Total investment securities	$	293,418	$	314,402	$	21,285	$	(301)

The amortized cost and fair values of investment securities at December 31, 2020, by contractual maturity, are as shown in the following table (dollars in thousands):


	Less than One Year		One to Five Years		Six to Ten Years		Over Ten Years		Total		Weighted Average Maturity1
Fixed maturity debt securities:
Amortized cost	$	31,029	$	76,646	$	119,966	$	8,977	$	236,618	4.90
Fair value	31,459		83,944		138,101		9,137		262,641

Residential mortgage-backed securities:
Amortized cost									$	8,913	2
Fair value									9,790

Total investment securities:
Amortized cost									$	245,531
Fair value									272,431

1Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty.

2The average expected lives of residential mortgage-backed securities were 4.0 years based upon current prepayment assumptions.

Temporarily Impaired Investment Securities

(in thousands):


	December 31, 2020
	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investment:
Municipal securities	6	$	2,451	$	40	$	2,043	$	104	$	4,494	$	144

Other debt securities	2	$	250	$	1	$	25	$	1	$	275	$	2
Total investment securities	8	$	2,701	$	41	$	2,068	$	105	$	4,769	$	146


	December 31, 2019
	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investment:
Municipal securities	15	$	1,001	$	1	$	9,747	$	299	$	10,748	$	300

Other debt securities	2	275		1		—		—		275		1
Total investment securities	17	$	1,276	$	2	$	9,747	$	299	$	11,023	$	301

Available for Sale Securities

The amortized cost and fair value of available for sale securities are as follows (in thousands):


	December 31, 2020
	Amortized		Fair		Gross Unrealized
	Cost		Value		Gain		Loss
U.S. Treasury	$	500	$	508	$	8	$	—
Municipal securities	165,318		167,979		2,666		(5)
Mortgage-backed securities:
Residential agency	9,019,013		9,340,471		328,183		(6,725)
Residential non-agency	17,563		32,770		15,207		—
Commercial agency	3,406,956		3,508,465		103,590		(2,081)
Other debt securities	500		472		—		(28)
Total available for sale securities	$	12,609,850	$	13,050,665	$	449,654	$	(8,839)


	December 31, 2019
	Amortized		Fair		Gross Unrealized
	Cost		Value		Gain		Loss
U.S. Treasury	$	1,598	$	1,600	$	2	$	—
Municipal securities	1,789		1,861		72		—
Mortgage-backed securities:
Residential agency	7,956,297		8,046,096		104,912		(15,113)
Residential non-agency	25,968		41,609		15,641		—
Commercial agency	3,145,342		3,178,005		37,808		(5,145)
Other debt securities	500		472		—		(28)
Total available for sale securities	$	11,131,494	$	11,269,643	$	158,435	$	(20,286)

The amortized cost and fair values of available for sale securities at December 31, 2020, by contractual maturity, are as shown in the following table (dollars in thousands):


	Less than One Year		One to Five Years		Six to Ten Years		Over Ten Years		Total		Weighted Average Maturity1
Fixed maturity debt securities:
Amortized cost	$	78,673	$	1,413,405	$	1,472,918	$	608,278	$	3,573,274	7.79
Fair value	78,918		1,469,630		1,498,376		630,500		3,677,424
Residential mortgage-backed securities:
Amortized cost									$	9,036,576	2
Fair value									9,373,241
Total available-for-sale securities:
Amortized cost									$	12,609,850
Fair value									13,050,665

1Expected maturities may differ from contractual maturities, because borrowers may have the right to call or prepay obligations with or without penalty.

2The average expected lives of residential mortgage-backed securities were 3.0 years based upon current prepayment assumptions.

Sales of available for sale securities resulted in gains and losses as follows (in thousands):


	Year Ended December 31,
	2020		2019		2018
Proceeds	$	384,507	$	1,211,718	$	745,643
Gross realized gains	9,976		14,996		7,117
Gross realized losses	(66)		(9,399)		(9,918)
Related federal and state income tax expense (benefit)	2,524		1,425		(713)

The fair value of debt securities pledged as collateral for repurchase agreements, public trust funds on deposit and for other purposes, as required by law was $11.6 billion at December 31, 2020 and $10.1 billion at December 31, 2019.

The secured parties do not have the right to sell or re-pledge these securities.

Temporarily Impaired Available for Sale Securities

(In thousands)


	December 31, 2020
	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available for sale:

Municipal securities	1	6,166		5		—		—		6,166		5
Mortgage-backed securities:
Residential agency	38	$	786,890	$	6,605	$	160,747	$	120	$	947,637	$	6,725

Commercial agency	37	350,506		1,587		277,627		494		628,133		2,081
Other debt securities	1	—		—		472		28		472		28
Total available for sale securities	77	$	1,143,562	$	8,197	$	438,846	$	642	$	1,582,408	$	8,839


	December 31, 2019
	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available for sale:

Municipal securities	—	—		—		—		—		—		—
Mortgage-backed securities:
Residential agency	133	$	1,352,597	$	6,690	$	686,002	$	8,423	$	2,038,599	$	15,113

Commercial agency	69	830,047		4,238		210,877		907		1,040,924		5,145
Other debt securities	1	—		—		472		28		472		28
Total available for sale securities	203	$	2,182,644	$	10,928	$	897,351	$	9,358	$	3,079,995	$	20,286

No credit impairment of available for sale securities was recognized in 2020. Unrealized losses related to changes in interest rates subsequent to purchase and are not attributable to credit. Based on evaluations of impaired securities as of December 31, 2020, the Company does not intend to sell any impaired available for sale securities before fair value recovers to the current amortized cost and it is more-likely-than-not that the Company will not be required to sell impaired securities before fair value recovers, which may be maturity.

Fair Value Option Securities

Fair value option securities represent securities which the Company has elected to carry at fair value and are separately identified on the Consolidated Balance Sheets with changes in the fair value recognized in earnings as they occur. Certain residential mortgage-backed securities issued by U.S. government agencies and derivative contracts are held as an economic hedge of the mortgage servicing rights.

The fair value and net unrealized gain (loss) included in fair value option securities is as follows (in thousands):


	December 31, 2020				December 31, 2019
	Fair Value		Net Unrealized Gain (Loss)		Fair Value		Net Unrealized Gain (Loss)
U.S. Treasury	$	—	$	—	$	9,917	$	(48)
Residential agency mortgage-backed securities	114,982		4,463		1,088,660		14,109
Total	$	114,982	$	4,463	$	1,098,577	$	14,061

Derivatives

12 Months Ended

Dec. 31, 2020

Derivative Instrument Detail [Abstract]

Derivatives [Text Block]

Derivatives

The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at December 31, 2020 (in thousands):


	Assets
	Notional1		Gross Fair Value		Netting Adjustments		Net Fair Value Before Cash Collateral		Cash Collateral		Fair Value Net of Cash Collateral
Customer risk management programs:
Interest rate contracts	$	3,212,469	$	113,524	$	(144)	$	113,380	$	—	$	113,380
Energy contracts	3,791,565		386,008		(211,468)		174,540		—		174,540
Agricultural contracts	14,765		3,859		—		3,859		—		3,859
Foreign exchange contracts	337,001		332,257		—		332,257		(420)		331,837
Equity option contracts	70,199		1,222		—		1,222		(285)		937
Total customer risk management programs	7,425,999		836,870		(211,612)		625,258		(705)		624,553
Trading	84,997,593		440,627		(240,655)		199,972		(26,958)		173,014
Interest rate risk management programs	995,123		17,352		(4,231)		13,121		—		13,121
Total derivative contracts	$	93,418,715	$	1,294,849	$	(456,498)	$	838,351	$	(27,663)	$	810,688

	Liabilities
	Notional¹		Gross Fair Value		Netting Adjustments		Net Fair Value Before Cash Collateral		Cash Collateral		Fair Value Net of Cash Collateral
Customer risk management programs:
Interest rate contracts	$	3,212,469	$	113,900	$	(144)	$	113,756	$	(104,202)	$	9,554
Energy contracts	3,617,678		361,334		(211,468)		149,866		(114,070)		35,796
Agricultural contracts	14,781		3,844		—		3,844		(3,844)		—
Foreign exchange contracts	336,223		331,035		—		331,035		(1,165)		329,870
Equity option contracts	70,199		1,222		—		1,222		—		1,222
Total customer risk management programs	7,251,350		811,335		(211,612)		599,723		(223,281)		376,442
Trading	88,929,916		414,801		(240,655)		174,146		(145,692)		28,454
Interest rate risk management programs	145,256		5,529		(4,231)		1,298		(415)		883
Total derivative contracts	$	96,326,522	$	1,231,665	$	(456,498)	$	775,167	$	(369,388)	$	405,779

1 Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.

The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at December 31, 2019 (in thousands):


	Assets
	Notional1		Gross Fair Value		Netting Adjustments		Net Fair Value Before Cash Collateral		Cash Collateral		Fair Value Net of Cash Collateral
Customer risk management programs:
Interest rate contracts	$	2,464,478	$	49,100	$	(1,839)	$	47,261	$	—	$	47,261
Energy contracts	2,151,096		144,906		(107,591)		37,315		(38)		37,277
Agricultural contracts	16,118		1,522		(22)		1,500		—		1,500
Foreign exchange contracts	214,119		213,007		—		213,007		—		213,007
Equity option contracts	81,455		3,233		—		3,233		(660)		2,573
Total customer risk management programs	4,927,266		411,768		(109,452)		302,316		(698)		301,618
Trading	69,721,932		131,561		(115,949)		15,612		—		15,612
Internal risk management programs	1,268,180		6,226		(81)		6,145		—		6,145
Total derivative contracts	$	75,917,378	$	549,555	$	(225,482)	$	324,073	$	(698)	$	323,375

	Liabilities
	Notional¹		Gross Fair Value		Netting Adjustments		Net Fair Value Before Cash Collateral		Cash Collateral		Fair Value Net of Cash Collateral
Customer risk management programs:
Interest rate contracts	$	2,464,478	$	49,194	$	(1,839)	$	47,355	$	(43,932)	$	3,423
Energy contracts	2,105,391		139,311		(107,591)		31,720		(6,031)		25,689
Agricultural contracts	16,139		1,507		(22)		1,485		(1,485)		—
Foreign exchange contracts	207,919		207,020		—		207,020		—		207,020
Equity option contracts	81,455		3,233		—		3,233		—		3,233
Total customer risk management programs	4,875,382		400,265		(109,452)		290,813		(51,448)		239,365
Trading	65,144,388		125,535		(115,949)		9,586		—		9,586
Internal risk management programs	380,401		3,121		(81)		3,040		(863)		2,177
Total derivative contracts	$	70,400,171	$	528,921	$	(225,482)	$	303,439	$	(52,311)	$	251,128

1 Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.

The following summarizes the pre-tax net gains (losses) on derivative instruments and where they are recorded in the Consolidated Statements of Earnings (in thousands):


	Year Ended December 31,
	2020				2019				2018
	Brokerage and Trading Revenue		Gain (Loss) on Derivatives, Net		Brokerage and Trading Revenue		Gain (Loss) on Derivatives, Net		Brokerage and Trading Revenue		Gain (Loss) on Derivatives, Net
Customer risk management programs:
Interest rate contracts
To-be-announced U.S. agency residential mortgage-backed securities1	$	—	$	—	$	9,579	$	—	$	27,190	$	—
Interest rate swaps	4,507		—		3,647		—		2,614		—
Energy contracts	17,287		—		5,064		—		8,443		—
Agricultural contracts	34		—		28		—		53		—
Foreign exchange contracts	921		—		623		—		535		—
Equity option contracts	—		—		—		—		—		—
Total customer risk management programs	22,749		—		18,941		—		38,835		—
Trading2	8,255		—		13,999		—		(13,643)		—
Internal risk management programs	—		42,320		—		14,951		—		(442)
Total derivative contracts	$	31,004	$	42,320	$	32,940	$	14,951	$	25,192	$	(442)

1 To-be-announced U.S. agency residential mortgage-backed securities customer hedging program transitioned to trading program during 2019.

2 Includes changes in fair value of to-be-announced U.S. agency residential mortgage-backed securities and other derivative instruments offered to mortgage banking customers to manage their market risk or held to mitigate market risk of trading securities portfolio, which is offset by changes in fair value of trading securities also included in Brokerage and trading revenue in the Consolidated Statement of Earnings.

As discussed in Note 7, certain derivative contracts not designated as hedging instruments related to mortgage loan commitments and forward sales contracts are included in Residential mortgage loans held for sale on the Consolidated Balance Sheets. See Note 7 for additional discussion of notional, fair value and impact on earnings of these contracts.

No derivative contracts have been designated as hedging instruments for financial reporting purposes.

Loans and Allowances for Credit Losses

12 Months Ended

Dec. 31, 2020

Loans and Leases Receivable, Net Amount [Abstract]

Loans [Text Block]

The portfolio segments of the loan portfolio are as follows (in thousands):


	December 31, 2020
	Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	1,805,286	$	11,105,090	$	167,159	$	13,077,535
Commercial real estate	1,021,443		3,649,849		27,246		4,698,538
Paycheck protection program	1,682,310		—		—		1,682,310
Loans to individuals	2,173,437		1,335,412		40,288		3,549,137
Total	$	6,682,476	$	16,090,351	$	234,693	$	23,007,520
Foregone interest on nonaccrual loans							$	22,870

At December 31, 2020, loans to businesses and individuals with collateral primarily located in Texas totaled $7.2 billion or 31% of the total loan portfolio. Loans to businesses and individuals with collateral primarily located in Oklahoma totaled $3.8 billion or 17% of our total loan portfolio. Loans to businesses and individuals with collateral primarily located in Colorado totaled $2.8 billion or 12% of our total loan portfolio. Loans for which the collateral location is not relevant, such as unsecured loans and reserve-based energy loans, are distributed by the borrower’s primary operating location. These geographic concentrations subject the loan portfolio to the general economic conditions within these areas.

At December 31, 2019, loans to businesses and individuals with collateral primarily located in Texas totaled $6.8 billion or 31% of the loan portfolio, loans to businesses and individuals with collateral primarily located in Oklahoma totaled $3.5 billion or 16% of the loan portfolio and loans to businesses and individuals with collateral primarily located in Colorado totaled $2.8 billion or 13% of the loan portfolio.

Commercial

Commercial loans represent loans for working capital, facilities acquisition or expansion, purchases of equipment and other needs of commercial customers primarily located within our geographical footprint. Commercial loans are underwritten individually and represent on-going relationships based on a thorough knowledge of the customer, the customer’s industry and market. While commercial loans are generally secured by the customer’s assets including real property, inventory, accounts receivable, operating equipment, interest in mineral rights and other property and may also include personal guarantees of the owners and related parties, the primary source of repayment of the loans is the on-going cash flow from operations of the customer’s business. Inherent lending risk is centrally monitored on a continuous basis from underwriting throughout the life of the loan for compliance with commercial lending policies.

At December 31, 2020, commercial loans with collateral primarily located in Texas totaled $4.3 billion or 33% of the commercial loan portfolio segment. Commercial loans with collateral primarily located in Oklahoma totaled $1.8 billion or 14% of the commercial loan portfolio segment. Commercial loans with collateral primarily located in Colorado totaled $1.7 billion or 13% of the commercial loan portfolio segment. The commercial loan portfolio segment is further divided into loan classes. The services loan class totaled $3.5 billion or 15% of total loans. Approximately $1.8 billion of loans in the services class consisted of loans with individual balances of less than $10 million. Businesses included in the services class include Native American tribal and state and local municipal government entities, Native American tribal casino operations, educational services, foundations and not-for-profit organizations and specialty trade contractors. The energy loan class totaled $3.5 billion or 15% of total loans, including $2.6 billion of outstanding loans to energy producers. Approximately 67% of the committed production loans are secured by properties primarily producing oil and 33% of the committed production loans are secured by properties primarily producing natural gas. The healthcare loan class totaled $3.3 billion or 14% of total loans. The healthcare loan class consists primarily of loans for the development and operation of senior housing and care facilities, including independent living, assisted living and skilled nursing. Healthcare also includes loans to hospitals and other medical service providers.

At December 31, 2019, commercial loans with collateral primarily located in Texas totaled $4.7 billion or 33% of the commercial loan portfolio segment, commercial loans with collateral primarily located in Oklahoma totaled $2.0 billion or 14% of the commercial loan portfolio segment and commercial loans with collateral primarily located in Colorado totaled $2.0 billion or 14% of the commercial loan portfolio segment. The energy loan class totaled $4.0 billion or 18% of total loans, including $3.1 billion of outstanding loans to energy producers. At December 31, 2019, approximately 58% of committed production loans were secured by properties primarily producing oil and 42% were secured by properties producing natural gas. The services loan class totaled $3.8 billion or 18% of total loans. Approximately $1.5 billion of loans in the services category consisted of loans with individual balances of less than $10 million. The healthcare loan class totaled $3.0 billion or 14% of total loans.

Commercial Real Estate

Commercial real estate loans are for the construction of buildings or other improvements to real estate and property held by borrowers for investment purposes primarily within our geographical footprint. We require collateral values in excess of the loan amounts, demonstrated cash flows in excess of expected debt service requirements, equity investment in the project and a portion of the project already sold, leased or permanent financing already secured. The expected cash flows from all significant new or renewed income producing property commitments are stress tested to reflect the risks in varying interest rates, vacancy rates and rental rates. As with commercial loans, inherent lending risks are centrally monitored on a continuous basis from underwriting throughout the life of the loan for compliance with applicable lending policies.

At December 31, 2020, 27% of commercial real estate loans were secured by properties primarily located in the Dallas and Houston metropolitan areas of Texas and 10% of commercial real estate loans were secured by properties located primarily in the Tulsa and Oklahoma City metropolitan areas of Oklahoma. At December 31, 2019, 24% of commercial real estate loans are secured by properties primarily located in the Dallas and Houston metropolitan areas of Texas, 12% of commercial real estate loans were secured by properties located primarily in the Tulsa and Oklahoma City metropolitan areas of Oklahoma and 11% of commercial real estate loans are secured by properties located primarily in the Denver, Colorado metropolitan area.

Paycheck Protection Program

BOK Financial is actively participating in programs initiated by the Coronavirus Aid, Relief and Economic Security Act ("CARES Act"), including the Small Business Administration's ("SBA") Paycheck Protection Program ("PPP") that began on April 3, 2020. PPP provided fully forgivable loans when utilized for qualified expenditures, including to help small business maintain payrolls during the COVID-19 pandemic. These loans generally have a contractual term of two years, though most are expected to be forgiven prior to maturity after completion of a compliance period. Loans are guaranteed and amounts forgiven will be reimbursed to the Company by the SBA. The loans carry a rate of 1 percent. Interest plus loan fees, which vary depending on loan size, are accrued over the contractual life of the loan. Any unaccreted origination fees will be recognized when the loan is paid.

Loans to Individuals

Loans to individuals include residential mortgage and personal loans. Residential mortgage loans provide funds for our customers to purchase or refinance their primary residence or to borrow against the equity in their home. These loans are secured by a first or second mortgage on the customer's primary residence. These loans are made in accordance with underwriting policies we believe to be conservative and are fully documented. Loans may be individually underwritten or credit scored based on size and other criteria. Credit scoring is assessed based on significant credit characteristics including credit history, residential and employment stability.

In general, we sell the majority of our conforming fixed rate loan originations in the secondary market and retain the majority of our non-conforming and adjustable-rate mortgage loans. Our mortgage loan portfolio does not include payment option adjustable rate mortgage loans or adjustable rate mortgage loans with initial rates that are below market. Home equity loans are primarily first-lien and fully amortizing.

Residential mortgage, which includes home equity loans, and personal loans are made in accordance with underwriting policies we believe to be conservative and are fully documented. Loans may be individually underwritten or credit scored based on size and other criteria. Credit scoring is assessed based on significant credit characteristics including credit history, residential and employment stability.

Personal loans consist primarily of loans to Wealth Management clients secured by the cash surrender value of insurance policies and marketable securities. It also includes direct loans secured by and for the purchase of automobiles, recreational and marine equipment as well as unsecured loans.

Approximately 91% of the loans in this segment are secured by collateral located within our geographical footprint. Loans for which the collateral location is less relevant, such as unsecured loans are categorized by the borrower’s primary operating location.

Residential mortgage loans guaranteed by U.S. government agencies have limited credit exposure because of the agency guarantee. This amount includes residential mortgage loans previously sold into GNMA mortgage pools that the Company may repurchase when certain defined delinquency criteria are met. Because of this repurchase right, the Company is deemed to have regained effective control over these loans and must include them on the Consolidated Balance Sheet.

Credit Commitments

Commitments to extend credit are agreements to lend to a customer as long as there is no violation of conditions established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. At December 31, 2020, outstanding commitments totaled $11.0 billion. Because some commitments are expected to expire before being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. BOK Financial uses the same credit policies in making commitments as it does loans.

The amount of collateral obtained, if deemed necessary, is based upon management’s credit evaluation of the borrower.

Standby letters of credit are conditional commitments issued to guarantee the performance of a customer to a third party. Because the credit risk involved in issuing standby letters of credit is essentially the same as that involved in extending loan commitments, BOK Financial uses the same credit policies in evaluating the creditworthiness of the customer. Additionally, BOK Financial uses the same evaluation process in obtaining collateral on standby letters of credit as it does for loan commitments. The term of these standby letters of credit is defined in each commitment and typically corresponds with the underlying loan commitment. At December 31, 2020, outstanding standby letters of credit totaled $681 million.

Allowances for Credit Losses and Accrual for Off-balance Sheet Credit Risk from Unfunded Loans Commitments

BOK Financial maintains an allowance for loan losses and accrual for off-balance sheet credit risk from unfunded commitments. The allowance consists of specific allowances attributed to certain individual loans, generally nonaccruing loans, with dissimilar risk characteristics that have not yet been charged down to amounts we expect to recover and general allowances for estimated credit losses on pools of loans that share similar risk characteristics based on probability of default, loss given default and exposure at default for each loan class developed based on current and forecasted relevant economic loss drivers.

The accrual for off-balance sheet credit risk is maintained at a level that is appropriate to cover estimated losses associated with credit instruments that are not currently recognized as assets such as loan commitments, standby letters of credit or guarantees that are not unconditionally cancellable by the bank.

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit is for the year ended December 31, 2020 summarized as follows (in thousands):


	Commercial		Commercial Real Estate		Paycheck Protection Program		Loans to Individuals		Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	118,187	$	51,805	$	—	$	23,572	$	17,195	$	210,759
Transition adjustment	33,681		(4,620)		—		13,943		(17,195)		25,809
Beginning balance, adjusted	151,868		47,185		—		37,515		—		236,568
Provision for loan losses	171,800		40,407		—		10,253		—		222,460
Loans charged off	(73,370)		(1,300)		—		(4,729)		—		(79,399)
Recoveries of loans previously charged off	4,636		266		—		4,109		—		9,011
Ending balance	$	254,934	$	86,558	$	—	$	47,148	$	—	$	388,640

Allowance for off-balance sheet credit risk from unfunded loan commitments:
Beginning balance	$	1,434	$	107	$	—	$	44	$	—	$	1,585
Transition adjustment	10,144		11,660		—		1,748		—		23,552
Beginning balance, adjusted	11,578		11,767		—		1,792		—		25,137
Provision for off-balance sheet credit risk	2,844		8,804		—		136		—		11,784
Ending balance	$	14,422	$	20,571	$	—	$	1,928	$	—	$	36,921

Changes in our reasonable and supportable forecasts of macroeconomic variables, primarily due to the anticipated impact of the on-going COVID-19 pandemic, and other assumptions, resulted in a $99.1 million increase in the allowance for lending activities during the year ended December 31, 2020. Changes in the loan portfolio characteristics, including specific impairment and losses, loan balances and risk grading resulted in a $135.2 million increase in the allowance for lending activities.

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2020 is as follows (in thousands):


	Collectively Measured for General Allowances				Individually Measured for Specific Allowances				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	12,910,376	$	235,882	$	167,159	$	19,052	$	13,077,535	$	254,934
Commercial real estate	4,671,292		83,169		27,246		3,389		4,698,538		86,558
Paycheck protection program	1,682,310		—		—		—		1,682,310		—
Loans to individuals	3,508,849		47,148		40,288		—		3,549,137		47,148
Total	$	22,772,827	$	366,199	$	234,693	$	22,441	$	23,007,520	$	388,640

Credit Quality Indicators

The Company utilizes risk grading as primary credit quality indicators as it influences the probability of default which is a key attribute in the expected credit losses calculation. Substantially all commercial as well as commercial real estate loans and certain loans to individuals are risk graded based on a quarterly evaluation of the borrowers’ ability to repay the loans. Certain commercial loans and most loans to individuals are small, homogeneous pools that are not risk-graded. The credit quality of these loans is based on past due days in accordance with regulatory guidelines.

We have included in the credit quality indicator “pass” loans that are in compliance with the original terms of the agreement and currently exhibit no factors that cause management to have doubts about the borrowers’ ability to remain in compliance with the original terms of the agreement, which is consistent with the regulatory guideline of “pass.” This also includes past due residential mortgages that are guaranteed by agencies of the U.S. government that continue to accrue interest based on criteria of the guarantors’ programs.

Other loans especially mentioned ("Special Mention") are currently performing in compliance with the original terms of the agreement but may have a potential weakness that deserves management’s close attention, consistent with regulatory guidelines. Non-graded loans 30 to 59 days past due are categorized as Special Mention.

The risk grading process identified certain loans that have a well-defined weakness (for example, inadequate debt service coverage or liquidity or marginal capitalization; repayment may depend on collateral or other risk mitigation) that may jeopardize liquidation of the debt and represent a greater risk due to deterioration in the financial condition of the borrower. This is consistent with the regulatory guideline for “substandard.” Because the borrowers are still performing in accordance with the original terms of the loan agreements, these loans remain on accruing status. Non-graded loans 60 to 89 days past due are categorized as Accruing Substandard.

Nonaccruing loans represent loans for which full collection of principal and interest is uncertain. This includes certain loans considered “substandard” and all loans considered “doubtful” by regulatory guidelines. Non-graded loans 90 or more days past due are categorized as Nonaccrual.

Probability of default is lowest for pass graded loans and increases for each credit quality indicator, Special Mention, and Accruing Substandard.

Vintage represents the year of origination, except for revolving loans which are considered in aggregate. Loans that were once revolving but have converted to term loans without additional underwriting appear in a separate vintage column.

The following table summarizes the Company's loan portfolio at December 31, 2020 by the risk grade categories and vintage (in thousands):


	Origination Year
	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Commercial:
Energy
Pass	$	112,614	$	51,863	$	89,346	$	7,178	$	1,148	$	7,956	$	2,548,663	$	—	$	2,818,768
Special Mention	—		—		—		—		—		—		202,590		—		202,590
Accruing Substandard	24,000		1,363		1,453		—		12,667		—		283,294		—		322,777
Nonaccrual	21,076		2,607		—		—		—		21,064		80,312		—		125,059
Total energy	157,690		55,833		90,799		7,178		13,815		29,020		3,114,859		—		3,469,194



Healthcare
Pass	536,745		615,221		638,302		422,834		234,399		658,286		147,132		—		3,252,919
Special Mention	—		27,500		—		—		—		8,282		5		—		35,787
Accruing Substandard	—		—		1,191		929		132		11,387		—		—		13,639
Nonaccrual	—		18		183		—		—		2,935		509		—		3,645
Total healthcare	536,745		642,739		639,676		423,763		234,531		680,890		147,646		—		3,305,990



Services
Pass	534,853		436,384		372,867		307,374		373,785		683,936		665,491		682		3,375,372
Special Mention	150		9,057		389		291		2,038		2,000		3,063		—		16,988
Accruing Substandard	429		6,380		26,008		6,027		5,030		7,954		38,797		—		90,625
Nonaccrual	4,833		448		—		12,590		1,049		6,138		540		—		25,598
Total services	540,265		452,269		399,264		326,282		381,902		700,028		707,891		682		3,508,583



General business
Pass	419,756		394,985		310,273		236,222		103,987		186,600		1,055,878		2,316		2,710,017
Special Mention	197		4,519		9,713		7,803		2,511		3,159		2,483		19		30,404
Accruing Substandard	1,432		3,069		6,694		10,935		10,042		3,729		4,449		140		40,490
Nonaccrual	1,675		3,728		4,863		1,436		530		107		477		41		12,857
Total general business	423,060		406,301		331,543		256,396		117,070		193,595		1,063,287		2,516		2,793,768



Total commercial	1,657,760		1,557,142		1,461,282		1,013,619		747,318		1,603,533		5,033,683		3,198		13,077,535

Commercial real estate:
Pass	725,577		1,211,338		954,226		489,193		314,899		722,475		223,131		38		4,640,877
Special Mention	—		—		259		12,311		2,725		5,831		—		—		21,126
Accruing Substandard	—		—		—		4,410		—		4,852		27		—		9,289
Nonaccrual	—		8,300		—		232		7,468		11,246		—		—		27,246
Total commercial real estate	725,577		1,219,638		954,485		506,146		325,092		744,404		223,158		38		4,698,538


	Origination Year
	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Paycheck protection program:
Pass	1,682,310		—		—		—		—		—		—		—		1,682,310
Total paycheck protection program	1,682,310		—		—		—		—		—		—		—		1,682,310
Loans to individuals:
Residential mortgage
Pass	564,325		149,832		120,875		124,930		158,801		348,292		335,259		24,553		1,826,867
Special Mention	33		11		2,094		—		59		318		950		10		3,475
Accruing Substandard	—		—		51		—		—		34		272		76		433
Nonaccrual	648		104		1,658		784		2,010		22,415		3,835		774		32,228
Total residential mortgage	565,006		149,947		124,678		125,714		160,870		371,059		340,316		25,413		1,863,003



Residential mortgage guaranteed by U.S. government agencies
Pass	4,859		33,880		34,464		43,099		58,264		226,380		—		—		400,946
Special Mention	—		—		—		—		—		—		—		—		—
Accruing Substandard	—		—		—		—		—		—		—		—		—
Nonaccrual	—		—		545		—		309		6,887		—		—		7,741
Total residential mortgage guaranteed by U.S. government agencies	4,859		33,880		35,009		43,099		58,573		233,267		—		—		408,687



Personal:
Pass	219,873		200,580		76,246		100,229		64,104		102,126		510,571		1,510		1,275,239
Special Mention	39		55		66		—		469		31		965		—		1,625
Accruing Substandard	11		214		10		—		—		—		29		—		264
Nonaccrual	28		17		57		73		50		49		45		—		319
Total personal	219,951		200,866		76,379		100,302		64,623		102,206		511,610		1,510		1,277,447



Total loans to individuals	789,816		384,693		236,066		269,115		284,066		706,532		851,926		26,923		3,549,137
Total loans	$	4,855,463	$	3,161,473	$	2,651,833	$	1,788,880	$	1,356,476	$	3,054,469	$	6,108,767	$	30,159	$	23,007,520

Nonaccruing Loans

A summary of nonaccruing loans as of December 31, 2020 follows (in thousands):


	Total		With No Allowance		With Allowance		Related Allowance
Commercial:
Energy	$	125,059	$	76,633	$	48,426	$	16,478
Healthcare	3,645		3,645		—		—
Services	25,598		20,810		4,788		2,574
General business	12,857		12,857		—		—
Total commercial	167,159		113,945		53,214		19,052

Commercial real estate	27,246		13,645		13,601		3,389

Loans to individuals:
Residential mortgage	32,228		32,228		—		—
Residential mortgage guaranteed by U.S. government agencies	7,741		7,741		—		—
Personal	319		319		—		—
Total loans to individuals	40,288		40,288		—		—

Total	$	234,693	$	167,878	$	66,815	$	22,441

Troubled Debt Restructurings

At December 31, 2020 the Company has $187 million in troubled debt restructurings (TDRs), of which $152 million are accruing residential mortgage loans guaranteed by U.S. government agencies. Approximately $95 million of TDRs are performing in accordance with the modified terms. The loans designated as TDRs had $20.9 million in charge offs during the year ended December 31, 2020.

At December 31, 2019, TDRs totaled $132 million, of which $92 million were accruing residential mortgage loans guaranteed by U.S. government agencies. Approximately $57 million of TDRs were performing. The loans designated as TDRs had $18.6 million in charge offs during the year ended December 31, 2019.

TDRs generally consist of interest rate concessions, payment stream concessions or a combination of concessions to distressed borrowers. During the year ended December 31, 2020, $83 million of loans were restructured. During the year ended December 31, 2019, $37 million of loans were restructured.

Past Due Loans

Past due status for all loan classes is based on the actual number of days since the last payment was due according to the contractual terms of the loans, as modified for short-term payment deferral forbearance.

A summary of loans currently performing and past due as of December 31, 2020 is as follows (in thousands):


			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Total		Past Due 90 Days or More and Accruing
Commercial:
Energy	$	3,410,995	$	12,735	4,050		$	41,414	$	3,469,194	$	—
Healthcare	3,302,345		—		—		3,645		3,305,990		—
Services	3,489,423		3,278		177		15,705		3,508,583		326
General business	2,776,038		1,206		6,277		10,247		2,793,768		4,495
Total commercial	12,978,801		17,219		10,504		71,011		13,077,535		4,821

Commercial real estate	4,672,279		276		5,310		20,673		4,698,538		5,126

Paycheck protection program	1,682,310		—		—		—		1,682,310		—

Loans to individuals
Permanent mortgage	1,849,304		5,812		837		7,050		1,863,003		181
Permanent mortgages guaranteed by U.S. government agencies	262,102		41,389		22,041		83,155		408,687		78,349
Personal	1,273,702		3,317		90		338		1,277,447		241
Total loans to individuals	3,385,108		50,518		22,968		90,543		3,549,137		78,771

Total	$	22,718,498	$	68,013	$	38,782	$	182,227	$	23,007,520	$	88,718

Following is disclosure of loans and the combined allowance for loan losses and accrual for off-balance sheet credit losses under the previous incurred loss model.

Portfolio segments of the loan portfolio are as follows (in thousands):


	December 31, 2019
	Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	3,231,485	$	10,684,749	$	115,416	$	14,031,650
Commercial real estate	1,056,321		3,349,836		27,626		4,433,783
Residential mortgage	1,652,653		393,897		37,622		2,084,172
Personal	193,903		1,007,192		287		1,201,382
Total	$	6,134,362	$	15,435,674	$	180,951	$	21,750,987
Accruing loans past due (90 days)1							$	7,680
Foregone interest on nonaccrual loans							$	17,409

1.Excludes residential mortgage loans guaranteed by agencies of the U.S. government

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit is for the year ended December 31, 2019 summarized as follows (in thousands):


	Commercial		Commercial Real Estate		Residential Mortgage		Personal		Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	102,226	$	60,026	$	17,964	$	9,473	$	17,768	$	207,457
Provision for loan losses	57,125		(12,046)		(3,838)		3,537		(573)		44,205
Loans charged off	(43,185)		(1,161)		(288)		(6,343)		—		(50,977)
Recoveries	2,021		4,986		562		2,505		—		10,074
Ending balance	$	118,187	$	51,805	$	14,400	$	9,172	$	17,195	$	210,759
Allowance for off-balance sheet credit losses:
Beginning balance	1,655		52		52		31		—		1,790
Provision for off-balance sheet credit losses	(221)		55		(8)		(31)		—		(205)
Ending balance	$	1,434	$	107	$	44	$	—	$	—	$	1,585

Total provision for credit losses	$	56,904	$	(11,991)	$	(3,846)	$	3,506	$	(573)	$	44,000

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit is for the year ended December 31, 2018 summarized as follows (in thousands):


	Commercial		Commercial Real Estate		Residential Mortgage		Personal		Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	124,269	$	56,621	$	18,451	$	9,124	$	22,217	$	230,682
Provision for loan losses	12,521		(147)		(1,156)		3,175		(4,449)		9,944
Loans charged off	(37,880)		—		(378)		(5,325)		—		(43,583)
Recoveries	3,316		3,552		1,047		2,499		—		10,414
Ending balance	$	102,226	$	60,026	$	17,964	$	9,473	$	17,768	$	207,457
Allowance for off-balance sheet credit losses:
Beginning balance	3,644		45		43		2		—		3,734
Provision for off-balance sheet credit losses	(1,989)		7		9		29		—		(1,944)
Ending balance	$	1,655	$	52	$	52	$	31	$	—	$	1,790

Total provision for credit losses	$	10,532	$	(140)	$	(1,147)	$	3,204	$	(4,449)	$	8,000

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2019 is as follows (in thousands):


	Collectively Measured for Impairment				Individually Measured for Impairment				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	13,916,234	$	100,773	$	115,416	$	17,414	$	14,031,650	$	118,187
Commercial real estate	4,406,157		51,805		27,626		—		4,433,783		51,805
Residential mortgage	2,046,550		14,400		37,622		—		2,084,172		14,400
Personal	1,201,095		9,172		287		—		1,201,382		9,172
Total	21,570,036		176,150		180,951		17,414		21,750,987		193,564

Nonspecific allowance	—		—		—		—		—		17,195

Total	$	21,570,036	$	176,150	$	180,951	$	17,414	$	21,750,987	$	210,759

The allowance for loan losses and recorded investment of the related loans by portfolio segment for risk graded and non-risk graded loans at December 31, 2019 is as follows (in thousands):


	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	13,997,538	$	117,236	$	34,112	$	951	$	14,031,650	$	118,187
Commercial real estate	4,433,783		51,805		—		—		4,433,783		51,805
Residential mortgage	279,113		3,085		1,805,059		11,315		2,084,172		14,400
Personal	1,116,297		7,003		85,085		2,169		1,201,382		9,172
Total	19,826,731		179,129		1,924,256		14,435		21,750,987		193,564

Nonspecific allowance	—		—		—		—		—		17,195

Total	$	19,826,731	$	179,129	$	1,924,256	$	14,435	$	21,750,987	$	210,759

The following table summarizes the Company's loan portfolio at December 31, 2019 by the risk grade categories (in thousands):


	Internally Risk Graded								Non-Graded
	Performing
	Pass		Other Loans Especially Mentioned		Accruing Substandard		Nonaccrual		Performing		Nonaccrual		Total
Commercial:
Energy	$	3,700,406	$	117,298	$	63,951	$	91,722	$	—	$	—	$	3,973,377
Services	3,050,946		29,943		33,791		7,483		—		—		3,122,163
Wholesale/retail	1,749,023		5,281		5,399		1,163		—		—		1,760,866
Manufacturing	623,219		18,214		13,883		10,133		—		—		665,449
Healthcare	2,995,514		13,117		20,805		4,480		—		—		3,033,916
Public finance	709,868		—		—		—		—		—		709,868
Other commercial and industrial	709,729		4,028		17,744		398		34,075		37		766,011
Total commercial	13,538,705		187,881		155,573		115,379		34,075		37		14,031,650

Commercial real estate:
Residential construction and land development	150,529		—		—		350		—		—		150,879
Retail	743,343		12,067		1,243		18,868		—		—		775,521
Office	923,202		5,177		—		—		—		—		928,379
Multifamily	1,257,005		1,604		95		6,858		—		—		1,265,562
Industrial	852,539		1,658		1,011		909		—		—		856,117
Other commercial real estate	455,045		1,639		—		641		—		—		457,325
Total commercial real estate	4,381,663		22,145		2,349		27,626		—		—		4,433,783

Residential mortgage:
Permanent mortgage	276,138		78		2,404		493		758,260		19,948		1,057,321
Permanent mortgage guaranteed by U.S. government agencies	—		—		—		—		191,694		6,100		197,794
Home equity	—		—		—		—		817,976		11,081		829,057
Total residential mortgage	276,138		78		2,404		493		1,767,930		37,129		2,084,172

Personal	1,116,196		45		—		56		84,853		232		1,201,382

Total	$	19,312,702	$	210,149	$	160,326	$	143,554	$	1,886,858	$	37,398	$	21,750,987

Impaired Loans

Loans are considered to be impaired when it is probable that the Company will not be able to collect all amounts due according to the contractual terms of the loan agreement. This generally includes all nonaccruing loans, all loans modified in a TDR and all loans repurchased from GNMA pools.

Generally, no interest income is recognized on impaired loans until all principal balances, including amounts charged-off, are recovered.

A summary of impaired loans at December 31, 2019 follows (in thousand):


	As of December 31, 2019										Year Ended
			Recorded Investment								December 31, 2019
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance		Average Recorded Investment		Interest Income Recognized
Commercial:
Energy	$	149,441	$	91,722	$	44,244	$	47,478	$	16,854	$	69,119	$	—
Services	10,923		7,483		6,301		1,182		240		5,854		—
Wholesale/retail	1,980		1,163		902		261		101		916		—
Manufacturing	10,848		10,133		9,914		219		219		9,144		—
Healthcare	13,774		4,480		4,480		—		—		7,798		—
Public finance	—		—		—		—		—		—		—
Other commercial and industrial	8,227		435		435		—		—		8,568		—
Total commercial	195,193		115,416		66,276		49,140		17,414		101,399		—

Commercial real estate:
Residential construction and land development	1,306		350		350		—		—		350		—
Retail	20,265		18,868		18,868		—		—		19,573		—
Office	—		—		—		—		—		—		—
Multifamily	6,858		6,858		6,858		—		—		3,580		—
Industrial	909		909		909		—		—		454		—
Other commercial real estate	801		641		641		—		—		666		—
Total commercial real estate	30,139		27,626		27,626		—		—		24,623		—

Residential mortgage:
Permanent mortgage	24,868		20,441		20,441		—		—		22,196		1,198
Permanent mortgage guaranteed by U.S. government agencies1	204,187		197,794		197,794		—		—		195,009		7,733
Home equity	12,967		11,081		11,081		—		—		10,776		—
Total residential mortgage	242,022		229,316		229,316		—		—		227,981		8,931

Personal	360		287		287		—		—		259		—

Total	$	467,714	$	372,645	$	323,505	$	49,140	$	17,414	$	354,262	$	8,931

1 All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2019, the majority were accruing based on the guarantee by U.S. government agencies.

A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of December 31, 2019 is as follows (in thousands):


			Past Due
	Current		30 to 59 Days		60 to 89 Days	90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	3,881,244	$	401	10	$	—	$	91,722	$	3,973,377
Services	3,105,621		1,737		523	6,799		7,483		3,122,163
Wholesale/retail	1,758,878		712		113	—		1,163		1,760,866
Manufacturing	654,329		410		190	387		10,133		665,449
Healthcare	3,027,329		2,039		—	68		4,480		3,033,916
Public finance	707,638		2,230		—	—		—		709,868
Other commercial and industrial	764,390		414		772	—		435		766,011
Total commercial	13,899,429		7,943		1,608	7,254		115,416		14,031,650

Commercial real estate:
Residential construction and land development	147,379		3,093		—	57		350		150,879
Retail	756,653		—		—	—		18,868		775,521
Office	928,379		—		—	—		—		928,379
Multifamily	1,258,704		—		—	—		6,858		1,265,562
Industrial	855,208		—		—	—		909		856,117
Other commercial real estate	454,253		1,827		250	354		641		457,325
Total commercial real estate	4,400,576		4,920		250	411		27,626		4,433,783

Residential mortgage:
Permanent mortgage	1,034,716		2,011		153	—		20,441		1,057,321
Permanent mortgages guaranteed by U.S. government agencies	46,898		24,203		18,187	102,406		6,100		197,794
Home equity	814,325		3,343		308	—		11,081		829,057
Total residential mortgage	1,895,939		29,557		18,648	102,406		37,622		2,084,172

Personal	1,196,362		4,664		54	15		287		1,201,382

Total	$	21,392,306	$	47,084	20,560	$	110,086	$	180,951	$	21,750,987

Premises and Equipment and Leases

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Premises and Equipment Disclosure [Text Block]

Premises and Equipment and Leases

Premises and equipment at December 31 are summarized as follows (in thousands):


	December 31,
	2020		2019
Land	$	69,776	$	69,960
Buildings and improvements	440,528		421,952
Software and related integration	120,444		98,487
Furniture and equipment	165,344		135,153
Construction in progress	46,949		53,498
Premises and equipment	843,041		779,050
Less accumulated depreciation	291,733		243,531
Premises and equipment, net of accumulated depreciation	$	551,308	$	535,519

Depreciation expense of premises and equipment was $54.3 million, $51.6 million and $51.2 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Effective January 1, 2019, premises and equipment included right-of-use assets for leased office space and facilities. Leases are at market rates at inception and may contain escalations based on consumer price index or similar benchmarks and options to renew at then market rates.

Right-of-use assets of $166 million at December 31, 2020 and $180 million at December 31, 2019 are included in buildings and improvements and related right-of-use liabilities are included in other liabilities. At December 31, 2020, the weighted-average remaining lease term was 11 years and the weighted average discount rate on operating leases was 3.0 percent. Operating lease costs recognized as occupancy and equipment expense were $25.0 million and $24.2 million for the years ended December 31, 2020 and December 31, 2019, respectively. Operating cash flows from operating leases were $25.6 million and $23.3 million for the years ended December 31, 2020 and December 31, 2019, respectively.

Total rent expense for BOK Financial was $42.0 million in 2020, $43.0 million in 2019 and $28.5 million in 2018. At December 31, 2020, un-discounted operating lease liabilities are scheduled to mature as follows: $26.3 million in 2021, $21.2 million in 2022, $20.1 million in 2023, $19.6 million in 2024, $18.9 million in 2025 and $116 million thereafter. Operating expense and short term lease costs total $13.4 million and $12.6 million for the year ended December 31, 2020 and December 31, 2019, respectively. BOKF, NA is obligated under a long-term lease for its bank premises in downtown Tulsa. The original lease dated November 1, 1976 was renegotiated on July 1, 2019. The new lease will terminate on December 31, 2034. The Company has the option to renew for an additional 10 years. Premises leases may include options to renew at then current market rates and may include escalation provisions based upon changes in consumer price index or similar benchmarks.

The Company may lease owned properties or sublease unoccupied leased facilities. Income on these leases is immaterial.

Goodwill and Intangible Assets

12 Months Ended

Dec. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Intangible Assets [Text Block]

Goodwill and Intangible Assets

The following table presents the original cost and accumulated amortization of intangible assets (in thousands):


	Dec. 31,
	2020		2019
Core deposit premiums	$	103,200	$	103,200
Less accumulated amortization	32,256		19,364
Net core deposit premiums	70,944		83,836

Other identifiable intangible assets	82,731		74,372
Less accumulated amortization	40,239		32,937
Net other identifiable intangible assets	42,492		41,435

Total intangible assets, net	$	113,436	$	125,271

Expected amortization expense for intangible assets that will continue to be amortized (in thousands):


	Core Deposit Premiums		Other Identifiable Intangible Assets		Total
2021	$	11,893	$	6,599	$	18,492
2022	10,981		5,232		16,213
2023	10,145		4,191		14,336
2024	9,379		3,178		12,557
2025	8,675		2,767		11,442
Thereafter	19,871		20,525		40,396
	$	70,944	$	42,492	$	113,436

The changes in the carrying value of goodwill by operating segment are as follows (in thousands):


	Commercial Banking		Consumer Banking		Wealth Management		Funds Management and Other		Total



Balance, December 31, 2018	$	313,270	$	43,458	$	90,702	$	601,833	$	1,049,263



Adjustment1	600,661		—		—		(601,833)		(1,172)




Balance, December 31, 2019	913,931		43,458		90,702		—		1,048,091









Balance, December 31, 2020	$	913,931	$	43,458	$	90,702	$	—	$	1,048,091

1 Goodwill related to the CoBiz acquisition was not yet allocated to the operating segments as of December 31, 2018 and was included in Funds Management and Other in 2018 then allocated during 2019.

At October 1, 2020, the Company performed a qualitative impairment assessment of goodwill based on factors including, but not limited to, general economic conditions, financial services industry considerations, regional economic conditions, global health concerns and related medical developments, general BOKF Financial performance and reporting unit performance. During 2020, the U.S. and global economies were negatively impacted by the spread of COVID-19. This resulted in the need for quarterly qualitative impairment analyses and quantitative corroboration of the annual qualitative impairment assessment. No impairment was indicated for any reporting unit.

Deposits

12 Months Ended

Dec. 31, 2020

Deposits [Abstract]

Deposits [Text Block]

Interest expense on deposits is summarized as follows (in thousands):


	Year Ended December 31,
	2020		2019		2018
Transaction deposits	$	60,424	$	132,854	$	65,859
Savings	385		677		439
Time:
Certificates of deposits under $100,000	6,741		8,299		5,751
Certificates of deposits $100,000 and over	18,270		29,288		19,739
Other time deposits	4,176		4,420		3,729
Total time	29,187		42,007		29,219
Total	$	89,996	$	175,538	$	95,517

The aggregate amounts of time deposits in denominations of $250,000 or more at December 31, 2020 and 2019 were $815 million and $845 million, respectively.

Time deposit maturities are as follows: 2021 – $1.5 billion, 2022 – $172 million, 2023 – $90 million, 2024 – $54 million, 2025 – $41 million and $100 million thereafter.

The aggregate amount of overdrawn customer transaction deposits that have been reclassified as loan balances was $3.1 million at December 31, 2020 and $8.7 million at December 31, 2019.

Other Borrowed Funds

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Other Borrowed Funds [Text Block]

Other Borrowed Funds

Information relating to other borrowings is summarized as follows (dollars in thousands):


	As of				Year Ended
	December 31, 2020				December 31, 2020
	Balance		Rate		Average Balance		Rate		Maximum Outstanding At Any Month End
Funds purchased	769,365		0.05	%	2,045,795		0.58	%	3,311,938
Repurchase agreements	893,021		0.09	%	1,589,746		0.24	%	3,230,097
Other borrowings:
Federal Home Loan Bank advances	200,000		0.29	%	3,393,989		1.00	%	7,500,000
GNMA repurchase liability	19,500		4.35	%	42,771		4.18	%	126,569
Federal Reserve Bank advances	—		—	%	42,464		0.26	%	—
Paycheck protection program liquidity facility	1,635,963		0.35	%	1,152,073		0.35	%	2,013,414
Other	27,507		5.24	%	28,156		5.12	%	49,376
Total other borrowings	1,882,970				4,659,453		0.88	%
Subordinated debentures1	276,005		4.72	%	275,965		5.05	%	276,005
Total other borrowed funds	$	3,821,361			$	8,570,959	0.82	%


	As of				Year Ended
	December 31, 2019				December 31, 2019
	Balance		Rate		Average Balance		Rate		Maximum Outstanding At Any Month End
Funds purchased	3,390,528		1.53	%	2,438,376		2.08	%	3,390,528
Repurchase agreements	427,822		0.50	%	399,785		0.57	%	427,822
Other borrowings:
Federal Home Loan Bank advances	4,500,000		1.79	%	7,122,466		2.44	%	8,000,000
GNMA repurchase liability	15,417		4.32	%	13,746		4.47	%	19,581
Other	11,638		5.09	%	11,144		5.30	%	34,676
Total other borrowings	4,527,055				7,147,356		2.45	%
Subordinated debentures1	275,923		5.15	%	276,075		5.47	%	275,923
Total other borrowed funds	$	8,621,328			$	10,261,592	2.37	%


	As of				Year Ended
	December 31, 2018				December 31, 2018
	Balance		Rate		Average Balance		Rate		Maximum Outstanding At Any Month End
Funds purchased	402,450		2.34	%	419,322		1.89	%	949,531
Repurchase agreements	615,961		0.36	%	464,582		0.28	%	615,961
Other borrowings:
Federal Home Loan Bank advances	6,100,000		2.65	%	6,207,142		2.06	%	6,500,000
GNMA repurchase liability	15,552		4.43	%	14,783		4.47	%	16,529
Other	8,838		2.90	%	14,516		2.67	%	20,422
Total other borrowings	6,124,390				6,236,441		2.07	%
Subordinated debentures1	275,913		5.34	%	177,884		5.52	%	275,913
Total other borrowed funds	$	7,418,714			$	7,298,229	2.03	%

1 Parent Company only.

Aggregate annual principal repayments at December 31, 2020 are as follows (in thousands):



2021	$	1,884,974
2022	1,639,735
2023	9,625
2024	625
2025	10,555
Thereafter	275,847
Total	$	3,821,361

Funds purchased are unsecured and generally mature within one day to ninety days from the transaction date. Securities repurchase agreements are recorded as secured borrowings that generally mature within ninety days and are secured by certain available for sale securities.

