Reclassification adjustments included in earnings:

21,958

45,475

33,369

166,566

Interest revenue, Investment securities, Taxable securities

0

(43)

0

(112)

Other comprehensive income before income taxes

(380)

(5,326)

(2,429)

(9,290)

21,578

40,106

30,940

157,164

Other comprehensive income, net of income taxes

8,393

15,583

12,009

^[1]

61,119

^[1]

13,185

24,523

18,931

96,045

Comprehensive income

102,051

90,795

196,461

203,305

Comprehensive income (loss) attributable to non-controlling interests

719

471

1,027

(1,105)

Comprehensive income attributable to BOK Financial Corp. shareholders

$ 101,332

$ 90,324

$ 195,434

$ 204,410

[1]	Calculated using a 39 percent effective tax rate.

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Assets [Abstract]
Cash and due from banks	$ 561,587	$ 620,846	$ 498,713
Interest-bearing cash and cash equivalents	2,078,831	1,916,651	1,907,838
Trading securities	441,414	337,628	211,622
Investment securities	490,426	546,145	560,711
Available for sale securities	8,341,041	8,676,829	8,830,689
Fair value option securities	445,169	77,046	263,265
Restricted equity securities	311,033	307,240	319,639
Residential mortgage loans held for sale	287,259	301,897	430,728
Loans	17,183,645	16,989,660	16,406,749
Allowance for loan losses	(250,061)	(246,159)	(243,259)
Loans, net of allowance	16,933,584	16,743,501	16,163,490
Premises and equipment, net	321,038	325,849	315,199
Receivables	295,042	772,952	173,638
Goodwill	446,697	448,899	382,739
Intangible assets, net	40,755	46,931	43,372
Mortgage servicing rights	245,239	247,073	190,747
Real estate and other repossessed assets, net of allowance	39,436	44,287	24,054
Derivative contracts, net	280,289	689,872	883,673
Cash surrender value of bank-owned life insurance	312,774	308,430	307,860
Receivable on unsettled securities sales	33,177	7,188	142,820
Other assets	358,741	353,017	319,653
Total assets	32,263,532	32,772,281	31,970,450
Deposits [Abstract]
Noninterest-bearing demand deposits	9,568,895	9,235,720	8,424,609
Interest-bearing deposits: [Abstract]
Transaction	10,087,139	10,865,105	9,668,869
Savings	464,318	425,470	419,262
Time	2,196,122	2,221,800	2,247,061
Total deposits	22,316,474	22,748,095	20,759,801
Funds purchased	67,990	57,929	56,780
Repurchase agreements	396,333	668,661	472,683
Other borrowings	5,232,343	4,846,072	5,830,736
Subordinated debentures	144,658	144,640	371,812
Accrued interest, taxes and expense	133,198	146,704	197,742
Derivative contracts, net	285,819	664,531	719,159
Due on unsettled securities purchases	32,636	6,508	11,757
Other liabilities	204,536	182,784	147,242
Total liabilities	28,813,987	29,465,924	28,567,712
Shareholders' equity: [Abstract]
Common stock	4	4	4
Capital surplus	1,017,495	1,006,535	990,106
Retained earnings	2,942,447	2,823,334	2,755,766
Treasury stock	(545,441)	(544,052)	(494,675)
Accumulated other comprehensive income (loss)	7,964	(10,967)	117,632
Total shareholders’ equity	3,422,469	3,274,854	3,368,833
Non-controlling interests	27,076	31,503	33,905
Total equity	3,449,545	3,306,357	3,402,738
Total liabilities and equity	$ 32,263,532	$ 32,772,281	$ 31,970,450

Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Investment securities [Abstract]
Investment Securities, fair value	$ 515,675	$ 565,493	$ 599,062
Allowance for real estate and other repossessed assets - Accounts 1953055, 1953056, 1953555	$ 8,576	$ 9,562	$ 9,448
Shareholders' equity: [Abstract]
Common stock, par value (in dollars per share)	$ 0.00006	$ 0.00006	$ 0.00006
Common stock, shares authorized (in shares)	2,500,000,000	2,500,000,000	2,500,000,000
Common stock, shares issued (in shares)	75,089,152	74,993,407	74,817,155
Common stock, shares outstanding (in shares)	75,089,152	74,993,407	74,817,155
Treasury stock, shares at cost (in shares)	9,672,749	9,655,975	8,950,838