Additional information relating to securities sold under agreements to repurchase and related liabilities at December 31, 2020 and 2019 is as follows (dollars in thousands):


	December 31, 2020
	Amortized		Fair		Repurchase
Security Sold/Maturity	Cost		Value		Liability1		Rate

U.S. government agency mortgage-backed securities:
Overnight1	$	893,069	$	910,885	$	893,021	0.09	%
Long-term	—		—		—		—	%
Total Agency Securities	$	893,069	$	910,885	$	893,021	0.09	%

	December 31, 2019
	Amortized		Fair		Repurchase
Security Sold/Maturity	Cost		Value		Liability1		Rate

U.S. government agency mortgage-backed securities:
Overnight1	$	431,939	$	435,898	$	427,822	0.50	%
Long-term	—		—		—		—	%
Total Agency Securities	$	431,939	$	435,898	$	427,822	0.50	%

1 BOK Financial maintains control over the securities underlying overnight repurchase agreements and generally transfers control over securities underlying longer-term dealer repurchase agreements to the respective counterparty.

Borrowings from the Federal Home Loan Banks are used for funding purposes. In accordance with policies of the Federal Home Loan Banks, BOK Financial has granted a blanket pledge of eligible assets (generally unencumbered U.S. Treasury and residential mortgage-backed securities, 1-4 family loans and multifamily loans) as collateral for these advances. The Federal Home Loan Banks have issued letters of credit totaling $381 million to secure BOK Financial’s obligations to depositors of public funds. The unused credit available to BOK Financial at December 31, 2020 pursuant to the Federal Home Loan Bank’s collateral policies is $8.6 billion.

In 2016, BOK Financial issued $150 million of subordinated debt that will mature on June 30, 2056. Interest on this debt bears an interest rate of 5.375%, payable quarterly. On June 30, 2021, BOK Financial will have the option to redeem the debt at the principal amount plus accrued interest, subject to regulatory approval.

As a result of the acquisition of CoBiz Financial, we obtained $60 million of subordinated debt issued in June 2015 that will mature on June 25, 2030. This debt bears interest at the rate of 5.625% through June 2025 and thereafter, the notes will bear interest at an annual floating rate equal to three-month LIBOR plus 3.17%. The debt contains a call option that allows for repayment prior to contractual maturity. The call option is available on June 25, 2025 and quarterly thereafter at 100% of the principal amount.

Also through CoBiz Financial, we acquired junior subordinated debentures split across three issuance tranches. Junior subordinated debentures of $21 million will mature September 17, 2033 and bear an interest rate of three-month LIBOR plus 2.95% that resets quarterly. Junior subordinated debentures of $31 million will mature on July 23, 2034 and bear an interest rate of three-month LIBOR plus 2.60% that resets quarterly. Junior subordinated debentures of $20 million will mature on September 30, 2035 and bear an interest rate of three-month LIBOR plus 1.45% that resets quarterly. The junior subordinated debentures are subject to early redemption prior to maturity.

BOK Financial Securities, Inc. may borrow funds from Pershing, LLC ("Pershing"), a clearing broker/dealer and a wholly owned subsidiary of Bank of New York Mellon, for the purposes of financing securities purchases or to facilitate funding of investment banking activities, on terms to be negotiated at the time of the borrowing. BOK Financial Securities, Inc. had no borrowings outstanding at December 31, 2020 and December 31, 2019.

The Company has a liability related to the repurchase of certain delinquent residential mortgage loans previously sold into GNMA mortgage pools. Interest is payable at rates contractually due to investors.

Federal and State Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Federal and State Income Taxes [Text Block]

Federal and State Income Taxes

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of deferred tax assets and liabilities are as follows (in thousands):


	December 31,
	2020		2019
Deferred tax assets:
Credit loss reserves	$	101,265	$	50,611
Lease liability	44,794		46,084
Deferred compensation	29,504		25,976
Unearned fees	14,584		9,080
Purchased loan discount	11,537		18,042
Share-based compensation	6,525		7,392
Valuation adjustments	3,834		1,545

Other	29,963		26,384
Total deferred tax assets	242,006		185,114

Deferred tax liabilities:
Available for sale securities mark to market	105,769		33,140
Right-of-use asset	38,635		42,180
Mortgage servicing rights	24,182		48,435
Acquired identifiable intangible	18,138		23,181
Depreciation	13,754		18,909
Lease financing	11,828		10,720
Other	39,210		34,826
Total deferred tax liabilities	251,516		211,391
Net deferred tax liabilities	$	(9,510)	$	(26,277)

No valuation allowance was necessary on deferred tax assets as of December 31, 2020 and 2019.

The significant components of the provision for income taxes attributable to continuing operations for BOK Financial are shown below (in thousands):


	Year Ended December 31,
	2020		2019		2018
Current income tax expense:
Federal	$	173,888	$	110,887	$	103,748
State	29,889		15,088		15,253
Total current income tax expense	203,777		125,975		119,001

Deferred income tax expense (benefit):
Federal	(65,989)		3,416		(190)
State	(8,995)		792		250
Total deferred income tax expense (benefit)	(74,984)		4,208		60
Total income tax expense	$	128,793	$	130,183	$	119,061

The reconciliations of income attributable to continuing operations at the U.S. federal statutory tax rate to income tax expense are as follows (in thousands):


	Year Ended December 31,
	2020		2019		2018
Amount:
Federal statutory tax	$	118,412	$	132,482	$	118,752
Tax exempt revenue	(7,035)		(12,227)		(8,311)
Effect of state income taxes, net of federal benefit	14,251		12,715		12,430
Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments	(6,994)		(5,127)		(4,559)





Other, net	10,159		2,340		749
Total income tax expense	$	128,793	$	130,183	$	119,061


	Year Ended December 31,
	2020		2019		2018
Percent of pretax income:
Federal statutory tax	21.0	%	21.0	%	21.0	%
Tax exempt revenue	(1.2)		(1.9)		(1.5)
Effect of state income taxes, net of federal benefit	2.5		2.0		2.2
Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments	(1.2)		(0.8)		(0.8)



Other, net	1.7		0.3		0.2
Total	22.8	%	20.6	%	21.1	%

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands):


	2020		2019		2018
Balance as of January 1	$	20,465	$	18,869	$	18,110
Additions for tax for current year positions	6,384		5,649		2,649
Settlements during the period	—		—		—
Lapses of applicable statute of limitations	(3,947)		(4,053)		(1,890)
Balance as of December 31	$	22,902	$	20,465	$	18,869

Of the above unrecognized tax benefits, $17.2 million, if recognized, would have affected the effective tax rate.

BOK Financial recognizes interest and penalties accrued related to unrecognized tax benefits in income tax expense. The Company recognized $2.4 million for 2020, $2.2 million for 2019 and $1.7 million for 2018 in interest and penalties. The Company had approximately $5.9 million and $5.6 million accrued for the payment of interest and penalties at December 31, 2020 and 2019, respectively. Federal statutes remain open for federal tax returns filed in the previous three reporting periods. Various state income tax statutes remain open for the previous three to six reporting periods.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Employee Benefits

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Employee Benefits [Text Block]

Employee Benefits

BOK Financial sponsors a defined benefit cash balance Pension Plan for all employees who satisfy certain age and service requirements. Pension Plan benefits were curtailed as of April 1, 2006. No participants may be added to the plan and no additional service benefits will be accrued. Interest continues to accrue on employees' account balances at a variable rate tied to the five-year trailing average of five-year U.S. Treasury securities plus 1.5%. The rate has a floor of 3.0% and a ceiling of 5.0%. The 2020 quarterly variable rates ranged from 3.28% to 3.40%.

The projected benefit obligation and fair value of plan assets, respectively, were $24 million and $38 million at December 31, 2020 and $25 million and $36 million at December 31, 2019. The net periodic benefit credit was $1.3 million for December 31, 2020, $815 thousand for December 31, 2019 and $583 thousand for December 31, 2018. Total expected future benefit payments related to the Pension Plan were $26.6 million at December 31, 2020.

The following table presents the weighted-average assumptions used in the measurement of the Company's net periodic benefit cost as of December 31:


	2020		2019
Discount rate	2.69	%	4.10	%
Expected return on plan assets	5.50	%	5.50	%

Assets of the Pension Plan consist primarily of shares in the Cavanal Hill Active Core Fund. The stated objective of this fund is to provide an attractive total return with a well-balanced mix of equities and bonds. The typical portfolio mix is approximately 60% equities and 40% bonds. The net asset value of shares in the Cavanal Hill Funds is reported daily based on market quotations for the Fund’s securities. Management considers the Fund's recent and long-term performance as indicators when setting the expected return on plan assets. No minimum contribution was required for 2020, 2019 or 2018.

Employee contributions to the Thrift Plan are eligible for Company matching equal to 6% of base compensation, as defined in the plan. The Company-provided matching contribution rates range from 50% for employees with less than 4 years of service to 200% for employees with 15 or more years of service. Additionally, a maximum Company-provided, non-elective annual contribution of up to $750 per participant is provided for employees whose annual base compensation is less than $40,000. Participants may direct investments in their accounts to a variety of options, including a BOK Financial common stock fund and Cavanal Hill funds. Employer contributions, which are invested in accordance with the participant’s investment options, vest over five years. Thrift Plan expenses were $29.9 million for 2020, $27.6 million for 2019 and $25.1 million for 2018.

- Definition

The entire disclosure for retirement benefits.

+ References

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+ Details

Share-Based Compensation Plans

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Share-Based Compensation Plans [Text Block]

Share-Based Compensation Plans

The shareholders and Board of Directors of BOK Financial have approved various share-based compensation plans. An independent compensation committee of the Board of Directors determines the number of awards granted to the Chief Executive Officer and other senior executives. Share-based compensation is granted to other officers and employees as determined by the Chief Executive Officer.

The following table presents stock options outstanding under these plans (in thousands, except for per share data):


	Number	Weighted- Average Exercise Price		Aggregate Intrinsic Value
Options outstanding at:





December 31, 2018	63,058	$	54.89	$	1,163




December 31, 2019	36,100	56.75		1,106




December 31, 2020	17,671	57.35		197
Options vested at:
December 31, 2018	33,573	$	53.09	$	679
December 31, 2019	27,193	57.08		824
December 31, 2020	17,671	57.35		197

No options have been awarded since 2013. At December 31, 2020, the weighted average remaining contractual life of options outstanding was 1.03 years and the weighted average remaining contractual life of vested options was 1.03 years. The aggregate intrinsic value of options exercised was $318 thousand for 2020, $761 thousand for 2019 and $2.3 million for 2018.

The Company also awards restricted stock to certain officers and employees and restricted stock units ("RSUs) to certain executives, (collectively "non-vested shares"). Vesting of all non-vested shares is subject to service requirements. Additionally, vesting of certain non-vested shares is subject to performance criteria based on changes in the Company's earnings per share relative to defined peers. The following represents a summary of the non-vested shares for the three years ended December 31, 2020 (in thousands):


	Restricted Stock			Restricted Stock Units
	Shares	Weighted Average Grant Date Fair Value		Units	Weighted Average Grant Date Fair Value
Non-vested at January 1, 2018	667,103			—
Granted	150,419	$	85.58	—	—
Vested	(242,215)	74.85		—	—
Forfeited	(47,700)	75.68		—	—
Non-vested at December 31, 2018	527,607			—
Granted	145,724	$	76.74	46,689	$	87.40
Vested	(114,201)	61.28		—	—
Forfeited	(131,952)	83.69		—	—
Non-vested at December 31, 2019	427,178			46,689
Granted	236,750	$	83.49	22,980	$	77.36
Vested	(225,527)	83.50		—	—
Forfeited	(18,167)	83.10		—	—
Non-vested at December 31, 2020	420,234			69,669

Compensation expense recognized on non-vested shares totaled $16.0 million for 2020, $15.1 million for 2019 and $3.6 million for 2018. Unrecognized compensation cost of non-vested shares totaled $16.3 million at December 31, 2020. We expect to recognize compensation expense of $10.8 million in 2021, $5.4 million in 2022, and $134 thousand in 2023.

Compensation cost for restricted stock units is variable based on the current fair value of BOK Financial common shares. Vesting of 244,392 non-vested shares may be increased or decreased based on performance criteria defined in the plan documents.

Related Parties

12 Months Ended

Dec. 31, 2020

Related Parties [Text Block]

Related Parties

In compliance with applicable banking regulations, the Company may extend credit to certain executive officers, directors, principal shareholders and their affiliates (collectively referred to as “related parties”) in the ordinary course of business. The Company’s loans to related parties do not involve more than the normal credit risk.

Activity in loans to related parties is summarized as follows (in thousands):


	Year Ended December 31,
	2020		2019
Beginning balance	$	75,189	$	75,265
Advances	498,425		886,610
Payments	(484,958)		(896,643)
Adjustments1	4,284		9,957
Ending balance	$	92,940	$	75,189

1 Adjustments generally consist of changes in status as a related party.

As defined by banking regulations, loan commitments and equity investments from the subsidiary banks to a single affiliate may not exceed 10% of unimpaired capital and surplus while loan commitments and equity investments to all affiliates may not exceed 20% of unimpaired capital and surplus. All loans to affiliates must be fully secured by eligible collateral. At December 31, 2020, loan commitments and equity investments were limited to $416 million to a single affiliate and $832 million to all affiliates. The largest loan commitment and equity investment to a single affiliate was $264 million and the aggregate loan commitments and equity investments to all affiliates were $324 million. The largest outstanding amount to a single affiliate at December 31, 2020 was $4.1 million and the total outstanding amounts to all affiliates were $5.3 million. At December 31, 2019, total loan commitments and equity investments to all affiliates were $392 million and the total outstanding amounts to all affiliates were $5.0 million.

Certain related parties are customers of the Company for services other than loans, including consumer banking, corporate banking, risk management, wealth management, brokerage and trading, or fiduciary/trust services. The Company engages in transactions with related parties in the ordinary course of business in compliance with applicable regulations.

QuikTrip Corporation has entered into a fee sharing agreement with TransFund, BOKF’s electronic funds transfer network (“TransFund”), respecting transactions completed at TransFund automated teller machines placed in QuikTrip locations. In 2020, BOKF paid QuikTrip approximately $10.0 million pursuant to this agreement. A BOK Financial director is Chief Executive Officer, Chairman, and a significant shareholder of QuikTrip Corporation.

Cavanal Hill Investment Management, Inc., a wholly-owned subsidiary of BOKF, NA, is the administrator to and investment advisor for the Cavanal Hill Funds (the "Funds"), a diversified, open-ended investment company established as a business trust under the Investment Company Act of 1940 (the "1940 Act"). BOKF, NA is custodian and Cavanal Hill Distributors, Inc. is distributor for the Funds. The Funds’ products are offered to customers, employee benefit plans, trusts and the general public in the ordinary course of business. Approximately 80% of the Funds’ assets of $3.7 billion are held for the Company's clients. A Company executive officer serves on the Funds' board of trustees and officers of BOKF, NA serve as president and secretary of the Funds. A majority of the members of the Funds’ board of trustees are, however, independent of the Company and the Funds are managed by its board of trustees.

Commitments and Contingent Liabilities	12 Months Ended
Commitments and Contingent Liabilities	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities [Text Block]	Commitments and Contingent Liabilities Litigation Contingencies As a member of Visa, BOK Financial is obligated for a proportionate share of certain covered litigation losses incurred by Visa under a retrospective responsibility plan. A contingent liability was recognized for the Company’s share of Visa’s covered litigation liabilities. Visa funded an escrow account to cover litigation claims, including covered litigation losses under the retrospective responsibility plan, with proceeds from its initial public offering in 2008 and from available cash. BOK Financial currently owns 252,233 Visa Class B shares which are convertible into 409,324 shares of Visa Class A shares after the final settlement of all covered litigation. Class B shares may be diluted in the future if the escrow fund is not adequate to cover future covered litigation costs. No value has been currently assigned to the Class B shares. On June 24, 2015, BOKF, NA received a complaint alleging that an employee had colluded with a bond issuer and an individual in misusing revenues pledged to municipal bonds for which BOKF, NA served as trustee under the bond indenture. The Company conducted an investigation and concluded that employees in one of its Corporate Trust offices had, with respect to a single group of affiliated bond issuances, violated Company policies and procedures by waiving financial covenants, granting forbearances and accepting without disclosure to the bondholders, debt service payments from sources other than pledged revenues. The relationship manager was terminated. The Company reported the circumstances to, and cooperated with an investigation by, the Securities and Exchange Commission ("SEC"). On September 7, 2016, BOKF, NA agreed, and the SEC entered, a consent order finding that BOKF, NA had violated Section 17(a) of the Securities Act of 1933 and Section 10(b) of the Securities Exchange Act and requiring BOKF, NA to disgorge $1,067,721 of fees and pay a civil penalty of $600,000. BOKF, NA disgorged the fees and paid the penalty. On December 28, 2015, in an action brought by the SEC, the United States District Court for the District of New Jersey entered a judgment against the principals involved in issuing the bonds, precluding the principals from denying the alleged violations of the federal securities laws and requiring the principals to pay all outstanding principal, accrued interest, and other amounts required under the bond documents, less the value of the facilities securing repayment of the bonds, subject to oversight by a court appointed monitor (“Payment Plan”). On August 26, 2016, BOKF, NA was sued in the United States District Court for New Jersey by two bondholders in a putative class action on behalf of all holders of the bonds alleging BOKF, NA participated in the fraudulent sale of securities by the principals. The New Jersey Federal District Action remains stayed with no current deadlines pending. On September 14, 2016, BOKF, NA was sued in the District Court of Tulsa County, Oklahoma by 19 bondholders alleging BOKF, NA participated in the fraudulent sale of securities by the principals. The Tulsa County District Court Action is pending on BOKF, NA’s motion to dismiss the plaintiff's Third Amended Petition. On January 8, 2020, the New Jersey District Court entered judgment against the principal individual and his wife for $36,805,051 in principal amount and $10,937,831 in pre-judgment interest. On January 17, 2020, the New Jersey Federal District Court formally terminated the Payment Plan. Management is no longer able to conclude that the individual principal and his wife will be successful in paying the obligations they have to pay the bonds in full but such obligations remain and are not dischargeable in bankruptcy. Beginning September 2020, the SEC filed multiple garnishments on entities either related to or holding assets for the debtor. If the individual principal and his wife do not have the financial ability to pay the bonds in full, a bondholder loss could become probable. Management has been advised by counsel that BOKF, NA has valid defenses to claims of bondholders and that no loss to the company is probable. No provision for losses has been made at this time. BOKF, NA estimates that, upon sale of all remaining collateral securing payment of the bonds, approximately $20 million will remain outstanding. A reasonable estimate cannot be made of the amount of any bondholder loss, though the amount of bondholder loss could be material to the company in the event a loss to the company becomes probable. On March 5, 2018, BOKF, NA was sued in the Fulton, Georgia County District Court by a Wrongful Death Judgment Creditor of one of the operators of a nursing home financed by one of the bonds which are the subject of the litigation discussed above. The judgment is alleged to total approximately $8 million in principal and interest at this time. Plaintiff alleges that BOKF, as Trustee, colluded with the borrower and others to defraud creditors of the nursing home by misleading the public about the solvency of the nursing home. Plaintiff alleges that this conduct has prevented her from collecting on her judgment. On April 19, 2019, the Court granted BOKF, NA's Motion to Dismiss. On May 3, 2019, the plaintiff filed a Motion for Reconsideration which remains pending. BOKF, NA is advised by counsel that BOKF, NA has valid defenses to the plaintiffs’ claims and no loss is probable. On March 14, 2017, BOKF, NA was sued in the United States District Court for the Northern District of Oklahoma by bondholders in a second putative class action representing a different set of municipal securities. The bondholders in this second action alleged two individuals purchased facilities from the principals who are the subject of the SEC New Jersey proceedings by means of the fraudulent sale of $60 million of municipal securities for which BOKF, NA also served as indenture trustee. On December 18, 2020, the action was dismissed with prejudice in exchange for a nominal payment. On March 7, 2017, a plaintiff filed a putative class action in the United States District Court for the Northern District of Texas alleging an extended overdraft fee charged by BOKF, NA is interest and exceeds permitted rates. On September 18, 2018, the District Court dismissed the Texas action and the plaintiff appealed the dismissal to the United States Court of Appeals for the Fifth Circuit which heard argument on October 8, 2019. On August 22, 2018, a plaintiff filed a second putative class action in the United States District Court for New Mexico making the same allegations as the Texas action. The District Court dismissed the plaintiff's action. The plaintiff has appealed to the United States Court of Appeals for the Tenth Circuit. Management is advised by counsel that a loss is not probable in either the now dismissed Texas action or the New Mexico action and that the loss, if any, cannot be reasonably estimated. On March 7, 2020, three former employees sued BOKF, NA, the Plan Committee of the BOKF, NA 401k Plan, and Cavanal Hill Investment Management, Inc., a subsidiary of BOKF, NA, alleging that the Defendants included proprietary investment products as investment options in the BOKF, NA 401k Plan, whose fees were too high and performance too low, for the purpose of earning fees. The action is brought as a putative class action on behalf of all Plan Participants. The action is pending on the defendants' motion to dismiss. Management is advised by counsel that a loss is not probable and that the loss, if any, cannot be reasonably estimated. On May 12, 2020, an accounting firm filed a putative class action in the District Court of Colorado alleging that BOKF, NA and other national banks failed to pay the agents of borrowers making application through the Bank to the Small Business Administration for Paycheck Protection Program (CARES Act) loans. The action has now been dismissed with prejudice by the plaintiff. In the ordinary course of business, BOK Financial and its subsidiaries are subject to legal actions and complaints. Management believes, based upon the opinion of counsel, that the actions and liability or loss, if any, resulting from the final outcomes of the proceedings, will not have a material effect on the Company’s financial condition, results of operations or cash flows. Alternative Investment Commitments The Company sponsors a private equity fund and invests in several tax credit entities and other funds as permitted by banking regulations. Consolidation of these investments is based on the variable interest model. At December 31, 2020, the Company has $290 million in interests in various alternative investments generally consisting of unconsolidated limited partnership interests in entities for which investment return is in the form of low income housing tax credits or other investments in merchant banking activities. The investment balance also includes $94 million in unfunded commitments included in Other liabilities on the Consolidated Balance Sheets. At December 31, 2019, the Company had $259 million in interests in various alternative investments and included $82 million in unfunded commitments in Other liabilities. Other Commitments and Contingencies Cavanal Hill Funds’ assets include U.S. Treasury and government securities money market funds. Assets of these funds consist of highly-rated, short-term obligations of the U.S. Treasury and Agencies. The net asset value of units in these funds was $1.00 at December 31, 2020. An investment in these funds is not insured by the Federal Deposit Insurance Corporation or guaranteed by BOK Financial or any of its subsidiaries. BOK Financial may, but is not obligated to purchase assets from these funds to maintain the net asset value at $1.00. No assets were purchased from the funds in 2020 or 2019. The Federal Reserve Bank requires member banks to maintain certain minimum average cash balances. Member banks may satisfy reserve balance requirements through holdings of vault cash and balances maintained directly with a Federal Reserve Bank. The combined average balance of vault cash and balances held at the Federal Reserve Bank was $727 million for the year ended December 31, 2020 and $618 million for the year ended December 31, 2019.

Earnings Per Share

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Earnings Per Share [Text Block]

Earnings Per Share

The following table presents the computation of basic and diluted earnings per share (dollars in thousands, except per share data):


	Year Ended
	2020		2019		2018
Numerator:
Net income attributable to BOK Financial Corp. shareholders	$	435,030	$	500,758	$	445,646
Less: Earnings allocated to participating securities	2,612		3,227		3,737
Numerator for basic earnings per share – income available to common shareholders	432,418		497,531		441,909
Effect of reallocating undistributed earnings of participating securities	—		—		1
Numerator for diluted earnings per share – income available to common shareholders	$	432,418	$	497,531	$	441,910

Denominator:
Weighted average shares outstanding	70,259,553		71,250,081		67,190,257
Less: Participating securities included in weighted average shares outstanding	418,576		462,381		561,617
Denominator for basic earnings per common share	69,840,977		70,787,700		66,628,640
Dilutive effect of employee stock compensation plans	3,195		14,912		33,633
Denominator for diluted earnings per common share	69,844,172		70,802,612		66,662,273

Basic earnings per share	$	6.19	$	7.03	$	6.63
Diluted earnings per share	$	6.19	$	7.03	$	6.63

Shareholders' Equity

12 Months Ended

Dec. 31, 2020

Stockholders' Equity Note [Abstract]

Shareholders' Equity [Text Block]

Shareholders Equity

Preferred Stock

One billion shares of preferred stock with a par value of $0.00005 per share are authorized. The Series A Preferred Stock has no voting rights except as otherwise provided by Oklahoma corporate law and may be converted into one share of Common Stock for each 36 shares of Series A Preferred Stock at the option of the holder. Dividends are cumulative at an annual rate of ten percent of the $0.06 per share liquidation preference value when declared and are payable in cash. Aggregate liquidation preference is $15 million. No Series A Preferred Stock was outstanding in 2020, 2019 or 2018.

Common Stock

Common stock consists of 2.5 billion authorized shares with a $0.00006 par value. Holders of common shares are entitled to one vote per share at the election of the Board of Directors and on any question arising at any shareholders’ meeting and to receive dividends when and as declared. Additionally, regulations restrict the ability of national banks and bank holding companies to pay dividends.

Subsidiary Bank

The amounts of dividends that BOK Financial’s subsidiary bank can declare and the amounts of loans the subsidiary bank can extend to affiliates are limited by various federal banking regulations and state corporate law. Generally, dividends declared during a calendar year are limited to net profits, as defined, for the year plus retained profits for the preceding two years. Dividends are further restricted by minimum capital requirements.

Regulatory Capital

BOK Financial and the subsidiary bank is subject to various capital requirements administered by the federal banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory and additional discretionary actions by regulators that could have a material effect on BOK Financial's operations. These capital requirements include quantitative measures of assets, liabilities and certain off-balance sheet items. The capital standards are also subject to qualitative judgments by the regulators.

A bank falling below the minimum capital requirements, including the capital conservation buffer, would be subject to regulatory restrictions on capital distributions (including but not limited to dividends and share repurchases) and executive bonus payments. For a banking institution to qualify as well capitalized, Common Equity Tier 1, Tier I, Total and Leverage capital ratios must be at least 6.5%, 8%, 10% and 5%, respectively. Tier I capital consists primarily of common stockholders' equity, excluding unrealized gains or losses on available for sale securities, less goodwill, core deposit premiums and certain other intangible assets. Total capital consists primarily of Tier I capital plus preferred stock, subordinated debt and allowances for credit losses, subject to certain limitations. The subsidiary bank exceeded the regulatory definition of well capitalized as of December 31, 2020 and December 31, 2019.

A summary of regulatory capital minimum requirements and levels follows (dollars in thousands):


	Minimum Capital Requirement	Capital Conservation Buffer	Minimum Capital Requirement Including Capital Conservation Buffer	Well Capitalized Bank Requirement	December 31, 2020				December 31, 2019
Common Equity Tier 1 Capital (to Risk Weighted Assets):
Consolidated	4.50%	2.50%	7.00%	N/A	$	3,881,912	11.95	%	$	3,608,821	11.39	%
BOKF, NA	4.50%	N/A	4.50%	6.50%	3,756,950		11.66	%	3,414,446		10.90	%
Tier I Capital (to Risk Weighted Assets):
Consolidated	6.00%	2.50%	8.50%	N/A	$	3,881,912	11.95	%	$	3,608,821	11.39	%
BOKF, NA	6.00%	N/A	6.00%	8.00%	3,756,950		11.66	%	3,414,446		10.90	%
Total Capital (to Risk Weighted Assets):
Consolidated	8.00%	2.50%	10.50%	N/A	$	4,489,110	13.82	%	$	4,097,087	12.94	%
BOKF, NA	8.00%	N/A	8.00%	10.00%	4,153,347		12.89	%	3,692,010		11.79	%
Leverage (Tier I Capital to Average Assets):
Consolidated	4.00%	N/A	4.00%	N/A	$	3,881,912	8.28	%	$	3,608,820	8.40	%
BOKF, NA	4.00%	N/A	4.00%	5.00%	3,756,950		8.04	%	3,414,446		7.98	%

Accumulated Other Comprehensive Income (Loss)

AOCI includes unrealized gains and losses on available for sale ("AFS") securities and non-credit related unrealized losses on AFS securities for which an other-than-temporary impairment has been recorded in earnings. Unrealized losses on employee benefit plans will be reclassified into income as pension plan costs are recognized over the remaining service period of plan participants. Gains and losses in AOCI are net of deferred income taxes.

A rollforward of the components of accumulated other comprehensive income (loss) is included as follows (in thousands):


	Unrealized Gain (Loss) on
	Available for Sale Securities		Employee Benefit Plans		Total
Balance, December 31, 2017	$	(35,385)	$	(789)	$	(36,174)
Transition adjustment for net unrealized gains on equity securities	(2,709)		—		(2,709)
Net change in unrealized gain (loss)	(46,941)		(1,069)		(48,010)
Reclassification adjustments included in earnings:



Loss on available for sale securities, net	2,801		—		2,801
Other comprehensive income (loss), before income taxes	(44,140)		(1,069)		(45,209)
Federal and state income tax	(11,235)		(272)		(11,507)
Other comprehensive income (loss), net of income taxes	(32,905)		(797)		(33,702)
Balance, December 31, 2018	(70,999)		(1,586)		(72,585)
Net change in unrealized gain (loss)	239,017		2,030		241,047
Reclassification adjustments included in earnings:



Gain on available for sale securities, net	(5,597)		—		(5,597)
Other comprehensive income (loss), before income taxes	233,420		2,030		235,450
Federal and state income tax	57,425		517		57,942
Other comprehensive income (loss), net of income taxes	175,995		1,513		177,508
Balance, December 31, 2019	104,996		(73)		104,923
Net change in unrealized gain (loss)	312,576		1,220		313,796
Reclassification adjustments included in earnings:



Gain on available for sale securities, net	(9,910)		—		(9,910)
Other comprehensive income (loss), before income taxes	302,666		1,220		303,886
Federal and state income tax	72,630		311		72,941
Other comprehensive income (loss), net of income taxes	230,036		909		230,945
Balance, December 31, 2020	$	335,032	$	836	$	335,868

Reportable Segments

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Reportable Segments [Text Block]

Reportable Segments

BOK Financial operates three principal lines of business: Commercial Banking, Consumer Banking and Wealth Management. Commercial Banking includes lending, treasury and cash management services and customer risk management products to small businesses, middle market and larger commercial customers. Commercial Banking also includes the TransFund EFT network. Consumer Banking includes retail lending and deposit services, lending and deposit services to small business customers served through the consumer branch network and all mortgage banking activities. Wealth Management provides fiduciary services, private bank services, insurance and investment advisory services in all markets. Wealth Management also underwrites state and municipal securities and engages in brokerage and trading activities.

In addition to its lines of business, BOK Financial has a Funds Management unit. The primary purpose of this unit is to manage overall liquidity needs and interest rate risk. Each line of business borrows funds from and provides funds to the Funds Management unit as needed to support their operations. Operating results for Funds Management and Other include the effect of interest rate risk positions and risk management activities, securities gains and losses including impairment charges, the provision for credit losses in excess of net loans charged off, tax planning strategies and certain executive compensation costs that are not attributed to the lines of business.

BOK Financial allocates resources and evaluates performance of its lines of business after allocation of funds, actual net credit losses and capital costs. In addition, we measure the performance of our business lines after allocation of certain indirect expenses and taxes on statutory rates. The allocation for the prior comparable periods have been revised on a comparable basis.

The cost of funds borrowed from the Funds Management unit by the operating lines of business is transfer priced at rates that approximate market rates for funds with similar duration. Market rates are generally based on the applicable LIBOR or interest rate swap rates, adjusted for prepayment risk. This method of transfer-pricing funds that support assets of the operating lines of business tends to insulate them from interest rate risk.

The value of funds provided by the operating lines of business to the Funds Management unit is based on rates which approximate the wholesale market rates for funds with similar duration and re-pricing characteristics. Market rates are generally based on LIBOR or interest rate swap rates. The funds credit formula applied to deposit products with indeterminate maturities is established based on their re-pricing characteristics reflected in a combination of the short-term LIBOR rates and a moving average of an intermediate term swap rate, with an appropriate spread applied to both. Shorter duration products are weighted towards the short-term LIBOR rate and longer duration products are weighted towards intermediate swap rates. The expected duration ranges from 30 days for certain rate-sensitive deposits to five years.

Substantially all revenue is from domestic customers. No single external customer accounts for more than 10% of total revenue.

Net loans charged off and provision for credit losses represents net loans charged off as attributed to the lines of business and the provision for credit losses in excess of net charge-offs attributed to Funds Management and Other.

The operations of CoBiz, acquired on October 1, 2018 were allocated to the operating segments in the second quarter of 2019. Prior to April 1, 2019, CoBiz operations were included in Funds Management and other.

Reportable segments reconciliation to the Consolidated Financial Statements for the year ended December 31, 2020 is as follows (in thousands):


	Commercial		Consumer		Wealth Management		Funds Management and Other		BOK Financial Consolidated
Net interest and dividend revenue from external sources	$	714,932	$	78,004	$	130,818	$	184,690	$	1,108,444
Net interest revenue (expense) from internal sources	(126,444)		69,000		(13,528)		70,972		—
Net interest and dividend revenue	588,488		147,004		117,290		255,662		1,108,444
Provision for credit losses	69,475		2,805		(209)		150,521		222,592
Net interest and dividend revenue after provision for credit losses	519,013		144,199		117,499		105,141		885,852
Other operating revenue	187,361		243,719		398,834		14,035		843,949
Other operating expense	258,903		233,425		325,608		348,001		1,165,937
Net direct contribution	447,471		154,493		190,725		(228,825)		563,864
Gain (loss) on financial instruments, net	193		95,344		4		(95,541)		—
Change in fair value of mortgage servicing rights	—		(79,524)		—		79,524		—
Gain (loss) on repossessed assets, net	(2,677)		276		—		2,401		—
Corporate expense allocations	24,862		42,638		35,331		(102,831)		—
Net income before taxes	420,125		127,951		155,398		(139,610)		563,864
Federal and state income taxes	114,120		32,591		39,770		(57,688)		128,793
Net income	306,005		95,360		115,628		(81,922)		435,071
Net income attributable to non-controlling interests	—		—		—		41		41
Net income attributable to BOK Financial Corp. shareholders	$	306,005	$	95,360	$	115,628	$	(81,963)	$	435,030

Average assets	$	26,994,075	$	9,842,125	$	15,695,646	$	(3,827,456)	$	48,704,390

Reportable segments reconciliation to the Consolidated Financial Statements for the year ended December 31, 2019 is as follows (in thousands):


	Commercial		Consumer		Wealth Management		Funds Management and Other		BOK Financial Consolidated
Net interest and dividend revenue from external sources	$	919,148	$	99,679	$	61,277	$	32,775	$	1,112,879
Net interest revenue (expense) from internal sources	(242,907)		95,775		38,815		108,317		—
Net interest and dividend revenue	676,241		195,454		100,092		141,092		1,112,879
Provision for credit losses	39,011		6,271		(308)		(974)		44,000
Net interest and dividend revenue after provision for credit losses	637,230		189,183		100,400		142,066		1,068,879
Other operating revenue	170,412		187,500		341,389		(4,931)		694,370
Other operating expense	252,459		230,916		277,267		371,739		1,132,381
Net direct contribution	555,183		145,767		164,522		(234,604)		630,868
Gain (loss) on financial instruments, net	106		30,375		2		(30,483)		—
Change in fair value of mortgage servicing rights	—		(53,517)		—		53,517		—
Gain (loss) on repossessed assets, net	331		496		—		(827)		—
Corporate expense allocations	43,055		47,169		36,239		(126,463)		—
Net income before taxes	512,565		75,952		128,285		(85,934)		630,868
Federal and state income taxes	137,759		19,346		32,954		(59,876)		130,183
Net income	374,806		56,606		95,331		(26,058)		500,685
Net loss attributable to non-controlling interests	—		—		—		(73)		(73)
Net income attributable to BOK Financial Corp. shareholders	$	374,806	$	56,606	$	95,331	$	(25,985)	$	500,758

Average assets	$	22,807,589	$	9,301,341	$	10,204,426	$	(219,009)	$	42,094,347

Reportable segments reconciliation to the Consolidated Financial Statements for the year ended December 31, 2018 is as follows (in thousands):


	Commercial		Consumer		Wealth Management		Funds Management and Other		BOK Financial Consolidated
Net interest and dividend revenue from external sources	$	726,855	$	83,231	$	81,528	$	93,253	$	984,867
Net interest revenue (expense) from internal sources	(159,954)		73,448		31,480		55,026		—
Net interest and dividend revenue	566,901		156,679		113,008		148,279		984,867
Provision for credit losses	30,358		5,143		(288)		(27,213)		8,000
Net interest and dividend revenue after provision for credit losses	536,543		151,536		113,296		175,492		976,867
Other operating revenue	162,701		178,123		296,369		(20,409)		616,784
Other operating expense	202,095		231,075		257,650		337,346		1,028,166
Net direct contribution	497,149		98,584		152,015		(182,263)		565,485
Gain (loss) on financial instruments, net	26		(25,021)		7		24,988		—
Change in fair value of mortgage servicing rights	—		4,668		—		(4,668)		—
Gain (loss) on repossessed assets, net	(6,532)		247		—		6,285		—
Corporate expense allocations	36,670		44,398		35,920		(116,988)		—
Net income before taxes	453,973		34,080		116,102		(38,670)		565,485
Federal and state income taxes	120,458		8,681		30,075		(40,153)		119,061
Net income	333,515		25,399		86,027		1,483		446,424
Net income attributable to non-controlling interests	—		—		—		778		778
Net income attributable to BOK Financial Corp. shareholders	$	333,515	$	25,399	$	86,027	$	705	$	445,646

Average assets	$	18,432,035	$	8,303,263	$	8,447,784	$	(245,552)	$	34,937,530

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Fees and Commission Revenue (Notes)

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Abstract]

Fees and Commissions Revenue [Text Block]

Fees and Commissions Revenue

Fees and commissions revenue by reportable segment and primary service line is as follows for the year ended December 31, 2020.


	Commercial		Consumer		Wealth Management		Funds Management and Other		Consolidated		Out of Scope1		In Scope2
Trading revenue	$	—	$	—	$	144,299	$	—	$	144,299	$	144,299	$	—
Customer hedging revenue	22,767		—		395		(413)		22,749		22,749		—
Retail brokerage revenue	—		—		15,690		—		15,690		—		15,690
Insurance brokerage revenue	—		—		12,702		—		12,702		—		12,702
Investment banking revenue	9,183		—		17,391		(181)		26,393		8,530		17,863
Brokerage and trading revenue	31,950		—		190,477		(594)		221,833		175,578		46,255
TransFund EFT network revenue	75,363		3,058		(56)		5		78,370		—		78,370
Merchant services revenue	9,172		60		—		—		9,232		—		9,232
Corporate card revenue	2,362		—		75		143		2,580		—		2,580
Transaction card revenue	86,897		3,118		19		148		90,182		—		90,182
Personal trust revenue	—		—		84,759		—		84,759		—		84,759
Corporate trust revenue	—		—		19,308		—		19,308		—		19,308
Institutional trust & retirement plan services revenue	—		—		46,253		—		46,253		—		46,253
Investment management services and other	—		—		17,290		(165)		17,125		—		17,125
Fiduciary and asset management revenue	—		—		167,610		(165)		167,445		—		167,445
Commercial account service charge revenue	44,489		1,654		2,282		(4)		48,421		—		48,421
Overdraft fee revenue	132		21,679		74		7		21,892		—		21,892
Check card revenue	—		21,355		—		—		21,355		—		21,355
Automated service charge and other deposit fee revenue	311		4,749		74		3		5,137		—		5,137
Deposit service charges and fees	44,932		49,437		2,430		6		96,805		—		96,805
Mortgage production revenue	—		125,848		—		—		125,848		125,848		—
Mortgage servicing revenue	—		58,249		—		(1,737)		56,512		56,512		—
Mortgage banking revenue	—		184,097		—		(1,737)		182,360		182,360		—
Other revenue	23,340		8,902		38,693		(19,240)		51,695		39,092		12,603
Total fees and commissions revenue	$	187,119	$	245,554	$	399,229	$	(21,582)	$	810,320	$	397,030	$	413,290

1 Out of scope revenue generally relates to financial instruments or contractual rights and obligations within the scope of other applicable accounting guidance.

2 In scope revenue represents revenue subject to FASB ASC Topic 606, Revenue from Contracts with Customers.

Fees and commissions revenue by reportable segment and primary service line is as follows for the year ended December 31, 2019.


	Commercial		Consumer		Wealth Management		Funds Management and Other		Consolidated		Out of Scope1		In Scope2
Trading revenue	$	—	$	—	$	88,558	$	—	$	88,558	$	88,558	$	—
Customer hedging revenue	8,422		—		9,667		852		18,941		18,941		—
Retail brokerage revenue	—		—		16,251		(115)		16,136		—		16,136
Insurance brokerage revenue	—		—		10,131		3,730		13,861		—		13,861
Investment banking revenue	10,136		—		12,194		—		22,330		8,678		13,652
Brokerage and trading revenue	18,558		—		136,801		4,467		159,826		116,177		43,649
TransFund EFT network revenue	73,479		3,924		(82)		3		77,324		—		77,324
Merchant services revenue	8,607		56		—		123		8,786		—		8,786
Corporate card revenue	1,072		—		32		2		1,106		—		1,106
Transaction card revenue	83,158		3,980		(50)		128		87,216		—		87,216
Personal trust revenue	—		—		81,763		—		81,763		—		81,763
Corporate trust revenue	—		—		24,635		—		24,635		—		24,635
Institutional trust & retirement plan services revenue	—		—		45,084		—		45,084		—		45,084
Investment management services and other	—		—		23,993		1,550		25,543		—		25,543
Fiduciary and asset management revenue	—		—		175,475		1,550		177,025		—		177,025
Commercial account service charge revenue	42,251		1,713		2,137		1,804		47,905		—		47,905
Overdraft fee revenue	313		35,134		138		(229)		35,356		—		35,356
Check card revenue	—		21,865		—		165		22,030		—		22,030
Automated service charge and other deposit fee revenue	823		6,155		168		48		7,194		—		7,194
Deposit service charges and fees	43,387		64,867		2,443		1,788		112,485		—		112,485
Mortgage production revenue	—		42,724		—		(4)		42,720		42,720		—
Mortgage servicing revenue	—		66,692		—		(1,871)		64,821		64,821		—
Mortgage banking revenue	—		109,416		—		(1,875)		107,541		107,541		—
Other revenue	23,564		9,733		26,664		(1,853)		58,108		39,428		18,680
Total fees and commissions revenue	$	168,667	$	187,996	$	341,333	$	4,205	$	702,201	$	263,146	$	439,055

1 Out of scope revenue generally relates to financial instruments or contractual rights and obligations within the scope of other applicable accounting guidance.

2 In scope revenue represents revenue subject to FASB ASC Topic 606, Revenue from Contracts with Customers.

Fees and commissions revenue by reportable segment and primary service line is as follows for the year ended December 31, 2018.


	Commercial		Consumer		Wealth Management		Funds Management and Other		Consolidated		Out of Scope1		In Scope2
Trading revenue	$	—	$	—	$	28,077	$	—	$	28,077	$	28,077	$	—
Customer hedging revenue	7,748		—		27,512		3,574		38,834		38,834		—
Retail brokerage revenue	—		—		19,030		(1,078)		17,952		—		17,952
Insurance brokerage revenue	—		—		—		4,198		4,198		—		4,198
Investment banking revenue	7,628		—		11,634		—		19,262		6,380		12,882
Brokerage and trading revenue	15,376		—		86,253		6,694		108,323		73,291		35,032
TransFund EFT network revenue	72,280		4,017		(82)		6		76,221		—		76,221
Merchant services revenue	7,666		59		—		79		7,804		—		7,804
Corporate card revenue	—		—		—		—		—		—		—
Transaction card revenue	79,946		4,076		(82)		85		84,025		—		84,025
Personal trust revenue	—		—		96,839		—		96,839		—		96,839
Corporate trust revenue	—		—		22,292		—		22,292		—		22,292
Institutional trust & retirement plan services revenue	—		—		44,400		76		44,476		—		44,476
Investment management services and other	—		—		19,729		1,367		21,096		—		21,096
Fiduciary and asset management revenue	—		—		183,260		1,443		184,703		—		184,703
Commercial account service charge revenue	41,931		1,445		2,331		1,565		47,272		—		47,272
Overdraft fee revenue	370		36,177		134		(145)		36,536		—		36,536
Check card revenue	—		20,967		—		339		21,306		—		21,306
Automated service charge and other deposit fee revenue	282		6,621		62		74		7,039		—		7,039
Deposit service charges and fees	42,583		65,210		2,527		1,833		112,153		—		112,153
Mortgage production revenue	—		31,690		—		—		31,690		31,690		—
Mortgage servicing revenue	—		67,980		—		(1,883)		66,097		66,097		—
Mortgage banking revenue	—		99,670		—		(1,883)		97,787		97,787		—
Other revenue	24,044		9,218		24,507		(1,584)		56,185		38,306		17,879
Total fees and commissions revenue	$	161,949	$	178,174	$	296,465	$	6,588	$	643,176	$	209,384	$	433,792

1 Out of scope revenue generally relates to financial instruments or contractual rights and obligations within the scope of other applicable accounting guidance.

2 In scope revenue represents revenue subject to FASB ASC Topic 606, Revenue from Contracts with Customers.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-URI http://asc.fasb.org/topic&trid=49130388

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130551-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130556-203045

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130550-203045

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130558-203045

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

+ Details

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements [Text Block]

Fair Value Measurements

Fair value is defined by applicable accounting guidance as the price to sell an asset or transfer a liability in an orderly transaction between market participants in the principal market for the given asset or liability at the measurement date based on market conditions at that date. An orderly transaction assumes exposure to the market for a customary period for marketing activities prior to the measurement date and not a forced liquidation or distressed sale. Certain assets and liabilities are recorded in the Company’s financial statements at fair value. Some are recorded on a recurring basis and some on a non-recurring basis.

For some assets and liabilities, observable market transactions and market information might be available. For other assets and liabilities, observable market transactions and market information might not be available. A hierarchy for fair value has been established which categorizes into three levels the inputs to valuation techniques used to measure fair value. The three levels are as follows:

Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) - fair value is based on unadjusted quoted prices in active markets for identical assets or liabilities.

Significant Other Observable Inputs (Level 2) - fair value is based on significant other observable inputs which are generally determined based on a single price for each financial instrument provided to us by an applicable third-party pricing service and is based on one or more of the following:

•Quoted prices for similar, but not identical, assets or liabilities in active markets;

•Quoted prices for identical or similar assets or liabilities in inactive markets;

•Inputs other than quoted prices that are observable, such as interest rate and yield curves, volatilities, prepayment speeds, loss severities, credit risks and default rates;

•Other inputs derived from or corroborated by observable market inputs.

Significant Unobservable Inputs (Level 3) - fair value is based upon model-based valuation techniques for which at least one significant assumption is not observable in the market.

Transfers between levels are recognized as of the end of the reporting period. There were no transfers in or out of quoted prices in active markets for identical instruments to significant other observable inputs or significant unobservable inputs during the year ended December 31, 2020 and 2019, respectively. Transfers between significant other observable inputs and significant unobservable inputs during the year ended December 31, 2020 and 2019 are included in the summary of changes in recurring fair values measured using unobservable inputs.

The underlying methods used by the third-party pricing services are considered in determining the primary inputs used to determine fair values. Management has evaluated the methodologies employed by the third-party pricing services by comparing the price provided by the pricing service with other sources, including brokers' quotes, sales or purchases of similar instruments and discounted cash flows to establish a basis for reliance on the pricing service values. Significant differences between the pricing service provided value and other sources are discussed with the pricing service to understand the basis for their values. Based on all observable inputs, management may adjust prices obtained from third-party pricing services to more appropriately reflect the prices that would be received to sell assets or paid to transfer liabilities in orderly transactions in the current market. No significant adjustments were made to prices provided by third-party pricing services at December 31, 2020 and 2019.

Assets and Liabilities Measured at Fair Value on a Recurring Basis

The fair value of financial assets and liabilities that are measured on a recurring basis is as follows as of December 31, 2020 (in thousands):


	Total		Quoted Prices in Active Markets for Identical Instruments		Significant Other Observable Inputs		Significant Unobservable Inputs
Assets:
Trading securities:
U.S. government securities	$	9,183	$	4,999	$	4,184	$	—
Residential agency mortgage-backed securities	4,669,148		—		4,669,148		—
Municipal securities	19,172		—		19,172		—

Other trading securities	10,472		—		10,472		—
Total trading securities	4,707,975		4,999		4,702,976		—
Available for sale securities:
U.S. Treasury	508		508		—		—
Municipal securities	167,979		—		167,979		—
Residential agency mortgage-backed securities	9,340,471		—		9,340,471		—
Residential non-agency mortgage-backed securities	32,770		—		32,770		—
Commercial agency mortgage-backed securities	3,508,465		—		3,508,465		—
Other debt securities	472		—		—		472
Total available for sale securities	13,050,665		508		13,049,685		472



Fair value option securities — Residential agency mortgage-backed securities	114,982		—		114,982		—
Residential mortgage loans held for sale1	252,316		—		245,299		7,017
Mortgage servicing rights, net2	101,172		—		—		101,172
Derivative contracts, net of cash margin3	810,688		10,780		799,908		—
Liabilities:
Derivative contracts, net of cash margin3	405,779		—		405,779		—

1Residential mortgage loans held for sale measured at fair value on a recurring basis using significant unobservable inputs (Level 3) consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards and are valued at 94.57% of the unpaid principal balance.

2A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 7, Mortgage Banking Activities.

3See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts in asset positions that were valued based on quoted prices in active markets for identical instruments (Level 1) are primarily exchange-traded interest rate derivative contracts. Derivative contracts in liability positions that were valued using quoted prices in active markets for identical instruments are exchange-traded interest rate, energy and agricultural derivative contracts, fully offset by cash margin.

The fair value of financial assets and liabilities that are measured on a recurring basis is as follows as of December 31, 2019 (in thousands):


	Total		Quoted Prices in Active Markets for Identical Instruments		Significant Other Observable Inputs		Significant Unobservable Inputs
Assets:
Trading securities:
U.S. government securities	$	44,264	$	—	$	44,264	$	—
Residential agency mortgage-backed securities	1,504,651		—		1,504,651		—
Municipal securities	26,196		—		26,196		—
Asset-backed securities	14,084		—		14,084		—
Other trading securities	34,726		—		34,726		—
Total trading securities	1,623,921		—		1,623,921		—
Available for sale securities:
U.S. Treasury	1,600		1,600		—		—
Municipal securities	1,861		—		1,861		—
Residential agency mortgage-backed securities	8,046,096		—		8,046,096		—
Residential non-agency mortgage-backed securities	41,609		—		41,609		—
Commercial agency mortgage-backed securities	3,178,005		—		3,178,005		—
Other debt securities	472		—		—		472
Total available for sale securities	11,269,643		1,600		11,267,571		472
Fair value option securities:
U.S. Treasury	9,917		9,917		—		—
Residential agency mortgage-backed securities	1,088,660		—		1,088,660		—
Total fair value option securities	1,098,577		9,917		1,088,660		—
Residential mortgage loans held for sale1	182,271		—		173,958		8,313
Mortgage servicing rights, net2	201,886		—		—		201,886
Derivative contracts, net of cash margin3	323,375		8,944		314,431		—
Liabilities:
Derivative contracts, net of cash margin3	251,128		—		251,128		—

1Residential mortgage loans held for sale measured at fair value on a recurring basis using significant unobservable inputs (Level 3) consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards and are valued at 95.23% of the unpaid principal balance.

2A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 7, Mortgage Banking Activities.

3See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts based on quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate and energy derivative contracts, net of cash margin. Derivative contracts in liability positions that were valued using quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate and agricultural contracts, fully offset by cash margin.

Following is a description of the Company's valuation methodologies used for assets and liabilities measured on a recurring basis:

Securities

The fair values of trading, available for sale and fair value option securities are based on quoted prices for identical instruments in active markets, when available. If quoted prices for identical instruments are not available, fair values are based on significant other observable inputs such as quoted prices of comparable instruments or interest rates and credit spreads, yield curves, volatilities, prepayment speeds and loss severities.

The fair value of certain available for sale and held-to-maturity municipal and other debt securities may be based on significant unobservable inputs. These significant unobservable inputs include limited observed trades, projected cash flows, current credit rating of the issuers and, when applicable, the insurers of the debt and observed trades of similar debt. Discount rates are primarily based on reference to interest rate spreads on comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies adjusted for a lack of trading volume. Significant unobservable inputs are developed by investment securities professionals involved in the active trading of similar securities. A summary of significant inputs used to value these securities follows. A management committee composed of senior members from the Company's Capital Markets, Risk Management and Finance departments assess the appropriateness of these inputs quarterly.

Derivatives

All derivative instruments are carried on the balance sheet at fair value. Fair values for exchange-traded contracts are based on quoted prices. Fair values for over-the-counter interest rate, commodity and foreign exchange contracts are based on valuations provided either by third-party dealers in the contracts, quotes provided by independent pricing services, or a third-party provided pricing model that uses significant other observable market inputs.

Credit risk is considered in determining the fair value of derivative instruments. Management determines fair value adjustments based on various risk factors including but not limited to counterparty credit rating or equivalent loan grading, derivative contract notional size, price volatility of the underlying commodity, duration of the derivative contracts and expected loss severity. Expected loss severity is based on historical losses for similarly risk graded commercial loan customers. Decreases in counterparty credit rating or grading and increases in price volatility and expected loss severity all tend to increase the credit quality adjustment which reduces the fair value of asset contracts.

We also consider our own credit risk in determining the fair value of derivative contracts. Changes in our credit rating would affect the fair value of our derivative liabilities. In the event of a credit downgrade, the fair value of our derivative liabilities would increase.

Residential Mortgage Loans Held for Sale

Residential mortgage loans held for sale are carried on the balance sheet at fair value. The fair values of conforming residential mortgage loans held for sale are based upon quoted market prices of such loans sold in securitization transactions, including related unfunded loan commitments. The fair value of mortgage loans that are unable to be sold to U.S. government agencies is determined using quoted prices of loans that are sold in securitization transactions with a liquidity discount applied.

Fair Value of Assets and Liabilities Measured on a Non-Recurring Basis

Assets measured at fair value on a non-recurring basis include pension plan assets, which are based on quoted prices in active markets for identical instruments, collateral for certain impaired loans and real property and other assets acquired to satisfy loans, which are based primarily on comparisons to completed sales of similar assets.

The following represents the carrying value of assets measured at fair value on a non-recurring basis and related losses recorded during the year. The carrying value represents only those assets with the balance sheet date for which the fair value was adjusted during the year:


	Carrying Value at December 31, 2020						Fair Value Adjustments for the Year Ended December 31, 2020 Recognized In:
	Quoted Prices in Active Markets for Identical Instruments		Significant Other Observable Inputs		Significant Unobservable Inputs		Gross charge-offs against allowance for loan losses		Net losses (gains) and expenses of repossessed assets, net
Nonaccrual loans	$	—	$	801	$	20,423	$	39,299	$	—
Real estate and other repossessed assets	—		18,188		2,842		—		(4,602)


	Carrying Value at December 31, 2019						Fair Value Adjustments for the Year Ended December 31, 2019 Recognized In:
	Quoted Prices in Active Markets for Identical Instruments		Significant Other Observable Inputs		Significant Unobservable Inputs		Gross charge-offs against allowance for loan losses		Net losses (gains) and expenses of repossessed assets, net
Nonaccrual loans	$	—	$	41	$	55,665	$	31,305	$	—
Real estate and other repossessed assets	—		5,986		1,551		—		(461)

The fair value of collateral-dependent nonaccruing loans and real estate and other repossessed assets and the related fair value adjustments are generally based on unadjusted third-party appraisals. Our appraisal review policies require appraised values to be supported by observed inputs derived principally from or corroborated by observable market data. Appraisals that are not based on observable inputs or that require significant adjustments or fair value measurements that are not based on third-party appraisals are considered to be based on significant unobservable inputs. Non-recurring fair value measurements of collateral-dependent nonaccruing loans and real estate and other repossessed assets based on significant unobservable inputs are generally due to estimates of current fair values between appraisal dates. Significant unobservable inputs include listing prices for comparable assets, uncorroborated expert opinions or management's knowledge of the collateral or industry. Non-recurring fair value measurements of collateral dependent loans secured by mineral rights are generally determined by our internal staff of engineers on projected cash flows under current market conditions and are based on significant unobservable inputs. Projected cash flows are discounted according to risk characteristics of the underlying oil and gas properties. Assets are evaluated to demonstrate with reasonable certainty that crude oil, natural gas and natural gas liquids can be recovered from known oil and gas reservoirs under existing economic and operating conditions at current prices with existing conventional equipment, operating methods and costs. Significant unobservable inputs are developed by asset management and workout professionals and approved by senior Credit Administration executives.

A summary of quantitative information about Non-recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of December 31, 2020 follows (in thousands):

Quantitative Information about Level 3 Non-recurring Fair Value Measurements

Fair Value

Valuation Technique(s)

Significant Unobservable Input

Range
(Weighted Average)

Nonaccrual loans

$

20,423

Discounted cash flows

Management knowledge of industry and non-real estate collateral including but not limited to recoverable oil & gas reserves, forward looking commodity prices, and estimated operating costs

1% - 91% (23%)1

Real estate and other repossessed assets

2,842

Discounted cash flows

Management knowledge of industry and non-real estate collateral including but not limited to recoverable oil & gas reserves, forward looking commodity prices, and estimated operating costs

N/A

1 Represents fair value as a percentage of the unpaid principal balance.

A summary of quantitative information about Non-recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of December 31, 2019 follows (in thousands):

Quantitative Information about Level 3 Non-recurring Fair Value Measurements

Fair Value

Valuation Technique(s)

Significant Unobservable Input

Range
(Weighted Average)

Nonaccrual loans

$

55,665

Discounted cash flows

Management knowledge of industry and non-real estate collateral including but not limited to recoverable oil & gas reserves, forward looking commodity prices, and estimated operating costs

4% - 94% (55%)1

Real estate and other repossessed assets

1,551

Discounted cash flows

Marketability adjustments off appraised value2

74% - 86% (84%)

1 Represents fair value as a percentage of the unpaid principal balance.

2 Marketability adjustments include consideration of estimated costs to sell which is approximately 10% of the fair value.

The fair value of pension plan assets was approximately $38 million at December 31, 2020 and $36 million at December 31, 2019, determined by significant other observable inputs. Fair value adjustments of pension plan assets along with changes in the projected benefit obligation are recognized in other comprehensive income.

Fair Value of Financial Instruments

The following table presents the carrying values and estimated fair values of all financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring basis or non-recurring (dollars in thousands):


	December 31, 2020
	Carrying Value		Estimated Fair Value		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and due from banks	$	798,757	$	798,757	$	798,757	$	—	$	—
Interest-bearing cash and cash equivalents	381,816		381,816		381,816		—		—
Trading securities:
U.S. government securities	9,183		9,183		4,999		4,184		—
Residential agency mortgage-backed securities	4,669,148		4,669,148		—		4,669,148		—
Municipal securities	19,172		19,172		—		19,172		—

Other trading securities	10,472		10,472		—		10,472		—
Total trading securities	4,707,975		4,707,975		4,999		4,702,976		—
Investment securities:
Municipal securities	229,245		255,270		—		69,404		185,866
Residential agency mortgage-backed securities	8,913		9,790		—		9,790		—
Other debt securities	7,373		7,371		—		7,371		—
Total investment securities	245,531		272,431		—		86,565		185,866
Allowance for credit losses	(688)		—		—		—		—
Investment securities, net of allowance	244,843		272,431		—		86,565		185,866
Available for sale securities:
U.S. Treasury	508		508		508		—		—
Municipal securities	167,979		167,979		—		167,979		—
Residential agency mortgage-backed securities	9,340,471		9,340,471		—		9,340,471		—
Residential non-agency mortgage-backed securities	32,770		32,770		—		32,770		—
Commercial agency mortgage-backed securities	3,508,465		3,508,465		—		3,508,465		—
Other debt securities	472		472		—		—		472
Total available for sale securities	13,050,665		13,050,665		508		13,049,685		472



Fair value option securities — Residential agency mortgage-backed securities	114,982		114,982		—		114,982		—
Residential mortgage loans held for sale	252,316		252,316		—		245,299		7,017
Loans:
Commercial	13,077,535		13,003,383		—		—		13,003,383
Commercial real estate	4,698,538		4,649,763		—		—		4,649,763
Paycheck protection program	1,682,310		1,669,461		—		—		1,669,461
Loans to individuals	3,549,137		3,563,199		—		—		3,563,199
Total loans	23,007,520		22,885,806		—		—		22,885,806
Allowance for loan losses	(388,640)		—		—		—		—
Loans, net of allowance	22,618,880		22,885,806		—		—		22,885,806
Mortgage servicing rights	101,172		101,172		—		—		101,172
Derivative instruments with positive fair value, net of cash margin	810,688		810,688		10,780		799,908		—
Deposits with no stated maturity	34,176,752		34,176,752		—		—		34,176,752
Time deposits	1,967,128		1,976,936		—		—		1,976,936
Other borrowed funds	3,545,356		3,542,489		—		—		3,542,489
Subordinated debentures	276,005		269,544		—		269,544		—
Derivative instruments with negative fair value, net of cash margin	405,779		405,779		—		405,779		—


	December 31, 2019
	Carrying Value		Estimated Fair Value		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and due from banks	$	735,836	$	735,836	$	735,836	$	—	$	—
Interest-bearing cash and cash equivalents	522,985		522,985		522,985		—		—
Trading securities:
U.S. government securities	44,264		44,264		—		44,264		—
Residential agency mortgage-backed securities	1,504,651		1,504,651		—		1,504,651		—
Municipal securities	26,196		26,196		—		26,196		—
Asset-backed securities	14,084		14,084		—		14,084		—
Other trading securities	34,726		34,726		—		34,726		—
Total trading securities	1,623,921		1,623,921		—		1,623,921		—
Investment securities:
Municipal securities	274,535		295,032		—		96,897		198,135
Residential agency mortgage-backed securities	10,676		11,164		—		11,164		—
Other debt securities	8,207		8,206		—		8,206		—
Total investment securities	293,418		314,402		—		116,267		198,135
Available for sale securities:
U.S. Treasury securities	1,600		1,600		1,600		—		—
Municipal securities	1,861		1,861		—		1,861		—
Residential agency mortgage-backed securities	8,046,096		8,046,096		—		8,046,096		—
Residential non-agency mortgage-backed securities	41,609		41,609		—		41,609		—
Commercial agency mortgage-backed securities	3,178,005		3,178,005		—		3,178,005		—
Other debt securities	472		472		—		—		472
Total available for sale securities	11,269,643		11,269,643		1,600		11,267,571		472
Fair value option securities:
U.S. Treasury	9,917		9,917		9,917		—		—
Residential agency mortgage-backed securities	1,088,660		1,088,660		—		1,088,660		—
Total fair value option securities	1,098,577		1,098,577		9,917		1,088,660		—
Residential mortgage loans held for sale	182,271		182,271		—		173,958		8,313
Loans:
Commercial	14,031,650		13,966,221		—		—		13,966,221
Commercial real estate	4,433,783		4,422,717		—		—		4,422,717
Residential mortgage	2,084,172		2,098,093		—		—		2,098,093
Personal	1,201,382		1,202,298		—		—		1,202,298
Total loans	21,750,987		21,689,329		—		—		21,689,329
Allowance for loan losses	(210,759)		—		—		—		—
Loans, net of allowance	21,540,228		21,689,329		—		—		21,689,329
Mortgage servicing rights	201,886		201,886		—		—		201,886
Derivative instruments with positive fair value, net of cash margin	323,375		323,375		8,944		314,431		—
Deposits with no stated maturity	25,403,319		25,403,319		—		—		25,403,319
Time deposits	2,217,849		2,212,467		—		—		2,212,467
Other borrowed funds	8,345,405		8,315,860		—		—		8,315,860
Subordinated debentures	275,923		284,627		—		284,627		—
Derivative instruments with negative fair value, net of cash margin	251,128		251,128		—		251,128		—

Because no market exists for certain of these financial instruments and management does not intend to sell these financial instruments, the fair values shown in the tables above may not represent values at which the respective financial instruments could be sold individually or in the aggregate at the given reporting date.

Fair Value Election

As more fully disclosed in Note 2 and Note 7 to the Consolidated Financial Statements, the Company has elected to carry all securities held as economic hedges against changes in the fair value of mortgage servicing rights and all residential mortgage loans originated for sale at fair value. Changes in the fair value of these financial instruments are recognized in earnings.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Parent Company Only Financial Statements Parent Company Only Financial Statements

12 Months Ended

Dec. 31, 2020

Condensed Financial Information Disclosure [Abstract]

Condensed Financial Information of Parent Company Only Disclosure [Text Block]

Parent Company Only Financial Statements

Summarized financial information for BOK Financial – Parent Company Only follows:

Balance Sheets

(In thousands)


	December 31,
	2020		2019
Assets
Cash and cash equivalents	$	183,805	$	214,779

Loan to bank subsidiary	65,204		65,220
Investment in bank subsidiaries	5,079,336		4,602,977
Investment in non-bank subsidiaries	195,768		216,542
Other assets	24,338		38,082
Total assets	$	5,548,451	$	5,137,600

Liabilities and Shareholders’ Equity
Liabilities:
Other liabilities	$	6,180	$	5,882
Subordinated debentures	276,005		275,923
Total liabilities	282,185		281,805
Shareholders’ equity:
Common stock	5		5
Capital surplus	1,368,062		1,350,995
Retained earnings	3,973,675		3,729,778
Treasury stock	(411,344)		(329,906)
Accumulated other comprehensive income	335,868		104,923
Total shareholders’ equity	5,266,266		4,855,795
Total liabilities and shareholders’ equity	$	5,548,451	$	5,137,600

Statements of Earnings

(In thousands)


	Year Ended December 31,
	2020		2019		2018
Dividends, interest and fees received from bank subsidiaries	$	179,140	$	344,007	$	426,071
Dividends, interest and fees received from non-bank subsidiaries	25,050		9,325		12,800
Other revenue	907		1,036		954

Total revenue	205,097		354,368		439,825
Interest expense	13,944		15,113		9,827
Other operating expense	2,697		2,352		12,110
Total expense	16,641		17,465		21,937
Net income before taxes, other losses, net, and equity in undistributed income of subsidiaries	188,456		336,903		417,888
Other gains (losses), net	1,465		3,310		(3,921)
Net income before taxes and equity in undistributed income of subsidiaries	189,921		340,213		413,967
Federal and state income taxes	(4,502)		(4,516)		(7,078)
Net income before equity in undistributed income of subsidiaries	194,423		344,729		421,045
Equity in undistributed income of bank subsidiaries	276,217		166,797		37,515
Equity in undistributed income of non-bank subsidiaries	(35,610)		(10,768)		(12,914)
Net income attributable to BOK Financial Corp. shareholders	$	435,030	$	500,758	$	445,646

Statements of Cash Flows

(In thousands)


	Year Ended December 31,
	2020		2019		2018
Cash Flows From Operating Activities:
Net income	$	435,030	$	500,758	$	445,646
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed income of bank subsidiaries	(276,217)		(166,797)		(37,515)
Equity in undistributed income of non-bank subsidiaries	35,610		10,768		12,914
Change in other assets	13,760		(5,075)		(1,072)
Change in other liabilities	850		855		(13,434)
Net cash provided by operating activities	209,033		340,509		406,539
Cash Flows From Investing Activities:
Investment in subsidiaries	(14,807)		(19,837)		(31,901)
Acquisitions, net of cash acquired	—		—		(232,680)
Net cash used in investing activities	(14,807)		(19,837)		(264,581)
Cash Flows From Financing Activities:
Issuance of common and treasury stock, net	(4,933)		(7)		(88)
Dividends paid	(144,437)		(143,496)		(127,188)
Repurchase of common stock	(75,830)		(129,483)		(53,465)
Net cash used in financing activities	(225,200)		(272,986)		(180,741)
Net increase (decrease) in cash and cash equivalents	(30,974)		47,686		(38,783)
Cash and cash equivalents at beginning of period	214,779		167,093		205,876
Cash and cash equivalents at end of period	$	183,805	$	214,779	$	167,093
Cash paid for interest	$	14,064	$	15,099	$	11,457

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events The Company evaluated events from the date of the Consolidated Financial Statements on December 31, 2020 through the issuance of those consolidated financial statements included in this Annual Report on Form 10-K. No events were identified requiring recognition in and/or disclosure in the Consolidated Financial Statements.

Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation [Policy Text Block]	The Consolidated Financial Statements of BOK Financial Corporation (“BOK Financial” or “the Company”) have been prepared in conformity with accounting principles generally accepted in the United States ("U.S. GAAP"), including interpretations of U.S. GAAP issued by federal banking regulators and general practices of the banking industry.
Consolidation [Policy Text Block]	The Consolidated Financial Statements include the accounts of BOK Financial and its subsidiaries, principally BOKF, NA, BOK Financial Securities, Inc., BOK Financial Private Wealth, Inc., BOK Financial Insurance, Inc. and Cavanal Hill Distributors, Inc. All significant intercompany transactions are eliminated in consolidation. The Consolidated Financial Statements include the assets, liabilities, non-controlling interests and results of operations of variable interest entities (“VIEs”) when BOK Financial is determined to be the primary beneficiary. Variable interest entities are generally defined as entities that either do not have sufficient equity to finance their activities without support from other parties or whose equity investors lack a controlling financial interest. Determination that the Company is the primary beneficiary considers the power to direct the activities that most significantly impact the variable interest's economic performance and the obligation to absorb losses of the variable interest or the right to receive benefits of the variable interest that could be significant to the variable interest.
Reclassifications [Text Block]	Certain prior year amounts have been reclassified to conform to current year presentation.
Nature of Operations [Text Block]	Nature of Operations BOK Financial, through its subsidiaries, provides a wide range of financial services to commercial and industrial customers, other financial institutions, municipalities, and consumers. These services include depository and cash management; lending and lease financing; mortgage banking; securities brokerage, trading and underwriting; and personal and corporate trust. BOKF, NA operates as Bank of Oklahoma primarily in the Tulsa and Oklahoma City metropolitan areas of the state of Oklahoma and Bank of Texas primarily in the Dallas, Fort Worth and Houston metropolitan areas of the state of Texas. In addition, BOKF, NA does business as BOK Financial in the metropolitan areas of Phoenix, Arizona; Northwest Arkansas; Denver, Colorado; Kansas City, Missouri/Kansas; and as Bank of Albuquerque in Albuquerque, New Mexico. BOKF, NA also operates the TransFund electronic funds network, Cavanal Hill Investment Management, and BOK Financial Asset Management, Inc.
Use of Estimates [Policy Text Block]	Use of Estimates Preparation of BOK Financial's Consolidated Financial Statements requires management to make estimates of future economic activities, including loan collectability, loss contingencies, prepayments and cash flows from customer accounts. These estimates are based upon current conditions and information available to management. Actual results may differ significantly from these estimates.
Acquisitions [Policy Text Block]	Acquisitions Assets and liabilities acquired, including identifiable intangible assets, are recorded at fair value on the acquisition date. The purchase price includes consideration paid at closing and the estimated fair value of contingent consideration that will be paid in the future, subject to achieving defined performance criteria. Premiums and discounts assigned to interest-earning assets and interest-bearing liabilities are amortized over the lives of the acquired assets and liabilities on either an individual instrument or pool basis. Provision for credit losses is recognized for changes in credit quality after the acquisition date. Goodwill is recognized as the excess of the purchase price over the net fair value of assets acquired and liabilities assumed. The Consolidated Statements of Earnings include the results of operations from the acquisition date.
Goodwill and Intangible Assets [Policy Text Block]	Goodwill and Intangible Assets Goodwill and intangible assets generally result from business combinations and are evaluated for each of BOK Financial's reporting units for impairment annually or more frequently if conditions indicate impairment. The evaluation of possible impairment of goodwill and intangible assets involves significant judgment based upon short-term and long-term projections of future performance. Reporting units are defined by the Company as significant lines of business within each operating segment. This definition is consistent with the manner in which the chief operating decision maker assesses the performance of the Company and makes decisions concerning the allocation of resources. The Company qualitatively assesses whether it is more likely than not that the fair value of the reporting units are less than their carrying value, including goodwill. Reporting unit carrying value includes sufficient capital to exceed regulatory requirements. This assessment includes consideration of relevant events and circumstances including but not limited to macroeconomic conditions, industry and market conditions, the financial and stock performance of the Company and other relevant factors. If the Company concludes based on the qualitative assessment that goodwill may be impaired, a quantitative one-step impairment test will be applied to goodwill at all reporting units. The quantitative analysis compares the fair value of the reporting unit with its carrying value, including goodwill. The fair value of each reporting unit is estimated by the discounted future earnings method. Goodwill is considered impaired if the fair value of the reporting unit is less than the carrying value of the reporting unit, including goodwill. Intangible assets are generally composed of customer relationships, naming rights, non-compete agreements and core deposit premiums. They are amortized using accelerated or straight-line methods, as appropriate, over the estimated benefit periods. These periods range from 3 years to 20 years. The net book values of identifiable intangible assets are evaluated for impairment when economic conditions indicate impairment may exist.
Cash Equivalents [Policy Text Block]	Cash Equivalents Due from banks, funds sold (generally federal funds sold for one day), resell agreements (which generally mature within one day to 30 days) and investments in money market funds are considered cash equivalents.
Securities [Policy Text Block]	Securities Securities are identified as trading, investment (held to maturity) or available for sale at the time of purchase based upon the intent of management, liquidity and capital requirements, regulatory limitations and other relevant factors. Trading securities, which are acquired for profit through resale, are carried at fair value with unrealized gains and losses included in current period earnings. Investment securities are carried at amortized cost. Amortization is computed by methods that approximate level yield and is adjusted for changes in prepayment estimates. Securities identified as available for sale are carried at fair value. Unrealized gains and losses are recorded, net of deferred income taxes, as accumulated other comprehensive income in shareholders' equity. Available for sale securities are separately identified as pledged to creditors if the creditor has the right to sell or re-pledge the collateral. The purchase or sale of securities is recognized on a trade date basis. Realized gains and losses on sales of securities are based upon specific identification of the security sold. A receivable or payable is recognized for subsequent transaction settlement. On a quarterly basis, the Company performs separate evaluations of debt investment and available for sale securities for the presence of impairment. We assess whether impairment is present on an individual security basis when the fair value of a debt security is less than the amortized cost. Management determines whether it intends to sell or if it is more likely than not that it will be required to sell impaired securities. This determination considers current and forecasted liquidity requirements and securities portfolio management. If the Company intends to sell or it is more likely than not that it will be required to sell the impaired debt security, a charge is recognized against earnings for the entire unrealized loss. For all impaired debt securities for which there is no intent or expected requirement to sell, the evaluation considers all available evidence to assess whether it is more likely than not that all amounts due would not be collected according to the security's contractual terms and whether there is any impairment attributable to credit-related factors. If an impairment exists, the amount attributed to credit-related factors is measured and an allowance for credit loss is recognized. Declines in fair value that are not recorded in the allowance are recorded in other comprehensive income, net of taxes. BOK Financial may elect to carry certain securities that are not held for trading purposes at fair value with changes in fair value recognized in current period income. These securities are held with the intent that gains or losses will offset changes in the fair value of mortgage servicing rights or other financial instruments. Restricted equity securities represent equity interests the Company is required to hold in the Federal Reserve Banks and Federal Home Loan Banks. Restricted equity securities are carried at cost as these securities do not have a readily determined fair value because ownership of these shares is restricted and they lack a market. The fair value of our securities portfolio is generally based on a single price for each financial instrument provided to us by a third-party pricing service determined by one or more of the following: •Quoted prices for similar, but not identical, assets or liabilities in active markets; •Quoted prices for identical or similar assets or liabilities in inactive markets; •Inputs other than quoted prices that are observable, such as interest rate and yield curves, volatilities, prepayment speeds, loss severities, credit risks and default rates; and •Other inputs derived from or corroborated by observable market inputs. The underlying methods used by the third-party pricing services are considered in determining the primary inputs used to determine fair values. We evaluate the methodologies employed by the third-party pricing services by comparing the price provided by the pricing service with other sources, including brokers' quotes, sales or purchases of similar instruments and discounted cash flows to establish a basis for reliance on the pricing service values. Significant differences between the pricing service provided value and other sources are discussed with the pricing service to understand the basis for their values. Based on all observable inputs, management may adjust prices obtained from third-party pricing services to more appropriately reflect the prices that would be received to sell assets or paid to transfer liabilities in orderly transactions in the current market.
Derivatives Instruments [Policy Text Block]	Derivative Instruments Derivative instruments may be used by the Company as part of its internal risk management programs or may be offered to customers. All derivative instruments are carried at fair value and changes in fair value are generally reported in income as they occur. The determination of fair value of derivative instruments considers changes in interest rates, commodity prices and foreign exchange rates. Fair values for exchange-traded contracts are based on quoted prices in an active market for identical instruments. Fair values for over-the-counter contracts are generated internally using third-party valuation models. Inputs used in third-party valuation models to determine fair values are considered significant other observable inputs. Credit risk is also considered in determining fair value. Deterioration in the credit rating of customers or other counterparties reduces the fair value of asset contracts. Deterioration of our credit rating could decrease the fair value of our derivative liabilities. When bilateral netting agreements or similar agreements exist between the Company and its counterparties that create a single legal claim or obligation to pay or receive the net amount in settlement of the individual derivative contracts, the Company reports derivative assets and liabilities on a net by derivative contract by counterparty basis. Derivative contracts may also require the Company to provide or receive cash margin as collateral for derivative assets and liabilities. Derivative assets and liabilities are reported net of cash margin when certain conditions are met. In addition, derivative contracts executed with customers under Customer Risk Management Programs may be secured by non-cash collateral in conjunction with a credit agreement with that customer. Access to collateral in the event of default is reasonably assured. BOK Financial offers programs that permit its customers to manage various risks, including fluctuations in energy, cattle and other agricultural products, interest rates and foreign exchange rates with derivative contracts. Customers may also manage interest rate risk through interest rate swaps used by the borrower to modify interest rate terms of their loans. Derivative contracts are executed between the customers and BOK Financial. Offsetting contracts are executed between BOK Financial and other selected counterparties to minimize market risk from changes in commodity prices, interest rates or foreign exchange rates. The counterparty contracts are identical to customer contracts, except for a fixed pricing spread or fee paid to BOK Financial as profit and compensation for administrative costs and credit risk which is recognized over the life of the contracts and included in Other Operating Revenue - Brokerage and trading revenue in the Consolidated Statements of Earnings. BOK Financial may offer derivative instruments such as to-be-announced U.S. agency residential mortgage-backed securities to mortgage banking customers to enable them to manage their market risk or to mitigate the Company's market risk of holding trading securities. Changes in the fair value of derivative instruments for trading purposes or used to mitigate the market risk of holding trading securities are included in Other Operating Revenue - Brokerage and trading revenue. BOK Financial may use derivative instruments in managing its interest rate sensitivity, as part of its economic hedge of the changes in the fair value of mortgage servicing rights. Changes in the fair value of derivative instruments used in managing interest rate sensitivity and as part of its economic hedge of changes in the fair value of mortgage servicing rights are included in Other Operating Revenue - Gain (loss) on derivatives, net in the Consolidated Statements of Earnings. BOK Financial also enters into mortgage loan commitments that are considered derivative contracts. Forward sales contracts that have not been designated as hedging instruments are used to economically hedge these mortgage loan commitments as well as mortgage loans held for sale. Mortgage loan commitments, forward sales contracts, and residential mortgage loans held for sale are carried at fair value. Changes in the fair value are reported in Other Operating Revenue - Mortgage banking revenue.
Loans [Policy Text Block]	Loans Loans are either secured or unsecured based on the type of loan and the financial condition of the borrower. Repayment is generally expected from cash flow or proceeds from the sale of selected assets of the borrower. BOK Financial is exposed to risk of loss on loans due to the borrower's financial difficulties, which may arise from any number of factors, including problems within the respective industry or local economic conditions. Access to collateral, in the event of borrower default, is reasonably assured through adherence to applicable lending laws and through sound lending standards and credit review procedures. Accounting policies for all loans, excluding residential mortgage loans guaranteed by U.S. government agencies, are as follows. Interest is accrued at the applicable interest rate on the outstanding principal amount. Loans are placed on nonaccruing status when, in the opinion of management, full collection of principal or interest is uncertain. Internally risk graded loans are individually evaluated for nonaccruing status quarterly. Non-risk graded loans are generally placed on nonaccruing status when 90 days or more past due or within 60 days of being notified of the borrower's bankruptcy filing. Interest previously accrued but not collected is charged against interest income when the loan is placed on nonaccruing status. Payments received on nonaccruing loans are applied to principal or recognized as interest income, according to management's judgment as to the collectability of principal. Loans may be returned to accruing status when, in the opinion of management, full collection of principal and interest, including principal previously charged off, is probable based on improvements in the borrower's financial condition or a sustained period of performance. For loans acquired with no evidence of credit deterioration, discounts are accreted on either an individual basis for loans with unique characteristics or on a pool basis for groups of homogeneous loans. Accretion is discontinued when a loan with an individually attributed discount is placed on nonaccruing status. Loans to borrowers experiencing financial difficulties may be modified in troubled debt restructurings ("TDRs"). TDRs are generally classified as nonaccruing, excluding loans guaranteed by U.S. government agencies. Modifications generally consist of extension of payment terms or interest rate concessions and may result either voluntarily through negotiations with the borrower or involuntarily through court order. Payment deferrals of up to six months are generally considered to be short-term modifications. Generally, principal and accrued but unpaid interest is not voluntarily forgiven. Performing loans may be renewed under the then current collateral, debt service ratio and other underwriting standards. Nonaccruing loans may also be renewed and will remain classified as nonaccruing. Occasionally, loans, other than residential mortgage loans, may be held for sale in order to manage credit concentration. These loans are carried at the lower of cost or fair value with gains or losses recognized in gain (loss) on assets. All loans are charged-off when the loan balance or a portion of the loan balance is no longer supported by the paying capacity of the borrower or when the required cash flow is reduced in a TDR. The charge-off amount is determined through an evaluation of available cash resources and collateral value. Internally risk graded loans are evaluated quarterly and charge-offs are taken in the quarter in which the loss is identified. Non-risk graded loans that are past due between 60 days and 180 days, based on the loan product type, are charged off. Loans to borrowers whose personal obligation has been discharged through Chapter 7 bankruptcy proceedings are charged off within 60 days of notice of the bankruptcy filing, regardless of payment status. Loan origination and commitment fees and direct loan acquisition and origination costs are deferred and amortized as an adjustment to yield over the life of the loan or over the commitment period, as applicable. Amortization does not anticipate loan prepayments. Net unamortized fees are recognized in full at time of payoff. Qualifying residential mortgage loans guaranteed by U.S. government agencies have been sold into GNMA pools. Under certain performance conditions specified in government programs, the Company has the right, but not the obligation to repurchase loans from GNMA pools. These loans no longer qualify for sale accounting and are recognized in the Consolidated Balance Sheets. Guaranteed loans are considered to be impaired because we do not expect to receive all principal and interest based on the loan's contractual terms. A portion of the principal balance continues to be guaranteed; however, interest accrues at a curtailed rate as specified in the programs. The carrying value of these loans is reduced based on an estimate of expected cash flows discounted at the original note rate plus a liquidity spread. Guaranteed loans may be modified in TDRs in accordance with U.S. government agency guidelines. Interest continues to accrue at the modified rate. Guaranteed loans may either be resold into GNMA pools after a performance period specified by the programs or foreclosed and conveyed to the guarantors. Loans are disaggregated into portfolio segments and further disaggregated into classes. The portfolio segment is the level at which the Company develops and documents a systematic method for determining its Allowance for Credit Losses. Classes are based on the risk characteristics of the loans and the Company's method for monitoring and assessing credit risk.
Allowance for Loan Losses and Accrual for Off-Balance Sheet Credit Losses [Policy Text Block]	Allowances for Credit Losses and Accrual for Off-balance Sheet Credit Risk from Unfunded Loans Commitments BOK Financial’s accounting policies have changed significantly with the adoption of CECL as of January 1, 2020. Prior periods are not restated. Prior to January 1, 2020, general allowances and nonspecific allowances were based on incurred credit losses in accordance with accounting policies disclosed in Note 1 of the Consolidated Financial Statements included in the 2019 Form 10-K. The allowance for loan losses and accrual for off-balance sheet credit risk from unfunded loan commitments represent the portion of the amortized cost basis of loans that we do not expect to collect over the asset’s contractual life, considering past events, current conditions, and reasonable and supportable forecasts of future economic conditions. The appropriateness of the allowance for credit losses, including industry and product adjustments, is assessed quarterly by a senior management Allowance Committee. This review is based on an on-going evaluation of the estimated expected credit losses in the portfolio and on unused commitments to provide financing. A well-documented methodology has been developed and is applied by an independent Credit Administration department to assure consistency across the Company. The allowance for loan losses consists of specific allowances attributed to certain individual loans, generally nonaccruing loans, with dissimilar risk characteristics that have not yet been charged down to amounts we expect to recover and general allowances for estimated credit losses on pools of loans that share similar risk characteristics. When full collection of principal or interest is uncertain, the loan’s risk characteristics have changed, and we exclude the loan from the general allowance pool, typically designating it as nonaccruing. For these loans, a specific allowance reflects the expected credit loss. We measure specific allowances for loans excluded from the general allowance pool by an evaluation of estimated future cash flows discounted at the loans initial effective interest rate or the fair value of collateral for certain collateral dependent loans. For a non-collateral dependent loan, the specific allowance is the amount by which the loan’s amortized cost basis exceeds its net realizable value. We measure the specific allowance for collateral dependent loans as the amount by which the loan’s amortized cost basis exceeds its fair value. When repayment is expected to be provided substantially through the sale of collateral, we deduct estimated selling costs from the collateral’s fair value. Generally, third party appraisals that conform to Uniform Standards of Professional Appraisal Practice serve as the basis for the fair value of real property held as collateral. These appraised values are on an “as-is” basis and generally are not adjusted by the Company. We obtain updated appraisals at least annually or more frequently if market conditions indicate collateral values may have declined. For energy loans, our internal staff of engineers generally determines collateral value of mineral rights based on projected cash flows from proven oil and gas reserves under existing economic and operating conditions. For real property held as collateral for other loans, third party appraisals that conform to Uniform Standards of Professional Appraisal Practice generally serve as the basis for the fair value. These appraised values are on an “as-is” basis and generally are not adjusted by the Company. We obtain updated appraisals at least annually or more frequently if market conditions indicate collateral values may have declined. Our special assets staff generally determines the value of other collateral based on projected liquidation cash flows under current market conditions. We evaluate collateral values and available cash resources quarterly. Historical statistics may be used to estimate specific allowances in limited situations, such as when a collateral dependent loan is removed from the general allowance pool near the end of a reporting period until an appraisal of collateral value is received or a full assessment of future cash flows is completed. General allowances estimate expected credit losses on pools of loans sharing similar risk characteristics that are expected to occur over the loan’s estimated remaining life. The loan’s estimated remaining life represents the contractual term adjusted for amortization, estimates of prepayments, and borrower-owned extension options. Approximately 90 percent of the committed dollars in the loan portfolio is risk graded loans with general allowance model inputs that include probability of default, loss given default, and exposure at default. Probability of default is based on the migration of loans from performing to nonperforming using historical life of loan analysis periods. Loss given default is based on the aggregate losses incurred, net of estimated recoveries. Exposure at default represents an estimate of the outstanding amount of credit exposure at the time a default may occur. Charge-off migration is used to calculate the general allowance for the majority of non-risk graded loans to individuals. The expected credit loss on less than 10 percent of the committed dollars in the portfolio is calculated using charge-off migration. The expected credit loss on approximately 1 percent of the committed dollars in the portfolio is calculated using a non-modeled approach. Specifically, the calculation applies a long-term net charge-off rate to the loan balances, adjusted for the weighted average remaining maturity of each portfolio. In estimating the expected credit losses for general allowances on performing risk-graded loans, each portfolio class is assigned relevant economic loss drivers which best explain variations in portfolio net loss rates. The probability of default estimates for each portfolio class are adjusted for current and forecasted economic conditions. The result is applied to the exposure at default and loss given default to calculate the lifetime expected credit loss estimate. Selection of relevant economic loss drivers is re-evaluated periodically and involves statistical analysis as well as management judgment. The unemployment rate factors significantly in the allowance for loan losses calculation, affecting commercial and loans to individuals segments. Other primary factors impacting the commercial portfolio include BBB corporate spreads, real gross domestic product growth rate, and energy commodity prices. The primary commercial real estate variables are vacancy rate and BBB corporate spreads. In addition to the unemployment rate, the forecast for loans to individuals is tied to home price index. The forecasts may include regional economic factors when localized conditions diverge from national conditions. An Economic Forecast Committee, consisting of senior management with members largely independent of the allowance process develops a twelve-month forward-looking forecast for the relevant economic loss drivers. Management develops these forecasts based on external data as well as a view of future economic conditions, which may include adjustments for regional conditions. The forecast includes three economic scenarios and probability weights for each scenario. The base forecast represents management's view of the most likely outcome, while the downside forecast reflects reasonably possible worsening economic conditions, and the upside forecast projects reasonably possible improving conditions. At the end of the one-year reasonable and supportable forecast period, we transition from shorter-term expected losses to long-term loss averages for the loan’s estimated remaining life. The difference between short-term loss forecasts and long-term loss averages is run-off over the reversion horizon, up to three years, depending on the forecasted economic scenarios. General allowances also consider the estimated impact of factors that are not captured in the modeled results or historical experience. These factors may increase or decrease modeled results by amounts determined by the Allowance Committee. Factors not captured in modeled results or historical experience may include for example, new lines of business, market conditions that have not been previously encountered, observed changes in credit risk that are not yet reflected in macro-economic factors, or economic conditions that impact loss given default assumptions. The accrual for off-balance sheet credit risk is maintained at a level that is appropriate to cover estimated losses associated with credit instruments that are not currently recognized as assets such as loan commitments, standby letters of credit or guarantees that are not unconditionally cancellable by the bank. This accrual is included in other liabilities in the Consolidated Balance Sheets. The appropriateness of the accrual is determined in the same manner as the allowance for loan losses, with the added consideration of commitment usage over the remaining life for those loans that the bank can not unconditionally cancel. A provision for credit losses is charged against or credited to earnings in amounts necessary to maintain an appropriate Allowance for Credit Losses. Recoveries of loans previously charged off are added to the allowance when received.
Real Estate and Other Repossessed Assets [Policy Text Block]	Real Estate and Other Repossessed Assets Real estate and other repossessed assets are acquired in partial or total forgiveness of loans. These assets are initially recognized at cost, which is determined by fair value at date of foreclosure less estimated disposal costs. They are subsequently carried at the lower of cost or current fair value less estimated disposal costs. Decreases in fair value below cost are recognized as asset-specific valuation allowances which may be reversed when supported by future increases in fair value. Subsequent increases in fair value may be used to reduce the allowance but not below zero. Fair values of real estate are based on “as is” appraisals which are updated at least annually or more frequently for certain asset types or assets located in certain distressed markets. Fair values based on appraisals are generally considered to be based on significant other observable inputs. The Company also considers decreases in listing price and other relevant information in quarterly evaluations and reduces the carrying value of real estate and other repossessed assets when necessary. Fair values based on list prices and other relevant information are generally considered to be based on significant unobservable inputs. Additional costs incurred to complete real estate and other repossessed assets may increase the carrying value, up to current fair value based on “as completed” appraisals. The fair value of mineral rights included in repossessed assets is generally determined by our internal staff of engineers based on projected cash flows from proven oil and gas reserves under existing economic and operating conditions. The value of other repossessed assets is generally determined by our special assets staff based on projected liquidation cash flows under current market conditions. Income generated by these assets is recognized as received. Operating expenses are recognized as incurred. Gains or losses on sales of real estate and other repossessed assets are based on the cash proceeds received less the cost basis of the asset, net of any valuation allowances. The estimated disposal costs of real estate and other repossessed assets are evaluated by the Company on an annual basis based on actual results.
Transfers of Financial Assets [Policy Text Block]	Transfers of Financial Assets BOK Financial regularly transfers financial assets as part of its mortgage banking activities and periodically may transfer other financial assets. Transfers are recorded as sales when the criteria for surrender of control are met. The Company has elected to carry certain residential mortgage loans held for sale at fair value under the fair value option. Changes in fair value are recognized in net income as they occur. These loans are reported separately in the Consolidated Balance Sheets and changes in fair value are recorded in Other Operating Revenue - Mortgage banking revenue in the Consolidated Statements of Earnings. Fair value of conforming residential mortgage loans that will be sold to U.S. government agencies is based on sales commitments or market quotes considered Level 2 inputs. Fair value of mortgage loans that are unable to be sold to U.S. government agencies is based on Level 3 inputs using quoted prices of loans that are sold in securitization transactions with a liquidity discount applied. The fair value is corroborated with an independent third party on at least an annual basis. BOK Financial retains a repurchase obligation under underwriting representations and warranties related to residential mortgage loans transferred and generally retains the right to service the loans. These are not credit obligations. The Company may incur a recourse obligation in limited circumstances. Separate accruals are recognized in Other liabilities in the Consolidated Balance Sheets for repurchase and recourse obligations. These reserves reflect the estimated amount of probable loss the Company will incur as a result of repurchasing a loan, indemnifications, and other settlement resolutions. Repurchases of loans with an origination defect that are also credit impaired are considered collateral dependent and are initially recognized at net realizable value (appraised value less the cost to sell). The difference between unpaid principal balance and net realizable value is not accreted. Repurchases of loans with an origination defect that are not credit impaired are carried at fair value as of the repurchase date. Interest income continues to accrue on these loans and the discount is accreted over the estimated life of the loan. The Company may also choose to purchase GNMA loans once certain mandated delinquency criteria are met. The loans that are eligible and are chosen to be repurchased are initially recognized at fair value based on expected cash flows discounted using the average agency guaranteed debenture rates, average actual principal loss rates and liquidity premium.
Mortgage Servicing Rights [Policy Text Block]	Mortgage Servicing Rights Mortgage servicing rights may be purchased or may be recognized when mortgage loans are originated and sold with servicing rights retained. All mortgage servicing rights are carried at fair value. Changes in the fair value are recognized in earnings as they occur. Mortgage servicing rights are not traded in active markets. A cash flow model is used to determine fair value. Key assumptions and estimates, including projected prepayment speeds and assumed servicing costs, earnings on escrow deposits, ancillary income and discount rates, used by this model are based on current market sources. Assumptions used to value mortgage servicing rights are considered significant unobservable inputs. A separate third-party model is used to estimate prepayment speeds based on interest rates, housing turnover rates, estimated loan curtailment, anticipated defaults and other relevant factors. The prepayment model is updated daily for changes in market conditions and adjusted to better correlate with actual performance of BOK Financial's servicing portfolio. Fair value estimates from outside sources are received at least annually to corroborate the results of the valuation model.
Premises and Equipment [Policy Text Block]	Premises and Equipment Premises and equipment are carried at cost, including capitalized interest when appropriate, less accumulated depreciation and amortization. Depreciation and amortization are computed on a straight-line basis over the estimated useful lives of the assets or, for leasehold improvements, over the shorter of the estimated useful lives or remaining lease terms. Useful lives range from 5 years to 40 years for buildings and improvements, 3 years to 10 years for software and related implementation costs, and 3 years to 10 years for furniture and equipment. Construction in progress represents facilities construction and data processing systems projects underway that have not yet been placed into service. Depreciation and amortization begin once the assets are placed into service. Repair and maintenance costs, including software maintenance and enhancement costs, are charged to expense as incurred. Software licensing costs are generally charged to expense as incurred. Software licensing costs are capitalized if the contractual right to take possession of the software exists and it is feasible to take possession without significant penalty. Capitalized costs are amortized over the shorter of the estimated useful life of the software or remaining contractual life of the license. Premises no longer used by the Company are transferred to real estate and other repossessed assets. The transferred amount is the lower of cost less accumulated depreciation or fair value less estimated disposal costs as of the transfer date. Premises and equipment includes rights to use leased facilities and equipment. Right of use assets are initially measured by the present value of future rent payments over lease terms, adjusted for rent concessions. Rent payments exclude both payments made for non-lease components such as services and variable lease payments other than payments dependent on an index at lease commencement. Lease term includes options reasonably certain to be exercised. The right of use assets and lease liabilities are amortized to achieve straight-line expense over the lease term. Upon lease modification, the right of use asset and liability are reassessed and remeasured. Right of use assets are evaluated for impairment when facts and circumstances change that indicate an impairment may be necessary. Leases less than twelve months are excluded from capitalization. Ongoing technology projects of significant size or length are reviewed at least annually for impairment. Accumulated costs are reviewed for projects or components of projects that do not support the value of the asset being developed. Findings of obsolescence, duplicate effort or other conditions that do not support the recorded value are impaired, with the cost of the impaired components being charged to current-year earnings.
Federal and State Income Taxes [Policy Text Block]	Federal and State Income Taxes BOK Financial and its subsidiaries file consolidated tax returns. The subsidiaries provide for income taxes on a separate return basis and remit to BOK Financial amounts determined to be currently payable. BOK Financial is an agent for its subsidiaries under the Company's tax sharing agreements and has no ownership rights to any refunds received for the benefit of its subsidiaries. Current income tax expense or benefit is based on an evaluation that considers estimated taxable income, tax credits, and statutory federal and state income tax rates. The amount of current income tax expense or benefit recognized in any period may differ from amounts reported to taxing authorities. Annually, tax returns are filed with each jurisdiction where the Company conducts business and recognized current income tax expense or benefit is adjusted to the filed tax returns. Deferred tax assets and liabilities are based upon the temporary differences between the values of assets and liabilities as recognized in the financial statements and their related tax basis using enacted tax rates in effect for the year in which the differences are expected to be recovered or settled. The effect of changes in statutory tax rates on the measurement of deferred tax assets and liabilities is recognized through income tax expense in the period the change is enacted. A valuation allowance is provided when it is more likely than not that some portion of the entire deferred tax asset may not be realized. BOK Financial has unrecognized tax benefits, which are included in accrued current income taxes payable, for the uncertain portion of recorded tax benefits and related interest. These uncertainties result from the application of complex tax laws, rules, regulations and interpretations, primarily in state taxing jurisdictions. Unrecognized tax benefits are assessed quarterly and may be adjusted through current income tax expense in future periods based on changing facts and circumstances, completion of examinations by taxing authorities or expiration of a statute of limitations. Estimated penalties and interest on uncertain tax positions are recognized in income tax expense.
Employee Benefit Plans [Policy Text Block]	Employee Benefit Plans BOK Financial sponsors a defined contribution plan (“Thrift Plan”) and a defined benefit cash balance pension plan (“Pension Plan”). Employer contributions to the Thrift Plan, which matches employee contributions subject to percentage and years of service limits, are expensed when incurred. Pension Plan costs, which are based upon actuarial computations of current costs, are expensed annually. Pension Plan benefits were curtailed as of April 1, 2006. No participants may be added to the Pension Plan and no additional service benefits will be accrued. BOK Financial recognizes the funded status of its employee benefit plans. Adjustments required to recognize the Pension Plan's net funded status are made through accumulated other comprehensive income, net of deferred income taxes.
Shared-Based Compensation Plans [Policy Text Block]	Share-Based Compensation Plans BOK Financial awards non-vested common shares and stock options as compensation to certain officers. The grant date fair value of non-vested shares is based on the then-current market value of BOK Financial common stock. Non-vested shares generally cliff vest in 3 years and are subject to a holding period after vesting of 2 years. The grant date fair value of stock options is based on the Black-Scholes option pricing model. Stock options generally have graded vesting over 7 years. Each tranche is considered a separate award for valuation and compensation cost recognition. Compensation cost is initially based on the grant date fair value of the award and recognized as expense over the service period, which is generally the vesting period. Expense is reduced for estimated forfeitures over the vesting period and adjusted for actual forfeitures as they occur. Share-based compensation awarded to certain officers has performance conditions that affect the number of awards granted. Compensation cost is adjusted based on the probable outcome of the performance conditions. Restricted stock units ("RSUs") may also be awarded for certain executives who have elected to defer income recognition upon vesting of their awards. RSUs are subject to the same vesting criteria as non-vested shares. The value of the awards will vary in amounts equal to changes in the fair value of an equal number of BOK Financial common shares. Tax effects of share-based payments are recognized through tax expense. Dividends on non-vested shares are charged to retained earnings. Dividend equivalents on RSUs are charged to expense.
Other Operating Revenue [Policy Text Block]	Other Operating Revenue Fees and commissions revenue is generated through the sales of products, consisting primarily of financial instruments, and the performance of services for customers under contractual obligations. Revenue from providing services for customers is recognized at the time services are provided in an amount that reflects the consideration we expect to be entitled to for those services. Revenue is recognized based on the application of five steps: •Identify the contract with a customer •Identify the performance obligations in the contract •Determine the transaction price •Allocate the transaction price to the performance obligations in the contract •Recognize revenue when (or as) the Company satisfies a performance obligation For contracts with multiple performance obligations, individual performance obligations are accounted for separately if the customer can benefit from the good or service on its own or with other resources readily available to the customer and the promise to transfer goods and services to the customer is separately identifiable in the contract. The transaction price is allocated to the performance obligations based on relative standalone selling prices. Revenue is recognized on a gross basis whenever we have primary responsibility and risk in providing the services or products to our customers and have discretion in establishing the price for the services or products. Revenue is recognized on a net basis whenever we act as an agent for products or services of others. Brokerage and trading revenue includes revenues from trading, customer hedging, retail brokerage, investment banking and insurance brokerage. Trading revenue includes net realized and unrealized gains primarily related to sales of securities to institutional customers and related derivative contracts. Customer hedging revenue includes realized and unrealized changes in the fair value of derivative contracts held for customer risk management programs including credit valuation adjustments, as necessary. We offer commodity, interest rate, foreign exchange and equity derivatives to our customers. These customer contracts are offset with contracts with selected counterparties and exchanges to minimize changes in market risk from changes in commodity prices, interest rates or foreign exchange rates. Retail brokerage revenue represents fees and commissions earned on sales of fixed income securities, annuities, mutual funds and other financial instruments to retail customers. Investment banking revenue includes fees earned upon completion of underwriting and financial advisory services. Investment banking revenue also includes fees earned in conjunction with loan syndications. Insurance brokerage revenues represent fees and commissions earned on placement of insurance products with carriers for property and casualty and health coverage. Transaction card revenue includes merchant discount fees and electronic funds transfer network fees, net of interchange fees paid to card issuers and assessments paid to card networks. Merchant discount fees represent fees paid by customers for account management and electronic processing of card transactions. Merchant discount fees are recognized at the time the customer’s transactions are processed or other services are performed. The Company also maintains the TransFund electronic funds transfer network for the benefit of its members, which includes BOKF, NA. Electronic funds transfer fees are recognized as electronic transactions are processed on behalf of its members. Fiduciary and asset management revenue includes fees from asset management, custody, recordkeeping, investment advisory and administration services. Revenue is recognized on an accrual basis at the time the services are performed and may be based on either the fair value of the account or the service provided. Deposit service charges and fees include commercial account service charges, overdraft fees, check card fee revenue and automated service charge and other deposit service fees. Fees are recognized at least quarterly in accordance with published deposit account agreements and disclosure statements for retail accounts or contractual agreements for commercial accounts. Item charges for overdraft or non-sufficient funds items are recognized as items are presented for payment. Account balance charges and activity fees are accrued monthly and collected in arrears. Commercial account activity fees may be offset by an earnings credit based on account balances. Check card fees represent interchange fees paid by a merchant bank for transactions processed from cards issued by the Company. Check card fees are recognized when transactions are processed. Mortgage banking revenue includes revenues recognized in conjunction with the origination, marketing and servicing of conventional and government-sponsored residential mortgage loans. Mortgage production revenue includes net realized gains (losses) on sales of residential mortgage loans in the secondary market and the net change in unrealized gains (losses) on residential mortgage loans held for sale. Mortgage production revenue also includes changes in the fair value of derivative contracts not designated as hedging instruments related to residential mortgage loan commitments and forward sales contracts. Mortgage servicing revenue includes servicing fee income and late charges on loans serviced for others.
Newly Adopted and Pending Accounting Pronouncements [Policy Text Block]	Newly Adopted and Pending Accounting Pronouncements The following is a summary of newly adopted and pending accounting pronouncements that may have a more than insignificant effect on the Company's financial statements. Financial Accounting Standards Board ("FASB") FASB Accounting Standards Update No. 2016-02, Leases (Topic 842) ("ASU 2016-02") On February 25, 2016, the FASB issued ASU 2016-02 to increase transparency and comparability by recognizing lease assets and liabilities on the balance sheet and disclosing key information about leasing arrangements. The Company adopted the new standard January 1, 2019 through a cumulative effect adjustment to retained earnings. The implementation of ASU 2016-02 increased the reported right-of-use asset and lease liability by $137 million. The effect on retained earnings was immaterial. FASB Accounting Standards Update No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Assets Measured at Amortized Cost ("ASU 2016-13") On June 16, 2016, the FASB issued ASU 2016-13 to provide more timely recording of credit losses on loans and other financial assets measured at amortized cost. The Company adopted the new standard January 1, 2020, through a cumulative effect adjustment to retained earnings. Prior periods were not restated. Under ASU 2016-13, acquired loans must be reserved in a manner consistent with originated loans while the incurred loss model excluded purchased loans because the loans had been marked to fair value at acquisition. Under ASU 2016-13, the fair value discount will remain in place and be accreted into interest income over the life of any acquired loans in the portfolio. Another transition adjustment component is related to expected credit losses for residential mortgage loans sold that exceed amounts guaranteed by the U.S. Department of Veterans Affairs as we retain the credit risk for any amounts exceeding the guarantee as well as for recourse loans. Prior to ASU 2016-13, held-to-maturity non-agency securities carried no reserve for credit losses. Note 4 disaggregates the transition adjustment for loans and unfunded loan commitments among portfolio segments as well as on-and off-balance sheet reserves. FASB Accounting Standards Update No. 2019-04, Codification Improvements to Topic 326, Financial Instruments-Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments ("ASU 2019-04") On April 25, 2019, the FASB issued ASU 2019-04 which clarifies certain aspects of the accounting for credit losses, hedging activities, and financial instruments addressed by ASUs 2016-13, 2017-12, and 2016-01, respectively. Significant amendments made to the provisions of ASU 2016-13 by ASU 2019-04 include providing certain alternatives for the measurement of the allowance for credit losses on accrued interest receivable and clarifying steps entities should take when recording the transfer of loans or debt securities between measurement classification or categories. ASU 2019-04 further clarifies the expectation that entities include recoveries of financial assets in the calculation of the current expected credit losses allowance for both pools of financial assets and individual financial assets. Significant amendments made to the provisions of ASU 2017-12 by ASU 2019-04 include clarification on partial-term fair value hedges of interest rate risk, amortization of fair value hedge basis adjustments and disclosure of fair value hedge basis adjustments. Significant amendments made to provisions of ASU 2016-01 include clarification of the measurement alternative practice for equity securities and remeasurement of equity securities at historical exchange rates. ASU 2019-04 includes other amendments which clarify various provisions within the codification. The Company adopted ASU 2019-04 in the first quarter of 2020. Adoption of ASU 2019-04 did not have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2019-05, Financial Instruments-Credit Losses (Topic 326): Targeted Transition Relief ("ASU 2019-05") On May 15, 2019, the FASB issued ASU 2019-05 which provides transition relief for entities adopting the Board's credit losses standard, ASU 2016-13. ASU 2019-05 amends ASU 2016-13 to allow companies to irrevocably elect, upon adoption of ASU 2016-13, the fair value option for financial instruments that meet specific requirements and is effective for the Company for annual reporting periods beginning after December 15, 2019. The Company did not elect the fair value option for additional financial instruments. FASB Accounting Standards Update No. 2019-11, Codification Improvements to Topic 326: Financial Instruments-Credit Losses ("ASU 2019-11") On November 27, 2019, the FASB issued ASU 2019-11 which revises certain aspects of new guidance on credit losses. Topics addressed include purchased credit-deteriorated assets, transition relief for troubled debt restructurings, disclosure relief for accrued interest receivable, and financial assets secured by collateral maintenance provisions. ASU 2019-11 is effective for the Company for annual reporting periods beginning after December 15, 2019. The Company adopted ASU 2019-11 in the first quarter of 2020. Adoption of ASU 2019-11 did not have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ("ASU 2019-12") On December 18, 2019, the FASB issued ASU 2019-12 which simplifies the accounting for income taxes by eliminating certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The ASU also simplifies aspects of accounting for franchise taxes and enacted changes in tax laws or rates and clarifies accounting for transactions that result in a step-up in the tax basis of goodwill. ASU 2019-12 is effective for the Company for annual reporting periods beginning after December 15, 2020, and interim periods within; however, early adoption is permitted. The Company adopted ASU 2019-12 in the first quarter of 2020. Adoption of ASU 2019-12 did not have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting ("ASU 2020-04") On March 12, 2020, the FASB issued ASU 2020-04 which provides optional expedients and exceptions for applying U.S. GAAP to contract modifications and hedging relationships that reference LIBOR or another reference rate expected to be discontinued, subject to meeting certain criteria. Under the new guidance, an entity can elect by accounting topic or industry subtopic to account for the modification of a contract affected by reference rate reform as a continuation of the existing contract, if certain conditions are met. In addition, the new guidance allows an entity to elect on a hedge-by-hedge basis to continue to apply hedge accounting for hedging relationships in which the critical terms change due to reference rate reform, if certain conditions are met. A one-time election to sell and/or transfer held-to-maturity debt securities that reference a rate affected by reference rate reform is also allowed. ASU 2020-04 became effective for all entities as of March 12, 2020 and will apply to all LIBOR reference rate modifications through December 31, 2022. Management is currently evaluating the impact of ASU 2020-04 on the Company's financial statements. FASB Accounting Standards Update No. 2021-01, Reference Rate Reform (Topic 848): Scope ("ASU 2021-01") On January 7, 2021, the FASB issued ASU 2021-01 which clarifies that certain optional expedients and exceptions in Topic 848 for contract modifications and hedge accounting apply to derivatives that are affected by the discounting transition. The amendments in this update are elective and apply to all entities that have derivative instruments that use an interest rate for margining, discounting, or contract price alignment that is modified as a result of reference rate reform. The amendments also optionally apply to all entities that designate receive-variable rate, pay-variable-rate cross-currency interest rate swaps as hedging instruments in net investment hedges that are modified as a result of reference rate reform. ASU 2021-01 is effective immediately for all entities and amendments may be applied on a full retrospective basis as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020. Management is currently evaluating the impact of ASU 2021-01 on the Company's financial statements.

Reclassifications (Policies)	12 Months Ended
Reclassifications (Policies)	Dec. 31, 2020
Accounting Policies [Abstract]
Reclassifications [Text Block]	Certain prior year amounts have been reclassified to conform to current year presentation.

Securities (Tables)

12 Months Ended

Dec. 31, 2020

Marketable Securities [Abstract]

Trading Securities [Table Text Block]

The fair value and net unrealized gain (loss) included in trading securities is as follows (in thousands):


	December 31, 2020				December 31, 2019
	Fair Value		Net Unrealized Gain (Loss)		Fair Value		Net Unrealized Gain (Loss)
U.S. government securities	$	9,183	$	—	$	44,264	$	6
Residential agency mortgage-backed securities	4,669,148		(3,624)		1,504,651		2,293
Municipal securities	19,172		42		26,196		60
Asset-backed securities	—		—		14,084		(21)
Other debt securities	10,472		22		34,726		21
Total trading securities	$	4,707,975	$	(3,560)	$	1,623,921	$	2,359

Investment Securities (Held-to-Maturity) [Table Text Block]

The amortized cost and fair values of investment securities are as follows (in thousands):


	December 31, 2020
	Amortized		Fair		Gross Unrealized
	Cost		Value		Gain		Loss
Municipal securities	$	229,245	$	255,270	$	26,169	$	(144)
Residential agency mortgage-backed securities	8,913		9,790		877		—
Other debt securities	7,373		7,371		—		(2)
Total investment securities	$	245,531	$	272,431	$	27,046	$	(146)
Allowance for credit losses1	(688)
Investment securities, net of allowance	$	244,843	$	272,431	$	27,046	$	(146)

1 Effective with the adoption of FASB ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326) on January 1, 2020.


	December 31, 2019
	Amortized		Fair		Gross Unrealized
	Cost		Value		Gain		Loss
Municipal securities	$	274,535	$	295,032	$	20,797	$	(300)
Residential agency mortgage-backed securities	10,676		11,164		488		—
Other debt securities	8,207		8,206		—		(1)
Total investment securities	$	293,418	$	314,402	$	21,285	$	(301)

The amortized cost and fair values of investment securities at December 31, 2020, by contractual maturity, are as shown in the following table (dollars in thousands):


	Less than One Year		One to Five Years		Six to Ten Years		Over Ten Years		Total		Weighted Average Maturity1
Fixed maturity debt securities:
Amortized cost	$	31,029	$	76,646	$	119,966	$	8,977	$	236,618	4.90
Fair value	31,459		83,944		138,101		9,137		262,641

Residential mortgage-backed securities:
Amortized cost									$	8,913	2
Fair value									9,790

Total investment securities:
Amortized cost									$	245,531
Fair value									272,431

1Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty.

2The average expected lives of residential mortgage-backed securities were 4.0 years based upon current prepayment assumptions.

Temporarily Impaired Investment Securities

(in thousands):


	December 31, 2020
	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investment:
Municipal securities	6	$	2,451	$	40	$	2,043	$	104	$	4,494	$	144

Other debt securities	2	$	250	$	1	$	25	$	1	$	275	$	2
Total investment securities	8	$	2,701	$	41	$	2,068	$	105	$	4,769	$	146


	December 31, 2019
	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investment:
Municipal securities	15	$	1,001	$	1	$	9,747	$	299	$	10,748	$	300

Other debt securities	2	275		1		—		—		275		1
Total investment securities	17	$	1,276	$	2	$	9,747	$	299	$	11,023	$	301

Available for Sale Securities [Table Text Block]

The amortized cost and fair value of available for sale securities are as follows (in thousands):


	December 31, 2020
	Amortized		Fair		Gross Unrealized
	Cost		Value		Gain		Loss
U.S. Treasury	$	500	$	508	$	8	$	—
Municipal securities	165,318		167,979		2,666		(5)
Mortgage-backed securities:
Residential agency	9,019,013		9,340,471		328,183		(6,725)
Residential non-agency	17,563		32,770		15,207		—
Commercial agency	3,406,956		3,508,465		103,590		(2,081)
Other debt securities	500		472		—		(28)
Total available for sale securities	$	12,609,850	$	13,050,665	$	449,654	$	(8,839)


	December 31, 2019
	Amortized		Fair		Gross Unrealized
	Cost		Value		Gain		Loss
U.S. Treasury	$	1,598	$	1,600	$	2	$	—
Municipal securities	1,789		1,861		72		—
Mortgage-backed securities:
Residential agency	7,956,297		8,046,096		104,912		(15,113)
Residential non-agency	25,968		41,609		15,641		—
Commercial agency	3,145,342		3,178,005		37,808		(5,145)
Other debt securities	500		472		—		(28)
Total available for sale securities	$	11,131,494	$	11,269,643	$	158,435	$	(20,286)

The amortized cost and fair values of available for sale securities at December 31, 2020, by contractual maturity, are as shown in the following table (dollars in thousands):


	Less than One Year		One to Five Years		Six to Ten Years		Over Ten Years		Total		Weighted Average Maturity1
Fixed maturity debt securities:
Amortized cost	$	78,673	$	1,413,405	$	1,472,918	$	608,278	$	3,573,274	7.79
Fair value	78,918		1,469,630		1,498,376		630,500		3,677,424
Residential mortgage-backed securities:
Amortized cost									$	9,036,576	2
Fair value									9,373,241
Total available-for-sale securities:
Amortized cost									$	12,609,850
Fair value									13,050,665

1Expected maturities may differ from contractual maturities, because borrowers may have the right to call or prepay obligations with or without penalty.

2The average expected lives of residential mortgage-backed securities were 3.0 years based upon current prepayment assumptions.

Sales of available for sale securities resulted in gains and losses as follows (in thousands):


	Year Ended December 31,
	2020		2019		2018
Proceeds	$	384,507	$	1,211,718	$	745,643
Gross realized gains	9,976		14,996		7,117
Gross realized losses	(66)		(9,399)		(9,918)
Related federal and state income tax expense (benefit)	2,524		1,425		(713)

Debt Securities, Available for Sale, Unrealized Loss Position [Table Text Block]

Temporarily Impaired Available for Sale Securities

(In thousands)


	December 31, 2020
	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available for sale:

Municipal securities	1	6,166		5		—		—		6,166		5
Mortgage-backed securities:
Residential agency	38	$	786,890	$	6,605	$	160,747	$	120	$	947,637	$	6,725

Commercial agency	37	350,506		1,587		277,627		494		628,133		2,081
Other debt securities	1	—		—		472		28		472		28
Total available for sale securities	77	$	1,143,562	$	8,197	$	438,846	$	642	$	1,582,408	$	8,839


	December 31, 2019
	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available for sale:

Municipal securities	—	—		—		—		—		—		—
Mortgage-backed securities:
Residential agency	133	$	1,352,597	$	6,690	$	686,002	$	8,423	$	2,038,599	$	15,113

Commercial agency	69	830,047		4,238		210,877		907		1,040,924		5,145
Other debt securities	1	—		—		472		28		472		28
Total available for sale securities	203	$	2,182,644	$	10,928	$	897,351	$	9,358	$	3,079,995	$	20,286

Fair Value Option Securities [Table Text Block]

The fair value and net unrealized gain (loss) included in fair value option securities is as follows (in thousands):


	December 31, 2020				December 31, 2019
	Fair Value		Net Unrealized Gain (Loss)		Fair Value		Net Unrealized Gain (Loss)
U.S. Treasury	$	—	$	—	$	9,917	$	(48)
Residential agency mortgage-backed securities	114,982		4,463		1,088,660		14,109
Total	$	114,982	$	4,463	$	1,098,577	$	14,061

Derivatives (Tables)

12 Months Ended

Dec. 31, 2020

Derivative Instrument Detail [Abstract]

Derivative Contracts [Table Text Block]

The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at December 31, 2020 (in thousands):


	Assets
	Notional1		Gross Fair Value		Netting Adjustments		Net Fair Value Before Cash Collateral		Cash Collateral		Fair Value Net of Cash Collateral
Customer risk management programs:
Interest rate contracts	$	3,212,469	$	113,524	$	(144)	$	113,380	$	—	$	113,380
Energy contracts	3,791,565		386,008		(211,468)		174,540		—		174,540
Agricultural contracts	14,765		3,859		—		3,859		—		3,859
Foreign exchange contracts	337,001		332,257		—		332,257		(420)		331,837
Equity option contracts	70,199		1,222		—		1,222		(285)		937
Total customer risk management programs	7,425,999		836,870		(211,612)		625,258		(705)		624,553
Trading	84,997,593		440,627		(240,655)		199,972		(26,958)		173,014
Interest rate risk management programs	995,123		17,352		(4,231)		13,121		—		13,121
Total derivative contracts	$	93,418,715	$	1,294,849	$	(456,498)	$	838,351	$	(27,663)	$	810,688

	Liabilities
	Notional¹		Gross Fair Value		Netting Adjustments		Net Fair Value Before Cash Collateral		Cash Collateral		Fair Value Net of Cash Collateral
Customer risk management programs:
Interest rate contracts	$	3,212,469	$	113,900	$	(144)	$	113,756	$	(104,202)	$	9,554
Energy contracts	3,617,678		361,334		(211,468)		149,866		(114,070)		35,796
Agricultural contracts	14,781		3,844		—		3,844		(3,844)		—
Foreign exchange contracts	336,223		331,035		—		331,035		(1,165)		329,870
Equity option contracts	70,199		1,222		—		1,222		—		1,222
Total customer risk management programs	7,251,350		811,335		(211,612)		599,723		(223,281)		376,442
Trading	88,929,916		414,801		(240,655)		174,146		(145,692)		28,454
Interest rate risk management programs	145,256		5,529		(4,231)		1,298		(415)		883
Total derivative contracts	$	96,326,522	$	1,231,665	$	(456,498)	$	775,167	$	(369,388)	$	405,779

1 Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.

The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at December 31, 2019 (in thousands):


	Assets
	Notional1		Gross Fair Value		Netting Adjustments		Net Fair Value Before Cash Collateral		Cash Collateral		Fair Value Net of Cash Collateral
Customer risk management programs:
Interest rate contracts	$	2,464,478	$	49,100	$	(1,839)	$	47,261	$	—	$	47,261
Energy contracts	2,151,096		144,906		(107,591)		37,315		(38)		37,277
Agricultural contracts	16,118		1,522		(22)		1,500		—		1,500
Foreign exchange contracts	214,119		213,007		—		213,007		—		213,007
Equity option contracts	81,455		3,233		—		3,233		(660)		2,573
Total customer risk management programs	4,927,266		411,768		(109,452)		302,316		(698)		301,618
Trading	69,721,932		131,561		(115,949)		15,612		—		15,612
Internal risk management programs	1,268,180		6,226		(81)		6,145		—		6,145
Total derivative contracts	$	75,917,378	$	549,555	$	(225,482)	$	324,073	$	(698)	$	323,375

	Liabilities
	Notional¹		Gross Fair Value		Netting Adjustments		Net Fair Value Before Cash Collateral		Cash Collateral		Fair Value Net of Cash Collateral
Customer risk management programs:
Interest rate contracts	$	2,464,478	$	49,194	$	(1,839)	$	47,355	$	(43,932)	$	3,423
Energy contracts	2,105,391		139,311		(107,591)		31,720		(6,031)		25,689
Agricultural contracts	16,139		1,507		(22)		1,485		(1,485)		—
Foreign exchange contracts	207,919		207,020		—		207,020		—		207,020
Equity option contracts	81,455		3,233		—		3,233		—		3,233
Total customer risk management programs	4,875,382		400,265		(109,452)		290,813		(51,448)		239,365
Trading	65,144,388		125,535		(115,949)		9,586		—		9,586
Internal risk management programs	380,401		3,121		(81)		3,040		(863)		2,177
Total derivative contracts	$	70,400,171	$	528,921	$	(225,482)	$	303,439	$	(52,311)	$	251,128

1 Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.

Derivative Instruments, Gain (Loss) in Statement of Earnings [Table Text Block]

The following summarizes the pre-tax net gains (losses) on derivative instruments and where they are recorded in the Consolidated Statements of Earnings (in thousands):


	Year Ended December 31,
	2020				2019				2018
	Brokerage and Trading Revenue		Gain (Loss) on Derivatives, Net		Brokerage and Trading Revenue		Gain (Loss) on Derivatives, Net		Brokerage and Trading Revenue		Gain (Loss) on Derivatives, Net
Customer risk management programs:
Interest rate contracts
To-be-announced U.S. agency residential mortgage-backed securities1	$	—	$	—	$	9,579	$	—	$	27,190	$	—
Interest rate swaps	4,507		—		3,647		—		2,614		—
Energy contracts	17,287		—		5,064		—		8,443		—
Agricultural contracts	34		—		28		—		53		—
Foreign exchange contracts	921		—		623		—		535		—
Equity option contracts	—		—		—		—		—		—
Total customer risk management programs	22,749		—		18,941		—		38,835		—
Trading2	8,255		—		13,999		—		(13,643)		—
Internal risk management programs	—		42,320		—		14,951		—		(442)
Total derivative contracts	$	31,004	$	42,320	$	32,940	$	14,951	$	25,192	$	(442)

Loans and Allowances for Credit Losses (Tables)

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Loans and Leases Receivable, Net Amount [Abstract]

Schedule of the Loans by Portfolio Segment [Table Text Block]

The portfolio segments of the loan portfolio are as follows (in thousands):


	December 31, 2020
	Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	1,805,286	$	11,105,090	$	167,159	$	13,077,535
Commercial real estate	1,021,443		3,649,849		27,246		4,698,538
Paycheck protection program	1,682,310		—		—		1,682,310
Loans to individuals	2,173,437		1,335,412		40,288		3,549,137
Total	$	6,682,476	$	16,090,351	$	234,693	$	23,007,520
Foregone interest on nonaccrual loans							$	22,870

Portfolio segments of the loan portfolio are as follows (in thousands):


	December 31, 2019
	Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	3,231,485	$	10,684,749	$	115,416	$	14,031,650
Commercial real estate	1,056,321		3,349,836		27,626		4,433,783
Residential mortgage	1,652,653		393,897		37,622		2,084,172
Personal	193,903		1,007,192		287		1,201,382
Total	$	6,134,362	$	15,435,674	$	180,951	$	21,750,987
Accruing loans past due (90 days)1							$	7,680
Foregone interest on nonaccrual loans							$	17,409

1.Excludes residential mortgage loans guaranteed by agencies of the U.S. government

Rollforward of Allowance For Loan Losses And Accrual for Off-Balnace Sheet Credit Losses [Table Text Block]

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit is for the year ended December 31, 2020 summarized as follows (in thousands):


	Commercial		Commercial Real Estate		Paycheck Protection Program		Loans to Individuals		Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	118,187	$	51,805	$	—	$	23,572	$	17,195	$	210,759
Transition adjustment	33,681		(4,620)		—		13,943		(17,195)		25,809
Beginning balance, adjusted	151,868		47,185		—		37,515		—		236,568
Provision for loan losses	171,800		40,407		—		10,253		—		222,460
Loans charged off	(73,370)		(1,300)		—		(4,729)		—		(79,399)
Recoveries of loans previously charged off	4,636		266		—		4,109		—		9,011
Ending balance	$	254,934	$	86,558	$	—	$	47,148	$	—	$	388,640

Allowance for off-balance sheet credit risk from unfunded loan commitments:
Beginning balance	$	1,434	$	107	$	—	$	44	$	—	$	1,585
Transition adjustment	10,144		11,660		—		1,748		—		23,552
Beginning balance, adjusted	11,578		11,767		—		1,792		—		25,137
Provision for off-balance sheet credit risk	2,844		8,804		—		136		—		11,784
Ending balance	$	14,422	$	20,571	$	—	$	1,928	$	—	$	36,921

Changes in our reasonable and supportable forecasts of macroeconomic variables, primarily due to the anticipated impact of the on-going COVID-19 pandemic, and other assumptions, resulted in a $99.1 million increase in the allowance for lending activities during the year ended December 31, 2020. Changes in the loan portfolio characteristics, including specific impairment and losses, loan balances and risk grading resulted in a $135.2 million increase in the allowance for lending activities.

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2020 is as follows (in thousands):


	Collectively Measured for General Allowances				Individually Measured for Specific Allowances				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	12,910,376	$	235,882	$	167,159	$	19,052	$	13,077,535	$	254,934
Commercial real estate	4,671,292		83,169		27,246		3,389		4,698,538		86,558
Paycheck protection program	1,682,310		—		—		—		1,682,310		—
Loans to individuals	3,508,849		47,148		40,288		—		3,549,137		47,148
Total	$	22,772,827	$	366,199	$	234,693	$	22,441	$	23,007,520	$	388,640

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit is for the year ended December 31, 2019 summarized as follows (in thousands):


	Commercial		Commercial Real Estate		Residential Mortgage		Personal		Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	102,226	$	60,026	$	17,964	$	9,473	$	17,768	$	207,457
Provision for loan losses	57,125		(12,046)		(3,838)		3,537		(573)		44,205
Loans charged off	(43,185)		(1,161)		(288)		(6,343)		—		(50,977)
Recoveries	2,021		4,986		562		2,505		—		10,074
Ending balance	$	118,187	$	51,805	$	14,400	$	9,172	$	17,195	$	210,759
Allowance for off-balance sheet credit losses:
Beginning balance	1,655		52		52		31		—		1,790
Provision for off-balance sheet credit losses	(221)		55		(8)		(31)		—		(205)
Ending balance	$	1,434	$	107	$	44	$	—	$	—	$	1,585

Total provision for credit losses	$	56,904	$	(11,991)	$	(3,846)	$	3,506	$	(573)	$	44,000

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit is for the year ended December 31, 2018 summarized as follows (in thousands):


	Commercial		Commercial Real Estate		Residential Mortgage		Personal		Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	124,269	$	56,621	$	18,451	$	9,124	$	22,217	$	230,682
Provision for loan losses	12,521		(147)		(1,156)		3,175		(4,449)		9,944
Loans charged off	(37,880)		—		(378)		(5,325)		—		(43,583)
Recoveries	3,316		3,552		1,047		2,499		—		10,414
Ending balance	$	102,226	$	60,026	$	17,964	$	9,473	$	17,768	$	207,457
Allowance for off-balance sheet credit losses:
Beginning balance	3,644		45		43		2		—		3,734
Provision for off-balance sheet credit losses	(1,989)		7		9		29		—		(1,944)
Ending balance	$	1,655	$	52	$	52	$	31	$	—	$	1,790

Total provision for credit losses	$	10,532	$	(140)	$	(1,147)	$	3,204	$	(4,449)	$	8,000

Schedule of Credit Quality Indicators [Table Text Block]


	Origination Year
	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Commercial:
Energy
Pass	$	112,614	$	51,863	$	89,346	$	7,178	$	1,148	$	7,956	$	2,548,663	$	—	$	2,818,768
Special Mention	—		—		—		—		—		—		202,590		—		202,590
Accruing Substandard	24,000		1,363		1,453		—		12,667		—		283,294		—		322,777
Nonaccrual	21,076		2,607		—		—		—		21,064		80,312		—		125,059
Total energy	157,690		55,833		90,799		7,178		13,815		29,020		3,114,859		—		3,469,194



Healthcare
Pass	536,745		615,221		638,302		422,834		234,399		658,286		147,132		—		3,252,919
Special Mention	—		27,500		—		—		—		8,282		5		—		35,787
Accruing Substandard	—		—		1,191		929		132		11,387		—		—		13,639
Nonaccrual	—		18		183		—		—		2,935		509		—		3,645
Total healthcare	536,745		642,739		639,676		423,763		234,531		680,890		147,646		—		3,305,990



Services
Pass	534,853		436,384		372,867		307,374		373,785		683,936		665,491		682		3,375,372
Special Mention	150		9,057		389		291		2,038		2,000		3,063		—		16,988
Accruing Substandard	429		6,380		26,008		6,027		5,030		7,954		38,797		—		90,625
Nonaccrual	4,833		448		—		12,590		1,049		6,138		540		—		25,598
Total services	540,265		452,269		399,264		326,282		381,902		700,028		707,891		682		3,508,583



General business
Pass	419,756		394,985		310,273		236,222		103,987		186,600		1,055,878		2,316		2,710,017
Special Mention	197		4,519		9,713		7,803		2,511		3,159		2,483		19		30,404
Accruing Substandard	1,432		3,069		6,694		10,935		10,042		3,729		4,449		140		40,490
Nonaccrual	1,675		3,728		4,863		1,436		530		107		477		41		12,857
Total general business	423,060		406,301		331,543		256,396		117,070		193,595		1,063,287		2,516		2,793,768



Total commercial	1,657,760		1,557,142		1,461,282		1,013,619		747,318		1,603,533		5,033,683		3,198		13,077,535

Commercial real estate:
Pass	725,577		1,211,338		954,226		489,193		314,899		722,475		223,131		38		4,640,877
Special Mention	—		—		259		12,311		2,725		5,831		—		—		21,126
Accruing Substandard	—		—		—		4,410		—		4,852		27		—		9,289
Nonaccrual	—		8,300		—		232		7,468		11,246		—		—		27,246
Total commercial real estate	725,577		1,219,638		954,485		506,146		325,092		744,404		223,158		38		4,698,538


	Origination Year
	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
Paycheck protection program:
Pass	1,682,310		—		—		—		—		—		—		—		1,682,310
Total paycheck protection program	1,682,310		—		—		—		—		—		—		—		1,682,310
Loans to individuals:
Residential mortgage
Pass	564,325		149,832		120,875		124,930		158,801		348,292		335,259		24,553		1,826,867
Special Mention	33		11		2,094		—		59		318		950		10		3,475
Accruing Substandard	—		—		51		—		—		34		272		76		433
Nonaccrual	648		104		1,658		784		2,010		22,415		3,835		774		32,228
Total residential mortgage	565,006		149,947		124,678		125,714		160,870		371,059		340,316		25,413		1,863,003



Residential mortgage guaranteed by U.S. government agencies
Pass	4,859		33,880		34,464		43,099		58,264		226,380		—		—		400,946
Special Mention	—		—		—		—		—		—		—		—		—
Accruing Substandard	—		—		—		—		—		—		—		—		—
Nonaccrual	—		—		545		—		309		6,887		—		—		7,741
Total residential mortgage guaranteed by U.S. government agencies	4,859		33,880		35,009		43,099		58,573		233,267		—		—		408,687



Personal:
Pass	219,873		200,580		76,246		100,229		64,104		102,126		510,571		1,510		1,275,239
Special Mention	39		55		66		—		469		31		965		—		1,625
Accruing Substandard	11		214		10		—		—		—		29		—		264
Nonaccrual	28		17		57		73		50		49		45		—		319
Total personal	219,951		200,866		76,379		100,302		64,623		102,206		511,610		1,510		1,277,447



Total loans to individuals	789,816		384,693		236,066		269,115		284,066		706,532		851,926		26,923		3,549,137
Total loans	$	4,855,463	$	3,161,473	$	2,651,833	$	1,788,880	$	1,356,476	$	3,054,469	$	6,108,767	$	30,159	$	23,007,520

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2019 is as follows (in thousands):


	Collectively Measured for Impairment				Individually Measured for Impairment				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	13,916,234	$	100,773	$	115,416	$	17,414	$	14,031,650	$	118,187
Commercial real estate	4,406,157		51,805		27,626		—		4,433,783		51,805
Residential mortgage	2,046,550		14,400		37,622		—		2,084,172		14,400
Personal	1,201,095		9,172		287		—		1,201,382		9,172
Total	21,570,036		176,150		180,951		17,414		21,750,987		193,564

Nonspecific allowance	—		—		—		—		—		17,195

Total	$	21,570,036	$	176,150	$	180,951	$	17,414	$	21,750,987	$	210,759

The allowance for loan losses and recorded investment of the related loans by portfolio segment for risk graded and non-risk graded loans at December 31, 2019 is as follows (in thousands):


	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	13,997,538	$	117,236	$	34,112	$	951	$	14,031,650	$	118,187
Commercial real estate	4,433,783		51,805		—		—		4,433,783		51,805
Residential mortgage	279,113		3,085		1,805,059		11,315		2,084,172		14,400
Personal	1,116,297		7,003		85,085		2,169		1,201,382		9,172
Total	19,826,731		179,129		1,924,256		14,435		21,750,987		193,564

Nonspecific allowance	—		—		—		—		—		17,195

Total	$	19,826,731	$	179,129	$	1,924,256	$	14,435	$	21,750,987	$	210,759

The following table summarizes the Company's loan portfolio at December 31, 2019 by the risk grade categories (in thousands):


	Internally Risk Graded								Non-Graded
	Performing
	Pass		Other Loans Especially Mentioned		Accruing Substandard		Nonaccrual		Performing		Nonaccrual		Total
Commercial:
Energy	$	3,700,406	$	117,298	$	63,951	$	91,722	$	—	$	—	$	3,973,377
Services	3,050,946		29,943		33,791		7,483		—		—		3,122,163
Wholesale/retail	1,749,023		5,281		5,399		1,163		—		—		1,760,866
Manufacturing	623,219		18,214		13,883		10,133		—		—		665,449
Healthcare	2,995,514		13,117		20,805		4,480		—		—		3,033,916
Public finance	709,868		—		—		—		—		—		709,868
Other commercial and industrial	709,729		4,028		17,744		398		34,075		37		766,011
Total commercial	13,538,705		187,881		155,573		115,379		34,075		37		14,031,650

Commercial real estate:
Residential construction and land development	150,529		—		—		350		—		—		150,879
Retail	743,343		12,067		1,243		18,868		—		—		775,521
Office	923,202		5,177		—		—		—		—		928,379
Multifamily	1,257,005		1,604		95		6,858		—		—		1,265,562
Industrial	852,539		1,658		1,011		909		—		—		856,117
Other commercial real estate	455,045		1,639		—		641		—		—		457,325
Total commercial real estate	4,381,663		22,145		2,349		27,626		—		—		4,433,783

Residential mortgage:
Permanent mortgage	276,138		78		2,404		493		758,260		19,948		1,057,321
Permanent mortgage guaranteed by U.S. government agencies	—		—		—		—		191,694		6,100		197,794
Home equity	—		—		—		—		817,976		11,081		829,057
Total residential mortgage	276,138		78		2,404		493		1,767,930		37,129		2,084,172

Personal	1,116,196		45		—		56		84,853		232		1,201,382

Total	$	19,312,702	$	210,149	$	160,326	$	143,554	$	1,886,858	$	37,398	$	21,750,987

Summary of Impaired Loans [Table Text Block]

A summary of impaired loans at December 31, 2019 follows (in thousand):


	As of December 31, 2019										Year Ended
			Recorded Investment								December 31, 2019
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance		Average Recorded Investment		Interest Income Recognized
Commercial:
Energy	$	149,441	$	91,722	$	44,244	$	47,478	$	16,854	$	69,119	$	—
Services	10,923		7,483		6,301		1,182		240		5,854		—
Wholesale/retail	1,980		1,163		902		261		101		916		—
Manufacturing	10,848		10,133		9,914		219		219		9,144		—
Healthcare	13,774		4,480		4,480		—		—		7,798		—
Public finance	—		—		—		—		—		—		—
Other commercial and industrial	8,227		435		435		—		—		8,568		—
Total commercial	195,193		115,416		66,276		49,140		17,414		101,399		—

Commercial real estate:
Residential construction and land development	1,306		350		350		—		—		350		—
Retail	20,265		18,868		18,868		—		—		19,573		—
Office	—		—		—		—		—		—		—
Multifamily	6,858		6,858		6,858		—		—		3,580		—
Industrial	909		909		909		—		—		454		—
Other commercial real estate	801		641		641		—		—		666		—
Total commercial real estate	30,139		27,626		27,626		—		—		24,623		—

Residential mortgage:
Permanent mortgage	24,868		20,441		20,441		—		—		22,196		1,198
Permanent mortgage guaranteed by U.S. government agencies1	204,187		197,794		197,794		—		—		195,009		7,733
Home equity	12,967		11,081		11,081		—		—		10,776		—
Total residential mortgage	242,022		229,316		229,316		—		—		227,981		8,931

Personal	360		287		287		—		—		259		—

Total	$	467,714	$	372,645	$	323,505	$	49,140	$	17,414	$	354,262	$	8,931

1 All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2019, the majority were accruing based on the guarantee by U.S. government agencies.

Summary of Loans by Aging Status [Table Text Block]

A summary of loans currently performing and past due as of December 31, 2020 is as follows (in thousands):


			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Total		Past Due 90 Days or More and Accruing
Commercial:
Energy	$	3,410,995	$	12,735	4,050		$	41,414	$	3,469,194	$	—
Healthcare	3,302,345		—		—		3,645		3,305,990		—
Services	3,489,423		3,278		177		15,705		3,508,583		326
General business	2,776,038		1,206		6,277		10,247		2,793,768		4,495
Total commercial	12,978,801		17,219		10,504		71,011		13,077,535		4,821

Commercial real estate	4,672,279		276		5,310		20,673		4,698,538		5,126

Paycheck protection program	1,682,310		—		—		—		1,682,310		—

Loans to individuals
Permanent mortgage	1,849,304		5,812		837		7,050		1,863,003		181
Permanent mortgages guaranteed by U.S. government agencies	262,102		41,389		22,041		83,155		408,687		78,349
Personal	1,273,702		3,317		90		338		1,277,447		241
Total loans to individuals	3,385,108		50,518		22,968		90,543		3,549,137		78,771

Total	$	22,718,498	$	68,013	$	38,782	$	182,227	$	23,007,520	$	88,718

A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of December 31, 2019 is as follows (in thousands):


			Past Due
	Current		30 to 59 Days		60 to 89 Days	90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	3,881,244	$	401	10	$	—	$	91,722	$	3,973,377
Services	3,105,621		1,737		523	6,799		7,483		3,122,163
Wholesale/retail	1,758,878		712		113	—		1,163		1,760,866
Manufacturing	654,329		410		190	387		10,133		665,449
Healthcare	3,027,329		2,039		—	68		4,480		3,033,916
Public finance	707,638		2,230		—	—		—		709,868
Other commercial and industrial	764,390		414		772	—		435		766,011
Total commercial	13,899,429		7,943		1,608	7,254		115,416		14,031,650

Commercial real estate:
Residential construction and land development	147,379		3,093		—	57		350		150,879
Retail	756,653		—		—	—		18,868		775,521
Office	928,379		—		—	—		—		928,379
Multifamily	1,258,704		—		—	—		6,858		1,265,562
Industrial	855,208		—		—	—		909		856,117
Other commercial real estate	454,253		1,827		250	354		641		457,325
Total commercial real estate	4,400,576		4,920		250	411		27,626		4,433,783

Residential mortgage:
Permanent mortgage	1,034,716		2,011		153	—		20,441		1,057,321
Permanent mortgages guaranteed by U.S. government agencies	46,898		24,203		18,187	102,406		6,100		197,794
Home equity	814,325		3,343		308	—		11,081		829,057
Total residential mortgage	1,895,939		29,557		18,648	102,406		37,622		2,084,172

Personal	1,196,362		4,664		54	15		287		1,201,382

Total	$	21,392,306	$	47,084	20,560	$	110,086	$	180,951	$	21,750,987

Financing Receivable, Nonaccrual [Table Text Block]

A summary of nonaccruing loans as of December 31, 2020 follows (in thousands):


	Total		With No Allowance		With Allowance		Related Allowance
Commercial:
Energy	$	125,059	$	76,633	$	48,426	$	16,478
Healthcare	3,645		3,645		—		—
Services	25,598		20,810		4,788		2,574
General business	12,857		12,857		—		—
Total commercial	167,159		113,945		53,214		19,052

Commercial real estate	27,246		13,645		13,601		3,389

Loans to individuals:
Residential mortgage	32,228		32,228		—		—
Residential mortgage guaranteed by U.S. government agencies	7,741		7,741		—		—
Personal	319		319		—		—
Total loans to individuals	40,288		40,288		—		—

Total	$	234,693	$	167,878	$	66,815	$	22,441

Premises and Equipment and Leases Premises and Equipment and Leases (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Premises and Equipment [Table Text Block]

Premises and equipment at December 31 are summarized as follows (in thousands):


	December 31,
	2020		2019
Land	$	69,776	$	69,960
Buildings and improvements	440,528		421,952
Software and related integration	120,444		98,487
Furniture and equipment	165,344		135,153
Construction in progress	46,949		53,498
Premises and equipment	843,041		779,050
Less accumulated depreciation	291,733		243,531
Premises and equipment, net of accumulated depreciation	$	551,308	$	535,519

Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Finite-Lived Intangible Assets [Table Text Block]

The following table presents the original cost and accumulated amortization of intangible assets (in thousands):


	Dec. 31,
	2020		2019
Core deposit premiums	$	103,200	$	103,200
Less accumulated amortization	32,256		19,364
Net core deposit premiums	70,944		83,836

Other identifiable intangible assets	82,731		74,372
Less accumulated amortization	40,239		32,937
Net other identifiable intangible assets	42,492		41,435

Total intangible assets, net	$	113,436	$	125,271

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

Expected amortization expense for intangible assets that will continue to be amortized (in thousands):


	Core Deposit Premiums		Other Identifiable Intangible Assets		Total
2021	$	11,893	$	6,599	$	18,492
2022	10,981		5,232		16,213
2023	10,145		4,191		14,336
2024	9,379		3,178		12,557
2025	8,675		2,767		11,442
Thereafter	19,871		20,525		40,396
	$	70,944	$	42,492	$	113,436

Schedule of Goodwill [Table Text Block]

The changes in the carrying value of goodwill by operating segment are as follows (in thousands):


	Commercial Banking		Consumer Banking		Wealth Management		Funds Management and Other		Total



Balance, December 31, 2018	$	313,270	$	43,458	$	90,702	$	601,833	$	1,049,263



Adjustment1	600,661		—		—		(601,833)		(1,172)




Balance, December 31, 2019	913,931		43,458		90,702		—		1,048,091









Balance, December 31, 2020	$	913,931	$	43,458	$	90,702	$	—	$	1,048,091

1 Goodwill related to the CoBiz acquisition was not yet allocated to the operating segments as of December 31, 2018 and was included in Funds Management and Other in 2018 then allocated during 2019.

Mortgage Banking Activities (Tables)

12 Months Ended

Dec. 31, 2020

Mortgage Banking [Abstract]

Components of Residential Mortgage Loans Held For Sale [Table Text Block]

The unpaid principal balance of residential mortgage loans held for sale, notional amounts of derivative contracts related to residential mortgage loan commitments and forward contract sales and their related fair values included in Mortgage loans held for sale on the Consolidated Balance Sheets were (in thousands):


	December 31, 2020				December 31, 2019
	Unpaid Principal Balance/ Notional		Fair Value		Unpaid Principal Balance/ Notional		Fair Value
Residential mortgage loans held for sale	$	227,161	$	236,444	$	175,117	$	177,703
Residential mortgage loan commitments	380,637		20,435		158,460		5,233
Forward sales contracts	549,414		(4,563)		315,203		(665)
			$	252,316			$	182,271

Mortgage Banking Revenue [Table Text Block]

Mortgage banking revenue was as follows (in thousands):


	Year Ended
	2020		2019		2018
Production revenue:
Net realized gains on sales of mortgage loans	$	107,847	$	39,730	$	36,379
Net change in unrealized gain on mortgage loans held for sale	6,697		672		(674)
Net change in the fair value of mortgage loan commitments	15,202		(145)		(1,145)
Net change in the fair value of forward sales contracts	(3,898)		2,463		(2,870)
Total mortgage production revenue	125,848		42,720		31,690
Servicing revenue	56,512		64,821		66,097
Total mortgage banking revenue	$	182,360	$	107,541	$	97,787

Summary of Mortgage Servicing Rights [Table Text Block]

The following represents a summary of mortgage servicing rights (Dollars in thousands):


	December 31,
	2020			2019			2018
Number of residential mortgage loans serviced for others	106,201			126,828			132,463
Outstanding principal balance of residential mortgage loans serviced for others	$	16,228,449		$	20,727,106		$	21,658,335
Weighted average interest rate	3.84		%	3.98		%	3.99		%
Remaining contractual term (in months)	280			289			293

Activity in Capitalized Mortgage Servicing Rights [Table Text Block]

Activity in capitalized mortgage servicing rights during the three years ended December 31, 2020 is as follows (in thousands):



Balance, December 31, 2017	$	252,867
Additions, net	35,247
Change in fair value due to loan runoff	(33,528)
Change in fair value due to market changes	4,668
Balance, December 31, 2018	259,254
Additions, net	35,128
Change in fair value due to loan runoff	(38,979)
Change in fair value due to market changes	(53,517)
Balance, December 31, 2019	201,886
Additions	31,209
Disposals	(10,801)
Change in fair value due to loan runoff	(41,598)
Change in fair value due to market changes	(79,524)
Balance, December 31, 2020	$	101,172

Assumptions to Value Mortgage Servicing Rights [Table Text Block]

Significant assumptions used to determine fair value considered to be significant unobservable inputs were as follows:


	December 31,
	2020	2019
Discount rate – risk-free rate plus a market premium	9.14%	9.81%
Prepayment rate - based upon loan interest rate, original term and loan type	9.41% - 21.87%	8.28% - 16.05%
Loan servicing costs – annually per loan based upon loan type:
Performing loans	$69 - $94	$68 - $94
Delinquent loans	$150 - $500	$150 - $500
Loans in foreclosure	$1,000 - $4,000	$1,000 - $4,000
Primary/secondary mortgage rate spread	105 bps	104 bps
Escrow earnings rate – indexed to rates paid on deposit accounts with comparable average life	0.43%	1.73%
Delinquency rate	3.54%	2.73%

Deposits (Tables)

12 Months Ended

Dec. 31, 2020

Deposits [Abstract]

Interest Expense on Deposits Disclosure [Table Text Block]

Interest expense on deposits is summarized as follows (in thousands):


	Year Ended December 31,
	2020		2019		2018
Transaction deposits	$	60,424	$	132,854	$	65,859
Savings	385		677		439
Time:
Certificates of deposits under $100,000	6,741		8,299		5,751
Certificates of deposits $100,000 and over	18,270		29,288		19,739
Other time deposits	4,176		4,420		3,729
Total time	29,187		42,007		29,219
Total	$	89,996	$	175,538	$	95,517

Other Borrowed Funds Other Borrowed Funds (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Schedule of Other Borrowed Funds [Table Text Block]

Information relating to other borrowings is summarized as follows (dollars in thousands):


	As of				Year Ended
	December 31, 2020				December 31, 2020
	Balance		Rate		Average Balance		Rate		Maximum Outstanding At Any Month End
Funds purchased	769,365		0.05	%	2,045,795		0.58	%	3,311,938
Repurchase agreements	893,021		0.09	%	1,589,746		0.24	%	3,230,097
Other borrowings:
Federal Home Loan Bank advances	200,000		0.29	%	3,393,989		1.00	%	7,500,000
GNMA repurchase liability	19,500		4.35	%	42,771		4.18	%	126,569
Federal Reserve Bank advances	—		—	%	42,464		0.26	%	—
Paycheck protection program liquidity facility	1,635,963		0.35	%	1,152,073		0.35	%	2,013,414
Other	27,507		5.24	%	28,156		5.12	%	49,376
Total other borrowings	1,882,970				4,659,453		0.88	%
Subordinated debentures1	276,005		4.72	%	275,965		5.05	%	276,005
Total other borrowed funds	$	3,821,361			$	8,570,959	0.82	%


	As of				Year Ended
	December 31, 2019				December 31, 2019
	Balance		Rate		Average Balance		Rate		Maximum Outstanding At Any Month End
Funds purchased	3,390,528		1.53	%	2,438,376		2.08	%	3,390,528
Repurchase agreements	427,822		0.50	%	399,785		0.57	%	427,822
Other borrowings:
Federal Home Loan Bank advances	4,500,000		1.79	%	7,122,466		2.44	%	8,000,000
GNMA repurchase liability	15,417		4.32	%	13,746		4.47	%	19,581
Other	11,638		5.09	%	11,144		5.30	%	34,676
Total other borrowings	4,527,055				7,147,356		2.45	%
Subordinated debentures1	275,923		5.15	%	276,075		5.47	%	275,923
Total other borrowed funds	$	8,621,328			$	10,261,592	2.37	%


	As of				Year Ended
	December 31, 2018				December 31, 2018
	Balance		Rate		Average Balance		Rate		Maximum Outstanding At Any Month End
Funds purchased	402,450		2.34	%	419,322		1.89	%	949,531
Repurchase agreements	615,961		0.36	%	464,582		0.28	%	615,961
Other borrowings:
Federal Home Loan Bank advances	6,100,000		2.65	%	6,207,142		2.06	%	6,500,000
GNMA repurchase liability	15,552		4.43	%	14,783		4.47	%	16,529
Other	8,838		2.90	%	14,516		2.67	%	20,422
Total other borrowings	6,124,390				6,236,441		2.07	%
Subordinated debentures1	275,913		5.34	%	177,884		5.52	%	275,913
Total other borrowed funds	$	7,418,714			$	7,298,229	2.03	%

Schedule of Maturities of Other Borrowed Funds [Table Text Block]

Aggregate annual principal repayments at December 31, 2020 are as follows (in thousands):



2021	$	1,884,974
2022	1,639,735
2023	9,625
2024	625
2025	10,555
Thereafter	275,847
Total	$	3,821,361

Schedule of Repurchase Agreements [Table Text Block]

Additional information relating to securities sold under agreements to repurchase and related liabilities at December 31, 2020 and 2019 is as follows (dollars in thousands):


	December 31, 2020
	Amortized		Fair		Repurchase
Security Sold/Maturity	Cost		Value		Liability1		Rate

U.S. government agency mortgage-backed securities:
Overnight1	$	893,069	$	910,885	$	893,021	0.09	%
Long-term	—		—		—		—	%
Total Agency Securities	$	893,069	$	910,885	$	893,021	0.09	%

	December 31, 2019
	Amortized		Fair		Repurchase
Security Sold/Maturity	Cost		Value		Liability1		Rate

U.S. government agency mortgage-backed securities:
Overnight1	$	431,939	$	435,898	$	427,822	0.50	%
Long-term	—		—		—		—	%
Total Agency Securities	$	431,939	$	435,898	$	427,822	0.50	%

1 BOK Financial maintains control over the securities underlying overnight repurchase agreements and generally transfers control over securities underlying longer-term dealer repurchase agreements to the respective counterparty.

Federal and State Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of deferred tax assets and liabilities are as follows (in thousands):


	December 31,
	2020		2019
Deferred tax assets:
Credit loss reserves	$	101,265	$	50,611
Lease liability	44,794		46,084
Deferred compensation	29,504		25,976
Unearned fees	14,584		9,080
Purchased loan discount	11,537		18,042
Share-based compensation	6,525		7,392
Valuation adjustments	3,834		1,545

Other	29,963		26,384
Total deferred tax assets	242,006		185,114

Deferred tax liabilities:
Available for sale securities mark to market	105,769		33,140
Right-of-use asset	38,635		42,180
Mortgage servicing rights	24,182		48,435
Acquired identifiable intangible	18,138		23,181
Depreciation	13,754		18,909
Lease financing	11,828		10,720
Other	39,210		34,826
Total deferred tax liabilities	251,516		211,391
Net deferred tax liabilities	$	(9,510)	$	(26,277)

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

The significant components of the provision for income taxes attributable to continuing operations for BOK Financial are shown below (in thousands):


	Year Ended December 31,
	2020		2019		2018
Current income tax expense:
Federal	$	173,888	$	110,887	$	103,748
State	29,889		15,088		15,253
Total current income tax expense	203,777		125,975		119,001

Deferred income tax expense (benefit):
Federal	(65,989)		3,416		(190)
State	(8,995)		792		250
Total deferred income tax expense (benefit)	(74,984)		4,208		60
Total income tax expense	$	128,793	$	130,183	$	119,061

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The reconciliations of income attributable to continuing operations at the U.S. federal statutory tax rate to income tax expense are as follows (in thousands):


	Year Ended December 31,
	2020		2019		2018
Amount:
Federal statutory tax	$	118,412	$	132,482	$	118,752
Tax exempt revenue	(7,035)		(12,227)		(8,311)
Effect of state income taxes, net of federal benefit	14,251		12,715		12,430
Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments	(6,994)		(5,127)		(4,559)





Other, net	10,159		2,340		749
Total income tax expense	$	128,793	$	130,183	$	119,061


	Year Ended December 31,
	2020		2019		2018
Percent of pretax income:
Federal statutory tax	21.0	%	21.0	%	21.0	%
Tax exempt revenue	(1.2)		(1.9)		(1.5)
Effect of state income taxes, net of federal benefit	2.5		2.0		2.2
Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments	(1.2)		(0.8)		(0.8)



Other, net	1.7		0.3		0.2
Total	22.8	%	20.6	%	21.1	%

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands):


	2020		2019		2018
Balance as of January 1	$	20,465	$	18,869	$	18,110
Additions for tax for current year positions	6,384		5,649		2,649
Settlements during the period	—		—		—
Lapses of applicable statute of limitations	(3,947)		(4,053)		(1,890)
Balance as of December 31	$	22,902	$	20,465	$	18,869

Employee Benefits (Tables)

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Valuation assumptions used [Table Text Block]


	2020		2019
Discount rate	2.69	%	4.10	%
Expected return on plan assets	5.50	%	5.50	%

Share-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Share-based Payment Arrangement, Option, Activity [Table Text Block]

The following table presents stock options outstanding under these plans (in thousands, except for per share data):


	Number	Weighted- Average Exercise Price		Aggregate Intrinsic Value
Options outstanding at:





December 31, 2018	63,058	$	54.89	$	1,163




December 31, 2019	36,100	56.75		1,106




December 31, 2020	17,671	57.35		197
Options vested at:
December 31, 2018	33,573	$	53.09	$	679
December 31, 2019	27,193	57.08		824
December 31, 2020	17,671	57.35		197

Schedule of Nonvested Share Activity [Table Text Block]

The following represents a summary of the non-vested shares for the three years ended December 31, 2020 (in thousands):


	Restricted Stock			Restricted Stock Units
	Shares	Weighted Average Grant Date Fair Value		Units	Weighted Average Grant Date Fair Value
Non-vested at January 1, 2018	667,103			—
Granted	150,419	$	85.58	—	—
Vested	(242,215)	74.85		—	—
Forfeited	(47,700)	75.68		—	—
Non-vested at December 31, 2018	527,607			—
Granted	145,724	$	76.74	46,689	$	87.40
Vested	(114,201)	61.28		—	—
Forfeited	(131,952)	83.69		—	—
Non-vested at December 31, 2019	427,178			46,689
Granted	236,750	$	83.49	22,980	$	77.36
Vested	(225,527)	83.50		—	—
Forfeited	(18,167)	83.10		—	—
Non-vested at December 31, 2020	420,234			69,669

Related Parties Related Parties (Tables)

12 Months Ended

Dec. 31, 2020

Activity in loans to related parties is summarized as follows (in thousands):


	Year Ended December 31,
	2020		2019
Beginning balance	$	75,189	$	75,265
Advances	498,425		886,610
Payments	(484,958)		(896,643)
Adjustments1	4,284		9,957
Ending balance	$	92,940	$	75,189

1 Adjustments generally consist of changes in status as a related party.

Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Earnings Per Share [Table Text Block]

The following table presents the computation of basic and diluted earnings per share (dollars in thousands, except per share data):


	Year Ended
	2020		2019		2018
Numerator:
Net income attributable to BOK Financial Corp. shareholders	$	435,030	$	500,758	$	445,646
Less: Earnings allocated to participating securities	2,612		3,227		3,737
Numerator for basic earnings per share – income available to common shareholders	432,418		497,531		441,909
Effect of reallocating undistributed earnings of participating securities	—		—		1
Numerator for diluted earnings per share – income available to common shareholders	$	432,418	$	497,531	$	441,910

Denominator:
Weighted average shares outstanding	70,259,553		71,250,081		67,190,257
Less: Participating securities included in weighted average shares outstanding	418,576		462,381		561,617
Denominator for basic earnings per common share	69,840,977		70,787,700		66,628,640
Dilutive effect of employee stock compensation plans	3,195		14,912		33,633
Denominator for diluted earnings per common share	69,844,172		70,802,612		66,662,273

Basic earnings per share	$	6.19	$	7.03	$	6.63
Diluted earnings per share	$	6.19	$	7.03	$	6.63

Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2020

Stockholders' Equity Note [Abstract]

Summary of Regulatory Capital Levels [Table Text Block]

A summary of regulatory capital minimum requirements and levels follows (dollars in thousands):


	Minimum Capital Requirement	Capital Conservation Buffer	Minimum Capital Requirement Including Capital Conservation Buffer	Well Capitalized Bank Requirement	December 31, 2020				December 31, 2019
Common Equity Tier 1 Capital (to Risk Weighted Assets):
Consolidated	4.50%	2.50%	7.00%	N/A	$	3,881,912	11.95	%	$	3,608,821	11.39	%
BOKF, NA	4.50%	N/A	4.50%	6.50%	3,756,950		11.66	%	3,414,446		10.90	%
Tier I Capital (to Risk Weighted Assets):
Consolidated	6.00%	2.50%	8.50%	N/A	$	3,881,912	11.95	%	$	3,608,821	11.39	%
BOKF, NA	6.00%	N/A	6.00%	8.00%	3,756,950		11.66	%	3,414,446		10.90	%
Total Capital (to Risk Weighted Assets):
Consolidated	8.00%	2.50%	10.50%	N/A	$	4,489,110	13.82	%	$	4,097,087	12.94	%
BOKF, NA	8.00%	N/A	8.00%	10.00%	4,153,347		12.89	%	3,692,010		11.79	%
Leverage (Tier I Capital to Average Assets):
Consolidated	4.00%	N/A	4.00%	N/A	$	3,881,912	8.28	%	$	3,608,820	8.40	%
BOKF, NA	4.00%	N/A	4.00%	5.00%	3,756,950		8.04	%	3,414,446		7.98	%

Accumulated Other Comprehensive Income (Loss) [Table Text Block]

A rollforward of the components of accumulated other comprehensive income (loss) is included as follows (in thousands):


	Unrealized Gain (Loss) on
	Available for Sale Securities		Employee Benefit Plans		Total
Balance, December 31, 2017	$	(35,385)	$	(789)	$	(36,174)
Transition adjustment for net unrealized gains on equity securities	(2,709)		—		(2,709)
Net change in unrealized gain (loss)	(46,941)		(1,069)		(48,010)
Reclassification adjustments included in earnings:



Loss on available for sale securities, net	2,801		—		2,801
Other comprehensive income (loss), before income taxes	(44,140)		(1,069)		(45,209)
Federal and state income tax	(11,235)		(272)		(11,507)
Other comprehensive income (loss), net of income taxes	(32,905)		(797)		(33,702)
Balance, December 31, 2018	(70,999)		(1,586)		(72,585)
Net change in unrealized gain (loss)	239,017		2,030		241,047
Reclassification adjustments included in earnings:



Gain on available for sale securities, net	(5,597)		—		(5,597)
Other comprehensive income (loss), before income taxes	233,420		2,030		235,450
Federal and state income tax	57,425		517		57,942
Other comprehensive income (loss), net of income taxes	175,995		1,513		177,508
Balance, December 31, 2019	104,996		(73)		104,923
Net change in unrealized gain (loss)	312,576		1,220		313,796
Reclassification adjustments included in earnings:



Gain on available for sale securities, net	(9,910)		—		(9,910)
Other comprehensive income (loss), before income taxes	302,666		1,220		303,886
Federal and state income tax	72,630		311		72,941
Other comprehensive income (loss), net of income taxes	230,036		909		230,945
Balance, December 31, 2020	$	335,032	$	836	$	335,868

Reportable Segments (Tables)

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Reportable Segments [Table Text Block]

Reportable segments reconciliation to the Consolidated Financial Statements for the year ended December 31, 2020 is as follows (in thousands):


	Commercial		Consumer		Wealth Management		Funds Management and Other		BOK Financial Consolidated
Net interest and dividend revenue from external sources	$	714,932	$	78,004	$	130,818	$	184,690	$	1,108,444
Net interest revenue (expense) from internal sources	(126,444)		69,000		(13,528)		70,972		—
Net interest and dividend revenue	588,488		147,004		117,290		255,662		1,108,444
Provision for credit losses	69,475		2,805		(209)		150,521		222,592
Net interest and dividend revenue after provision for credit losses	519,013		144,199		117,499		105,141		885,852
Other operating revenue	187,361		243,719		398,834		14,035		843,949
Other operating expense	258,903		233,425		325,608		348,001		1,165,937
Net direct contribution	447,471		154,493		190,725		(228,825)		563,864
Gain (loss) on financial instruments, net	193		95,344		4		(95,541)		—
Change in fair value of mortgage servicing rights	—		(79,524)		—		79,524		—
Gain (loss) on repossessed assets, net	(2,677)		276		—		2,401		—
Corporate expense allocations	24,862		42,638		35,331		(102,831)		—
Net income before taxes	420,125		127,951		155,398		(139,610)		563,864
Federal and state income taxes	114,120		32,591		39,770		(57,688)		128,793
Net income	306,005		95,360		115,628		(81,922)		435,071
Net income attributable to non-controlling interests	—		—		—		41		41
Net income attributable to BOK Financial Corp. shareholders	$	306,005	$	95,360	$	115,628	$	(81,963)	$	435,030

Average assets	$	26,994,075	$	9,842,125	$	15,695,646	$	(3,827,456)	$	48,704,390

Reportable segments reconciliation to the Consolidated Financial Statements for the year ended December 31, 2019 is as follows (in thousands):


	Commercial		Consumer		Wealth Management		Funds Management and Other		BOK Financial Consolidated
Net interest and dividend revenue from external sources	$	919,148	$	99,679	$	61,277	$	32,775	$	1,112,879
Net interest revenue (expense) from internal sources	(242,907)		95,775		38,815		108,317		—
Net interest and dividend revenue	676,241		195,454		100,092		141,092		1,112,879
Provision for credit losses	39,011		6,271		(308)		(974)		44,000
Net interest and dividend revenue after provision for credit losses	637,230		189,183		100,400		142,066		1,068,879
Other operating revenue	170,412		187,500		341,389		(4,931)		694,370
Other operating expense	252,459		230,916		277,267		371,739		1,132,381
Net direct contribution	555,183		145,767		164,522		(234,604)		630,868
Gain (loss) on financial instruments, net	106		30,375		2		(30,483)		—
Change in fair value of mortgage servicing rights	—		(53,517)		—		53,517		—
Gain (loss) on repossessed assets, net	331		496		—		(827)		—
Corporate expense allocations	43,055		47,169		36,239		(126,463)		—
Net income before taxes	512,565		75,952		128,285		(85,934)		630,868
Federal and state income taxes	137,759		19,346		32,954		(59,876)		130,183
Net income	374,806		56,606		95,331		(26,058)		500,685
Net loss attributable to non-controlling interests	—		—		—		(73)		(73)
Net income attributable to BOK Financial Corp. shareholders	$	374,806	$	56,606	$	95,331	$	(25,985)	$	500,758

Average assets	$	22,807,589	$	9,301,341	$	10,204,426	$	(219,009)	$	42,094,347

Reportable segments reconciliation to the Consolidated Financial Statements for the year ended December 31, 2018 is as follows (in thousands):


	Commercial		Consumer		Wealth Management		Funds Management and Other		BOK Financial Consolidated
Net interest and dividend revenue from external sources	$	726,855	$	83,231	$	81,528	$	93,253	$	984,867
Net interest revenue (expense) from internal sources	(159,954)		73,448		31,480		55,026		—
Net interest and dividend revenue	566,901		156,679		113,008		148,279		984,867
Provision for credit losses	30,358		5,143		(288)		(27,213)		8,000
Net interest and dividend revenue after provision for credit losses	536,543		151,536		113,296		175,492		976,867
Other operating revenue	162,701		178,123		296,369		(20,409)		616,784
Other operating expense	202,095		231,075		257,650		337,346		1,028,166
Net direct contribution	497,149		98,584		152,015		(182,263)		565,485
Gain (loss) on financial instruments, net	26		(25,021)		7		24,988		—
Change in fair value of mortgage servicing rights	—		4,668		—		(4,668)		—
Gain (loss) on repossessed assets, net	(6,532)		247		—		6,285		—
Corporate expense allocations	36,670		44,398		35,920		(116,988)		—
Net income before taxes	453,973		34,080		116,102		(38,670)		565,485
Federal and state income taxes	120,458		8,681		30,075		(40,153)		119,061
Net income	333,515		25,399		86,027		1,483		446,424
Net income attributable to non-controlling interests	—		—		—		778		778
Net income attributable to BOK Financial Corp. shareholders	$	333,515	$	25,399	$	86,027	$	705	$	445,646

Average assets	$	18,432,035	$	8,303,263	$	8,447,784	$	(245,552)	$	34,937,530

Fees and Commission Revenue Fees and Commissions Revenue (Tables)

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Abstract]

Disaggregation of Fees and Commissions Revenue [Table Text Block]

Fees and commissions revenue by reportable segment and primary service line is as follows for the year ended December 31, 2020.


	Commercial		Consumer		Wealth Management		Funds Management and Other		Consolidated		Out of Scope1		In Scope2
Trading revenue	$	—	$	—	$	144,299	$	—	$	144,299	$	144,299	$	—
Customer hedging revenue	22,767		—		395		(413)		22,749		22,749		—
Retail brokerage revenue	—		—		15,690		—		15,690		—		15,690
Insurance brokerage revenue	—		—		12,702		—		12,702		—		12,702
Investment banking revenue	9,183		—		17,391		(181)		26,393		8,530		17,863
Brokerage and trading revenue	31,950		—		190,477		(594)		221,833		175,578		46,255
TransFund EFT network revenue	75,363		3,058		(56)		5		78,370		—		78,370
Merchant services revenue	9,172		60		—		—		9,232		—		9,232
Corporate card revenue	2,362		—		75		143		2,580		—		2,580
Transaction card revenue	86,897		3,118		19		148		90,182		—		90,182
Personal trust revenue	—		—		84,759		—		84,759		—		84,759
Corporate trust revenue	—		—		19,308		—		19,308		—		19,308
Institutional trust & retirement plan services revenue	—		—		46,253		—		46,253		—		46,253
Investment management services and other	—		—		17,290		(165)		17,125		—		17,125
Fiduciary and asset management revenue	—		—		167,610		(165)		167,445		—		167,445
Commercial account service charge revenue	44,489		1,654		2,282		(4)		48,421		—		48,421
Overdraft fee revenue	132		21,679		74		7		21,892		—		21,892
Check card revenue	—		21,355		—		—		21,355		—		21,355
Automated service charge and other deposit fee revenue	311		4,749		74		3		5,137		—		5,137
Deposit service charges and fees	44,932		49,437		2,430		6		96,805		—		96,805
Mortgage production revenue	—		125,848		—		—		125,848		125,848		—
Mortgage servicing revenue	—		58,249		—		(1,737)		56,512		56,512		—
Mortgage banking revenue	—		184,097		—		(1,737)		182,360		182,360		—
Other revenue	23,340		8,902		38,693		(19,240)		51,695		39,092		12,603
Total fees and commissions revenue	$	187,119	$	245,554	$	399,229	$	(21,582)	$	810,320	$	397,030	$	413,290

1 Out of scope revenue generally relates to financial instruments or contractual rights and obligations within the scope of other applicable accounting guidance.

2 In scope revenue represents revenue subject to FASB ASC Topic 606, Revenue from Contracts with Customers.

Fees and commissions revenue by reportable segment and primary service line is as follows for the year ended December 31, 2019.


	Commercial		Consumer		Wealth Management		Funds Management and Other		Consolidated		Out of Scope1		In Scope2
Trading revenue	$	—	$	—	$	88,558	$	—	$	88,558	$	88,558	$	—
Customer hedging revenue	8,422		—		9,667		852		18,941		18,941		—
Retail brokerage revenue	—		—		16,251		(115)		16,136		—		16,136
Insurance brokerage revenue	—		—		10,131		3,730		13,861		—		13,861
Investment banking revenue	10,136		—		12,194		—		22,330		8,678		13,652
Brokerage and trading revenue	18,558		—		136,801		4,467		159,826		116,177		43,649
TransFund EFT network revenue	73,479		3,924		(82)		3		77,324		—		77,324
Merchant services revenue	8,607		56		—		123		8,786		—		8,786
Corporate card revenue	1,072		—		32		2		1,106		—		1,106
Transaction card revenue	83,158		3,980		(50)		128		87,216		—		87,216
Personal trust revenue	—		—		81,763		—		81,763		—		81,763
Corporate trust revenue	—		—		24,635		—		24,635		—		24,635
Institutional trust & retirement plan services revenue	—		—		45,084		—		45,084		—		45,084
Investment management services and other	—		—		23,993		1,550		25,543		—		25,543
Fiduciary and asset management revenue	—		—		175,475		1,550		177,025		—		177,025
Commercial account service charge revenue	42,251		1,713		2,137		1,804		47,905		—		47,905
Overdraft fee revenue	313		35,134		138		(229)		35,356		—		35,356
Check card revenue	—		21,865		—		165		22,030		—		22,030
Automated service charge and other deposit fee revenue	823		6,155		168		48		7,194		—		7,194
Deposit service charges and fees	43,387		64,867		2,443		1,788		112,485		—		112,485
Mortgage production revenue	—		42,724		—		(4)		42,720		42,720		—
Mortgage servicing revenue	—		66,692		—		(1,871)		64,821		64,821		—
Mortgage banking revenue	—		109,416		—		(1,875)		107,541		107,541		—
Other revenue	23,564		9,733		26,664		(1,853)		58,108		39,428		18,680
Total fees and commissions revenue	$	168,667	$	187,996	$	341,333	$	4,205	$	702,201	$	263,146	$	439,055

1 Out of scope revenue generally relates to financial instruments or contractual rights and obligations within the scope of other applicable accounting guidance.

2 In scope revenue represents revenue subject to FASB ASC Topic 606, Revenue from Contracts with Customers.

Fees and commissions revenue by reportable segment and primary service line is as follows for the year ended December 31, 2018.


	Commercial		Consumer		Wealth Management		Funds Management and Other		Consolidated		Out of Scope1		In Scope2
Trading revenue	$	—	$	—	$	28,077	$	—	$	28,077	$	28,077	$	—
Customer hedging revenue	7,748		—		27,512		3,574		38,834		38,834		—
Retail brokerage revenue	—		—		19,030		(1,078)		17,952		—		17,952
Insurance brokerage revenue	—		—		—		4,198		4,198		—		4,198
Investment banking revenue	7,628		—		11,634		—		19,262		6,380		12,882
Brokerage and trading revenue	15,376		—		86,253		6,694		108,323		73,291		35,032
TransFund EFT network revenue	72,280		4,017		(82)		6		76,221		—		76,221
Merchant services revenue	7,666		59		—		79		7,804		—		7,804
Corporate card revenue	—		—		—		—		—		—		—
Transaction card revenue	79,946		4,076		(82)		85		84,025		—		84,025
Personal trust revenue	—		—		96,839		—		96,839		—		96,839
Corporate trust revenue	—		—		22,292		—		22,292		—		22,292
Institutional trust & retirement plan services revenue	—		—		44,400		76		44,476		—		44,476
Investment management services and other	—		—		19,729		1,367		21,096		—		21,096
Fiduciary and asset management revenue	—		—		183,260		1,443		184,703		—		184,703
Commercial account service charge revenue	41,931		1,445		2,331		1,565		47,272		—		47,272
Overdraft fee revenue	370		36,177		134		(145)		36,536		—		36,536
Check card revenue	—		20,967		—		339		21,306		—		21,306
Automated service charge and other deposit fee revenue	282		6,621		62		74		7,039		—		7,039
Deposit service charges and fees	42,583		65,210		2,527		1,833		112,153		—		112,153
Mortgage production revenue	—		31,690		—		—		31,690		31,690		—
Mortgage servicing revenue	—		67,980		—		(1,883)		66,097		66,097		—
Mortgage banking revenue	—		99,670		—		(1,883)		97,787		97,787		—
Other revenue	24,044		9,218		24,507		(1,584)		56,185		38,306		17,879
Total fees and commissions revenue	$	161,949	$	178,174	$	296,465	$	6,588	$	643,176	$	209,384	$	433,792

1 Out of scope revenue generally relates to financial instruments or contractual rights and obligations within the scope of other applicable accounting guidance.

2 In scope revenue represents revenue subject to FASB ASC Topic 606, Revenue from Contracts with Customers.

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Assets And Liabilities Measured On A Recurring Basis [Table Text Block]

The fair value of financial assets and liabilities that are measured on a recurring basis is as follows as of December 31, 2020 (in thousands):


	Total		Quoted Prices in Active Markets for Identical Instruments		Significant Other Observable Inputs		Significant Unobservable Inputs
Assets:
Trading securities:
U.S. government securities	$	9,183	$	4,999	$	4,184	$	—
Residential agency mortgage-backed securities	4,669,148		—		4,669,148		—
Municipal securities	19,172		—		19,172		—

Other trading securities	10,472		—		10,472		—
Total trading securities	4,707,975		4,999		4,702,976		—
Available for sale securities:
U.S. Treasury	508		508		—		—
Municipal securities	167,979		—		167,979		—
Residential agency mortgage-backed securities	9,340,471		—		9,340,471		—
Residential non-agency mortgage-backed securities	32,770		—		32,770		—
Commercial agency mortgage-backed securities	3,508,465		—		3,508,465		—
Other debt securities	472		—		—		472
Total available for sale securities	13,050,665		508		13,049,685		472



Fair value option securities — Residential agency mortgage-backed securities	114,982		—		114,982		—
Residential mortgage loans held for sale1	252,316		—		245,299		7,017
Mortgage servicing rights, net2	101,172		—		—		101,172
Derivative contracts, net of cash margin3	810,688		10,780		799,908		—
Liabilities:
Derivative contracts, net of cash margin3	405,779		—		405,779		—

1Residential mortgage loans held for sale measured at fair value on a recurring basis using significant unobservable inputs (Level 3) consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards and are valued at 94.57% of the unpaid principal balance.

2A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 7, Mortgage Banking Activities.

3See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts in asset positions that were valued based on quoted prices in active markets for identical instruments (Level 1) are primarily exchange-traded interest rate derivative contracts. Derivative contracts in liability positions that were valued using quoted prices in active markets for identical instruments are exchange-traded interest rate, energy and agricultural derivative contracts, fully offset by cash margin.

The fair value of financial assets and liabilities that are measured on a recurring basis is as follows as of December 31, 2019 (in thousands):


	Total		Quoted Prices in Active Markets for Identical Instruments		Significant Other Observable Inputs		Significant Unobservable Inputs
Assets:
Trading securities:
U.S. government securities	$	44,264	$	—	$	44,264	$	—
Residential agency mortgage-backed securities	1,504,651		—		1,504,651		—
Municipal securities	26,196		—		26,196		—
Asset-backed securities	14,084		—		14,084		—
Other trading securities	34,726		—		34,726		—
Total trading securities	1,623,921		—		1,623,921		—
Available for sale securities:
U.S. Treasury	1,600		1,600		—		—
Municipal securities	1,861		—		1,861		—
Residential agency mortgage-backed securities	8,046,096		—		8,046,096		—
Residential non-agency mortgage-backed securities	41,609		—		41,609		—
Commercial agency mortgage-backed securities	3,178,005		—		3,178,005		—
Other debt securities	472		—		—		472
Total available for sale securities	11,269,643		1,600		11,267,571		472
Fair value option securities:
U.S. Treasury	9,917		9,917		—		—
Residential agency mortgage-backed securities	1,088,660		—		1,088,660		—
Total fair value option securities	1,098,577		9,917		1,088,660		—
Residential mortgage loans held for sale1	182,271		—		173,958		8,313
Mortgage servicing rights, net2	201,886		—		—		201,886
Derivative contracts, net of cash margin3	323,375		8,944		314,431		—
Liabilities:
Derivative contracts, net of cash margin3	251,128		—		251,128		—

1Residential mortgage loans held for sale measured at fair value on a recurring basis using significant unobservable inputs (Level 3) consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards and are valued at 95.23% of the unpaid principal balance.

2A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 7, Mortgage Banking Activities.

3See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts based on quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate and energy derivative contracts, net of cash margin. Derivative contracts in liability positions that were valued using quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate and agricultural contracts, fully offset by cash margin.

Fair Value Assets Measured on Nonrecurring Basis [Table Text Block]

The following represents the carrying value of assets measured at fair value on a non-recurring basis and related losses recorded during the year. The carrying value represents only those assets with the balance sheet date for which the fair value was adjusted during the year:


	Carrying Value at December 31, 2020						Fair Value Adjustments for the Year Ended December 31, 2020 Recognized In:
	Quoted Prices in Active Markets for Identical Instruments		Significant Other Observable Inputs		Significant Unobservable Inputs		Gross charge-offs against allowance for loan losses		Net losses (gains) and expenses of repossessed assets, net
Nonaccrual loans	$	—	$	801	$	20,423	$	39,299	$	—
Real estate and other repossessed assets	—		18,188		2,842		—		(4,602)


	Carrying Value at December 31, 2019						Fair Value Adjustments for the Year Ended December 31, 2019 Recognized In:
	Quoted Prices in Active Markets for Identical Instruments		Significant Other Observable Inputs		Significant Unobservable Inputs		Gross charge-offs against allowance for loan losses		Net losses (gains) and expenses of repossessed assets, net
Nonaccrual loans	$	—	$	41	$	55,665	$	31,305	$	—
Real estate and other repossessed assets	—		5,986		1,551		—		(461)

Fair Value Inputs, Fair Value Measured On a Nonrecurring Basis, Quantitative Information [Table Text Block]

A summary of quantitative information about Non-recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of December 31, 2020 follows (in thousands):

Quantitative Information about Level 3 Non-recurring Fair Value Measurements

Fair Value

Valuation Technique(s)

Significant Unobservable Input

Range
(Weighted Average)

Nonaccrual loans

$

20,423

Discounted cash flows

Management knowledge of industry and non-real estate collateral including but not limited to recoverable oil & gas reserves, forward looking commodity prices, and estimated operating costs

1% - 91% (23%)1

Real estate and other repossessed assets

2,842

Discounted cash flows

Management knowledge of industry and non-real estate collateral including but not limited to recoverable oil & gas reserves, forward looking commodity prices, and estimated operating costs

N/A

1 Represents fair value as a percentage of the unpaid principal balance.

A summary of quantitative information about Non-recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of December 31, 2019 follows (in thousands):

Quantitative Information about Level 3 Non-recurring Fair Value Measurements

Fair Value

Valuation Technique(s)

Significant Unobservable Input

Range
(Weighted Average)

Nonaccrual loans

$

55,665

Discounted cash flows

Management knowledge of industry and non-real estate collateral including but not limited to recoverable oil & gas reserves, forward looking commodity prices, and estimated operating costs

4% - 94% (55%)1

Real estate and other repossessed assets

1,551

Discounted cash flows

Marketability adjustments off appraised value2

74% - 86% (84%)

1 Represents fair value as a percentage of the unpaid principal balance.

2 Marketability adjustments include consideration of estimated costs to sell which is approximately 10% of the fair value.

Fair Value of Financial Instruments [Table Text Block]

The following table presents the carrying values and estimated fair values of all financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring basis or non-recurring (dollars in thousands):


	December 31, 2020
	Carrying Value		Estimated Fair Value		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and due from banks	$	798,757	$	798,757	$	798,757	$	—	$	—
Interest-bearing cash and cash equivalents	381,816		381,816		381,816		—		—
Trading securities:
U.S. government securities	9,183		9,183		4,999		4,184		—
Residential agency mortgage-backed securities	4,669,148		4,669,148		—		4,669,148		—
Municipal securities	19,172		19,172		—		19,172		—

Other trading securities	10,472		10,472		—		10,472		—
Total trading securities	4,707,975		4,707,975		4,999		4,702,976		—
Investment securities:
Municipal securities	229,245		255,270		—		69,404		185,866
Residential agency mortgage-backed securities	8,913		9,790		—		9,790		—
Other debt securities	7,373		7,371		—		7,371		—
Total investment securities	245,531		272,431		—		86,565		185,866
Allowance for credit losses	(688)		—		—		—		—
Investment securities, net of allowance	244,843		272,431		—		86,565		185,866
Available for sale securities:
U.S. Treasury	508		508		508		—		—
Municipal securities	167,979		167,979		—		167,979		—
Residential agency mortgage-backed securities	9,340,471		9,340,471		—		9,340,471		—
Residential non-agency mortgage-backed securities	32,770		32,770		—		32,770		—
Commercial agency mortgage-backed securities	3,508,465		3,508,465		—		3,508,465		—
Other debt securities	472		472		—		—		472
Total available for sale securities	13,050,665		13,050,665		508		13,049,685		472



Fair value option securities — Residential agency mortgage-backed securities	114,982		114,982		—		114,982		—
Residential mortgage loans held for sale	252,316		252,316		—		245,299		7,017
Loans:
Commercial	13,077,535		13,003,383		—		—		13,003,383
Commercial real estate	4,698,538		4,649,763		—		—		4,649,763
Paycheck protection program	1,682,310		1,669,461		—		—		1,669,461
Loans to individuals	3,549,137		3,563,199		—		—		3,563,199
Total loans	23,007,520		22,885,806		—		—		22,885,806
Allowance for loan losses	(388,640)		—		—		—		—
Loans, net of allowance	22,618,880		22,885,806		—		—		22,885,806
Mortgage servicing rights	101,172		101,172		—		—		101,172
Derivative instruments with positive fair value, net of cash margin	810,688		810,688		10,780		799,908		—
Deposits with no stated maturity	34,176,752		34,176,752		—		—		34,176,752
Time deposits	1,967,128		1,976,936		—		—		1,976,936
Other borrowed funds	3,545,356		3,542,489		—		—		3,542,489
Subordinated debentures	276,005		269,544		—		269,544		—
Derivative instruments with negative fair value, net of cash margin	405,779		405,779		—		405,779		—


	December 31, 2019
	Carrying Value		Estimated Fair Value		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and due from banks	$	735,836	$	735,836	$	735,836	$	—	$	—
Interest-bearing cash and cash equivalents	522,985		522,985		522,985		—		—
Trading securities:
U.S. government securities	44,264		44,264		—		44,264		—
Residential agency mortgage-backed securities	1,504,651		1,504,651		—		1,504,651		—
Municipal securities	26,196		26,196		—		26,196		—
Asset-backed securities	14,084		14,084		—		14,084		—
Other trading securities	34,726		34,726		—		34,726		—
Total trading securities	1,623,921		1,623,921		—		1,623,921		—
Investment securities:
Municipal securities	274,535		295,032		—		96,897		198,135
Residential agency mortgage-backed securities	10,676		11,164		—		11,164		—
Other debt securities	8,207		8,206		—		8,206		—
Total investment securities	293,418		314,402		—		116,267		198,135
Available for sale securities:
U.S. Treasury securities	1,600		1,600		1,600		—		—
Municipal securities	1,861		1,861		—		1,861		—
Residential agency mortgage-backed securities	8,046,096		8,046,096		—		8,046,096		—
Residential non-agency mortgage-backed securities	41,609		41,609		—		41,609		—
Commercial agency mortgage-backed securities	3,178,005		3,178,005		—		3,178,005		—
Other debt securities	472		472		—		—		472
Total available for sale securities	11,269,643		11,269,643		1,600		11,267,571		472
Fair value option securities:
U.S. Treasury	9,917		9,917		9,917		—		—
Residential agency mortgage-backed securities	1,088,660		1,088,660		—		1,088,660		—
Total fair value option securities	1,098,577		1,098,577		9,917		1,088,660		—
Residential mortgage loans held for sale	182,271		182,271		—		173,958		8,313
Loans:
Commercial	14,031,650		13,966,221		—		—		13,966,221
Commercial real estate	4,433,783		4,422,717		—		—		4,422,717
Residential mortgage	2,084,172		2,098,093		—		—		2,098,093
Personal	1,201,382		1,202,298		—		—		1,202,298
Total loans	21,750,987		21,689,329		—		—		21,689,329
Allowance for loan losses	(210,759)		—		—		—		—
Loans, net of allowance	21,540,228		21,689,329		—		—		21,689,329
Mortgage servicing rights	201,886		201,886		—		—		201,886
Derivative instruments with positive fair value, net of cash margin	323,375		323,375		8,944		314,431		—
Deposits with no stated maturity	25,403,319		25,403,319		—		—		25,403,319
Time deposits	2,217,849		2,212,467		—		—		2,212,467
Other borrowed funds	8,345,405		8,315,860		—		—		8,315,860
Subordinated debentures	275,923		284,627		—		284,627		—
Derivative instruments with negative fair value, net of cash margin	251,128		251,128		—		251,128		—

Parent Company Only Financial Statements Parent Company Only Financial Statements (Tables)

12 Months Ended

Dec. 31, 2020

Condensed Financial Information Disclosure [Abstract]

Condensed Balance Sheet [Table Text Block]

Balance Sheets

(In thousands)


	December 31,
	2020		2019
Assets
Cash and cash equivalents	$	183,805	$	214,779

Loan to bank subsidiary	65,204		65,220
Investment in bank subsidiaries	5,079,336		4,602,977
Investment in non-bank subsidiaries	195,768		216,542
Other assets	24,338		38,082
Total assets	$	5,548,451	$	5,137,600

Liabilities and Shareholders’ Equity
Liabilities:
Other liabilities	$	6,180	$	5,882
Subordinated debentures	276,005		275,923
Total liabilities	282,185		281,805
Shareholders’ equity:
Common stock	5		5
Capital surplus	1,368,062		1,350,995
Retained earnings	3,973,675		3,729,778
Treasury stock	(411,344)		(329,906)
Accumulated other comprehensive income	335,868		104,923
Total shareholders’ equity	5,266,266		4,855,795
Total liabilities and shareholders’ equity	$	5,548,451	$	5,137,600

Condensed Income Statement [Table Text Block]

Statements of Earnings

(In thousands)


	Year Ended December 31,
	2020		2019		2018
Dividends, interest and fees received from bank subsidiaries	$	179,140	$	344,007	$	426,071
Dividends, interest and fees received from non-bank subsidiaries	25,050		9,325		12,800
Other revenue	907		1,036		954

Total revenue	205,097		354,368		439,825
Interest expense	13,944		15,113		9,827
Other operating expense	2,697		2,352		12,110
Total expense	16,641		17,465		21,937
Net income before taxes, other losses, net, and equity in undistributed income of subsidiaries	188,456		336,903		417,888
Other gains (losses), net	1,465		3,310		(3,921)
Net income before taxes and equity in undistributed income of subsidiaries	189,921		340,213		413,967
Federal and state income taxes	(4,502)		(4,516)		(7,078)
Net income before equity in undistributed income of subsidiaries	194,423		344,729		421,045
Equity in undistributed income of bank subsidiaries	276,217		166,797		37,515
Equity in undistributed income of non-bank subsidiaries	(35,610)		(10,768)		(12,914)
Net income attributable to BOK Financial Corp. shareholders	$	435,030	$	500,758	$	445,646

Condensed Cash Flow Statement [Table Text Block]

Statements of Cash Flows

(In thousands)


	Year Ended December 31,
	2020		2019		2018
Cash Flows From Operating Activities:
Net income	$	435,030	$	500,758	$	445,646
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed income of bank subsidiaries	(276,217)		(166,797)		(37,515)
Equity in undistributed income of non-bank subsidiaries	35,610		10,768		12,914
Change in other assets	13,760		(5,075)		(1,072)
Change in other liabilities	850		855		(13,434)
Net cash provided by operating activities	209,033		340,509		406,539
Cash Flows From Investing Activities:
Investment in subsidiaries	(14,807)		(19,837)		(31,901)
Acquisitions, net of cash acquired	—		—		(232,680)
Net cash used in investing activities	(14,807)		(19,837)		(264,581)
Cash Flows From Financing Activities:
Issuance of common and treasury stock, net	(4,933)		(7)		(88)
Dividends paid	(144,437)		(143,496)		(127,188)
Repurchase of common stock	(75,830)		(129,483)		(53,465)
Net cash used in financing activities	(225,200)		(272,986)		(180,741)
Net increase (decrease) in cash and cash equivalents	(30,974)		47,686		(38,783)
Cash and cash equivalents at beginning of period	214,779		167,093		205,876
Cash and cash equivalents at end of period	$	183,805	$	214,779	$	167,093
Cash paid for interest	$	14,064	$	15,099	$	11,457

Significant Accounting Policies Goodwill and Intangible Assets (Details)	12 Months Ended
	Dec. 31, 2020
Minimum [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	3 years
Maximum [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	20 years

Significant Accounting Policies Cash Equivalents (Details)	12 Months Ended
	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Maturity of Federal Funds Sold Considered Cash Equivalents	one day
Maturity of Resell Agreement Considered Cash Equivalents, Minimum	one day
Maturity of Resell Agreements Considered Cash Equivalents, Maximum	30 days

Significant Accounting Policies Loans (Details)	12 Months Ended
Significant Accounting Policies Loans (Details)	Dec. 31, 2020
Loans [Abstract]
Loans, Number of Days Past Due for a Non-Risk Graded Loan to be Placed on Nonaccruing Status	90 days
Loans, Number of Days After Notification of Chapter 7 Bankruptcy Non-Risk Graded Loan is Placed on Nonaccruing Status	60 days
Loans, Minimum Number of Days After Which Past Due Non-Risk Graded Loans Are Charged Off	60 days
Loans, Maximum Number of Days After Which Past Due Non-Risk Graded Loans Are Charged Off	180 days
Loans, Number of Days After Notification of Chapter 7 Bankruptcy Non-Risk Graded Loan is Charged Off	60 days

Significant Accounting Policies Premises and Equipment (Details)	12 Months Ended
	Dec. 31, 2020
Buildings and improvements \| Minimum [Member]
Premises and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Buildings and improvements \| Maximum [Member]
Premises and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Software and Software Development Costs [Member] \| Minimum [Member]
Premises and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Software and Software Development Costs [Member] \| Maximum [Member]
Premises and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Furniture and equipment \| Minimum [Member]
Premises and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Furniture and equipment \| Maximum [Member]
Premises and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years

Significant Accounting Policies Share-Based Compensation (Details)	12 Months Ended
	Dec. 31, 2020
Stock Options [Member]
Share-based Compensation Arrangements by Share-based Payment Award [Line Items]
Vesting period (in years)	7 years
Restricted Stock [Member]
Share-based Compensation Arrangements by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Required Holding Period	2 years

Significant Accounting Policies Newly Adopted and Pending Accounting Pronouncements (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Increase of reported right of use assets and liabilities	$ 137

Trading Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Trading Securities [Line Items]
Trading securities	$ 4,707,975	$ 1,623,921
Trading Securities, Net Unrealized Gain (Loss)	(3,560)	2,359
U.S. government securities [Member]
Schedule of Trading Securities [Line Items]
Trading securities	9,183	44,264
Trading Securities, Net Unrealized Gain (Loss)	0	6
Residential agency mortgage-backed securities [Member]
Schedule of Trading Securities [Line Items]
Trading securities	4,669,148	1,504,651
Trading Securities, Net Unrealized Gain (Loss)	(3,624)	2,293
Municipal securities [Member]
Schedule of Trading Securities [Line Items]
Trading securities	19,172	26,196
Trading Securities, Net Unrealized Gain (Loss)	42	60
Asset-backed securities [Member]
Schedule of Trading Securities [Line Items]
Trading securities	0	14,084
Trading Securities, Net Unrealized Gain (Loss)	0	(21)
Other debt securities [Member]
Schedule of Trading Securities [Line Items]
Trading securities	10,472	34,726
Trading Securities, Net Unrealized Gain (Loss)	$ 22	$ 21

Investment (Held-to-Maturity) Securities (Details)
$ in Thousands

12 Months Ended

Dec. 31, 2020

USD ($)

Dec. 31, 2019

USD ($)

Schedule of Investment (Held-to-Maturity) Securities [Line Items]

Investment Securities, fair value

$ 272,431

$ 314,402

Investment Securities, Gross Unrealized Gain

27,046

21,285

Investment Securities, Gross Unrealized Loss

(146)

(301)

Debt Securities, Held-to-maturity, gross

245,531

Debt Securities, Held-to-maturity, Allowance for Credit Loss

688

Investment securities

244,843

293,418

Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Investment Securities, fair value

$ 272,431

$ 314,402

Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

8

17

Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 2,701

$ 1,276

Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

2,068

9,747

Investment Securities, Continuous Unrealized Loss Position, Fair Value

4,769

11,023

Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Losses

41

2

Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Losses

105

299

Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss

146

301

Fixed maturity securities [Member]

Investment Securities, Debt Maturities, Net, Amortized Cost [Abstract]

Investment Securities, Debt Maturities, Less than One Year, Net Carrying Value

31,029

Investment Securities, Debt Maturities, One to Five Years, Net Carrying Value

76,646

Investment Securities, Debt Maturities, Six to Ten Years, Net Carrying Value

119,966

Investment Securities, Debt Maturities, Over Ten Years, Net Carrying Value

8,977

Investment Securities, Debt Maturities, Single Maturity Date, Carrying Value

236,618

Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Investment Securities, Debt Maturities, Less than One Year, Fair Value

31,459

Investment Securities, Debt Maturities, One to Five Years, Fair Value

83,944

Investment Securities, Debt Maturities, Six to Ten Years, Fair Value

138,101

Investment Securities, Debt Maturities, Over Ten Years, Fair Value

9,137

Investment Securities, Debt Maturities, Single Maturity Date, Fair value

$ 262,641

Investment Securities, Debt Maturities, Weighted Average Maturity

^[1]

4.90

Municipal securities [Member]

Schedule of Investment (Held-to-Maturity) Securities [Line Items]

Investment Securities, fair value

$ 255,270

295,032

Investment Securities, Gross Unrealized Gain

26,169

20,797

Investment Securities, Gross Unrealized Loss

(144)

(300)

Debt Securities, Held-to-maturity, gross

229,245

274,535

Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Investment Securities, fair value

$ 255,270

$ 295,032

Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

6

15

Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 2,451

$ 1,001

Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

2,043

9,747

Investment Securities, Continuous Unrealized Loss Position, Fair Value

4,494

10,748

Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Losses

40

1

Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Losses

104

299

Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss

144

300

Residential agency mortgage-backed securities [Member]

Schedule of Investment (Held-to-Maturity) Securities [Line Items]

Investment Securities, fair value

9,790

11,164

Investment Securities, Gross Unrealized Gain

877

488

Investment Securities, Gross Unrealized Loss

0

Debt Securities, Held-to-maturity, gross

8,913

10,676

Investment Securities, Debt Maturities, Net, Amortized Cost [Abstract]

Investment Securities, Debt Maturities, without Single Maturity Date, Net Carrying value

^[2]

8,913

Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Investment Securities, Debt Maturities, without Single Maturity Date, Fair value

9,790

Investment Securities, fair value

$ 9,790

11,164

Investment Securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities

4.0 years

Other debt securities [Member]

Schedule of Investment (Held-to-Maturity) Securities [Line Items]

Investment Securities, fair value

$ 7,371

8,206

Investment Securities, Gross Unrealized Gain

0

Investment Securities, Gross Unrealized Loss

(2)

(1)

Debt Securities, Held-to-maturity, gross

7,373

8,207

Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Investment Securities, fair value

$ 7,371

$ 8,206

Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

2

Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 250

$ 275

Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

25

0

Investment Securities, Continuous Unrealized Loss Position, Fair Value

275

Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Losses

1

Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Losses

1

0

Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss

$ 2

$ 1

[1]	Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty.
[2]	The average expected lives of residential mortgage-backed securities were 4.0 years based upon current prepayment assumptions.

Available for Sale Securities (Details)
$ in Thousands

12 Months Ended

Dec. 31, 2020

USD ($)

Dec. 31, 2019

USD ($)

Dec. 31, 2018

USD ($)

Available for Sale Securities [Line Items]

Available for sale securities, Amortized Cost

$ 12,609,850

$ 11,131,494

Available for sale securities

13,050,665

11,269,643

Available for sale securities, Gross Unrealized Gain

449,654

158,435

Available for sale securities, Gross Unrealized Loss

(8,839)

(20,286)

Available for Sale Securities, Realized Gain (Loss) [Abstract]

Proceeds from sales of available for sale securities

384,507

1,211,718

$ 745,643

Available for sale securities, Gross realized gains

9,976

14,996

7,117

Available for sale securities, Gross realized losses

(66)

(9,399)

(9,918)

Available for sale securities, Related federal and state income tax expense

2,524

1,425

$ (713)

Available for sale securities, Pledged as Collateral, Fair Value

11,600,000

10,100,000

Fixed maturity securities [Member]

Available for Sale Securities, Debt Maturities, Amortized Cost, Rolling Maturity [Abstract]

Available for sale securities, Debt Maturities, Less than One Year, Amortized Cost

78,673

Available for sale securities, Debt Maturities, One to Five Years, Amortized Cost

1,413,405

Available for sale securities, Debt Maturities, Six to Ten Years, Amortized Cost

1,472,918

Available for sale securities, Debt Maturities, Over Ten Years, Amortized Cost

608,278

Available for sale securities, Maturity, Allocated and Single Maturity Date, Amortized Cost

3,573,274

Available for Sale Securities, Maturity, Fair Value, Rolling Maturity [Abstract]

Available for sale securities, Debt Maturities, Less Than One Year, Fair Value

78,918

Available for sale securities, Debt Maturities, One to Five Years, Fair Value

1,469,630

Available for sale securities, Debt Maturities, Six to Ten Years, Fair Value

1,498,376

Available for sale securities, Debt Maturities, Over Ten Years, Fair Value

630,500

Available for sale securities, Debt Maturities, Single Maturity Date, Fair value

$ 3,677,424

Available for sale securities, Debt Maturities, Weighted Average Maturity

^[1]

7.79

U.S. Treasury [Member]

Available for Sale Securities [Line Items]

Available for sale securities, Amortized Cost

$ 500

1,598

Available for sale securities

508

1,600

Available for sale securities, Gross Unrealized Gain

8

2

Available for sale securities, Gross Unrealized Loss

0

Municipal securities [Member]

Available for Sale Securities [Line Items]

Available for sale securities, Amortized Cost

165,318

1,789

Available for sale securities

167,979

1,861

Available for sale securities, Gross Unrealized Gain

2,666

72

Available for sale securities, Gross Unrealized Loss

(5)

0

Commercial agency mortgage-backed securities [Member]

Available for Sale Securities [Line Items]

Available for sale securities, Amortized Cost

3,406,956

3,145,342

Available for sale securities

3,508,465

3,178,005

Available for sale securities, Gross Unrealized Gain

103,590

37,808

Available for sale securities, Gross Unrealized Loss

(2,081)

(5,145)

Other debt securities [Member]

Available for Sale Securities [Line Items]

Available for sale securities, Amortized Cost

500

Available for sale securities

472

Available for sale securities, Gross Unrealized Gain

0

Available for sale securities, Gross Unrealized Loss

(28)

Residential Mortgage Backed Securities [Member]

Available for Sale Securities, Debt Maturities, Amortized Cost, Rolling Maturity [Abstract]

Available for sale securities, Maturity, without Single Maturity Date, Amortized Cost

^[2]

9,036,576

Available for Sale Securities, Maturity, Fair Value, Rolling Maturity [Abstract]

Available for sale securities, Debt Maturities, without Single Maturity Date, Fair value

$ 9,373,241

Available for sale securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities

3.0 years

Residential agency mortgage-backed securities [Member]

Available for Sale Securities [Line Items]

Available for sale securities, Amortized Cost

$ 9,019,013

7,956,297

Available for sale securities

9,340,471

8,046,096

Available for sale securities, Gross Unrealized Gain

328,183

104,912

Available for sale securities, Gross Unrealized Loss

(6,725)

(15,113)

Residential non-agency mortgage-backed securities [Member]

Available for Sale Securities [Line Items]

Available for sale securities, Amortized Cost

17,563

25,968

Available for sale securities

32,770

41,609

Available for sale securities, Gross Unrealized Gain

15,207

15,641

Available for sale securities, Gross Unrealized Loss

$ 0

[1]	Expected maturities may differ from contractual maturities, because borrowers may have the right to call or prepay obligations with or without penalty.
[2]	The average expected lives of residential mortgage-backed securities were 3.0 years based upon current prepayment assumptions.

Securities Available for sale, Unrealized Loss Position, Fair Value (Details) $ in Thousands	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	77	203
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 1,143,562	$ 2,182,644
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	438,846	897,351
Available for sale securities, Unrealized Loss Position, Fair Value	1,582,408	3,079,995
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	8,197	10,928
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	642	9,358
Available for sale securities, Unrealized Loss Position, Accumulated Loss	8,839	$ 20,286
Debt Securities, Available-for-sale, Allowance for Credit Loss	$ 0
Municipal securities [Member]
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	1	0
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 6,166	$ 0
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	0	0
Available for sale securities, Unrealized Loss Position, Fair Value	6,166	0
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	5	0
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Available for sale securities, Unrealized Loss Position, Accumulated Loss	$ 5	$ 0
Residential agency mortgage-backed securities [Member]
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	38	133
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 786,890	$ 1,352,597
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	160,747	686,002
Available for sale securities, Unrealized Loss Position, Fair Value	947,637	2,038,599
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	6,605	6,690
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	120	8,423
Available for sale securities, Unrealized Loss Position, Accumulated Loss	$ 6,725	$ 15,113
Commercial agency mortgage-backed securities [Member]
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	37	69
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 350,506	$ 830,047
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	277,627	210,877
Available for sale securities, Unrealized Loss Position, Fair Value	628,133	1,040,924
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,587	4,238
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	494	907
Available for sale securities, Unrealized Loss Position, Accumulated Loss	$ 2,081	$ 5,145
Other debt securities [Member]
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	1	1
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 0	$ 0
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	472	472
Available for sale securities, Unrealized Loss Position, Fair Value	472	472
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	28	28
Available for sale securities, Unrealized Loss Position, Accumulated Loss	$ 28	$ 28

Securities Fair Value Option Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Option Securities [Line Items]
Fair value option securities	$ 114,982	$ 1,098,577
Fair Value Option Securities Unrealized Gain or Loss	4,463	14,061
U.S. Treasury [Member]
Fair Value Option Securities [Line Items]
Fair value option securities	0	9,917
Fair Value Option Securities Unrealized Gain or Loss	0	(48)
Residential agency mortgage-backed securities [Member]
Fair Value Option Securities [Line Items]
Fair value option securities	114,982	1,088,660
Fair Value Option Securities Unrealized Gain or Loss	$ 4,463	$ 14,109

Derivatives, Fair Value of Derivatives Contracts (Details) - USD ($)
$ in Thousands

Dec. 31, 2020

Dec. 31, 2019

Derivative Assets, Fair Value, Net [Abstract]

Derivative Assets, Fair Value, Net of Cash Collateral

$ 810,688

$ 323,375

Derivative Liabilities, Fair Value, Net [Abstract]

Derivative Liabilities, Fair Value, Net of Cash Collateral

405,779

251,128

Not Designated as Hedging Instrument [Member]

Notional Amount of Derivatives [Abstract]

Derivative Assets, Notional

93,418,715

^[1]

75,917,378

^[2]

Derivative Liabilities, Notional

96,326,522

^[1]

70,400,171

^[2]

Derivative Assets, Fair Value, Net [Abstract]

Derivative Assets, Gross Fair Value

1,294,849

549,555

Derivative Assets, Netting Adjustments

(456,498)

(225,482)

Derivative Assets, Net Fair Value Before Cash Collateral

838,351

324,073

Derivative Assets, Cash Collateral

(27,663)

(698)

Derivative Assets, Fair Value, Net of Cash Collateral

810,688

323,375

Derivative Liabilities, Fair Value, Net [Abstract]

Derivative Liabilities, Gross Fair Value

1,231,665

528,921

Derivative Liabilities, Netting Adjustments

(456,498)

(225,482)

Derivative Liabilities, Net Fair Value Before Cash Collateral

775,167

303,439

Derivative Liabilities, Cash Collateral

(369,388)

(52,311)

Derivative Liabilities, Fair Value, Net of Cash Collateral

405,779

251,128

Not Designated as Hedging Instrument [Member] | Total customer risk management programs [Member]

Notional Amount of Derivatives [Abstract]

Derivative Assets, Notional

7,425,999

^[1]

4,927,266

^[2]

Derivative Liabilities, Notional

7,251,350

^[1]

4,875,382

^[2]

Derivative Assets, Fair Value, Net [Abstract]

Derivative Assets, Gross Fair Value

836,870

411,768

Derivative Assets, Netting Adjustments

(211,612)

(109,452)

Derivative Assets, Net Fair Value Before Cash Collateral

625,258

302,316

Derivative Assets, Cash Collateral

(705)

(698)

Derivative Assets, Fair Value, Net of Cash Collateral

624,553

301,618

Derivative Liabilities, Fair Value, Net [Abstract]

Derivative Liabilities, Gross Fair Value

811,335

400,265

Derivative Liabilities, Netting Adjustments

(211,612)

(109,452)

Derivative Liabilities, Net Fair Value Before Cash Collateral

599,723

290,813

Derivative Liabilities, Cash Collateral

(223,281)

(51,448)

Derivative Liabilities, Fair Value, Net of Cash Collateral

376,442

239,365

Not Designated as Hedging Instrument [Member] | Interest rate swaps [Member]

Notional Amount of Derivatives [Abstract]

Derivative Assets, Notional

3,212,469

^[1]

2,464,478

^[2]

Derivative Liabilities, Notional

3,212,469

^[1]

2,464,478

^[2]

Derivative Assets, Fair Value, Net [Abstract]

Derivative Assets, Gross Fair Value

113,524

49,100

Derivative Assets, Netting Adjustments

(144)

(1,839)

Derivative Assets, Net Fair Value Before Cash Collateral

113,380

47,261

Derivative Assets, Cash Collateral

0

Derivative Assets, Fair Value, Net of Cash Collateral

113,380

47,261

Derivative Liabilities, Fair Value, Net [Abstract]

Derivative Liabilities, Gross Fair Value

113,900

49,194

Derivative Liabilities, Netting Adjustments

(144)

(1,839)

Derivative Liabilities, Net Fair Value Before Cash Collateral

113,756

47,355

Derivative Liabilities, Cash Collateral

(104,202)

(43,932)

Derivative Liabilities, Fair Value, Net of Cash Collateral

9,554

3,423

Not Designated as Hedging Instrument [Member] | Energy contracts [Member]

Notional Amount of Derivatives [Abstract]

Derivative Assets, Notional

3,791,565

^[1]

2,151,096

^[2]

Derivative Liabilities, Notional

3,617,678

^[1]

2,105,391

^[2]

Derivative Assets, Fair Value, Net [Abstract]

Derivative Assets, Gross Fair Value

386,008

144,906

Derivative Assets, Netting Adjustments

(211,468)

(107,591)

Derivative Assets, Net Fair Value Before Cash Collateral

174,540

37,315

Derivative Assets, Cash Collateral

0

(38)

Derivative Assets, Fair Value, Net of Cash Collateral

174,540

37,277

Derivative Liabilities, Fair Value, Net [Abstract]

Derivative Liabilities, Gross Fair Value

361,334

139,311

Derivative Liabilities, Netting Adjustments

(211,468)

(107,591)

Derivative Liabilities, Net Fair Value Before Cash Collateral

149,866

31,720

Derivative Liabilities, Cash Collateral

(114,070)

(6,031)

Derivative Liabilities, Fair Value, Net of Cash Collateral

35,796

25,689

Not Designated as Hedging Instrument [Member] | Agricultural contracts [Member]

Notional Amount of Derivatives [Abstract]

Derivative Assets, Notional

14,765

^[1]

16,118

^[2]

Derivative Liabilities, Notional

14,781

^[1]

16,139

^[2]

Derivative Assets, Fair Value, Net [Abstract]

Derivative Assets, Gross Fair Value

3,859

1,522

Derivative Assets, Netting Adjustments

0

(22)

Derivative Assets, Net Fair Value Before Cash Collateral

3,859

1,500

Derivative Assets, Cash Collateral

0

Derivative Assets, Fair Value, Net of Cash Collateral

3,859

1,500

Derivative Liabilities, Fair Value, Net [Abstract]

Derivative Liabilities, Gross Fair Value

3,844

1,507

Derivative Liabilities, Netting Adjustments

0

(22)

Derivative Liabilities, Net Fair Value Before Cash Collateral

3,844

1,485

Derivative Liabilities, Cash Collateral

(3,844)

(1,485)

Derivative Liabilities, Fair Value, Net of Cash Collateral

0

Not Designated as Hedging Instrument [Member] | Foreign exchange contracts [Member]

Notional Amount of Derivatives [Abstract]

Derivative Assets, Notional

337,001

^[1]

214,119

^[2]

Derivative Liabilities, Notional

336,223

^[1]

207,919

^[2]

Derivative Assets, Fair Value, Net [Abstract]

Derivative Assets, Gross Fair Value

332,257

213,007

Derivative Assets, Netting Adjustments

0

Derivative Assets, Net Fair Value Before Cash Collateral

332,257

213,007

Derivative Assets, Cash Collateral

(420)

0

Derivative Assets, Fair Value, Net of Cash Collateral

331,837

213,007

Derivative Liabilities, Fair Value, Net [Abstract]

Derivative Liabilities, Gross Fair Value

331,035

207,020

Derivative Liabilities, Netting Adjustments

0

Derivative Liabilities, Net Fair Value Before Cash Collateral

331,035

207,020

Derivative Liabilities, Cash Collateral

(1,165)

0

Derivative Liabilities, Fair Value, Net of Cash Collateral

329,870

207,020

Not Designated as Hedging Instrument [Member] | Equity option contracts [Member]

Notional Amount of Derivatives [Abstract]

Derivative Assets, Notional

70,199

^[1]

81,455

^[2]

Derivative Liabilities, Notional

70,199

^[1]

81,455

^[2]

Derivative Assets, Fair Value, Net [Abstract]

Derivative Assets, Gross Fair Value

1,222

3,233

Derivative Assets, Netting Adjustments

0

Derivative Assets, Net Fair Value Before Cash Collateral

1,222

3,233

Derivative Assets, Cash Collateral

(285)

(660)

Derivative Assets, Fair Value, Net of Cash Collateral

937

2,573

Derivative Liabilities, Fair Value, Net [Abstract]

Derivative Liabilities, Gross Fair Value

1,222

3,233

Derivative Liabilities, Netting Adjustments

0

Derivative Liabilities, Net Fair Value Before Cash Collateral

1,222

3,233

Derivative Liabilities, Cash Collateral

0

Derivative Liabilities, Fair Value, Net of Cash Collateral

1,222

3,233

Not Designated as Hedging Instrument [Member] | Trading [Member]

Notional Amount of Derivatives [Abstract]

Derivative Assets, Notional

84,997,593

^[1]

69,721,932

^[2]

Derivative Liabilities, Notional

88,929,916

^[1]

65,144,388

^[2]

Derivative Assets, Fair Value, Net [Abstract]

Derivative Assets, Gross Fair Value

440,627

131,561

Derivative Assets, Netting Adjustments

(240,655)

(115,949)

Derivative Assets, Net Fair Value Before Cash Collateral

199,972

15,612

Derivative Assets, Cash Collateral

(26,958)

0

Derivative Assets, Fair Value, Net of Cash Collateral

173,014

15,612

Derivative Liabilities, Fair Value, Net [Abstract]

Derivative Liabilities, Gross Fair Value

414,801

125,535

Derivative Liabilities, Netting Adjustments

(240,655)

(115,949)

Derivative Liabilities, Net Fair Value Before Cash Collateral

174,146

9,586

Derivative Liabilities, Cash Collateral

(145,692)

0

Derivative Liabilities, Fair Value, Net of Cash Collateral

28,454

9,586

Not Designated as Hedging Instrument [Member] | Internal risk management programs [Member]

Notional Amount of Derivatives [Abstract]

Derivative Assets, Notional

995,123

^[1]

1,268,180

^[2]

Derivative Liabilities, Notional

145,256

^[1]

380,401

^[2]

Derivative Assets, Fair Value, Net [Abstract]

Derivative Assets, Gross Fair Value

17,352

6,226

Derivative Assets, Netting Adjustments

(4,231)

(81)

Derivative Assets, Net Fair Value Before Cash Collateral

13,121

6,145

Derivative Assets, Cash Collateral

0

Derivative Assets, Fair Value, Net of Cash Collateral

13,121

6,145

Derivative Liabilities, Fair Value, Net [Abstract]

Derivative Liabilities, Gross Fair Value

5,529

3,121

Derivative Liabilities, Netting Adjustments

(4,231)

(81)

Derivative Liabilities, Net Fair Value Before Cash Collateral

1,298

3,040

Derivative Liabilities, Cash Collateral

(415)

(863)

Derivative Liabilities, Fair Value, Net of Cash Collateral

$ 883

$ 2,177

[1]	Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.
[2]	Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.

Derivatives, Derivatives Instruments Gain (Loss) in Income Statement (Details) - Not Designated as Hedging Instrument [Member] - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Trading Activity, Gains and Losses, Net [Line Items]

Brokerage and Trading Revenue

$ 31,004

$ 32,940

$ 25,192

Gain (Loss) on Derivatives, Net

42,320

14,951

(442)

To-be-announced residential mortgage-backed securities [Member]

Trading Activity, Gains and Losses, Net [Line Items]

Brokerage and Trading Revenue

^[1]

0

9,579

27,190

Gain (Loss) on Derivatives, Net

^[1]

0

Interest rate swaps [Member]

Trading Activity, Gains and Losses, Net [Line Items]

Brokerage and Trading Revenue

4,507

3,647

2,614

Gain (Loss) on Derivatives, Net

0

Energy contracts [Member]

Trading Activity, Gains and Losses, Net [Line Items]

Brokerage and Trading Revenue

17,287

5,064

8,443

Gain (Loss) on Derivatives, Net

0

Agricultural contracts [Member]

Trading Activity, Gains and Losses, Net [Line Items]

Brokerage and Trading Revenue

34

28

53

Gain (Loss) on Derivatives, Net

0

Foreign exchange contracts [Member]

Trading Activity, Gains and Losses, Net [Line Items]

Brokerage and Trading Revenue

921

623

535

Gain (Loss) on Derivatives, Net

0

Equity option contracts [Member]

Trading Activity, Gains and Losses, Net [Line Items]

Brokerage and Trading Revenue

0

Gain (Loss) on Derivatives, Net

0

Total customer risk management programs [Member]

Trading Activity, Gains and Losses, Net [Line Items]

Brokerage and Trading Revenue

22,749

18,941

38,835

Gain (Loss) on Derivatives, Net

0

Trading [Member]

Trading Activity, Gains and Losses, Net [Line Items]

Brokerage and Trading Revenue

^[2]

8,255

13,999

(13,643)

Gain (Loss) on Derivatives, Net

^[2]

0

Internal risk management programs [Member]

Trading Activity, Gains and Losses, Net [Line Items]

Brokerage and Trading Revenue

0

Gain (Loss) on Derivatives, Net

$ 42,320

$ 14,951

$ (442)

[1]

To-be-announced U.S. agency residential mortgage-backed securities customer hedging program transitioned to trading program during 2019.

[2]

Includes changes in fair value of to-be-announced U.S. agency residential mortgage-backed securities and other derivative instruments offered to mortgage banking customers to manage their market risk or held to mitigate market risk of trading securities portfolio, which is offset by changes in fair value of trading securities also included in Brokerage and trading revenue in the Consolidated Statement of Earnings.

Loans and Allowances for Credit Losses, Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Loans receivables disclosure [Abstract]
Loans, fixed rate of interest	$ 6,682,476	$ 6,134,362
Loans, variable rate of interest	16,090,351	15,435,674
Loans, non-accrual	234,693	180,951
Total	23,007,520	21,750,987
Past Due 90 Days or More and Accruing	88,718	7,680
Foregone interest on nonaccrual loans	22,870	17,409
Credit Commitments [Abstract]
Outstanding commitments to extend credit	11,000,000
Outstanding standby letters of credit	681,000
Geographic Concentration Risk [Member] \| Texas [Member]
Loans receivables disclosure [Abstract]
Total	$ 7,200,000	$ 6,800,000
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Texas (in hundredths)	31.00%	31.00%
Geographic Concentration Risk [Member] \| Oklahoma [Member]
Loans receivables disclosure [Abstract]
Total	$ 3,800,000	$ 3,500,000
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Oklahoma (in hundredths)	17.00%	16.00%
Geographic Concentration Risk [Member] \| Colorado [Member]
Loans receivables disclosure [Abstract]
Total	$ 2,800,000	$ 2,800,000
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Colorado (in hundredths)	12.00%	13.00%
Commercial [Member]
Loans receivables disclosure [Abstract]
Loans, fixed rate of interest	$ 1,805,286	$ 3,231,485
Loans, variable rate of interest	11,105,090	10,684,749
Loans, non-accrual	167,159	115,416
Total	13,077,535	14,031,650
Past Due 90 Days or More and Accruing	4,821
Commercial [Member] \| Geographic Concentration Risk [Member] \| Texas [Member]
Loans receivables disclosure [Abstract]
Total	$ 4,300,000	$ 4,700,000
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Texas (in hundredths)	33.00%	33.00%
Commercial [Member] \| Geographic Concentration Risk [Member] \| Oklahoma [Member]
Loans receivables disclosure [Abstract]
Total	$ 1,800,000	$ 2,000,000
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Oklahoma (in hundredths)	14.00%	14.00%
Commercial [Member] \| Geographic Concentration Risk [Member] \| Colorado [Member]
Loans receivables disclosure [Abstract]
Total	$ 1,700,000	$ 2,000,000
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Colorado (in hundredths)	13.00%	14.00%
Commercial [Member] \| Services [Member]
Loans receivables disclosure [Abstract]
Total	$ 3,508,583	$ 3,122,163
Past Due 90 Days or More and Accruing	326
Loans receivable, other information [Abstract]
Amount of loans with individual balances less than $10 million	1,800,000	1,500,000
Commercial [Member] \| Services [Member] \| Credit Concentration Risk [Member]
Loans receivables disclosure [Abstract]
Total	$ 3,500,000	$ 3,800,000
Loans receivable, other information [Abstract]
Percentage of loan class to total loans	15.00%	18.00%
Commercial [Member] \| Energy [Member]
Loans receivables disclosure [Abstract]
Total	$ 3,469,194	$ 3,973,377
Past Due 90 Days or More and Accruing	0
Commercial [Member] \| Energy [Member] \| Credit Concentration Risk [Member]
Loans receivables disclosure [Abstract]
Total	$ 3,500,000	$ 4,000,000
Loans receivable, other information [Abstract]
Percentage of loan class to total loans	15.00%	18.00%
Commercial [Member] \| Energy Producers [Member] \| Credit Concentration Risk [Member]
Loans receivables disclosure [Abstract]
Total	$ 2,600,000	$ 3,100,000
Loans receivable, other information [Abstract]
Percentage of committed energy production loans secured by oil	67.00%	58.00%
Percentage of committed energy production loans secured by natural gas	33.00%	42.00%
Commercial [Member] \| Healthcare [Member]
Loans receivables disclosure [Abstract]
Total	$ 3,305,990	$ 3,033,916
Past Due 90 Days or More and Accruing	0
Commercial [Member] \| Healthcare [Member] \| Credit Concentration Risk [Member]
Loans receivables disclosure [Abstract]
Total	$ 3,300,000	$ 3,000,000
Loans receivable, other information [Abstract]
Percentage of loan class to total loans	14.00%	14.00%
Commercial real estate [Member]
Loans receivables disclosure [Abstract]
Loans, fixed rate of interest	$ 1,021,443	$ 1,056,321
Loans, variable rate of interest	3,649,849	3,349,836
Loans, non-accrual	27,246	27,626
Total	4,698,538	$ 4,433,783
Past Due 90 Days or More and Accruing	$ 5,126
Commercial real estate [Member] \| Geographic Concentration Risk [Member] \| Texas [Member]
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Texas (in hundredths)	27.00%	24.00%
Commercial real estate [Member] \| Geographic Concentration Risk [Member] \| Oklahoma [Member]
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Oklahoma (in hundredths)	10.00%	12.00%
Commercial real estate [Member] \| Geographic Concentration Risk [Member] \| Colorado [Member]
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Colorado (in hundredths)		11.00%
Paycheck Protection Program
Loans receivables disclosure [Abstract]
Loans, fixed rate of interest	$ 1,682,310
Loans, variable rate of interest	0
Loans, non-accrual	0
Total	1,682,310
Past Due 90 Days or More and Accruing	0
Loans to individuals [Member]
Loans receivables disclosure [Abstract]
Loans, fixed rate of interest	2,173,437
Loans, variable rate of interest	1,335,412
Loans, non-accrual	40,288
Total	3,549,137
Past Due 90 Days or More and Accruing	$ 78,771
Loans receivable, other information [Abstract]
Percentage of personal loans secured by collateral in our geographical footprint	91.00%
Loans to individuals [Member] \| Residential Mortgage [Member]
Loans receivables disclosure [Abstract]
Loans, fixed rate of interest		$ 1,652,653
Loans, variable rate of interest		393,897
Loans, non-accrual		37,622
Total		2,084,172
Loans to individuals [Member] \| Personal [Member]
Loans receivables disclosure [Abstract]
Loans, fixed rate of interest		193,903
Loans, variable rate of interest		1,007,192
Loans, non-accrual		287
Total	$ 1,277,447	$ 1,201,382
Past Due 90 Days or More and Accruing	$ 241

Loans and Allowances for Credit Losses, Activity in Allowance for Credit Losses (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	$ 236,568,000
Provision for loan losses - CECL	222,460,000
Loans charged off	(79,399,000)	$ (50,977,000)	$ (43,583,000)
Recoveries of loans previously charged off	9,011,000	10,074,000	10,414,000
Beginning balance, Incurred Loss Model	210,759,000	207,457,000	230,682,000
Provision for loan losses		44,205,000	9,944,000
Ending Balance - CECL	388,640,000	236,568,000
Ending balance, Incurred Loss Model	388,640,000	210,759,000	207,457,000
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	25,137,000
Provision for off-balance sheet credit risk	11,784,000
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL	36,921,000	25,137,000
Accrual for off-balance sheet credit losses [Roll Forward]
Beginning balance - Incurred loss model	1,585,000	1,790,000	3,734,000
Provision for off-balance sheet credit losses		(205,000)	(1,944,000)
Ending balance - Incurred loss model		1,585,000	1,790,000
Total provision for credit losses	222,592,000	44,000,000	8,000,000
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment				$ 22,772,827,000	$ 21,570,036,000
Individually measured for impairment, recorded investment				234,693,000	180,951,000
Total				23,007,520,000	21,750,987,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance				366,199,000	176,150,000
Individually measured for impairment, related allowance				22,441,000	17,414,000
Total measured for impairment, related allowance	210,759,000	210,759,000	207,457,000	388,640,000	210,759,000
Provision Details [Abstract]
Change in provision due to changes in reasonable and supportable forecasts, primarily due to COVID-19 pandemic [Line Items]	99,100,000
Other changes to provision	135,200,000
Commercial [Member]
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	151,868,000
Provision for loan losses - CECL	171,800,000
Loans charged off	(73,370,000)	(43,185,000)	(37,880,000)
Recoveries of loans previously charged off	4,636,000	2,021,000	3,316,000
Beginning balance, Incurred Loss Model	118,187,000	102,226,000	124,269,000
Provision for loan losses		57,125,000	12,521,000
Ending Balance - CECL	254,934,000	151,868,000
Ending balance, Incurred Loss Model	254,934,000	118,187,000	102,226,000
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	11,578,000
Provision for off-balance sheet credit risk	2,844,000
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL	14,422,000	11,578,000
Accrual for off-balance sheet credit losses [Roll Forward]
Beginning balance - Incurred loss model	1,434,000	1,655,000	3,644,000
Provision for off-balance sheet credit losses		(221,000)	(1,989,000)
Ending balance - Incurred loss model		1,434,000	1,655,000
Total provision for credit losses		56,904,000	10,532,000
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment				12,910,376,000	13,916,234,000
Individually measured for impairment, recorded investment				167,159,000	115,416,000
Total				13,077,535,000	14,031,650,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance				235,882,000	100,773,000
Individually measured for impairment, related allowance				19,052,000	17,414,000
Total measured for impairment, related allowance	118,187,000	118,187,000	124,269,000	254,934,000	118,187,000
Commercial real estate [Member]
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	47,185,000
Provision for loan losses - CECL	40,407,000
Loans charged off	(1,300,000)	(1,161,000)	0
Recoveries of loans previously charged off	266,000	4,986,000	3,552,000
Beginning balance, Incurred Loss Model	51,805,000	60,026,000	56,621,000
Provision for loan losses		(12,046,000)	(147,000)
Ending Balance - CECL	86,558,000	47,185,000
Ending balance, Incurred Loss Model	86,558,000	51,805,000	60,026,000
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	11,767,000
Provision for off-balance sheet credit risk	8,804,000
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL	20,571,000	11,767,000
Accrual for off-balance sheet credit losses [Roll Forward]
Beginning balance - Incurred loss model	107,000	52,000	45,000
Provision for off-balance sheet credit losses		55,000	7,000
Ending balance - Incurred loss model		107,000	52,000
Total provision for credit losses		(11,991,000)	(140,000)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment				4,671,292,000	4,406,157,000
Individually measured for impairment, recorded investment				27,246,000	27,626,000
Total				4,698,538,000	4,433,783,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance				83,169,000	51,805,000
Individually measured for impairment, related allowance				3,389,000	0
Total measured for impairment, related allowance	51,805,000	51,805,000	56,621,000	86,558,000	51,805,000
Paycheck Protection Program
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	0
Provision for loan losses - CECL	0
Loans charged off	0
Recoveries of loans previously charged off	0
Ending Balance - CECL	0	0
Ending balance, Incurred Loss Model	0
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	0
Provision for off-balance sheet credit risk	0
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL	0	0
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment				1,682,310,000
Individually measured for impairment, recorded investment				0
Total				1,682,310,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance				0
Individually measured for impairment, related allowance				0
Total measured for impairment, related allowance	0			0
Loans to individuals [Member]
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	37,515,000
Provision for loan losses - CECL	10,253,000
Loans charged off	(4,729,000)
Recoveries of loans previously charged off	4,109,000
Ending Balance - CECL	47,148,000	37,515,000
Ending balance, Incurred Loss Model	47,148,000
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	1,792,000
Provision for off-balance sheet credit risk	136,000
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL	1,928,000	1,792,000
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment				3,508,849,000
Individually measured for impairment, recorded investment				40,288,000
Total				3,549,137,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance				47,148,000
Individually measured for impairment, related allowance				0
Total measured for impairment, related allowance	47,148,000			47,148,000
Loans to individuals [Member] \| Residential Mortgage [Member]
Allowance for loan losses [Roll Forward]
Loans charged off		(288,000)	(378,000)
Recoveries of loans previously charged off		562,000	1,047,000
Beginning balance, Incurred Loss Model	14,400,000	17,964,000	18,451,000
Provision for loan losses		(3,838,000)	(1,156,000)
Ending balance, Incurred Loss Model		14,400,000	17,964,000
Accrual for off-balance sheet credit losses [Roll Forward]
Beginning balance - Incurred loss model	44,000	52,000	43,000
Provision for off-balance sheet credit losses		(8,000)	9,000
Ending balance - Incurred loss model		44,000	52,000
Total provision for credit losses		(3,846,000)	(1,147,000)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					2,046,550,000
Individually measured for impairment, recorded investment					37,622,000
Total					2,084,172,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance					14,400,000
Individually measured for impairment, related allowance					0
Total measured for impairment, related allowance	14,400,000	14,400,000	17,964,000		14,400,000
Loans to individuals [Member] \| Personal [Member]
Allowance for loan losses [Roll Forward]
Loans charged off		(6,343,000)	(5,325,000)
Recoveries of loans previously charged off		2,505,000	2,499,000
Beginning balance, Incurred Loss Model	9,172,000	9,473,000	9,124,000
Provision for loan losses		3,537,000	3,175,000
Ending balance, Incurred Loss Model		9,172,000	9,473,000
Accrual for off-balance sheet credit losses [Roll Forward]
Beginning balance - Incurred loss model	0	31,000	2,000
Provision for off-balance sheet credit losses		(31,000)	29,000
Ending balance - Incurred loss model		0	31,000
Total provision for credit losses		3,506,000	3,204,000
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					1,201,095,000
Individually measured for impairment, recorded investment					287,000
Total				$ 1,277,447,000	1,201,382,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance					9,172,000
Individually measured for impairment, related allowance					0
Total measured for impairment, related allowance	9,172,000	9,172,000	9,124,000		9,172,000
Nonspecific Allowance [Member]
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	0
Provision for loan losses - CECL	0
Loans charged off	0	0	0
Recoveries of loans previously charged off	0	0	0
Beginning balance, Incurred Loss Model	17,195,000	17,768,000	22,217,000
Provision for loan losses		(573,000)	(4,449,000)
Ending Balance - CECL	0	0
Ending balance, Incurred Loss Model		17,195,000	17,768,000
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	0
Provision for off-balance sheet credit risk	0
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL	0	0
Accrual for off-balance sheet credit losses [Roll Forward]
Beginning balance - Incurred loss model	0	0	0
Provision for off-balance sheet credit losses		0	0
Ending balance - Incurred loss model		0	0
Total provision for credit losses		(573,000)	(4,449,000)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					0
Individually measured for impairment, recorded investment					0
Total					0
Related allowance [Abstract]
Collectively measured for impairment, related allowance					0
Individually measured for impairment, related allowance					0
Total measured for impairment, related allowance	17,195,000	17,195,000	$ 22,217,000		17,195,000
Specific Allowance [Member]
Allowance for loan losses [Roll Forward]
Beginning balance, Incurred Loss Model	193,564,000
Ending balance, Incurred Loss Model		193,564,000
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					21,570,036,000
Individually measured for impairment, recorded investment					180,951,000
Total					21,750,987,000
Related allowance [Abstract]
Collectively measured for impairment, related allowance					176,150,000
Individually measured for impairment, related allowance					17,414,000
Total measured for impairment, related allowance	193,564,000	193,564,000			$ 193,564,000
Transition Adjustment [Member]
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	25,809,000
Ending Balance - CECL		25,809,000
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	23,552,000
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL		23,552,000
Transition Adjustment [Member] \| Commercial [Member]
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	33,681,000
Ending Balance - CECL		33,681,000
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	10,144,000
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL		10,144,000
Transition Adjustment [Member] \| Commercial real estate [Member]
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	(4,620,000)
Ending Balance - CECL		(4,620,000)
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	11,660,000
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL		11,660,000
Transition Adjustment [Member] \| Paycheck Protection Program
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	0
Ending Balance - CECL		0
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	0
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL		0
Transition Adjustment [Member] \| Loans to individuals [Member]
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	13,943,000
Ending Balance - CECL		13,943,000
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	1,748,000
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL		1,748,000
Transition Adjustment [Member] \| Nonspecific Allowance [Member]
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	(17,195,000)
Ending Balance - CECL		(17,195,000)
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	0
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL		0
Previously Reported [Member]
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	210,759,000
Ending Balance - CECL		210,759,000
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	1,585,000
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL		1,585,000
Previously Reported [Member] \| Commercial [Member]
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	118,187,000
Ending Balance - CECL		118,187,000
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	1,434,000
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL		1,434,000
Previously Reported [Member] \| Commercial real estate [Member]
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	51,805,000
Ending Balance - CECL		51,805,000
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	107,000
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL		107,000
Previously Reported [Member] \| Paycheck Protection Program
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	0
Ending Balance - CECL		0
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	0
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL		0
Previously Reported [Member] \| Loans to individuals [Member]
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	23,572,000
Ending Balance - CECL		23,572,000
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	44,000
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL		44,000
Previously Reported [Member] \| Nonspecific Allowance [Member]
Allowance for loan losses [Roll Forward]
Beginning balance - CECL	17,195,000
Ending Balance - CECL		17,195,000
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Beginning Balance - CECL	$ 0
Off-Balance Sheet, Credit Loss, Liability, Ending Balance - CECL		$ 0

Loans and Allowances for Credit Losses, Credit Quality Indicators (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	$ 4,855,463
Financing Receivable, Originated, 2019	3,161,473
Financing Receivable, Originated, 2018	2,651,833
Financing Receivable, Originated, 2017	1,788,880
Financing Receivable, Originated, 2016	1,356,476
Financing Receivable, Originated, 2015 or Prior	3,054,469
Financing Receivable, Revolving	6,108,767
Financing Receivable, Revolving, Converted to Term Loan	30,159
Total	23,007,520
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		$ 19,826,731
Non-Graded, Recorded Investment		1,924,256
Total	23,007,520	21,750,987
Related Allowance [Abstract]
Internally Risk Graded, Related Allowance		179,129
Non-Graded, Related Allowance		14,435
Total, Related Allowance	388,640	210,759	$ 207,457	$ 230,682
Commercial [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	1,657,760
Financing Receivable, Originated, 2019	1,557,142
Financing Receivable, Originated, 2018	1,461,282
Financing Receivable, Originated, 2017	1,013,619
Financing Receivable, Originated, 2016	747,318
Financing Receivable, Originated, 2015 or Prior	1,603,533
Financing Receivable, Revolving	5,033,683
Financing Receivable, Revolving, Converted to Term Loan	3,198
Total	13,077,535
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		13,997,538
Non-Graded, Recorded Investment		34,112
Total	13,077,535	14,031,650
Related Allowance [Abstract]
Internally Risk Graded, Related Allowance		117,236
Non-Graded, Related Allowance		951
Total, Related Allowance	254,934	118,187	102,226	124,269
Commercial [Member] \| Energy [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	157,690
Financing Receivable, Originated, 2019	55,833
Financing Receivable, Originated, 2018	90,799
Financing Receivable, Originated, 2017	7,178
Financing Receivable, Originated, 2016	13,815
Financing Receivable, Originated, 2015 or Prior	29,020
Financing Receivable, Revolving	3,114,859
Financing Receivable, Revolving, Converted to Term Loan	0
Total	3,469,194
Recorded Investment [Abstract]
Total	3,469,194	3,973,377
Commercial [Member] \| Healthcare [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	536,745
Financing Receivable, Originated, 2019	642,739
Financing Receivable, Originated, 2018	639,676
Financing Receivable, Originated, 2017	423,763
Financing Receivable, Originated, 2016	234,531
Financing Receivable, Originated, 2015 or Prior	680,890
Financing Receivable, Revolving	147,646
Financing Receivable, Revolving, Converted to Term Loan	0
Total	3,305,990
Recorded Investment [Abstract]
Total	3,305,990	3,033,916
Commercial [Member] \| Services [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	540,265
Financing Receivable, Originated, 2019	452,269
Financing Receivable, Originated, 2018	399,264
Financing Receivable, Originated, 2017	326,282
Financing Receivable, Originated, 2016	381,902
Financing Receivable, Originated, 2015 or Prior	700,028
Financing Receivable, Revolving	707,891
Financing Receivable, Revolving, Converted to Term Loan	682
Total	3,508,583
Recorded Investment [Abstract]
Total	3,508,583	3,122,163
Commercial [Member] \| General business [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	423,060
Financing Receivable, Originated, 2019	406,301
Financing Receivable, Originated, 2018	331,543
Financing Receivable, Originated, 2017	256,396
Financing Receivable, Originated, 2016	117,070
Financing Receivable, Originated, 2015 or Prior	193,595
Financing Receivable, Revolving	1,063,287
Financing Receivable, Revolving, Converted to Term Loan	2,516
Total	2,793,768
Recorded Investment [Abstract]
Total	2,793,768
Commercial [Member] \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Total		1,760,866
Commercial [Member] \| Manufacturing [Member]
Recorded Investment [Abstract]
Total		665,449
Commercial [Member] \| Public finance [Member]
Recorded Investment [Abstract]
Total		709,868
Commercial [Member] \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Total		766,011
Commercial real estate [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	725,577
Financing Receivable, Originated, 2019	1,219,638
Financing Receivable, Originated, 2018	954,485
Financing Receivable, Originated, 2017	506,146
Financing Receivable, Originated, 2016	325,092
Financing Receivable, Originated, 2015 or Prior	744,404
Financing Receivable, Revolving	223,158
Financing Receivable, Revolving, Converted to Term Loan	38
Total	4,698,538
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		4,433,783
Non-Graded, Recorded Investment		0
Total	4,698,538	4,433,783
Related Allowance [Abstract]
Internally Risk Graded, Related Allowance		51,805
Non-Graded, Related Allowance		0
Total, Related Allowance	86,558	51,805	60,026	56,621
Commercial real estate [Member] \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Total		150,879
Commercial real estate [Member] \| Retail [Member]
Recorded Investment [Abstract]
Total		775,521
Commercial real estate [Member] \| Office [Member]
Recorded Investment [Abstract]
Total		928,379
Commercial real estate [Member] \| Multifamily [Member]
Recorded Investment [Abstract]
Total		1,265,562
Commercial real estate [Member] \| Industrial [Member]
Recorded Investment [Abstract]
Total		856,117
Commercial real estate [Member] \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Total		457,325
Paycheck Protection Program
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	1,682,310
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	1,682,310
Recorded Investment [Abstract]
Total	1,682,310
Related Allowance [Abstract]
Total, Related Allowance	0
Loans to individuals [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	789,816
Financing Receivable, Originated, 2019	384,693
Financing Receivable, Originated, 2018	236,066
Financing Receivable, Originated, 2017	269,115
Financing Receivable, Originated, 2016	284,066
Financing Receivable, Originated, 2015 or Prior	706,532
Financing Receivable, Revolving	851,926
Financing Receivable, Revolving, Converted to Term Loan	26,923
Total	3,549,137
Recorded Investment [Abstract]
Total	3,549,137
Related Allowance [Abstract]
Total, Related Allowance	47,148
Loans to individuals [Member] \| Permanent residential mortgage [Member]
Recorded Investment [Abstract]
Total		1,057,321
Loans to individuals [Member] \| Permanent residential mortgage [Member] \| Loans Insured or Guaranteed by US Government Authorities
Recorded Investment [Abstract]
Total		197,794
Loans to individuals [Member] \| Home equity [Member]
Recorded Investment [Abstract]
Total		829,057
Loans to individuals [Member] \| Residential Mortgage [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	565,006
Financing Receivable, Originated, 2019	149,947
Financing Receivable, Originated, 2018	124,678
Financing Receivable, Originated, 2017	125,714
Financing Receivable, Originated, 2016	160,870
Financing Receivable, Originated, 2015 or Prior	371,059
Financing Receivable, Revolving	340,316
Financing Receivable, Revolving, Converted to Term Loan	25,413
Total	1,863,003
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		279,113
Non-Graded, Recorded Investment		1,805,059
Total		2,084,172
Related Allowance [Abstract]
Internally Risk Graded, Related Allowance		3,085
Non-Graded, Related Allowance		11,315
Total, Related Allowance		14,400	17,964	18,451
Loans to individuals [Member] \| Residential Mortgage [Member] \| US Government Agency Insured Loans
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	4,859
Financing Receivable, Originated, 2019	33,880
Financing Receivable, Originated, 2018	35,009
Financing Receivable, Originated, 2017	43,099
Financing Receivable, Originated, 2016	58,573
Financing Receivable, Originated, 2015 or Prior	233,267
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	408,687
Loans to individuals [Member] \| Personal [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	219,951
Financing Receivable, Originated, 2019	200,866
Financing Receivable, Originated, 2018	76,379
Financing Receivable, Originated, 2017	100,302
Financing Receivable, Originated, 2016	64,623
Financing Receivable, Originated, 2015 or Prior	102,206
Financing Receivable, Revolving	511,610
Financing Receivable, Revolving, Converted to Term Loan	1,510
Total	1,277,447
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,116,297
Non-Graded, Recorded Investment		85,085
Total	1,277,447	1,201,382
Related Allowance [Abstract]
Internally Risk Graded, Related Allowance		7,003
Non-Graded, Related Allowance		2,169
Total, Related Allowance		9,172	9,473	9,124
Loans to individuals [Member] \| Home Equity Loan
Recorded Investment [Abstract]
Total		829,057
Specific Allowance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		19,826,731
Non-Graded, Recorded Investment		1,924,256
Total		21,750,987
Related Allowance [Abstract]
Internally Risk Graded, Related Allowance		179,129
Non-Graded, Related Allowance		14,435
Total, Related Allowance		193,564
Nonspecific Allowance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		0
Total		0
Related Allowance [Abstract]
Internally Risk Graded, Related Allowance		0
Non-Graded, Related Allowance		0
Total, Related Allowance		17,195	$ 17,768	$ 22,217
Performing [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		1,886,858
Performing [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		19,312,702
Performing [Member] \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		210,149
Performing [Member] \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		160,326
Performing [Member] \| Commercial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		34,075
Performing [Member] \| Commercial [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		13,538,705
Performing [Member] \| Commercial [Member] \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		187,881
Performing [Member] \| Commercial [Member] \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		155,573
Performing [Member] \| Commercial [Member] \| Energy [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] \| Commercial [Member] \| Energy [Member] \| Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	112,614
Financing Receivable, Originated, 2019	51,863
Financing Receivable, Originated, 2018	89,346
Financing Receivable, Originated, 2017	7,178
Financing Receivable, Originated, 2016	1,148
Financing Receivable, Originated, 2015 or Prior	7,956
Financing Receivable, Revolving	2,548,663
Financing Receivable, Revolving, Converted to Term Loan	0
Total	2,818,768
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		3,700,406
Performing [Member] \| Commercial [Member] \| Energy [Member] \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	202,590
Financing Receivable, Revolving, Converted to Term Loan	0
Total	202,590
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		117,298
Performing [Member] \| Commercial [Member] \| Energy [Member] \| Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	24,000
Financing Receivable, Originated, 2019	1,363
Financing Receivable, Originated, 2018	1,453
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	12,667
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	283,294
Financing Receivable, Revolving, Converted to Term Loan	0
Total	322,777
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		63,951
Performing [Member] \| Commercial [Member] \| Healthcare [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] \| Commercial [Member] \| Healthcare [Member] \| Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	536,745
Financing Receivable, Originated, 2019	615,221
Financing Receivable, Originated, 2018	638,302
Financing Receivable, Originated, 2017	422,834
Financing Receivable, Originated, 2016	234,399
Financing Receivable, Originated, 2015 or Prior	658,286
Financing Receivable, Revolving	147,132
Financing Receivable, Revolving, Converted to Term Loan	0
Total	3,252,919
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		2,995,514
Performing [Member] \| Commercial [Member] \| Healthcare [Member] \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	27,500
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	8,282
Financing Receivable, Revolving	5
Financing Receivable, Revolving, Converted to Term Loan	0
Total	35,787
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		13,117
Performing [Member] \| Commercial [Member] \| Healthcare [Member] \| Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	1,191
Financing Receivable, Originated, 2017	929
Financing Receivable, Originated, 2016	132
Financing Receivable, Originated, 2015 or Prior	11,387
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	13,639
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		20,805
Performing [Member] \| Commercial [Member] \| Services [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] \| Commercial [Member] \| Services [Member] \| Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	534,853
Financing Receivable, Originated, 2019	436,384
Financing Receivable, Originated, 2018	372,867
Financing Receivable, Originated, 2017	307,374
Financing Receivable, Originated, 2016	373,785
Financing Receivable, Originated, 2015 or Prior	683,936
Financing Receivable, Revolving	665,491
Financing Receivable, Revolving, Converted to Term Loan	682
Total	3,375,372
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		3,050,946
Performing [Member] \| Commercial [Member] \| Services [Member] \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	150
Financing Receivable, Originated, 2019	9,057
Financing Receivable, Originated, 2018	389
Financing Receivable, Originated, 2017	291
Financing Receivable, Originated, 2016	2,038
Financing Receivable, Originated, 2015 or Prior	2,000
Financing Receivable, Revolving	3,063
Financing Receivable, Revolving, Converted to Term Loan	0
Total	16,988
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		29,943
Performing [Member] \| Commercial [Member] \| Services [Member] \| Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	429
Financing Receivable, Originated, 2019	6,380
Financing Receivable, Originated, 2018	26,008
Financing Receivable, Originated, 2017	6,027
Financing Receivable, Originated, 2016	5,030
Financing Receivable, Originated, 2015 or Prior	7,954
Financing Receivable, Revolving	38,797
Financing Receivable, Revolving, Converted to Term Loan	0
Total	90,625
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		33,791
Performing [Member] \| Commercial [Member] \| General business [Member] \| Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	419,756
Financing Receivable, Originated, 2019	394,985
Financing Receivable, Originated, 2018	310,273
Financing Receivable, Originated, 2017	236,222
Financing Receivable, Originated, 2016	103,987
Financing Receivable, Originated, 2015 or Prior	186,600
Financing Receivable, Revolving	1,055,878
Financing Receivable, Revolving, Converted to Term Loan	2,316
Total	2,710,017
Performing [Member] \| Commercial [Member] \| General business [Member] \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	197
Financing Receivable, Originated, 2019	4,519
Financing Receivable, Originated, 2018	9,713
Financing Receivable, Originated, 2017	7,803
Financing Receivable, Originated, 2016	2,511
Financing Receivable, Originated, 2015 or Prior	3,159
Financing Receivable, Revolving	2,483
Financing Receivable, Revolving, Converted to Term Loan	19
Total	30,404
Performing [Member] \| Commercial [Member] \| General business [Member] \| Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	1,432
Financing Receivable, Originated, 2019	3,069
Financing Receivable, Originated, 2018	6,694
Financing Receivable, Originated, 2017	10,935
Financing Receivable, Originated, 2016	10,042
Financing Receivable, Originated, 2015 or Prior	3,729
Financing Receivable, Revolving	4,449
Financing Receivable, Revolving, Converted to Term Loan	140
Total	40,490
Performing [Member] \| Commercial [Member] \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] \| Commercial [Member] \| Wholesale/retail [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,749,023
Performing [Member] \| Commercial [Member] \| Wholesale/retail [Member] \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		5,281
Performing [Member] \| Commercial [Member] \| Wholesale/retail [Member] \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		5,399
Performing [Member] \| Commercial [Member] \| Manufacturing [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] \| Commercial [Member] \| Manufacturing [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		623,219
Performing [Member] \| Commercial [Member] \| Manufacturing [Member] \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		18,214
Performing [Member] \| Commercial [Member] \| Manufacturing [Member] \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		13,883
Performing [Member] \| Commercial [Member] \| Public finance [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] \| Commercial [Member] \| Public finance [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		709,868
Performing [Member] \| Commercial [Member] \| Public finance [Member] \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] \| Commercial [Member] \| Public finance [Member] \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] \| Commercial [Member] \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		34,075
Performing [Member] \| Commercial [Member] \| Other commercial and industrial [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		709,729
Performing [Member] \| Commercial [Member] \| Other commercial and industrial [Member] \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		4,028
Performing [Member] \| Commercial [Member] \| Other commercial and industrial [Member] \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		17,744
Performing [Member] \| Commercial real estate [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] \| Commercial real estate [Member] \| Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	725,577
Financing Receivable, Originated, 2019	1,211,338
Financing Receivable, Originated, 2018	954,226
Financing Receivable, Originated, 2017	489,193
Financing Receivable, Originated, 2016	314,899
Financing Receivable, Originated, 2015 or Prior	722,475
Financing Receivable, Revolving	223,131
Financing Receivable, Revolving, Converted to Term Loan	38
Total	4,640,877
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		4,381,663
Performing [Member] \| Commercial real estate [Member] \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	259
Financing Receivable, Originated, 2017	12,311
Financing Receivable, Originated, 2016	2,725
Financing Receivable, Originated, 2015 or Prior	5,831
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	21,126
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		22,145
Performing [Member] \| Commercial real estate [Member] \| Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	4,410
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	4,852
Financing Receivable, Revolving	27
Financing Receivable, Revolving, Converted to Term Loan	0
Total	9,289
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		2,349
Performing [Member] \| Commercial real estate [Member] \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] \| Commercial real estate [Member] \| Residential construction and land development [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		150,529
Performing [Member] \| Commercial real estate [Member] \| Residential construction and land development [Member] \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] \| Commercial real estate [Member] \| Residential construction and land development [Member] \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] \| Commercial real estate [Member] \| Retail [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] \| Commercial real estate [Member] \| Retail [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		743,343
Performing [Member] \| Commercial real estate [Member] \| Retail [Member] \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		12,067
Performing [Member] \| Commercial real estate [Member] \| Retail [Member] \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,243
Performing [Member] \| Commercial real estate [Member] \| Office [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] \| Commercial real estate [Member] \| Office [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		923,202
Performing [Member] \| Commercial real estate [Member] \| Office [Member] \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		5,177
Performing [Member] \| Commercial real estate [Member] \| Office [Member] \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] \| Commercial real estate [Member] \| Multifamily [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] \| Commercial real estate [Member] \| Multifamily [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,257,005
Performing [Member] \| Commercial real estate [Member] \| Multifamily [Member] \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,604
Performing [Member] \| Commercial real estate [Member] \| Multifamily [Member] \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		95
Performing [Member] \| Commercial real estate [Member] \| Industrial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] \| Commercial real estate [Member] \| Industrial [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		852,539
Performing [Member] \| Commercial real estate [Member] \| Industrial [Member] \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,658
Performing [Member] \| Commercial real estate [Member] \| Industrial [Member] \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,011
Performing [Member] \| Commercial real estate [Member] \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] \| Commercial real estate [Member] \| Other commercial real estate [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		455,045
Performing [Member] \| Commercial real estate [Member] \| Other commercial real estate [Member] \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,639
Performing [Member] \| Commercial real estate [Member] \| Other commercial real estate [Member] \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] \| Paycheck Protection Program \| Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	1,682,310
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	1,682,310
Performing [Member] \| Loans to individuals [Member] \| Permanent residential mortgage [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		758,260
Performing [Member] \| Loans to individuals [Member] \| Permanent residential mortgage [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		276,138
Performing [Member] \| Loans to individuals [Member] \| Permanent residential mortgage [Member] \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		78
Performing [Member] \| Loans to individuals [Member] \| Permanent residential mortgage [Member] \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		2,404
Performing [Member] \| Loans to individuals [Member] \| Permanent residential mortgage [Member] \| Loans Insured or Guaranteed by US Government Authorities
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		191,694
Performing [Member] \| Loans to individuals [Member] \| Permanent residential mortgage [Member] \| Loans Insured or Guaranteed by US Government Authorities \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] \| Loans to individuals [Member] \| Permanent residential mortgage [Member] \| Loans Insured or Guaranteed by US Government Authorities \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] \| Loans to individuals [Member] \| Permanent residential mortgage [Member] \| Loans Insured or Guaranteed by US Government Authorities \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] \| Loans to individuals [Member] \| Residential Mortgage [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		1,767,930
Performing [Member] \| Loans to individuals [Member] \| Residential Mortgage [Member] \| Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	564,325
Financing Receivable, Originated, 2019	149,832
Financing Receivable, Originated, 2018	120,875
Financing Receivable, Originated, 2017	124,930
Financing Receivable, Originated, 2016	158,801
Financing Receivable, Originated, 2015 or Prior	348,292
Financing Receivable, Revolving	335,259
Financing Receivable, Revolving, Converted to Term Loan	24,553
Total	1,826,867
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		276,138
Performing [Member] \| Loans to individuals [Member] \| Residential Mortgage [Member] \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	33
Financing Receivable, Originated, 2019	11
Financing Receivable, Originated, 2018	2,094
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	59
Financing Receivable, Originated, 2015 or Prior	318
Financing Receivable, Revolving	950
Financing Receivable, Revolving, Converted to Term Loan	10
Total	3,475
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		78
Performing [Member] \| Loans to individuals [Member] \| Residential Mortgage [Member] \| Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	51
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	34
Financing Receivable, Revolving	272
Financing Receivable, Revolving, Converted to Term Loan	76
Total	433
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		2,404
Performing [Member] \| Loans to individuals [Member] \| Residential Mortgage [Member] \| US Government Agency Insured Loans \| Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	4,859
Financing Receivable, Originated, 2019	33,880
Financing Receivable, Originated, 2018	34,464
Financing Receivable, Originated, 2017	43,099
Financing Receivable, Originated, 2016	58,264
Financing Receivable, Originated, 2015 or Prior	226,380
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	400,946
Performing [Member] \| Loans to individuals [Member] \| Residential Mortgage [Member] \| US Government Agency Insured Loans \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	0
Performing [Member] \| Loans to individuals [Member] \| Residential Mortgage [Member] \| US Government Agency Insured Loans \| Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	0
Performing [Member] \| Loans to individuals [Member] \| Personal [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		84,853
Performing [Member] \| Loans to individuals [Member] \| Personal [Member] \| Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	219,873
Financing Receivable, Originated, 2019	200,580
Financing Receivable, Originated, 2018	76,246
Financing Receivable, Originated, 2017	100,229
Financing Receivable, Originated, 2016	64,104
Financing Receivable, Originated, 2015 or Prior	102,126
Financing Receivable, Revolving	510,571
Financing Receivable, Revolving, Converted to Term Loan	1,510
Total	1,275,239
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,116,196
Performing [Member] \| Loans to individuals [Member] \| Personal [Member] \| Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	39
Financing Receivable, Originated, 2019	55
Financing Receivable, Originated, 2018	66
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	469
Financing Receivable, Originated, 2015 or Prior	31
Financing Receivable, Revolving	965
Financing Receivable, Revolving, Converted to Term Loan	0
Total	1,625
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		45
Performing [Member] \| Loans to individuals [Member] \| Personal [Member] \| Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	11
Financing Receivable, Originated, 2019	214
Financing Receivable, Originated, 2018	10
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	29
Financing Receivable, Revolving, Converted to Term Loan	0
Total	264
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] \| Loans to individuals [Member] \| Home Equity Loan
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		817,976
Performing [Member] \| Loans to individuals [Member] \| Home Equity Loan \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] \| Loans to individuals [Member] \| Home Equity Loan \| Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] \| Loans to individuals [Member] \| Home Equity Loan \| Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		143,554
Non-Graded, Recorded Investment		37,398
Nonaccrual [Member] \| Commercial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		115,379
Non-Graded, Recorded Investment		37
Nonaccrual [Member] \| Commercial [Member] \| Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		91,722
Non-Graded, Recorded Investment		0
Nonaccrual [Member] \| Commercial [Member] \| Energy [Member] \| Nonaccruing substandard and doubtful
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	21,076
Financing Receivable, Originated, 2019	2,607
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	21,064
Financing Receivable, Revolving	80,312
Financing Receivable, Revolving, Converted to Term Loan	0
Total	125,059
Nonaccrual [Member] \| Commercial [Member] \| Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		4,480
Non-Graded, Recorded Investment		0
Nonaccrual [Member] \| Commercial [Member] \| Healthcare [Member] \| Nonaccruing substandard and doubtful
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	18
Financing Receivable, Originated, 2018	183
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	2,935
Financing Receivable, Revolving	509
Financing Receivable, Revolving, Converted to Term Loan	0
Total	3,645
Nonaccrual [Member] \| Commercial [Member] \| Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		7,483
Non-Graded, Recorded Investment		0
Nonaccrual [Member] \| Commercial [Member] \| Services [Member] \| Nonaccruing substandard and doubtful
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	4,833
Financing Receivable, Originated, 2019	448
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	12,590
Financing Receivable, Originated, 2016	1,049
Financing Receivable, Originated, 2015 or Prior	6,138
Financing Receivable, Revolving	540
Financing Receivable, Revolving, Converted to Term Loan	0
Total	25,598
Nonaccrual [Member] \| Commercial [Member] \| General business [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	1,675
Financing Receivable, Originated, 2019	3,728
Financing Receivable, Originated, 2018	4,863
Financing Receivable, Originated, 2017	1,436
Financing Receivable, Originated, 2016	530
Financing Receivable, Originated, 2015 or Prior	107
Financing Receivable, Revolving	477
Financing Receivable, Revolving, Converted to Term Loan	41
Total	12,857
Nonaccrual [Member] \| Commercial [Member] \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,163
Non-Graded, Recorded Investment		0
Nonaccrual [Member] \| Commercial [Member] \| Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		10,133
Non-Graded, Recorded Investment		0
Nonaccrual [Member] \| Commercial [Member] \| Public finance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		0
Nonaccrual [Member] \| Commercial [Member] \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		398
Non-Graded, Recorded Investment		37
Nonaccrual [Member] \| Commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		27,626
Non-Graded, Recorded Investment		0
Nonaccrual [Member] \| Commercial real estate [Member] \| Nonaccruing substandard and doubtful
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	8,300
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	232
Financing Receivable, Originated, 2016	7,468
Financing Receivable, Originated, 2015 or Prior	11,246
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	27,246
Nonaccrual [Member] \| Commercial real estate [Member] \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		350
Non-Graded, Recorded Investment		0
Nonaccrual [Member] \| Commercial real estate [Member] \| Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		18,868
Non-Graded, Recorded Investment		0
Nonaccrual [Member] \| Commercial real estate [Member] \| Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		0
Nonaccrual [Member] \| Commercial real estate [Member] \| Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		6,858
Non-Graded, Recorded Investment		0
Nonaccrual [Member] \| Commercial real estate [Member] \| Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		909
Non-Graded, Recorded Investment		0
Nonaccrual [Member] \| Commercial real estate [Member] \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		641
Non-Graded, Recorded Investment		0
Nonaccrual [Member] \| Loans to individuals [Member] \| Permanent residential mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		493
Non-Graded, Recorded Investment		19,948
Nonaccrual [Member] \| Loans to individuals [Member] \| Permanent residential mortgage [Member] \| Loans Insured or Guaranteed by US Government Authorities
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		6,100
Nonaccrual [Member] \| Loans to individuals [Member] \| Residential Mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		493
Non-Graded, Recorded Investment		37,129
Nonaccrual [Member] \| Loans to individuals [Member] \| Residential Mortgage [Member] \| Nonaccruing substandard and doubtful
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	648
Financing Receivable, Originated, 2019	104
Financing Receivable, Originated, 2018	1,658
Financing Receivable, Originated, 2017	784
Financing Receivable, Originated, 2016	2,010
Financing Receivable, Originated, 2015 or Prior	22,415
Financing Receivable, Revolving	3,835
Financing Receivable, Revolving, Converted to Term Loan	774
Total	32,228
Nonaccrual [Member] \| Loans to individuals [Member] \| Residential Mortgage [Member] \| US Government Agency Insured Loans \| Nonaccruing substandard and doubtful
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	545
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	309
Financing Receivable, Originated, 2015 or Prior	6,887
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	7,741
Nonaccrual [Member] \| Loans to individuals [Member] \| Personal [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		56
Non-Graded, Recorded Investment		232
Nonaccrual [Member] \| Loans to individuals [Member] \| Personal [Member] \| Nonaccruing substandard and doubtful
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	28
Financing Receivable, Originated, 2019	17
Financing Receivable, Originated, 2018	57
Financing Receivable, Originated, 2017	73
Financing Receivable, Originated, 2016	50
Financing Receivable, Originated, 2015 or Prior	49
Financing Receivable, Revolving	45
Financing Receivable, Revolving, Converted to Term Loan	0
Total	$ 319
Nonaccrual [Member] \| Loans to individuals [Member] \| Home Equity Loan
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		$ 11,081

Loans and Allowances for Credit Losses, Nonaccrual (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual	$ 234,693	$ 180,951
Financing Receivable, Nonaccrual, No Allowance	167,878
Financing receivable, Nonaccrual, With Allowance	66,815
Financing Receivable, Nonaccrual, Related Allowance	22,441
Commercial [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual	167,159	115,416
Financing Receivable, Nonaccrual, No Allowance	113,945
Financing receivable, Nonaccrual, With Allowance	53,214
Financing Receivable, Nonaccrual, Related Allowance	19,052
Commercial [Member] \| Energy [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual	125,059	91,722
Financing Receivable, Nonaccrual, No Allowance	76,633
Financing receivable, Nonaccrual, With Allowance	48,426
Financing Receivable, Nonaccrual, Related Allowance	16,478
Commercial [Member] \| Healthcare [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual	3,645	4,480
Financing Receivable, Nonaccrual, No Allowance	3,645
Financing receivable, Nonaccrual, With Allowance	0
Financing Receivable, Nonaccrual, Related Allowance	0
Commercial [Member] \| Services [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual	25,598	7,483
Financing Receivable, Nonaccrual, No Allowance	20,810
Financing receivable, Nonaccrual, With Allowance	4,788
Financing Receivable, Nonaccrual, Related Allowance	2,574
Commercial [Member] \| General business [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual	12,857
Financing Receivable, Nonaccrual, No Allowance	12,857
Financing receivable, Nonaccrual, With Allowance	0
Financing Receivable, Nonaccrual, Related Allowance	0
Commercial real estate [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual	27,246	27,626
Financing Receivable, Nonaccrual, No Allowance	13,645
Financing receivable, Nonaccrual, With Allowance	13,601
Financing Receivable, Nonaccrual, Related Allowance	3,389
Loans to individuals [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual	40,288
Financing Receivable, Nonaccrual, No Allowance	40,288
Financing receivable, Nonaccrual, With Allowance	0
Financing Receivable, Nonaccrual, Related Allowance	0
Loans to individuals [Member] \| Residential mortgage [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual	32,228
Financing Receivable, Nonaccrual, No Allowance	32,228
Financing receivable, Nonaccrual, With Allowance	0
Financing Receivable, Nonaccrual, Related Allowance	0
Loans to individuals [Member] \| Personal [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual	319	$ 287
Financing Receivable, Nonaccrual, No Allowance	319
Financing receivable, Nonaccrual, With Allowance	0
Financing Receivable, Nonaccrual, Related Allowance	0
US Government Agency Insured Loans \| Loans to individuals [Member] \| Residential mortgage [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual	7,741
Financing Receivable, Nonaccrual, No Allowance	7,741
Financing receivable, Nonaccrual, With Allowance	0
Financing Receivable, Nonaccrual, Related Allowance	$ 0

Loans and Allowances for Credit Losses, Troubled Debt Restructurings (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Troubled Debt Restructuring [Line Items]
Troubled Debt Restructuring, Recorded Investment	$ 187.0	$ 132.0
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	95.0	57.0
Troubled Debt Restructuring, Charge-offs	20.9	18.6
Troubled Debt Restructurings, Recorded Balance Modified During The Period	83.0	37.0
US Government Agency Insured Loans \| Residential Mortgage [Member] \| Loans to individuals [Member] \| Accruing [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Troubled Debt Restructuring, Recorded Investment	$ 152.0	$ 92.0

Loans and Allowances for Credit Losses, By Aging Category (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing receivable, recorded investment, aging [Abstract]
Current	$ 22,718,498	$ 21,392,306
Nonaccrual	234,693	180,951
Total	23,007,520	21,750,987
Past Due 90 Days or More and Accruing	88,718	7,680
30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	68,013	47,084
60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	38,782	20,560
90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	182,227	110,086
Commercial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	12,978,801	13,899,429
Nonaccrual	167,159	115,416
Total	13,077,535	14,031,650
Past Due 90 Days or More and Accruing	4,821
Commercial [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	17,219	7,943
Commercial [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	10,504	1,608
Commercial [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	71,011	7,254
Commercial [Member] \| Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	3,410,995	3,881,244
Nonaccrual	125,059	91,722
Total	3,469,194	3,973,377
Past Due 90 Days or More and Accruing	0
Commercial [Member] \| Energy [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	12,735	401
Commercial [Member] \| Energy [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	4,050	10
Commercial [Member] \| Energy [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	41,414	0
Commercial [Member] \| Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	3,302,345	3,027,329
Nonaccrual	3,645	4,480
Total	3,305,990	3,033,916
Past Due 90 Days or More and Accruing	0
Commercial [Member] \| Healthcare [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	2,039
Commercial [Member] \| Healthcare [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
Commercial [Member] \| Healthcare [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	3,645	68
Commercial [Member] \| Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	3,489,423	3,105,621
Nonaccrual	25,598	7,483
Total	3,508,583	3,122,163
Past Due 90 Days or More and Accruing	326
Commercial [Member] \| Services [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	3,278	1,737
Commercial [Member] \| Services [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	177	523
Commercial [Member] \| Services [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	15,705	6,799
Commercial [Member] \| Wholesale/retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Current		1,758,878
Nonaccrual		1,163
Total		1,760,866
Commercial [Member] \| Wholesale/retail [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		712
Commercial [Member] \| Wholesale/retail [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		113
Commercial [Member] \| Wholesale/retail [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial [Member] \| General business [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	2,776,038
Nonaccrual	12,857
Total	2,793,768
Past Due 90 Days or More and Accruing	4,495
Commercial [Member] \| General business [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	1,206
Commercial [Member] \| General business [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	6,277
Commercial [Member] \| General business [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	10,247
Commercial [Member] \| Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Current		654,329
Nonaccrual		10,133
Total		665,449
Commercial [Member] \| Manufacturing [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		410
Commercial [Member] \| Manufacturing [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		190
Commercial [Member] \| Manufacturing [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		387
Commercial [Member] \| Public finance [Member]
Financing receivable, recorded investment, aging [Abstract]
Current		707,638
Nonaccrual		0
Total		709,868
Commercial [Member] \| Public finance [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		2,230
Commercial [Member] \| Public finance [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial [Member] \| Public finance [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial [Member] \| Other commercial and industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current		764,390
Nonaccrual		435
Total		766,011
Commercial [Member] \| Other commercial and industrial [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		414
Commercial [Member] \| Other commercial and industrial [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		772
Commercial [Member] \| Other commercial and industrial [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	4,672,279	4,400,576
Nonaccrual	27,246	27,626
Total	4,698,538	4,433,783
Past Due 90 Days or More and Accruing	5,126
Commercial real estate [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	276	4,920
Commercial real estate [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	5,310	250
Commercial real estate [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	20,673	411
Commercial real estate [Member] \| Residential construction and land development [Member]
Financing receivable, recorded investment, aging [Abstract]
Current		147,379
Nonaccrual		350
Total		150,879
Commercial real estate [Member] \| Residential construction and land development [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		3,093
Commercial real estate [Member] \| Residential construction and land development [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial real estate [Member] \| Residential construction and land development [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		57
Commercial real estate [Member] \| Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Current		756,653
Nonaccrual		18,868
Total		775,521
Commercial real estate [Member] \| Retail [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial real estate [Member] \| Retail [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial real estate [Member] \| Retail [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial real estate [Member] \| Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Current		928,379
Nonaccrual		0
Total		928,379
Commercial real estate [Member] \| Office [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial real estate [Member] \| Office [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial real estate [Member] \| Office [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial real estate [Member] \| Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Current		1,258,704
Nonaccrual		6,858
Total		1,265,562
Commercial real estate [Member] \| Multifamily [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial real estate [Member] \| Multifamily [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial real estate [Member] \| Multifamily [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial real estate [Member] \| Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current		855,208
Nonaccrual		909
Total		856,117
Commercial real estate [Member] \| Industrial [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial real estate [Member] \| Industrial [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial real estate [Member] \| Industrial [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Commercial real estate [Member] \| Other commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Current		454,253
Nonaccrual		641
Total		457,325
Commercial real estate [Member] \| Other commercial real estate [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		1,827
Commercial real estate [Member] \| Other commercial real estate [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		250
Commercial real estate [Member] \| Other commercial real estate [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		354
Loans to individuals [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	3,385,108
Nonaccrual	40,288
Total	3,549,137
Past Due 90 Days or More and Accruing	78,771
Loans to individuals [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	50,518
Loans to individuals [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	22,968
Loans to individuals [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	90,543
Loans to individuals [Member] \| Residential mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,849,304
Nonaccrual	32,228
Total	1,863,003
Past Due 90 Days or More and Accruing	181
Loans to individuals [Member] \| Residential mortgage [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	5,812
Loans to individuals [Member] \| Residential mortgage [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	837
Loans to individuals [Member] \| Residential mortgage [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	7,050
Loans to individuals [Member] \| Residential mortgage [Member] \| US Government Agency Insured Loans
Financing receivable, recorded investment, aging [Abstract]
Current	262,102
Nonaccrual	7,741
Total	408,687
Past Due 90 Days or More and Accruing	78,349
Loans to individuals [Member] \| Residential mortgage [Member] \| US Government Agency Insured Loans \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	41,389
Loans to individuals [Member] \| Residential mortgage [Member] \| US Government Agency Insured Loans \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	22,041
Loans to individuals [Member] \| Residential mortgage [Member] \| US Government Agency Insured Loans \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	83,155
Loans to individuals [Member] \| Permanent residential mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Current		1,034,716
Nonaccrual		20,441
Total		1,057,321
Loans to individuals [Member] \| Permanent residential mortgage [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		2,011
Loans to individuals [Member] \| Permanent residential mortgage [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		153
Loans to individuals [Member] \| Permanent residential mortgage [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Loans to individuals [Member] \| Permanent residential mortgage [Member] \| US Government Agency Insured Loans
Financing receivable, recorded investment, aging [Abstract]
Nonaccrual		6,100
Loans to individuals [Member] \| Home equity [Member]
Financing receivable, recorded investment, aging [Abstract]
Current		814,325
Nonaccrual		11,081
Total		829,057
Loans to individuals [Member] \| Home equity [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		3,343
Loans to individuals [Member] \| Home equity [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		308
Loans to individuals [Member] \| Home equity [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		0
Loans to individuals [Member] \| Personal [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,273,702	1,196,362
Nonaccrual	319	287
Total	1,277,447	1,201,382
Past Due 90 Days or More and Accruing	241
Loans to individuals [Member] \| Personal [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	3,317	4,664
Loans to individuals [Member] \| Personal [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	90	54
Loans to individuals [Member] \| Personal [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	338	15
Loans to individuals [Member] \| Residential Mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Current		1,895,939
Nonaccrual		37,622
Total		2,084,172
Loans to individuals [Member] \| Residential Mortgage [Member] \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		29,557
Loans to individuals [Member] \| Residential Mortgage [Member] \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		18,648
Loans to individuals [Member] \| Residential Mortgage [Member] \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		102,406
Loans to individuals [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member] \| US Government Agency Insured Loans
Financing receivable, recorded investment, aging [Abstract]
Current		46,898
Total		197,794
Loans to individuals [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member] \| US Government Agency Insured Loans \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		24,203
Loans to individuals [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member] \| US Government Agency Insured Loans \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		18,187
Loans to individuals [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member] \| US Government Agency Insured Loans \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due		$ 102,406
Paycheck Protection Program
Financing receivable, recorded investment, aging [Abstract]
Current	1,682,310
Total	1,682,310
Past Due 90 Days or More and Accruing	0
Paycheck Protection Program \| 30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0
Paycheck Protection Program \| 60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0
Paycheck Protection Program \| 90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	$ 0

Loans and Allowances for Credit Losses, Impaired Loans (Details)
$ in Thousands

12 Months Ended

Dec. 31, 2019

USD ($)

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

$ 467,714

Impaired loans, recorded investment, total

372,645

Impaired loans, recorded investment with no related allowance

323,505

Impaired loans, recorded investment with related allowance

49,140

Impaired loans, related allowance

17,414

Impaired loans, average recorded investment

354,262

Impaired loans, interest income recognized

8,931

Commercial [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

195,193

Impaired loans, recorded investment, total

115,416

Impaired loans, recorded investment with no related allowance

66,276

Impaired loans, recorded investment with related allowance

49,140

Impaired loans, related allowance

17,414

Impaired loans, average recorded investment

101,399

Impaired loans, interest income recognized

0

Commercial [Member] | Energy [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

149,441

Impaired loans, recorded investment, total

91,722

Impaired loans, recorded investment with no related allowance

44,244

Impaired loans, recorded investment with related allowance

47,478

Impaired loans, related allowance

16,854

Impaired loans, average recorded investment

69,119

Impaired loans, interest income recognized

0

Commercial [Member] | Services [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

10,923

Impaired loans, recorded investment, total

7,483

Impaired loans, recorded investment with no related allowance

6,301

Impaired loans, recorded investment with related allowance

1,182

Impaired loans, related allowance

240

Impaired loans, average recorded investment

5,854

Impaired loans, interest income recognized

0

Commercial [Member] | Wholesale/retail [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

1,980

Impaired loans, recorded investment, total

1,163

Impaired loans, recorded investment with no related allowance

902

Impaired loans, recorded investment with related allowance

261

Impaired loans, related allowance

101

Impaired loans, average recorded investment

916

Impaired loans, interest income recognized

0

Commercial [Member] | Manufacturing [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

10,848

Impaired loans, recorded investment, total

10,133

Impaired loans, recorded investment with no related allowance

9,914

Impaired loans, recorded investment with related allowance

219

Impaired loans, related allowance

219

Impaired loans, average recorded investment

9,144

Impaired loans, interest income recognized

0

Commercial [Member] | Healthcare [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

13,774

Impaired loans, recorded investment, total

4,480

Impaired loans, recorded investment with no related allowance

4,480

Impaired loans, recorded investment with related allowance

0

Impaired loans, related allowance

0

Impaired loans, average recorded investment

7,798

Impaired loans, interest income recognized

0

Commercial [Member] | Public finance [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

0

Impaired loans, recorded investment, total

0

Impaired loans, recorded investment with no related allowance

0

Impaired loans, recorded investment with related allowance

0

Impaired loans, related allowance

0

Impaired loans, average recorded investment

0

Impaired loans, interest income recognized

0

Commercial [Member] | Other commercial and industrial [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

8,227

Impaired loans, recorded investment, total

435

Impaired loans, recorded investment with no related allowance

435

Impaired loans, recorded investment with related allowance

0

Impaired loans, related allowance

0

Impaired loans, average recorded investment

8,568

Impaired loans, interest income recognized

0

Commercial real estate [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

30,139

Impaired loans, recorded investment, total

27,626

Impaired loans, recorded investment with no related allowance

27,626

Impaired loans, recorded investment with related allowance

0

Impaired loans, related allowance

0

Impaired loans, average recorded investment

24,623

Impaired loans, interest income recognized

0

Commercial real estate [Member] | Residential construction and land development [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

1,306

Impaired loans, recorded investment, total

350

Impaired loans, recorded investment with no related allowance

350

Impaired loans, recorded investment with related allowance

0

Impaired loans, related allowance

0

Impaired loans, average recorded investment

350

Impaired loans, interest income recognized

0

Commercial real estate [Member] | Retail [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

20,265

Impaired loans, recorded investment, total

18,868

Impaired loans, recorded investment with no related allowance

18,868

Impaired loans, recorded investment with related allowance

0

Impaired loans, related allowance

0

Impaired loans, average recorded investment

19,573

Impaired loans, interest income recognized

0

Commercial real estate [Member] | Office [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

0

Impaired loans, recorded investment, total

0

Impaired loans, recorded investment with no related allowance

0

Impaired loans, recorded investment with related allowance

0

Impaired loans, related allowance

0

Impaired loans, average recorded investment

0

Impaired loans, interest income recognized

0

Commercial real estate [Member] | Multifamily [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

6,858

Impaired loans, recorded investment, total

6,858

Impaired loans, recorded investment with no related allowance

6,858

Impaired loans, recorded investment with related allowance

0

Impaired loans, related allowance

0

Impaired loans, average recorded investment

3,580

Impaired loans, interest income recognized

0

Commercial real estate [Member] | Industrial [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

909

Impaired loans, recorded investment, total

909

Impaired loans, recorded investment with no related allowance

909

Impaired loans, recorded investment with related allowance

0

Impaired loans, related allowance

0

Impaired loans, average recorded investment

454

Impaired loans, interest income recognized

0

Commercial real estate [Member] | Other commercial real estate [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

801

Impaired loans, recorded investment, total

641

Impaired loans, recorded investment with no related allowance

641

Impaired loans, recorded investment with related allowance

0

Impaired loans, related allowance

0

Impaired loans, average recorded investment

666

Impaired loans, interest income recognized

0

Loans to individuals [Member] | Permanent residential mortgage [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

24,868

Impaired loans, recorded investment, total

20,441

Impaired loans, recorded investment with no related allowance

20,441

Impaired loans, recorded investment with related allowance

0

Impaired loans, related allowance

0

Impaired loans, average recorded investment

22,196

Impaired loans, interest income recognized

1,198

Loans to individuals [Member] | Permanent residential mortgage [Member] | US Government Agency Insured Loans

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

204,187

^[1]

Impaired loans, recorded investment, total

197,794

^[1]

Impaired loans, recorded investment with no related allowance

197,794

^[1]

Impaired loans, recorded investment with related allowance

0

^[1]

Impaired loans, related allowance

0

^[1]

Impaired loans, average recorded investment

195,009

^[1]

Impaired loans, interest income recognized

7,733

^[1]

Loans to individuals [Member] | Home Equity Loan

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

12,967

Impaired loans, recorded investment, total

11,081

Impaired loans, recorded investment with no related allowance

11,081

Impaired loans, recorded investment with related allowance

0

Impaired loans, related allowance

0

Impaired loans, average recorded investment

10,776

Impaired loans, interest income recognized

0

Loans to individuals [Member] | Residential Mortgage [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

242,022

Impaired loans, recorded investment, total

229,316

Impaired loans, recorded investment with no related allowance

229,316

Impaired loans, recorded investment with related allowance

0

Impaired loans, related allowance

0

Impaired loans, average recorded investment

227,981

Impaired loans, interest income recognized

8,931

Loans to individuals [Member] | Personal [Member]

Impaired loans [Abstract]

Impaired loans, unpaid principal balance

360

Impaired loans, recorded investment, total

287

Impaired loans, recorded investment with no related allowance

287

Impaired loans, recorded investment with related allowance

0

Impaired loans, related allowance

0

Impaired loans, average recorded investment

259

Impaired loans, interest income recognized

$ 0

[1]	All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2019, the majority were accruing based on the guarantee by U.S. government agencies.

Premises and Equipment and Leases Premises and Equipment and Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Premises and Equipment [Line Items]
Premises and equipment	$ 843,041	$ 779,050
Less accumulated depreciation	291,733	243,531
Premises and equipment, net of accumulated depreciation	551,308	535,519
Depreciation Expense	54,300	51,600	$ 51,200
Lease, Cost [Abstract]
Operating Lease, Right-of-Use Asset	$ 166,000	180,000
Operating Lease, Weighted Average Remaining Lease Term	11 years
Operating Lease, Weighted Average Discount Rate, Percent	3.00%
Operating Lease, costs recognized as occupancy and equipment expense	$ 25,000	24,200
Operating Lease, operating cash flows	25,600	23,300
Lease, Cost	42,000	43,000	$ 28,500
Short-term Lease, Cost	13,400	12,600
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Operating Leases, Payments Due, 2021	26,300
Operating Leases, Payments, 2022	21,200
Operating Leases, Payments, 2023	20,100
Operating Leases, Payments, 2024	19,600
Operating Lease, Payments, 2025	18,900
Operating Leases, Payments, 2026 and later	116,000
Land
Premises and Equipment [Line Items]
Premises and equipment	69,776	69,960
Buildings and improvements
Premises and Equipment [Line Items]
Premises and equipment	440,528	421,952
Software and related integration
Premises and Equipment [Line Items]
Premises and equipment	120,444	98,487
Furniture and equipment
Premises and Equipment [Line Items]
Premises and equipment	165,344	135,153
Construction in progress
Premises and Equipment [Line Items]
Premises and equipment	$ 46,949	$ 53,498

Goodwill and Intangible Assets (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2019

Dec. 31, 2020

Finite-Lived Intangible Assets [Line Items]

Finite-lived intangible assets, net

$ 125,271

$ 113,436

Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]

18,492

16,213

14,336

12,557

11,442

40,396

Goodwill [Roll Forward]

Goodwill, Beginning Balance

1,049,263

Adjustment

^[1]

(1,172)

Goodwill, Ending Balance

1,048,091

Commercial [Member]

Goodwill [Roll Forward]

Goodwill, Beginning Balance

313,270

Adjustment

^[1]

600,661

Goodwill, Ending Balance

913,931

Consumer [Member]

Goodwill [Roll Forward]

Goodwill, Beginning Balance

43,458

Adjustment

^[1]

0

Goodwill, Ending Balance

43,458

Wealth Management [Member]

Goodwill [Roll Forward]

Goodwill, Beginning Balance

90,702

Adjustment

^[1]

0

Goodwill, Ending Balance

90,702

Funds Management and Other [Member]

Goodwill [Roll Forward]

Goodwill, Beginning Balance

601,833

Adjustment

^[1]

(601,833)

Goodwill, Ending Balance

0

Core deposits premiums [Member]

Finite-Lived Intangible Assets [Line Items]

Finite-lived intangible assets, gross

103,200

Accumulated amortization

19,364

32,256

Finite-lived intangible assets, net

83,836

70,944

Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]

11,893

10,981

10,145

9,379

8,675

19,871

Other identifiable intangible assets [Member]

Finite-Lived Intangible Assets [Line Items]

Finite-lived intangible assets, gross

74,372

82,731

Accumulated amortization

32,937

40,239

Finite-lived intangible assets, net

$ 41,435

42,492

Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]

6,599

5,232

4,191

3,178

2,767

$ 20,525

[1]	Goodwill related to the CoBiz acquisition was not yet allocated to the operating segments as of December 31, 2018 and was included in Funds Management and Other in 2018 then allocated during 2019.

Mortgage Banking Activities, Components of Loans Held For Sale (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Residential Mortgage Loans Held For Sale [Line Items]
Number of days for past due for a residential mortgage loan to be considered nonperforming (in days)	90	90
Residential mortgage loans held for sale, nonperforming	$ 0	$ 0
Credit losses recognized on residential mortgage loans held for sale	0	0	$ 0
Components of Residential Mortgage Loans Held for Sale [Abstract]
Unpaid principal balance	227,161	175,117
Residential mortgage loans held for sale, Fair value	236,444	177,703
Residential mortgage loans held for sale	$ 252,316	$ 182,271
Not Designated as Hedging Instrument [Member] \| Residential mortgage loan commitments [Member]
Schedule of Residential Mortgage Loans Held For Sale [Line Items]
General number of days outstanding for residential mortgage commitments, minimum (in days)	60	60
General number of days outstanding for residential mortgage commitments, maximum (in days)	90	90
Components of Residential Mortgage Loans Held for Sale [Abstract]
Derivative, Notional Amount	$ 380,637	$ 158,460
Derivative, Net fair value	$ 20,435	$ 5,233
Not Designated as Hedging Instrument [Member] \| Forward sales contracts [Member]
Schedule of Residential Mortgage Loans Held For Sale [Line Items]
General number of days for delivery of loans, for which the price is set by forward sales contracts, minimum (in days)	60	60
General number of days for delivery of loans, for which the price is set by forward sales contracts, maximum (in days)	90	90
Components of Residential Mortgage Loans Held for Sale [Abstract]
Derivative, Notional Amount	$ 549,414	$ 315,203
Derivative, Net fair value	$ (4,563)	$ (665)

Mortgage Banking Activities, Mortgage Banking Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Mortgage Banking Revenue [Abstract]
Net realized gains on sales of mortgage loans	$ 107,847	$ 39,730	$ 36,379
Net change in unrealized gain on mortgage loans held for sale	6,697	672	(674)
Net change in fair value of mortgage loan commitments	15,202	(145)	(1,145)
Net change in the fair value of forward sales contracts	(3,898)	2,463	(2,870)
Total mortgage production revenue	125,848	42,720	31,690
Servicing revenue	56,512	64,821	66,097
Total mortgage banking revenue	$ 182,360	$ 107,541	$ 97,787

Mortgage Banking Activities, Mortgage Servicing Rights (Details)	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Summary of Mortgage Servicing Rights [Abstract]
Number of residential mortgage loans serviced for others	106,201	126,828	132,463
Outstanding principal balance of residential mortgage loans serviced for others	$ 16,228,449,000	$ 20,727,106,000	$ 21,658,335,000
Weighted average interest rate (in hundredths)	3.84%	3.98%	3.99%
Remaining contractual term (in months)	280	289	293
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance	$ 201,886,000	$ 259,254,000	$ 252,867,000
Additions, net	31,209,000	35,128,000	35,247,000
Disposals	(10,801,000)
Change in fair value due to loan runoff	(41,598,000)	(38,979,000)	(33,528,000)
Change in fair value due to market changes	(79,524,000)	(53,517,000)	4,668,000
Ending balance	$ 101,172,000	$ 201,886,000	$ 259,254,000
Servicing Assets at Fair Value, Assumptions Used to Estimate Fair Value [Abstract]
Discount rate - risk-free rate plus a market premium (in hundredths)	9.14%	9.81%
Prepayment rate - based upon loan interest rate, original term and loan type, minimum	9.41%	8.28%
Prepayment rate - based upon loan interest rate, original term and loan type, maximum	21.87%	16.05%
Loan servicing costs - annually per loan based upon loan type, performing, minimum (in dollars per loan)	$ 69	$ 68
Loan servicing costs - annually per loan based upon loan type, performing, maximum (in dollars per loan)	94	94
Loan servicing costs - annually per loan based upon loan type, delinquent, minimum (in dollars per loan)	150	150
Loan servicing costs - annually per loan based upon loan type, delinquent, maximum (in dollars per loan)	500	500
Loan servicing costs - annually per loan based upon loan type, foreclosure, minimum (in dollars per loan)	1,000	1,000
Loan servicing costs - annually per loan based upon loan type, foreclosure, maximum (in dollars per loan)	$ 4,000	$ 4,000
Primary secondary mortgage rate spread (in basis points)	105	104
Escrow earnings rate - indexed to rates paid on deposit accounts with comparable average life	0.43%	1.73%
Delinquency rate	3.54%	2.73%

Deposits (Details) - USD ($) $ in Thousands	12 Months Ended
Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest expense on deposits [Abstract]
Transaction deposits	$ 60,424	$ 132,854	$ 65,859
Savings	385	677	439
Time Deposit, Interest Expense [Abstract]
Certificates of deposits under $100,000	6,741	8,299	5,751
Certificates of deposits $100,000 and over	18,270	29,288	19,739
Other time deposits	4,176	4,420	3,729
Total time	29,187	42,007	29,219
Total	89,996	175,538	$ 95,517
Time Deposit Information [Abstract]
Time deposits in denomination of $250,000 or more	815,000	845,000
Time Deposit Maturities [Abstract]
2021	1,500,000
2022	172,000
2023	90,000
2024	54,000
2025	41,000
Thereafter	100,000
Other Deposits Information [Abstract]
Overdrawn customer transaction deposits reclassified as loan balances	$ 3,100	$ 8,700

Other Borrowed Funds (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Other Borrowed Funds [Line Items]

Balance

$ 3,821,361

$ 8,621,328

$ 7,418,714

Average Balance

$ 8,570,959

$ 10,261,592

$ 7,298,229

Rate

0.82%

2.37%

2.03%

Other borrowed funds, Maturities [Abstract]

$ 1,884,974

1,639,735

9,625

625

10,555

275,847

Funds purchased [Member]

Other Borrowed Funds [Line Items]

Balance

$ 769,365

$ 3,390,528

$ 402,450

Rate

0.05%

1.53%

2.34%

Average Balance

$ 2,045,795

$ 2,438,376

$ 419,322

Rate

0.58%

2.08%

1.89%

Maximum Outstanding At Any Month End

$ 3,311,938

$ 3,390,528

$ 949,531

Repurchase agreements [Member]

Other Borrowed Funds [Line Items]

Balance

$ 893,021

$ 427,822

$ 615,961

Rate

0.09%

0.50%

0.36%

Average Balance

$ 1,589,746

$ 399,785

$ 464,582

Rate

0.24%

0.57%

0.28%

Maximum Outstanding At Any Month End

$ 3,230,097

$ 427,822

$ 615,961

Other Borrowings [Member]

Other Borrowed Funds [Line Items]

Balance

1,882,970

4,527,055

6,124,390

Average Balance

$ 4,659,453

$ 7,147,356

$ 6,236,441

Rate

0.88%

2.45%

2.07%

Federal Home Loan Bank advances [Member]

Other Borrowed Funds [Line Items]

Balance

$ 200,000

$ 4,500,000

$ 6,100,000

Rate

0.29%

1.79%

2.65%

Average Balance

$ 3,393,989

$ 7,122,466

$ 6,207,142

Rate

1.00%

2.44%

2.06%

Maximum Outstanding At Any Month End

$ 7,500,000

$ 8,000,000

$ 6,500,000

GNMA repurchase liability [Member]

Other Borrowed Funds [Line Items]

Balance

$ 19,500

$ 15,417

$ 15,552

Rate

4.35%

4.32%

4.43%

Average Balance

$ 42,771

$ 13,746

$ 14,783

Rate

4.18%

4.47%

Maximum Outstanding At Any Month End

$ 126,569

$ 19,581

$ 16,529

Federal Reserve Bank Advances

Other Borrowed Funds [Line Items]

$ 0

0.00%

$ 42,464

0.26%

Maximum Outstanding At Any Month End

$ 0

Paycheck protection program liquidity facility

Other Borrowed Funds [Line Items]

$ 1,635,963

0.35%

$ 1,152,073

0.35%

Maximum Outstanding At Any Month End

$ 2,013,414

Other [Member]

Other Borrowed Funds [Line Items]

Balance

$ 27,507

$ 11,638

$ 8,838

Rate

5.24%

5.09%

2.90%

Average Balance

$ 28,156

$ 11,144

$ 14,516

Rate

5.12%

5.30%

2.67%

Maximum Outstanding At Any Month End

$ 49,376

$ 34,676

$ 20,422

Subordinated debentures [Member]

Other Borrowed Funds [Line Items]

Balance

^[1]

$ 276,005

$ 275,923

$ 275,913

Rate

^[1]

4.72%

5.15%

5.34%

Average Balance

^[1]

$ 275,965

$ 276,075

$ 177,884

Rate

^[1]

5.05%

5.47%

5.52%

Maximum Outstanding At Any Month End

^[1]

$ 276,005

$ 275,923

$ 275,913

Subordinated debentures [Member] | Subordinated debentures, 2016 issuance [Member]

Other borrowed funds, Other Disclosures [Abstract]

Amount of debt issuance

$ 150,000

Maturity date

Jun. 30, 2056

Stated interest rate

5.375%

Debt Instrument, Call Date, Earliest

Jun. 30, 2021

Subordinated debentures [Member] | Subordinated debentures-acquired, 2015 Issuance [Member]

Other borrowed funds, Other Disclosures [Abstract]

Amount of debt issuance

$ 60,000

Maturity date

Jun. 25, 2030

Interest rate description

three-month LIBOR plus 3.17%

Stated interest rate

5.625%

Debt Instrument, Call Date, Earliest

Jun. 25, 2025

Subordinated debentures [Member] | Junior subordinated debentures-acquired, 2003 issuance [Member]

Other borrowed funds, Other Disclosures [Abstract]

Amount of debt issuance

$ 21,000

Maturity date

Sep. 17, 2033

Interest rate description

three-month LIBOR plus 2.95%

Subordinated debentures [Member] | Junior subordinated debentures-acquired, 2004 issuance [Member]

Other borrowed funds, Other Disclosures [Abstract]

Amount of debt issuance

$ 31,000

Maturity date

Jul. 23, 2034

Interest rate description

three-month LIBOR plus 2.60%

Subordinated debentures [Member] | Junior subordinated debentures-acquired, 2005 issuance [Member]

Other borrowed funds, Other Disclosures [Abstract]

Amount of debt issuance

$ 20,000

Maturity date

Sep. 30, 2035

Interest rate description

three-month LIBOR plus 1.45%

U.S. government agency mortgage-backed securities [Member]

Assets Sold under Agreements to Repurchase [Line Items]

Amortized Cost

$ 893,069

431,939

Fair Value

910,885

435,898

Repurchase Liability

^[2]

$ 893,021

$ 427,822

Average Rate (in hundredths)

0.09%

0.50%

U.S. government agency mortgage-backed securities [Member] | Overnight [Member]

Assets Sold under Agreements to Repurchase [Line Items]

Amortized Cost

$ 893,069

$ 431,939

Fair Value

910,885

435,898

Repurchase Liability

^[2]

$ 893,021

$ 427,822

Average Rate (in hundredths)

0.09%

0.50%

U.S. government agency mortgage-backed securities [Member] | Long-term [Member]

Assets Sold under Agreements to Repurchase [Line Items]

Amortized Cost

$ 0

Fair Value

0

Repurchase Liability

^[2]

$ 0

Average Rate (in hundredths)

0.00%

Subsidiaries [Member] | Funds purchased [Member]

Other borrowed funds, Other Disclosures [Abstract]

Number of days to maturity, minimum

one day

Number of days to maturity, maximum

ninety days

Subsidiaries [Member] | Repurchase agreements [Member]

Other borrowed funds, Other Disclosures [Abstract]

Number of days to maturity, maximum

ninety days

Subsidiaries [Member] | Federal Home Loan Bank advances [Member]

Other borrowed funds, Other Disclosures [Abstract]

Federal Home Loan Banks, Letters of credit issued to secure public funds

$ 381,000

Unused credit available pursuant to the FHLB's collateral policies

8,600,000

Subsidiaries [Member] | BOK Financial Securities, Inc. [Member] | Other [Member]

Other Borrowed Funds [Line Items]

Balance

$ 0

[1]	Parent Company only.
[2]	BOK Financial maintains control over the securities underlying overnight repurchase agreements and generally transfers control over securities underlying longer-term dealer repurchase agreements to the respective counterparty.

Federal and State Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets [Abstract]
Credit loss reserves	$ 101,265	$ 50,611
Lease liability	44,794	46,084
Deferred compensation	29,504	25,976
Unearned fees	14,584	9,080
Purchased loan discount	11,537	18,042
Share-based compensation	6,525	7,392
Valuation adjustments	3,834	1,545
Other	29,963	26,384
Total deferred tax assets	242,006	185,114
Valuation Allowance [Abstract]
Valuation allowance	0	0
Deferred tax liabilities [Abstract]
Available for sale securities mark to market	105,769	33,140
Right-of-use asset	38,635	42,180
Mortgage servicing rights	24,182	48,435
Acquired identifiable intangible	18,138	23,181
Depreciation	13,754	18,909
Lease financing	11,828	10,720
Other	39,210	34,826
Total deferred tax liabilities	251,516	211,391
Deferred Tax Liabilities, Net	(9,510)	(26,277)
Current income tax expense [Abstract]
Federal	173,888	110,887	$ 103,748
State	29,889	15,088	15,253
Total current income tax expense	203,777	125,975	119,001
Deferred income tax expense [Abstract]
Federal	(65,989)	3,416	(190)
State	(8,995)	792	250
Total deferred income tax expense (benefit)	(74,984)	4,208	60
Total income tax expense	128,793	130,183	119,061
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal statutory tax	118,412	132,482	118,752
Tax exempt revenue	(7,035)	(12,227)	(8,311)
Effect of state income taxes, net of federal benefit	14,251	12,715	12,430
Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments	(6,994)	(5,127)	(4,559)
Other, net	10,159	2,340	749
Total income tax expense	$ 128,793	$ 130,183	$ 119,061
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory tax (in thousandths)	21.00%	21.00%	21.00%
Tax exempt revenue (in thousandths)	(1.20%)	(1.90%)	(1.50%)
Effect of state income taxes, net of federal benefit (in thousandths)	2.50%	2.00%	2.20%
Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments (in thousandths)	(1.20%)	(0.80%)	(0.80%)
Other, net (in thousandths)	1.70%	0.30%	0.20%
Total (in thousandths)	22.80%	20.60%	21.10%
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of January 1	$ 20,465	$ 18,869	$ 18,110
Additions for tax for current year positions	6,384	5,649	2,649
Settlements during the period	0	0	0
Lapses of applicable statute of limitations	(3,947)	(4,053)	(1,890)
Balance as of December 31	22,902	20,465	18,869
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	17,200
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	2,400	2,200	$ 1,700
Unrecognized Tax Benefits, Penalties and Interest Accrued	$ 5,900	$ 5,600
Unrecognized Tax Benefits, Number of Reporting Periods Open for Examination, Federal	3
Unrecognized Tax Benefits, Number of Reporting Periods Open for Examination, State, Minimum	3
Unrecognized Tax Benefits, Number of Reporting Periods Open for Examination, State, Maximum	6

Employee Benefits (Details) - USD ($)	12 Months Ended
Employee Benefits (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
BOK Financial Pension Plan [Member]
BOK Financial Pension Plan [Abstract]
Interest percentage added to the five-year trailing average of five-year Treasury Securities	1.50%
Interest percentage accrued on employee account balances, Minimum	3.00%
Interest percentage accrued on employee account balances, Maximum	5.00%
Quarterly variable interest percentage accrued on employee account balances, minimum	3.28%
Quarterly variable interest percentage accrued on employee account balances, maximum	3.40%
Defined Benefit Plan, Benefit Obligation	$ 24,000,000	$ 25,000,000
Defined Benefit Plan, Plan Assets, Amount	38,000,000	36,000,000
Net periodic benefit cost (credit)	(1,300,000)	$ (815,000)	$ (583,000)
Total estimated future benefit payments	$ 26,600,000
BOK Financial Pension Plan Weighted-average Assumptions [Abstract]
Discount rate (in hundredths)	2.69%	4.10%
Expected return on plan assets (in hundredths)	5.50%	5.50%
BOK Financial Pension Plan [Member] \| Equity Securities [Member]
BOK Financial Pension Plan [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	60.00%
BOK Financial Pension Plan [Member] \| Bonds [Member]
BOK Financial Pension Plan [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	40.00%
BOK Financial 401(k) Plan [Member]
BOK Financial 401(k) Plan [Abstract]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	6.00%
Defined Contribution Plan, Minimum Years of Service for Employees to Obtain Maximum Employer Matching	4
Defined Contribution Plan, Maximum Years of Service for Employees to Obtain Minimum Employer Matching	15
Contributions Non-Elective Annual Contributions For Qualified Employees	$ 750
Defined Contribution Plan, Annual Base Employee Compensation to Qualify for Non-Elective Employer Contributions, Maximum	$ 40,000
Defined Contribution Plan, Vesting Period for Employer Contributions	five years
Defined Contribution Plan, Cost	$ 29,900,000	$ 27,600,000	$ 25,100,000
BOK Financial 401(k) Plan [Member] \| Minimum [Member]
BOK Financial 401(k) Plan [Abstract]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	50.00%
BOK Financial 401(k) Plan [Member] \| Maximum [Member]
BOK Financial 401(k) Plan [Abstract]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	200.00%

Share-Based Compensation Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock Options [Member]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Outstanding, Number of Options [Abstract]
Number of options outstanding, Ending balance (in shares)	17,671	36,100	63,058
Options vested (in shares)	17,671	27,193	33,573
Share-based Compensation Arrangements by Share-based Payment Award, Options, Weighted Average Exercise Price [Abstract]
Options outstanding, weighted average exercise price, ending balance (in dollars per share)	$ 57.35	$ 56.75	$ 54.89
Options vested, weighted average exercise price (in dollars per share)	$ 57.35	$ 57.08	$ 53.09
Share-based Compensation Arrangements by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options outstanding, aggregate intrinsic value	$ 197	$ 1,106	$ 1,163
Options vested, aggregate intrinsic value	197	824	679
Options exercised, aggregate intrinsic value	$ 318	$ 761	$ 2,300
Weighted average remaining contractual life of options outstanding (in years)	1 year 10 days
Weighted average remaining contractual life of options vested (in years)	1 year 10 days
Restricted Stock [Member]
Share-based Compensation Arrangements by Share-based Payment Award, Restricted Stock, Nonvested, Number of Shares [Roll Forward]
Non-vested shares awarded, beginning of period (in shares)	427,178	527,607	667,103
Non-vested shares that were granted during the period (in shares)	236,750	145,724	150,419
Non-vested shares that vested during period (in shares)	(225,527)	(114,201)	(242,215)
Non-vested shares that forfeited during period (in shares)	(18,167)	(131,952)	(47,700)
Non-vested shares awarded, end of period (in shares)	420,234	427,178	527,607
Share-based Compensation Arrangements by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted Average Grant Date Fair Value, Granted	$ 83.49	$ 76.74	$ 85.58
Weighted Average Grant Date Fair Value, Vested	83.50	61.28	74.85
Weighted average grant date fair value non-vested share awards forfeited (in dollars per share)	$ 83.10	$ 83.69	$ 75.68
Share-based Compensation Costs, Including Costs That May Be Recognized As Future Expense [Abstract]
Share-based Compensation Expense Recognized	$ 16,000	$ 15,100	$ 3,600
Unrecognized compensation cost of unvested awards, for future periods	16,300
Unrecognized compensation cost of unvested awards, Amount to be expensed in 2021	10,800
Unrecognized compensation cost of unvested awards, Amount to be expensed in 2022	5,400
Unrecognized compensation cost of unvested awards, Amount to be expensed in 2023	$ 134
Number of shares with required performance obligations	244,392
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangements by Share-based Payment Award, Restricted Stock, Nonvested, Number of Shares [Roll Forward]
Non-vested shares awarded, beginning of period (in shares)	46,689	0	0
Non-vested shares that were granted during the period (in shares)	22,980	46,689	0
Non-vested shares that vested during period (in shares)	0	0	0
Non-vested shares that forfeited during period (in shares)	0	0	0
Non-vested shares awarded, end of period (in shares)	69,669	46,689	0
Share-based Compensation Arrangements by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted Average Grant Date Fair Value, Granted	$ 77.36	$ 87.40	$ 0
Weighted Average Grant Date Fair Value, Vested	0	0	0
Weighted average grant date fair value non-vested share awards forfeited (in dollars per share)	$ 0	$ 0	$ 0

Related Parties Related Parties (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Directors and Senior Management [Member]

Loans and Leases Receivable, Related Parties [Roll Forward]

Beginning balance

$ 75,189

$ 75,265

Advances

498,425

886,610

Payments

(484,958)

(896,643)

Adjustments

^[1]

4,284

9,957

Ending balance

92,940

75,189

Director [Member]

Loan Commitments and Equity Investments [Abstract]

$ 10,000

Executive Officer [Member]

Loan Commitments and Equity Investments [Abstract]

Percentage of investment funds' assets held by clients

80.00%

Assets Held in Cavanal Hill Funds

$ 3,700,000

Subsidiaries [Member] | BOKF, NA [Member] | Affiliated Entity [Member]

Loan Commitments and Equity Investments [Abstract]

Maximum percentage of unimpaired capital on loan commitments and equity investments to a single affiliate (in hundredths)

10.00%

Maximum percentage of unimpaired capital on loan commitments and equity investments to all affiliates (in hundredths)

20.00%

Maximum loan commitments and equity investments to a single affiliate

$ 416,000

Maximum loan commitments and equity investments to all affiliates

832,000

Largest loan commitment and equity investment to a single affiliate

264,000

Aggregate loan commitment and equity investment to all affiliates

324,000

392,000

Outstanding amounts to all affiliates

5,300

$ 5,000

Largest amount outstanding to a single affiliate

$ 4,100

[1]	Adjustments generally consist of changes in status as a related party.

Commitments and Contingent Liabilities (Details)	12 Months Ended
Commitments and Contingent Liabilities (Details)	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)
Other Commitments [Abstract]
The Net Asset Value of Units in Mutual Funds (per unit)	1.00
Assets Purchased from Mutual Funds Managed		$ 0
Minimum Average Cash Balance Required to be Maintained at Federal Reserve by Subsidiary Bank	$ 727,000,000	$ 618,000,000
Misuse of Revenues Pledged to Municipal Bonds [Member] \| Judicial Ruling [Member]
Litigation Settlement [Abstract]
Disgorged fees	1,067,721
Litigation Settlement, Expense	$ 600,000
Misuse of Revenues Pledged to Municipal Bonds [Member] \| Pending Litigation [Member]
Litigation Settlement [Abstract]
Loss Contingency, Number of Plaintiffs	2
Alleged total of judgment against nursing home operator	$ 8,000,000
Bank Participation in Fraudulent Sale of Securities by Principals [Member] \| Pending Litigation [Member]
Litigation Settlement [Abstract]
Loss Contingency, Number of Plaintiffs	19
Principal amount of entered judgment against the principal individual and his wife	$ 36,805,051
Pre-judgment interest amount of entered judgment against the principal individual and his wife	10,937,831
Outstanding principal accrued interest and other amounts upon sale of facilities securing payment of the bonds	$ 20,000,000
Purchase of facilities from principals subject to SEC New Jersey proceedings [Member] \| Settled Litigation
Litigation Settlement [Abstract]
Number of individuals who purchased facilities from the principals subject to SEC New Jersey proceedings	2
Outstanding principal, accrued interest and other amounts required by bond documents	$ 60,000,000
Visa Membership [Member]
Loss Contingencies [Line Items]
Number of Visa Class B Shares Owned by Entity (in shares) \| shares	252,233
Number of Visa Class A Shares Visa Class B Shares Are Convertible To (in shares) \| shares	409,324

Commitments and Contingent Liabilities Variable Interest Entities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Other Assets [Member]
Variable Interest Entity [Line Items]
Amortization Method Qualified Affordable Housing Project Investments	$ 290	$ 259
Other Liabilities [Member]
Variable Interest Entity [Line Items]
Qualified Affordable Housing Project Investments, Commitment	$ 94	$ 82

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator: [Abstract]:
Net income attributable to BOK Financial Corp. shareholders	$ 435,030	$ 500,758	$ 445,646
Less: Earnings allocated to participating securities	2,612	3,227	3,737
Numerator for basic earnings per share - income available to common shareholders	432,418	497,531	441,909
Effect of reallocating undistributed earnings of participating securities	0	0	1
Numerator for diluted earnings per share - income available to common shareholders	$ 432,418	$ 497,531	$ 441,910
Denominator: [Abstract]
Weighted average shares outstanding	70,259,553	71,250,081	67,190,257
Less: Participating securities included in weighted average shares outstanding (in shares)	418,576	462,381	561,617
Denominator for basic earnings per common share (in shares)	69,840,977	70,787,700	66,628,640
Dilutive effect of employee stock compensation plans (in shares)	3,195	14,912	33,633
Denominator for diluted earnings per common share (in shares)	69,844,172	70,802,612	66,662,273
Basic (in dollars per share)	$ 6.19	$ 7.03	$ 6.63
Diluted earnings per share (per share)	$ 6.19	$ 7.03	$ 6.63

Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Common Stock [Abstract]
Common stock, shares authorized (in shares)	2,500,000,000	2,500,000,000
Common stock, par value (in dollars per share)	$ 0.00006	$ 0.00006
Perpetual preferred stock [Member]
Preferred Stock [Abstract]
Preferred stock, authorized (in shares)	1,000,000,000
Preferred stock at par value (in dollars per share)	$ 0.00005
Preferred stock conversion rate	one share of Common Stock for each 36 shares of Series A Preferred Stock at the option of the holder
Preferred stock, Rate of annual cumulative dividends (in hundredths)	10.00%
Preferred stock, Liquidation preference per share	$ 0.06
Preferred stock, Aggregate liquidation preference	$ 15
Preferred Stock, Shares Outstanding	0	0	0
Common Stock [Member]
Common Stock [Abstract]
Common stock, shares authorized (in shares)	2,500,000,000
Common stock, par value (in dollars per share)	$ 0.00006
Common stock, number of vote per share	$ 1

Shareholders' Equity Regulatory Capital (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Common Equity Tier 1 Capital [Abstract]
Minimum Capital Requirements, Common Equity Tier 1 to Risk Weighted Assets	4.50%	4.50%
Capital Conservation Buffer, Common Equity Tier 1 to Risk Weighted Assets	2.50%	2.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Common Equity Tier 1 to Risk Weighted Assets	7.00%	7.00%
Common Equity Tier 1 Capital	$ 3,881,912	$ 3,608,821
Common Equity Tier 1 Capital to Risk Weighted Assets	0.1195	0.1139
Tier I Capital (to Risk Weighted Assets) [Abstract]
Minimum Capital Requirement, Tier 1 Capital to Risk Weighted Assets	0.0600	0.0600
Capital Conservation Buffer, Tier 1 Capital to Risk Weighted Assets	2.50%	2.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Tier One to Risk Weighted Assets	8.50%	8.50%
Tier 1 Capital	$ 3,881,912	$ 3,608,821
Tier 1 Capital to Risk Weighted Assets	0.1195	0.1139
Total Capital (to Risk Weighted Assets) [Abstract]
Minimum Capital Requirement, Total Capital to Risk Weighted Assets	0.0800	0.0800
Capital Conservation Buffer, Total Capital to Risk Weighted Assets	2.50%	2.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Total Capital to Risk Weighted Assets	10.50%	10.50%
Total Capital	$ 4,489,110	$ 4,097,087
Total Capital to Risk Weighted Assets	0.1382	0.1294
Tier 1 Capital (to Average Assets) [Abstract]
Minimum Capital Requirement, Tier 1 Capital to Average Assets	0.0400	0.0400
Minimum Capital Requirements Including Capital Conservation Buffer, Tier 1 Capital to Average Assets	4.00%	4.00%
Tier 1 Leverage Capital	$ 3,881,912	$ 3,608,820
Tier 1 Capital to Average Assets	0.0828	0.0840
Subsidiaries [Member] \| BOKF, NA [Member]
Common Equity Tier 1 Capital [Abstract]
Common Equity Tier 1 Capital Ratio Required to be Well Capitalized	6.50%	6.50%
Minimum Capital Requirements, Common Equity Tier 1 to Risk Weighted Assets	4.50%	4.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Common Equity Tier 1 to Risk Weighted Assets	4.50%	4.50%
Common Equity Tier 1 Capital	$ 3,756,950	$ 3,414,446
Common Equity Tier 1 Capital to Risk Weighted Assets	0.1166	0.1090
Tier I Capital (to Risk Weighted Assets) [Abstract]
Tier I Capital Ratio Required to be Well Capitalized	0.0800	0.0800
Minimum Capital Requirement, Tier 1 Capital to Risk Weighted Assets	0.0600	0.0600
Minimum Capital Requirement Including Capital Conservation Buffer, Tier One to Risk Weighted Assets	6.00%	6.00%
Tier 1 Capital	$ 3,756,950	$ 3,414,446
Tier 1 Capital to Risk Weighted Assets	0.1166	0.1090
Total Capital (to Risk Weighted Assets) [Abstract]
Total Capital Ratio Required to be Well Capitalized	0.1000	0.1000
Minimum Capital Requirement, Total Capital to Risk Weighted Assets	0.0800	0.0800
Minimum Capital Requirement Including Capital Conservation Buffer, Total Capital to Risk Weighted Assets	8.00%	8.00%
Total Capital	$ 4,153,347	$ 3,692,010
Total Capital to Risk Weighted Assets	0.1289	0.1179
Tier 1 Capital (to Average Assets) [Abstract]
Leverage Ratio Required to be Well Capitalized	0.0500	0.0500
Minimum Capital Requirement, Tier 1 Capital to Average Assets	0.0400	0.0400
Minimum Capital Requirements Including Capital Conservation Buffer, Tier 1 Capital to Average Assets	4.00%	4.00%
Tier 1 Leverage Capital	$ 3,756,950	$ 3,414,446
Tier 1 Capital to Average Assets	0.0804	0.0798

Shareholders' Equity Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 104,923	$ (72,585)	$ (36,174)
Net change in unrealized gain (loss)	313,796	241,047	(48,010)
Reclassification adjustments included in earnings: [Abstract]
Loss (gain) on available for sale securities, net	(9,910)	(5,597)	2,801
Other comprehensive income (loss), before income taxes	303,886	235,450	(45,209)
Federal and state income taxes	72,941	57,942	(11,507)
Other comprehensive income (loss), net of income taxes	230,945	177,508	(33,702)
Ending balance	335,868	104,923	(72,585)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	5,291,561	4,863,919	4,443,045	$ 3,518,334
Cumulative Effect, Period of Adoption, Adjustment
Reclassification adjustments included in earnings: [Abstract]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest				(2,709)
Unrealized Gain (Loss) on Available for Sale Securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	104,996	(70,999)	(35,385)
Net change in unrealized gain (loss)	312,576	239,017	(46,941)
Reclassification adjustments included in earnings: [Abstract]
Loss (gain) on available for sale securities, net	(9,910)	(5,597)	2,801
Other comprehensive income (loss), before income taxes	302,666	233,420	(44,140)
Federal and state income taxes	72,630	57,425	(11,235)
Other comprehensive income (loss), net of income taxes	230,036	175,995	(32,905)
Ending balance	335,032	104,996	(70,999)
Unrealized Gain (Loss) on Available for Sale Securities [Member] \| Cumulative Effect, Period of Adoption, Adjustment
Reclassification adjustments included in earnings: [Abstract]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest				(2,709)
Unrealized Gain (Loss) on Employee Benefit Plans [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(73)	(1,586)	(789)
Net change in unrealized gain (loss)	1,220	2,030	(1,069)
Reclassification adjustments included in earnings: [Abstract]
Loss (gain) on available for sale securities, net	0	0	0
Other comprehensive income (loss), before income taxes	1,220	2,030	(1,069)
Federal and state income taxes	311	517	(272)
Other comprehensive income (loss), net of income taxes	909	1,513	(797)
Ending balance	$ 836	$ (73)	$ (1,586)
Unrealized Gain (Loss) on Employee Benefit Plans [Member] \| Cumulative Effect, Period of Adoption, Adjustment
Reclassification adjustments included in earnings: [Abstract]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest				$ 0

Reportable Segments (Details) - USD ($) $ in Thousands	12 Months Ended
Reportable Segments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	$ 1,108,444	$ 1,112,879	$ 984,867
Net interest revenue (expense) from internal sources	0	0	0
Net interest and dividend revenue	1,108,444	1,112,879	984,867
Provision for credit losses	222,592	44,000	8,000
Net interest and dividend revenue after provision for credit losses	885,852	1,068,879	976,867
Other operating revenue	843,949	694,370	616,784
Other operating expense	1,165,937	1,132,381	1,028,166
Net direct contribution	563,864	630,868	565,485
Gain (loss) on financial instruments, net	0	0	0
Change in fair value of mortgage servicing rights	0	0	0
Gain (loss) on repossessed assets, net	0	0	0
Corporate expense allocations	0	0	0
Net income before taxes	563,864	630,868	565,485
Federal and state income taxes	128,793	130,183	119,061
Net income	435,071	500,685	446,424
Net income (loss) attributable to Non-controlling interests	41	(73)	778
Net income attributable to BOK Financial Corp. shareholders	435,030	500,758	445,646
Average assets	48,704,390	42,094,347	34,937,530
Operating Segments [Member] \| Commercial [Member]
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	714,932	919,148	726,855
Net interest revenue (expense) from internal sources	(126,444)	(242,907)	(159,954)
Net interest and dividend revenue	588,488	676,241	566,901
Provision for credit losses	69,475	39,011	30,358
Net interest and dividend revenue after provision for credit losses	519,013	637,230	536,543
Other operating revenue	187,361	170,412	162,701
Other operating expense	258,903	252,459	202,095
Net direct contribution	447,471	555,183	497,149
Gain (loss) on financial instruments, net	193	106	26
Change in fair value of mortgage servicing rights	0	0	0
Gain (loss) on repossessed assets, net	(2,677)	331	(6,532)
Corporate expense allocations	24,862	43,055	36,670
Net income before taxes	420,125	512,565	453,973
Federal and state income taxes	114,120	137,759	120,458
Net income	306,005	374,806	333,515
Net income (loss) attributable to Non-controlling interests	0	0	0
Net income attributable to BOK Financial Corp. shareholders	306,005	374,806	333,515
Average assets	26,994,075	22,807,589	18,432,035
Operating Segments [Member] \| Consumer [Member]
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	78,004	99,679	83,231
Net interest revenue (expense) from internal sources	69,000	95,775	73,448
Net interest and dividend revenue	147,004	195,454	156,679
Provision for credit losses	2,805	6,271	5,143
Net interest and dividend revenue after provision for credit losses	144,199	189,183	151,536
Other operating revenue	243,719	187,500	178,123
Other operating expense	233,425	230,916	231,075
Net direct contribution	154,493	145,767	98,584
Gain (loss) on financial instruments, net	95,344	30,375	(25,021)
Change in fair value of mortgage servicing rights	(79,524)	(53,517)	4,668
Gain (loss) on repossessed assets, net	276	496	247
Corporate expense allocations	42,638	47,169	44,398
Net income before taxes	127,951	75,952	34,080
Federal and state income taxes	32,591	19,346	8,681
Net income	95,360	56,606	25,399
Net income (loss) attributable to Non-controlling interests	0	0	0
Net income attributable to BOK Financial Corp. shareholders	95,360	56,606	25,399
Average assets	9,842,125	9,301,341	8,303,263
Operating Segments [Member] \| Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	130,818	61,277	81,528
Net interest revenue (expense) from internal sources	(13,528)	38,815	31,480
Net interest and dividend revenue	117,290	100,092	113,008
Provision for credit losses	(209)	(308)	(288)
Net interest and dividend revenue after provision for credit losses	117,499	100,400	113,296
Other operating revenue	398,834	341,389	296,369
Other operating expense	325,608	277,267	257,650
Net direct contribution	190,725	164,522	152,015
Gain (loss) on financial instruments, net	4	2	7
Change in fair value of mortgage servicing rights	0	0	0
Gain (loss) on repossessed assets, net	0	0	0
Corporate expense allocations	35,331	36,239	35,920
Net income before taxes	155,398	128,285	116,102
Federal and state income taxes	39,770	32,954	30,075
Net income	115,628	95,331	86,027
Net income (loss) attributable to Non-controlling interests	0	0	0
Net income attributable to BOK Financial Corp. shareholders	115,628	95,331	86,027
Average assets	15,695,646	10,204,426	8,447,784
Funds Management and Other [Member]
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	184,690	32,775	93,253
Net interest revenue (expense) from internal sources	70,972	108,317	55,026
Net interest and dividend revenue	255,662	141,092	148,279
Provision for credit losses	150,521	(974)	(27,213)
Net interest and dividend revenue after provision for credit losses	105,141	142,066	175,492
Other operating revenue	14,035	(4,931)	(20,409)
Other operating expense	348,001	371,739	337,346
Net direct contribution	(228,825)	(234,604)	(182,263)
Gain (loss) on financial instruments, net	(95,541)	(30,483)	24,988
Change in fair value of mortgage servicing rights	79,524	53,517	(4,668)
Gain (loss) on repossessed assets, net	2,401	(827)	6,285
Corporate expense allocations	(102,831)	(126,463)	(116,988)
Net income before taxes	(139,610)	(85,934)	(38,670)
Federal and state income taxes	(57,688)	(59,876)	(40,153)
Net income	(81,922)	(26,058)	1,483
Net income (loss) attributable to Non-controlling interests	41	(73)	778
Net income attributable to BOK Financial Corp. shareholders	(81,963)	(25,985)	705
Average assets	$ (3,827,456)	$ (219,009)	$ (245,552)

Fees and Commission Revenue Fees and Commissions (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

$ 810,320

$ 702,201

$ 643,176

Fees and commissions revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

810,320

702,201

643,176

Fees and commissions revenue not from contracts with customers

397,030

^[1]

263,146

^[2]

209,384

^[3]

Fees and commissions revenue from contracts with customers

413,290

^[4]

439,055

^[5]

433,792

^[6]

Brokerage and trading revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

221,833

159,826

108,323

Fees and commissions revenue not from contracts with customers

175,578

^[1]

116,177

^[2]

73,291

^[3]

Fees and commissions revenue from contracts with customers

46,255

^[4]

43,649

^[5]

35,032

^[6]

Trading Revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

144,299

88,558

28,077

Fees and commissions revenue not from contracts with customers

144,299

^[1]

88,558

^[2]

28,077

^[3]

Fees and commissions revenue from contracts with customers

0

^[4]

0

^[5]

0

^[6]

Customer hedging revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

22,749

18,941

38,834

Fees and commissions revenue not from contracts with customers

22,749

^[1]

18,941

^[2]

38,834

^[3]

Fees and commissions revenue from contracts with customers

0

^[4]

0

^[5]

0

^[6]

Retail brokerage revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

15,690

16,136

17,952

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

15,690

^[4]

16,136

^[5]

17,952

^[6]

Insurance brokerage revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

12,702

13,861

4,198

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

12,702

^[4]

13,861

^[5]

4,198

^[6]

Investment banking revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

26,393

22,330

19,262

Fees and commissions revenue not from contracts with customers

8,530

^[1]

8,678

^[2]

6,380

^[3]

Fees and commissions revenue from contracts with customers

17,863

^[4]

13,652

^[5]

12,882

^[6]

Transaction card revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

90,182

87,216

84,025

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

90,182

^[4]

87,216

^[5]

84,025

^[6]

TransFund EFT network revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

78,370

77,324

76,221

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

78,370

^[4]

77,324

^[5]

76,221

^[6]

Merchant services revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

9,232

8,786

7,804

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

9,232

^[4]

8,786

^[5]

7,804

^[6]

Corporate card revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

2,580

1,106

0

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

2,580

^[4]

1,106

^[5]

0

^[6]

Fiduciary and asset management revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

167,445

177,025

184,703

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

167,445

^[4]

177,025

^[5]

184,703

^[6]

Personal trust revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

84,759

81,763

96,839

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

84,759

^[4]

81,763

^[5]

96,839

^[6]

Corporate trust revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

19,308

24,635

22,292

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

19,308

^[4]

24,635

^[5]

22,292

^[6]

Institutional trust & retirement plan services revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

46,253

45,084

44,476

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

46,253

^[4]

45,084

^[5]

44,476

^[6]

Investment management services and other [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

17,125

25,543

21,096

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

17,125

^[4]

25,543

^[5]

21,096

^[6]

Deposit service charges and fees [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

96,805

112,485

112,153

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

96,805

^[4]

112,485

^[5]

112,153

^[6]

Commercial account service charge revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

48,421

47,905

47,272

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

48,421

^[4]

47,905

^[5]

47,272

^[6]

Overdraft fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

21,892

35,356

36,536

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

21,892

^[4]

35,356

^[5]

36,536

^[6]

Check card fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

21,355

22,030

21,306

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

21,355

^[4]

22,030

^[5]

21,306

^[6]

Automated service charge and other deposit fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

5,137

7,194

7,039

Fees and commissions revenue not from contracts with customers

0

^[1]

0

^[2]

0

^[3]

Fees and commissions revenue from contracts with customers

5,137

^[4]

7,194

^[5]

7,039

^[6]

Mortgage banking revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

182,360

107,541

97,787

Fees and commissions revenue not from contracts with customers

182,360

^[1]

107,541

^[2]

97,787

^[3]

Fees and commissions revenue from contracts with customers

0

^[4]

0

^[5]

0

^[6]

Mortgage production revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

125,848

42,720

31,690

Fees and commissions revenue not from contracts with customers

125,848

^[1]

42,720

^[2]

31,690

^[3]

Fees and commissions revenue from contracts with customers

0

^[4]

0

^[5]

0

^[6]

Mortgage servicing revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

56,512

64,821

66,097

Fees and commissions revenue not from contracts with customers

56,512

^[1]

64,821

^[2]

66,097

^[3]

Fees and commissions revenue from contracts with customers

0

^[4]

0

^[5]

0

^[6]

Other revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

51,695

58,108

56,185

Fees and commissions revenue not from contracts with customers

39,092

^[1]

39,428

^[2]

38,306

^[3]

Fees and commissions revenue from contracts with customers

12,603

^[4]

18,680

^[5]

17,879

^[6]

Operating Segments [Member] | Commercial [Member] | Fees and commissions revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

187,119

168,667

161,949

Operating Segments [Member] | Commercial [Member] | Brokerage and trading revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

31,950

18,558

15,376

Operating Segments [Member] | Commercial [Member] | Trading Revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Commercial [Member] | Customer hedging revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

22,767

8,422

7,748

Operating Segments [Member] | Commercial [Member] | Retail brokerage revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Commercial [Member] | Insurance brokerage revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Commercial [Member] | Investment banking revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

9,183

10,136

7,628

Operating Segments [Member] | Commercial [Member] | Transaction card revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

86,897

83,158

79,946

Operating Segments [Member] | Commercial [Member] | TransFund EFT network revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

75,363

73,479

72,280

Operating Segments [Member] | Commercial [Member] | Merchant services revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

9,172

8,607

7,666

Operating Segments [Member] | Commercial [Member] | Corporate card revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

2,362

1,072

0

Operating Segments [Member] | Commercial [Member] | Fiduciary and asset management revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Commercial [Member] | Personal trust revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Commercial [Member] | Corporate trust revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Commercial [Member] | Institutional trust & retirement plan services revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Commercial [Member] | Investment management services and other [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Commercial [Member] | Deposit service charges and fees [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

44,932

43,387

42,583

Operating Segments [Member] | Commercial [Member] | Commercial account service charge revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

44,489

42,251

41,931

Operating Segments [Member] | Commercial [Member] | Overdraft fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

132

313

370

Operating Segments [Member] | Commercial [Member] | Check card fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Commercial [Member] | Automated service charge and other deposit fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

311

823

282

Operating Segments [Member] | Commercial [Member] | Mortgage banking revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Commercial [Member] | Mortgage production revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Commercial [Member] | Mortgage servicing revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Commercial [Member] | Other revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

23,340

23,564

24,044

Operating Segments [Member] | Consumer [Member] | Fees and commissions revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

245,554

187,996

178,174

Operating Segments [Member] | Consumer [Member] | Brokerage and trading revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Consumer [Member] | Trading Revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Consumer [Member] | Customer hedging revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Consumer [Member] | Retail brokerage revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Consumer [Member] | Insurance brokerage revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Consumer [Member] | Investment banking revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Consumer [Member] | Transaction card revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

3,118

3,980

4,076

Operating Segments [Member] | Consumer [Member] | TransFund EFT network revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

3,058

3,924

4,017

Operating Segments [Member] | Consumer [Member] | Merchant services revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

60

56

59

Operating Segments [Member] | Consumer [Member] | Corporate card revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Consumer [Member] | Fiduciary and asset management revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Consumer [Member] | Personal trust revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Consumer [Member] | Corporate trust revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Consumer [Member] | Institutional trust & retirement plan services revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Consumer [Member] | Investment management services and other [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Consumer [Member] | Deposit service charges and fees [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

49,437

64,867

65,210

Operating Segments [Member] | Consumer [Member] | Commercial account service charge revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

1,654

1,713

1,445

Operating Segments [Member] | Consumer [Member] | Overdraft fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

21,679

35,134

36,177

Operating Segments [Member] | Consumer [Member] | Check card fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

21,355

21,865

20,967

Operating Segments [Member] | Consumer [Member] | Automated service charge and other deposit fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

4,749

6,155

6,621

Operating Segments [Member] | Consumer [Member] | Mortgage banking revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

184,097

109,416

99,670

Operating Segments [Member] | Consumer [Member] | Mortgage production revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

125,848

42,724

31,690

Operating Segments [Member] | Consumer [Member] | Mortgage servicing revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

58,249

66,692

67,980

Operating Segments [Member] | Consumer [Member] | Other revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

8,902

9,733

9,218

Operating Segments [Member] | Wealth Management [Member] | Fees and commissions revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

399,229

341,333

296,465

Operating Segments [Member] | Wealth Management [Member] | Brokerage and trading revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

190,477

136,801

86,253

Operating Segments [Member] | Wealth Management [Member] | Trading Revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

144,299

88,558

28,077

Operating Segments [Member] | Wealth Management [Member] | Customer hedging revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

395

9,667

27,512

Operating Segments [Member] | Wealth Management [Member] | Retail brokerage revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

15,690

16,251

19,030

Operating Segments [Member] | Wealth Management [Member] | Insurance brokerage revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

12,702

10,131

0

Operating Segments [Member] | Wealth Management [Member] | Investment banking revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

17,391

12,194

11,634

Operating Segments [Member] | Wealth Management [Member] | Transaction card revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

19

(50)

(82)

Operating Segments [Member] | Wealth Management [Member] | TransFund EFT network revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

(56)

(82)

Operating Segments [Member] | Wealth Management [Member] | Merchant services revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Wealth Management [Member] | Corporate card revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

75

32

0

Operating Segments [Member] | Wealth Management [Member] | Fiduciary and asset management revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

167,610

175,475

183,260

Operating Segments [Member] | Wealth Management [Member] | Personal trust revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

84,759

81,763

96,839

Operating Segments [Member] | Wealth Management [Member] | Corporate trust revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

19,308

24,635

22,292

Operating Segments [Member] | Wealth Management [Member] | Institutional trust & retirement plan services revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

46,253

45,084

44,400

Operating Segments [Member] | Wealth Management [Member] | Investment management services and other [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

17,290

23,993

19,729

Operating Segments [Member] | Wealth Management [Member] | Deposit service charges and fees [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

2,430

2,443

2,527

Operating Segments [Member] | Wealth Management [Member] | Commercial account service charge revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

2,282

2,137

2,331

Operating Segments [Member] | Wealth Management [Member] | Overdraft fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

74

138

134

Operating Segments [Member] | Wealth Management [Member] | Check card fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Wealth Management [Member] | Automated service charge and other deposit fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

74

168

62

Operating Segments [Member] | Wealth Management [Member] | Mortgage banking revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Wealth Management [Member] | Mortgage production revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Wealth Management [Member] | Mortgage servicing revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Operating Segments [Member] | Wealth Management [Member] | Other revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

38,693

26,664

24,507

Funds Management and Other [Member] | Fees and commissions revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

(21,582)

4,205

6,588

Funds Management and Other [Member] | Brokerage and trading revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

(594)

4,467

6,694

Funds Management and Other [Member] | Trading Revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Funds Management and Other [Member] | Customer hedging revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

(413)

852

3,574

Funds Management and Other [Member] | Retail brokerage revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

(115)

(1,078)

Funds Management and Other [Member] | Insurance brokerage revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

3,730

4,198

Funds Management and Other [Member] | Investment banking revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

(181)

0

Funds Management and Other [Member] | Transaction card revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

148

128

85

Funds Management and Other [Member] | TransFund EFT network revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

5

3

6

Funds Management and Other [Member] | Merchant services revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

123

79

Funds Management and Other [Member] | Corporate card revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

143

2

0

Funds Management and Other [Member] | Fiduciary and asset management revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

(165)

1,550

1,443

Funds Management and Other [Member] | Personal trust revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Funds Management and Other [Member] | Corporate trust revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

Funds Management and Other [Member] | Institutional trust & retirement plan services revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

76

Funds Management and Other [Member] | Investment management services and other [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

(165)

1,550

1,367

Funds Management and Other [Member] | Deposit service charges and fees [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

6

1,788

1,833

Funds Management and Other [Member] | Commercial account service charge revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

(4)

1,804

1,565

Funds Management and Other [Member] | Overdraft fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

7

(229)

(145)

Funds Management and Other [Member] | Check card fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

165

339

Funds Management and Other [Member] | Automated service charge and other deposit fee revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

3

48

74

Funds Management and Other [Member] | Mortgage banking revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

(1,737)

(1,875)

(1,883)

Funds Management and Other [Member] | Mortgage production revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

0

(4)

0

Funds Management and Other [Member] | Mortgage servicing revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

(1,737)

(1,871)

(1,883)

Funds Management and Other [Member] | Other revenue [Member]

Disaggregation of Revenue [Line Items]

Fess and commissions revenue

$ (19,240)

$ (1,853)

$ (1,584)

[1]	Out of scope revenue generally relates to financial instruments or contractual rights and obligations within the scope of other applicable accounting guidance.
[2]	Out of scope revenue generally relates to financial instruments or contractual rights and obligations within the scope of other applicable accounting guidance.
[3]	Out of scope revenue generally relates to financial instruments or contractual rights and obligations within the scope of other applicable accounting guidance.
[4]	In scope revenue represents revenue subject to FASB ASC Topic 606, Revenue from Contracts with Customers.
[5]	In scope revenue represents revenue subject to FASB ASC Topic 606, Revenue from Contracts with Customers.
[6]	In scope revenue represents revenue subject to FASB ASC Topic 606, Revenue from Contracts with Customers.

Fair Value Measurements, Fair Value Of Financial Instruments as Measured On a Recurring Basis (Details) - USD ($)
$ in Thousands

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Assets [Abstract]

Trading securities

$ 4,707,975

$ 1,623,921

Available for sale securities

13,050,665

11,269,643

Fair value option securities

114,982

1,098,577

Mortgage servicing rights

101,172

201,886

$ 259,254

$ 252,867

Derivative contracts, net of cash margin, Assets, Fair Value

810,688

323,375

Liabilities [Abstract]

Derivative contracts, net of cash margin, Liabilities, Fair Value

405,779

251,128

U.S. government securities [Member]

Assets [Abstract]

Trading securities

9,183

44,264

Residential agency mortgage-backed securities [Member]

Assets [Abstract]

Trading securities

4,669,148

1,504,651

Available for sale securities

9,340,471

8,046,096

Fair value option securities

114,982

1,088,660

Municipal securities [Member]

Assets [Abstract]

Trading securities

19,172

26,196

Available for sale securities

167,979

1,861

Asset-backed securities [Member]

Assets [Abstract]

Trading securities

0

14,084

U.S. Treasury [Member]

Assets [Abstract]

Available for sale securities

508

1,600

Fair value option securities

0

9,917

Residential non-agency mortgage-backed securities [Member]

Assets [Abstract]

Available for sale securities

32,770

41,609

Commercial agency mortgage-backed securities [Member]

Assets [Abstract]

Available for sale securities

3,508,465

3,178,005

Other debt securities [Member]

Assets [Abstract]

Trading securities

10,472

34,726

Available for sale securities

472

Fair Value, Recurring [Member]

Assets [Abstract]

Trading securities

4,707,975

1,623,921

Available for sale securities

13,050,665

11,269,643

Fair value option securities

114,982

1,098,577

Residential mortgage loans held for sale

252,316

^[1]

182,271

^[2]

Mortgage servicing rights

101,172

^[3]

201,886

^[4]

Derivative contracts, net of cash margin, Assets, Fair Value

810,688

^[5]

323,375

^[6]

Liabilities [Abstract]

Derivative contracts, net of cash margin, Liabilities, Fair Value

405,779

^[5]

251,128

^[6]

Fair Value, Recurring [Member] | U.S. government securities [Member]

Assets [Abstract]

Trading securities

9,183

44,264

Fair Value, Recurring [Member] | Residential agency mortgage-backed securities [Member]

Assets [Abstract]

Trading securities

4,669,148

1,504,651

Available for sale securities

9,340,471

8,046,096

Fair value option securities

1,088,660

Fair Value, Recurring [Member] | Municipal securities [Member]

Assets [Abstract]

Trading securities

19,172

26,196

Available for sale securities

167,979

1,861

Fair Value, Recurring [Member] | Asset-backed securities [Member]

Assets [Abstract]

Trading securities

14,084

Fair Value, Recurring [Member] | U.S. Treasury [Member]

Assets [Abstract]

Available for sale securities

508

1,600

Fair value option securities

9,917

Fair Value, Recurring [Member] | Residential non-agency mortgage-backed securities [Member]

Assets [Abstract]

Available for sale securities

32,770

41,609

Fair Value, Recurring [Member] | Commercial agency mortgage-backed securities [Member]

Assets [Abstract]

Available for sale securities

3,508,465

3,178,005

Fair Value, Recurring [Member] | Other debt securities [Member]

Assets [Abstract]

Trading securities

10,472

34,726

Available for sale securities

472

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]

Assets [Abstract]

Trading securities

4,999

0

Available for sale securities

508

1,600

Fair value option securities

0

9,917

Residential mortgage loans held for sale

0

^[1]

0

^[2]

Mortgage servicing rights

0

^[3]

0

^[4]

Derivative contracts, net of cash margin, Assets, Fair Value

10,780

^[5]

8,944

^[6]

Liabilities [Abstract]

Derivative contracts, net of cash margin, Liabilities, Fair Value

0

^[5]

0

^[6]

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. government securities [Member]

Assets [Abstract]

Trading securities

4,999

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Residential agency mortgage-backed securities [Member]

Assets [Abstract]

Trading securities

0

Available for sale securities

0

Fair value option securities

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Municipal securities [Member]

Assets [Abstract]

Trading securities

0

Available for sale securities

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Asset-backed securities [Member]

Assets [Abstract]

Trading securities

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Treasury [Member]

Assets [Abstract]

Available for sale securities

508

1,600

Fair value option securities

9,917

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Residential non-agency mortgage-backed securities [Member]

Assets [Abstract]

Available for sale securities

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial agency mortgage-backed securities [Member]

Assets [Abstract]

Available for sale securities

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other debt securities [Member]

Assets [Abstract]

Trading securities

0

Available for sale securities

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]

Assets [Abstract]

Trading securities

4,702,976

1,623,921

Available for sale securities

13,049,685

11,267,571

Fair value option securities

114,982

1,088,660

Residential mortgage loans held for sale

245,299

^[1]

173,958

^[2]

Mortgage servicing rights

0

^[3]

0

^[4]

Derivative contracts, net of cash margin, Assets, Fair Value

799,908

^[5]

314,431

^[6]

Liabilities [Abstract]

Derivative contracts, net of cash margin, Liabilities, Fair Value

405,779

^[5]

251,128

^[6]

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. government securities [Member]

Assets [Abstract]

Trading securities

4,184

44,264

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Residential agency mortgage-backed securities [Member]

Assets [Abstract]

Trading securities

4,669,148

1,504,651

Available for sale securities

9,340,471

8,046,096

Fair value option securities

1,088,660

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Municipal securities [Member]

Assets [Abstract]

Trading securities

19,172

26,196

Available for sale securities

167,979

1,861

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Asset-backed securities [Member]

Assets [Abstract]

Trading securities

14,084

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Treasury [Member]

Assets [Abstract]

Available for sale securities

0

Fair value option securities

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Residential non-agency mortgage-backed securities [Member]

Assets [Abstract]

Available for sale securities

32,770

41,609

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial agency mortgage-backed securities [Member]

Assets [Abstract]

Available for sale securities

3,508,465

3,178,005

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other debt securities [Member]

Assets [Abstract]

Trading securities

10,472

34,726

Available for sale securities

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]

Assets [Abstract]

Trading securities

0

Available for sale securities

472

Fair value option securities

0

Residential mortgage loans held for sale

7,017

^[1]

8,313

^[2]

Mortgage servicing rights

101,172

^[3]

201,886

^[4]

Derivative contracts, net of cash margin, Assets, Fair Value

0

^[5]

0

^[6]

Liabilities [Abstract]

Derivative contracts, net of cash margin, Liabilities, Fair Value

$ 0

^[5]

$ 0

^[6]

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Residential mortgage loans held for sale [Member]

Liabilities [Abstract]

Liquidity Discount on Mortgage Loans Qualifying for Sale to US Govt Agencies

94.57%

95.23%

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. government securities [Member]

Assets [Abstract]

Trading securities

$ 0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Residential agency mortgage-backed securities [Member]

Assets [Abstract]

Trading securities

0

Available for sale securities

0

Fair value option securities

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Municipal securities [Member]

Assets [Abstract]

Trading securities

0

Available for sale securities

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Asset-backed securities [Member]

Assets [Abstract]

Trading securities

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Treasury [Member]

Assets [Abstract]

Available for sale securities

0

Fair value option securities

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Residential non-agency mortgage-backed securities [Member]

Assets [Abstract]

Available for sale securities

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial agency mortgage-backed securities [Member]

Assets [Abstract]

Available for sale securities

0

Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other debt securities [Member]

Assets [Abstract]

Trading securities

0

Available for sale securities

$ 472

[1]	Residential mortgage loans held for sale measured at fair value on a recurring basis using significant unobservable inputs (Level 3) consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards and are valued at 94.57% of the unpaid principal balance.
[2]	Residential mortgage loans held for sale measured at fair value on a recurring basis using significant unobservable inputs (Level 3) consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards and are valued at 95.23% of the unpaid principal balance.
[3]	A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 7, Mortgage Banking Activities.
[4]	A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 7, Mortgage Banking Activities.
[5]	See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts in asset positions that were valued based on quoted prices in active markets for identical instruments (Level 1) are primarily exchange-traded interest rate derivative contracts. Derivative contracts in liability positions that were valued using quoted prices in active markets for identical instruments are exchange-traded interest rate, energy and agricultural derivative contracts, fully offset by cash margin.
[6]	See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts based on quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate and energy derivative contracts, net of cash margin. Derivative contracts in liability positions that were valued using quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate and agricultural contracts, fully offset by cash margin.

Fair Value Measurements, Fair Value Measured On a Nonrecurring Basis (Details) - Fair Value, Nonrecurring [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Real estate and other repossessed assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross charge-offs against allowance for loan losses	$ 0	$ 0
Net losses and expenses of repossessed assets, net	(4,602)	(461)
Fair Value, Nonaccruing Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross charge-offs against allowance for loan losses	39,299	31,305
Net losses and expenses of repossessed assets, net	0	0
Fair Value, Inputs, Level 1 [Member] \| Real estate and other repossessed assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Nonaccruing Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member] \| Pension Plan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Plan Assets, Amount	38,000	36,000
Fair Value, Inputs, Level 2 [Member] \| Real estate and other repossessed assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	18,188	5,986
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Nonaccruing Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	801	41
Fair Value, Inputs, Level 3 [Member] \| Real estate and other repossessed assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	2,842	1,551
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Nonaccruing Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 20,423	$ 55,665

Fair Value Measurements Fair Value Measurement, Measured On Non-Recurring Basis, Signfiicant Unobservable Inputs, Quantitative Information (Details) - Fair Value, Nonrecurring [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($)
$ in Thousands

Dec. 31, 2020

Dec. 31, 2019

Real estate and other repossessed assets [Member]

Fair Value Measurement Inputs and Valuation Techniques [Line Items]

Assets, Fair Value Disclosure

$ 2,842

$ 1,551

Fair Value, Nonaccruing Loans

Fair Value Measurement Inputs and Valuation Techniques [Line Items]

Assets, Fair Value Disclosure

20,423

55,665

Discounted Cash Flow [Member] | Fair Value, Nonaccruing Loans | Management knowledge of Industry [Member]

Fair Value Measurement Inputs and Valuation Techniques [Line Items]

Assets, Fair Value Disclosure

20,423

55,665

Valuation Technique, Appraised Value as Adjusted | Real estate and other repossessed assets [Member] | Management knowledge of Industry [Member]

Fair Value Measurement Inputs and Valuation Techniques [Line Items]

Assets, Fair Value Disclosure

$ 2,842

Valuation Technique, Appraised Value as Adjusted | Real estate and other repossessed assets [Member] | Marketability adjustments off appraised value

Fair Value Measurement Inputs and Valuation Techniques [Line Items]

Assets, Fair Value Disclosure

$ 1,551

Minimum [Member] | Real estate and other repossessed assets [Member]

Fair Value Measurement Inputs and Valuation Techniques [Line Items]

Fair Value Measurement, Percentage of appraised value

74.00%

Minimum [Member] | Fair Value, Nonaccruing Loans

Fair Value Measurement Inputs and Valuation Techniques [Line Items]

Fair Value of Impaired Loans as Percentage of Unpaid Principal Balance

1.00%

^[1]

4.00%

^[2]

Maximum [Member] | Real estate and other repossessed assets [Member]

Fair Value Measurement Inputs and Valuation Techniques [Line Items]

Fair Value Measurement, Percentage of appraised value

86.00%

Maximum [Member] | Fair Value, Nonaccruing Loans

Fair Value Measurement Inputs and Valuation Techniques [Line Items]

Fair Value of Impaired Loans as Percentage of Unpaid Principal Balance

91.00%

^[1]

94.00%

^[2]

Weighted Average [Member] | Real estate and other repossessed assets [Member]

Fair Value Measurement Inputs and Valuation Techniques [Line Items]

Fair Value Measurement, Percentage of appraised value

84.00%

Weighted Average [Member] | Fair Value, Nonaccruing Loans

Fair Value Measurement Inputs and Valuation Techniques [Line Items]

Fair Value of Impaired Loans as Percentage of Unpaid Principal Balance

23.00%

^[1]

55.00%

^[2]

[1]	Represents fair value as a percentage of the unpaid principal balance.
[2]	Represents fair value as a percentage of the unpaid principal balance.

Fair Value Measurements, Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	$ 4,707,975	$ 1,623,921
Debt Securities, Held-to-maturity, gross	245,531
Debt Securities, Held-to-maturity, Allowance for Credit Loss	(688)
Investment securities	244,843	293,418
Available for sale securities	13,050,665	11,269,643
Fair value option securities	114,982	1,098,577
Residential mortgage loans held for sale	252,316	182,271
Loans	23,007,520	21,750,987
Allowance for loan losses	(388,640)	(210,759)	$ (207,457)	$ (230,682)
Loans, net of allowance	22,618,880	21,540,228
Mortgage servicing rights	101,172	201,886	259,254	252,867
Derivative contracts, net of cash margin, Assets, Fair Value	810,688	323,375
Time deposits	1,967,128	2,217,849
Subordinated debentures	276,005	275,923
Derivative contracts, net of cash margin, Liabilities, Fair Value	405,779	251,128
Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	13,077,535	14,031,650
Allowance for loan losses	(254,934)	(118,187)	(102,226)	(124,269)
Commercial real estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	4,698,538	4,433,783
Allowance for loan losses	(86,558)	(51,805)	$ (60,026)	$ (56,621)
Loans to individuals [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	3,549,137
Allowance for loan losses	(47,148)
Paycheck Protection Program
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,682,310
Allowance for loan losses	0
U.S. government securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	9,183	44,264
Residential agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	4,669,148	1,504,651
Debt Securities, Held-to-maturity, gross	8,913	10,676
Available for sale securities	9,340,471	8,046,096
Fair value option securities	114,982	1,088,660
Municipal securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	19,172	26,196
Debt Securities, Held-to-maturity, gross	229,245	274,535
Available for sale securities	167,979	1,861
U.S. Treasury [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	508	1,600
Fair value option securities	0	9,917
Residential non-agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	32,770	41,609
Commercial agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	3,508,465	3,178,005
Other debt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	10,472	34,726
Debt Securities, Held-to-maturity, gross	7,373	8,207
Available for sale securities	472	472
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	798,757	735,836
Interest-bearing cash and cash equivalents	381,816	522,985
Trading securities	4,707,975	1,623,921
Debt Securities, Held-to-maturity, gross	272,431
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0
Investment securities	272,431	314,402
Available for sale securities	13,050,665	11,269,643
Fair value option securities	114,982	1,098,577
Residential mortgage loans held for sale	252,316	182,271
Loans	22,885,806	21,689,329
Allowance for loan losses	0	0
Loans, net of allowance	22,885,806	21,689,329
Mortgage servicing rights	101,172	201,886
Derivative contracts, net of cash margin, Assets, Fair Value	810,688	323,375
Deposits with no stated maturity	34,176,752	25,403,319
Time deposits	1,976,936	2,212,467
Other borrowed funds	3,542,489	8,315,860
Subordinated debentures	269,544	284,627
Derivative contracts, net of cash margin, Liabilities, Fair Value	405,779	251,128
Estimate of Fair Value Measurement [Member] \| Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	13,003,383	13,966,221
Estimate of Fair Value Measurement [Member] \| Commercial real estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	4,649,763	4,422,717
Estimate of Fair Value Measurement [Member] \| Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans		2,098,093
Estimate of Fair Value Measurement [Member] \| Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans		1,202,298
Estimate of Fair Value Measurement [Member] \| Loans to individuals [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	3,563,199
Estimate of Fair Value Measurement [Member] \| Paycheck Protection Program
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,669,461
Estimate of Fair Value Measurement [Member] \| U.S. government securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	9,183	44,264
Estimate of Fair Value Measurement [Member] \| Residential agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	4,669,148	1,504,651
Debt Securities, Held-to-maturity, gross	9,790
Investment securities		11,164
Available for sale securities	9,340,471	8,046,096
Fair value option securities		1,088,660
Estimate of Fair Value Measurement [Member] \| Municipal securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	19,172	26,196
Debt Securities, Held-to-maturity, gross	255,270
Investment securities		295,032
Available for sale securities	167,979	1,861
Estimate of Fair Value Measurement [Member] \| Asset-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		14,084
Estimate of Fair Value Measurement [Member] \| Other trading securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	10,472	34,726
Estimate of Fair Value Measurement [Member] \| U.S. Treasury [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	508	1,600
Fair value option securities		9,917
Estimate of Fair Value Measurement [Member] \| Residential non-agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	32,770	41,609
Estimate of Fair Value Measurement [Member] \| Commercial agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	3,508,465	3,178,005
Estimate of Fair Value Measurement [Member] \| Other debt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Securities, Held-to-maturity, gross	7,371
Investment securities		8,206
Available for sale securities	472	472
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	798,757	735,836
Interest-bearing cash and cash equivalents	381,816	522,985
Trading securities	4,707,975	1,623,921
Debt Securities, Held-to-maturity, gross	245,531
Debt Securities, Held-to-maturity, Allowance for Credit Loss	(688)
Investment securities	244,843	293,418
Available for sale securities	13,050,665	11,269,643
Fair value option securities	114,982	1,098,577
Residential mortgage loans held for sale	252,316	182,271
Loans	23,007,520	21,750,987
Allowance for loan losses	(388,640)	(210,759)
Loans, net of allowance	22,618,880	21,540,228
Mortgage servicing rights	101,172	201,886
Derivative contracts, net of cash margin, Assets, Fair Value	810,688	323,375
Deposits with no stated maturity	34,176,752	25,403,319
Time deposits	1,967,128	2,217,849
Other borrowed funds	3,545,356	8,345,405
Subordinated debentures	276,005	275,923
Derivative contracts, net of cash margin, Liabilities, Fair Value	405,779	251,128
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	13,077,535	14,031,650
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Commercial real estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	4,698,538	4,433,783
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans		2,084,172
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans		1,201,382
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Loans to individuals [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	3,549,137
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Paycheck Protection Program
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,682,310
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| U.S. government securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	9,183	44,264
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Residential agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	4,669,148	1,504,651
Debt Securities, Held-to-maturity, gross	8,913
Investment securities		10,676
Available for sale securities	9,340,471	8,046,096
Fair value option securities		1,088,660
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Municipal securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	19,172	26,196
Debt Securities, Held-to-maturity, gross	229,245
Investment securities		274,535
Available for sale securities	167,979	1,861
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Asset-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		14,084
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Other trading securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	10,472	34,726
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| U.S. Treasury [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	508	1,600
Fair value option securities		9,917
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Residential non-agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	32,770	41,609
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Commercial agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	3,508,465	3,178,005
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Other debt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Securities, Held-to-maturity, gross	7,373
Investment securities		8,207
Available for sale securities	472	472
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	798,757	735,836
Interest-bearing cash and cash equivalents	381,816	522,985
Trading securities	4,999	0
Debt Securities, Held-to-maturity, gross	0
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0
Investment securities	0	0
Available for sale securities	508	1,600
Fair value option securities	0	9,917
Residential mortgage loans held for sale	0	0
Loans	0	0
Allowance for loan losses	0	0
Loans, net of allowance	0	0
Mortgage servicing rights	0	0
Derivative contracts, net of cash margin, Assets, Fair Value	10,780	8,944
Deposits with no stated maturity	0	0
Time deposits	0	0
Other borrowed funds	0	0
Subordinated debentures	0	0
Derivative contracts, net of cash margin, Liabilities, Fair Value	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial real estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans		0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans		0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Loans to individuals [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Paycheck Protection Program
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| U.S. government securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	4,999	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Debt Securities, Held-to-maturity, gross	0
Investment securities		0
Available for sale securities	0	0
Fair value option securities		0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Municipal securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Debt Securities, Held-to-maturity, gross	0
Investment securities		0
Available for sale securities	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Asset-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Other trading securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| U.S. Treasury [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	508	1,600
Fair value option securities		9,917
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential non-agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Other debt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Securities, Held-to-maturity, gross	0
Investment securities		0
Available for sale securities	0	0
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	0	0
Interest-bearing cash and cash equivalents	0	0
Trading securities	4,702,976	1,623,921
Debt Securities, Held-to-maturity, gross	86,565
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0
Investment securities	86,565	116,267
Available for sale securities	13,049,685	11,267,571
Fair value option securities	114,982	1,088,660
Residential mortgage loans held for sale	245,299	173,958
Loans	0	0
Allowance for loan losses	0	0
Loans, net of allowance	0	0
Mortgage servicing rights	0	0
Derivative contracts, net of cash margin, Assets, Fair Value	799,908	314,431
Deposits with no stated maturity	0	0
Time deposits	0	0
Other borrowed funds	0	0
Subordinated debentures	269,544	284,627
Derivative contracts, net of cash margin, Liabilities, Fair Value	405,779	251,128
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial real estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans		0
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans		0
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Loans to individuals [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Paycheck Protection Program
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| U.S. government securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	4,184	44,264
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	4,669,148	1,504,651
Debt Securities, Held-to-maturity, gross	9,790
Investment securities		11,164
Available for sale securities	9,340,471	8,046,096
Fair value option securities		1,088,660
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Municipal securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	19,172	26,196
Debt Securities, Held-to-maturity, gross	69,404
Investment securities		96,897
Available for sale securities	167,979	1,861
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Asset-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		14,084
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Other trading securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	10,472	34,726
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| U.S. Treasury [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0	0
Fair value option securities		0
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential non-agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	32,770	41,609
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	3,508,465	3,178,005
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Other debt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Securities, Held-to-maturity, gross	7,371
Investment securities		8,206
Available for sale securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	0	0
Interest-bearing cash and cash equivalents	0	0
Trading securities	0	0
Debt Securities, Held-to-maturity, gross	185,866
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0
Investment securities	185,866	198,135
Available for sale securities	472	472
Fair value option securities	0	0
Residential mortgage loans held for sale	7,017	8,313
Loans	22,885,806	21,689,329
Allowance for loan losses	0	0
Loans, net of allowance	22,885,806	21,689,329
Mortgage servicing rights	101,172	201,886
Derivative contracts, net of cash margin, Assets, Fair Value	0	0
Deposits with no stated maturity	34,176,752	25,403,319
Time deposits	1,976,936	2,212,467
Other borrowed funds	3,542,489	8,315,860
Subordinated debentures	0	0
Derivative contracts, net of cash margin, Liabilities, Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	13,003,383	13,966,221
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial real estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	4,649,763	4,422,717
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans		2,098,093
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans		1,202,298
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Loans to individuals [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	3,563,199
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Paycheck Protection Program
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,669,461
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| U.S. government securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Debt Securities, Held-to-maturity, gross	0
Investment securities		0
Available for sale securities	0	0
Fair value option securities		0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Municipal securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Debt Securities, Held-to-maturity, gross	185,866
Investment securities		198,135
Available for sale securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Asset-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities		0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Other trading securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| U.S. Treasury [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0	0
Fair value option securities		0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential non-agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Other debt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Securities, Held-to-maturity, gross	0
Investment securities		0
Available for sale securities	$ 472	$ 472

Parent Company Only Financial Statements Parent Company Only Financial Statements, Condensed Balance Sheet Statement (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets [Abstract]
Cash and cash equivalents	$ 1,180,573	$ 1,258,821	$ 1,143,424	$ 2,317,054
Loan to bank subsidiary	22,618,880	21,540,228
Other assets	907,218	547,995
Total assets	46,671,088	42,172,021
Liabilities [Abstract]
Other liabilities	427,213	372,230
Subordinated debentures	276,005	275,923
Total liabilities	41,379,527	37,308,102
Shareholders' equity: [Abstract]
Common stock	5	5
Capital surplus	1,368,062	1,350,995
Retained earnings	3,973,675	3,729,778
Treasury Stock, Value	(411,344)	(329,906)
Accumulated other comprehensive income (loss)	335,868	104,923	(72,585)	(36,174)
Total shareholders’ equity	5,266,266	4,855,795
Total liabilities and shareholders’ equity	46,671,088	42,172,021
Parent Company [Member]
Assets [Abstract]
Cash and cash equivalents	183,805	214,779	$ 167,093	$ 205,876
Loan to bank subsidiary	65,204	65,220
Investment in bank subsidiaries	5,079,336	4,602,977
Investment in non-bank subsidiaries	195,768	216,542
Other assets	24,338	38,082
Total assets	5,548,451	5,137,600
Liabilities [Abstract]
Other liabilities	6,180	5,882
Subordinated debentures	276,005	275,923
Total liabilities	282,185	281,805
Shareholders' equity: [Abstract]
Common stock	5	5
Capital surplus	1,368,062	1,350,995
Retained earnings	3,973,675	3,729,778
Treasury Stock, Value	(411,344)	(329,906)
Accumulated other comprehensive income (loss)	335,868	104,923
Total shareholders’ equity	5,266,266	4,855,795
Total liabilities and shareholders’ equity	$ 5,548,451	$ 5,137,600

Parent Company Only Financial Statements Parent Company Only Financial Statements, Condensed Income Statements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Income Statements, Captions [Line Items]
Interest expense	$ 160,556	$ 419,079	$ 243,559
Other operating expense	1,165,937	1,132,381	1,028,166
Other gains (losses), net	7,675	9,351	(2,265)
Federal and state income taxes	128,793	130,183	119,061
Net income attributable to BOK Financial Corp. shareholders	435,030	500,758	445,646
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Total revenue	205,097	354,368	439,825
Interest expense	13,944	15,113	9,827
Other operating expense	2,697	2,352	12,110
Total expense	16,641	17,465	21,937
Net income before taxes, other losses, net, and equity in undistributed income of subsidiaries	188,456	336,903	417,888
Other gains (losses), net	1,465	3,310	(3,921)
Net income before taxes, other losses, net, and equity in undistributed income of subsidiaries	189,921	340,213	413,967
Federal and state income taxes	(4,502)	(4,516)	(7,078)
Net income before equity in undistributed income of subsidiaries	194,423	344,729	421,045
Equity in undistributed income of bank subsidiaries	276,217	166,797	37,515
Equity in undistributed income of non-bank subsidiaries	(35,610)	(10,768)	(12,914)
Net income attributable to BOK Financial Corp. shareholders	435,030	500,758	445,646
Parent Company [Member] \| Dividends, interest and fees received from bank susidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Total revenue	179,140	344,007	426,071
Parent Company [Member] \| Dividends, interest and fees received from non-bank subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Total revenue	25,050	9,325	12,800
Parent Company [Member] \| Other revenue [Member]
Condensed Income Statements, Captions [Line Items]
Total revenue	$ 907	$ 1,036	$ 954

Parent Company Only Financial Statements Parent Company Only Financial Statements, Condensed Cash Flow Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows From Operating Activities: [Abstract]
Net income	$ 435,071	$ 500,685	$ 446,424
Adjustments to reconcile net income to net cash provided by operating activities: [Abstract]
Change in other assets	1,739	18,955	27,507
Change in other liabilities	8,895	92,463	(144,537)
Net cash provided by operating activities	(416,256)	(473,679)	(552,006)
Cash Flows From Investing Activities: [Abstract]
Acquisitions, net of cash acquired	0	0	(175,755)
Net cash used in investing activities	(2,458,835)	(2,323,737)	(1,807,631)
Cash Flows From Financing Activities: [Abstract]
Issuance of common and treasury stock, net	(4,933)	(7)	(88)
Dividends paid	(144,437)	(143,496)	(127,188)
Repurchase of common stock	(75,830)	(129,483)	(53,465)
Net cash used in financing activities	2,796,843	2,912,813	1,186,007
Net increase (decrease) in cash and cash equivalents	(78,248)	115,397	(1,173,630)
Cash and cash equivalents at beginning of period	1,258,821	1,143,424	2,317,054
Cash and cash equivalents at end of period	1,180,573	1,258,821	1,143,424
Cash paid for interest	160,288	417,070	243,121
Parent Company [Member]
Cash Flows From Operating Activities: [Abstract]
Net income	435,030	500,758	445,646
Adjustments to reconcile net income to net cash provided by operating activities: [Abstract]
Equity in undistributed income of bank subsidiaries	(276,217)	(166,797)	(37,515)
Equity in undistributed income of non-bank subsidiaries	35,610	10,768	12,914
Change in other assets	(13,760)	5,075	1,072
Change in other liabilities	850	855	(13,434)
Net cash provided by operating activities	209,033	340,509	406,539
Cash Flows From Investing Activities: [Abstract]
Investment in subsidiaries	(14,807)	(19,837)	(31,901)
Acquisitions, net of cash acquired	0	0	(232,680)
Net cash used in investing activities	(14,807)	(19,837)	(264,581)
Cash Flows From Financing Activities: [Abstract]
Issuance of common and treasury stock, net	(4,933)	(7)	(88)
Dividends paid	144,437	143,496	127,188
Repurchase of common stock	75,830	129,483	53,465
Net cash used in financing activities	(225,200)	(272,986)	(180,741)
Net increase (decrease) in cash and cash equivalents	(30,974)	47,686	(38,783)
Cash and cash equivalents at beginning of period	214,779	167,093	205,876
Cash and cash equivalents at end of period	183,805	214,779	167,093
Cash paid for interest	$ 14,064	$ 15,099	$ 11,457

Label	Element	Value
Consumer [Member]
Goodwill	us-gaap_Goodwill	$ 43,458,000
Wealth Management [Member]
Goodwill	us-gaap_Goodwill	90,702,000
Funds Management and Other [Member]
Goodwill	us-gaap_Goodwill	0
Commercial [Member]
Goodwill	us-gaap_Goodwill	$ 913,931,000