Consolidated Statements of Changes in Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total Shareholders' Equity [Member]	Non-Controlling Interests [Member]
Balance, beginning of period (in shares) at Dec. 31, 2015		74,530			8,636
Balance, beginning of period at Dec. 31, 2015	$ 3,267,639	$ 4	$ 982,009	$ 2,704,121	$ (477,165)	$ 21,587	$ 3,230,556	$ 37,083
Net income (loss)	107,260			108,365			108,365	(1,105)
Other comprehensive income	96,045					96,045	96,045
Repurchase of common stock (in shares)					305
Repurchase of common stock	(17,770)				$ (17,770)		(17,770)
Stock options exercised (in shares)		39
Stock options exercised	2,016		2,016				2,016
Non-vested shares awarded, net (in shares)		248
Vesting of non-vested shares (in shares)					10
Vesting of non-vested shares	(260)				$ 260		(260)
Tax effect from equity compensation, net	351		351				351
Share-based compensation	5,730		5,730				5,730
Cash dividends on common stock	(56,720)			(56,720)			(56,720)
Capital calls and distributions, net	(2,073)							(2,073)
Balance, end of period (in shares) at Jun. 30, 2016		74,817			8,951
Balance, end of period at Jun. 30, 2016	3,402,738	$ 4	990,106	2,755,766	$ (494,675)	117,632	3,368,833	33,905
Balance, beginning of period (in shares) at Dec. 31, 2016		74,993			9,656
Balance, beginning of period at Dec. 31, 2016	3,306,357	$ 4	1,006,535	2,823,334	$ (544,052)	(10,967)	3,274,854	31,503
Net income (loss)	177,530			176,503			176,503	1,027
Other comprehensive income	18,931					18,931	18,931
Stock options exercised (in shares)		41
Stock options exercised	1,977		1,977				1,977
Non-vested shares awarded, net (in shares)		55
Vesting of non-vested shares (in shares)					17
Vesting of non-vested shares	(1,389)				$ (1,389)		(1,389)
Share-based compensation	8,983		8,983				8,983
Cash dividends on common stock	(57,390)			(57,390)			(57,390)
Capital calls and distributions, net	(5,454)							(5,454)
Balance, end of period (in shares) at Jun. 30, 2017		75,089			9,673
Balance, end of period at Jun. 30, 2017	$ 3,449,545	$ 4	$ 1,017,495	$ 2,942,447	$ (545,441)	$ 7,964	$ 3,422,469	$ 27,076

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash Flows From Operating Activities: [Abstract]
Net income	$ 177,530	$ 107,260
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	0	55,000
Change in fair value of mortgage servicing rights due to market changes	5,087	44,271
Change in the fair value of mortgage servicing rights due to loan runoff	16,261	17,942
Net unrealized gains from derivative contracts	(5,928)	(15,459)
Share-based compensation	8,983	5,730
Depreciation and amortization	25,864	23,532
Net amortization of securities discounts and premiums	15,377	21,814
Net realized gains on financial instruments and other net gains	(4,351)	(9,787)
Net gain on mortgage loans held for sale	(25,229)	(37,151)
Mortgage loans originated for sale	(1,613,997)	(3,062,859)
Proceeds from sale of mortgage loans held for sale	1,651,018	2,981,973
Capitalized mortgage servicing rights	(19,514)	(34,355)
Change in trading and fair value option securities	(472,682)	90,484
Change in receivables	479,774	(9,698)
Change in other assets	(17,548)	(4,740)
Change in accrued interest, taxes and expense	(19,703)	20,299
Change in other liabilities	27,420	(8,854)
Net cash provided by operating activities	228,362	185,402
Cash Flows From Investing Activities: [Abstract]
Proceeds from maturities or redemptions of investment securities	71,654	52,463
Proceeds from maturities or redemptions of available for sale securities	899,096	721,432
Purchases of investment securities	(18,802)	(18,599)
Purchases of available for sale securities	(1,242,070)	(1,155,261)
Proceeds from sales of available for sale securities	700,412	795,140
Change in amount receivable on unsettled securities transactions	(25,989)	(102,627)
Loans originated, net of principal collected	(159,924)	(481,085)
Net payments on derivative asset contracts	420,996	(204,041)
Acquisitions, net of cash acquired	0	(7,700)
Proceeds from disposition of assets	127,699	78,629
Purchases of assets	(106,362)	(107,241)
Net cash provided by investing activities	666,710	(428,890)
Cash Flows From Financing Activities: [Abstract]
Net change in demand deposits, transaction deposits and savings accounts	(405,943)	(169,354)
Net change in time deposits	(25,678)	(159,003)
Net change in other borrowed funds	64,833	259,359
Issuance of subordinated debentures	0	145,390
Net proceeds on derivative liability contracts	(422,016)	196,225
Net change in derivative margin accounts	27,327	(188,823)
Change in amount due on unsettled security transactions	26,128	(5,140)
Issuance of common and treasury stock, net	588	2,276
Repurchase of common stock	0	17,770
Dividends paid	(57,390)	(56,720)
Net cash provided by (used in) financing activities	(792,151)	6,440
Net increase (decrease) in cash and cash equivalents	102,921	(237,048)
Cash and cash equivalents at beginning of period	2,537,497	2,643,599
Cash and cash equivalents at end of period	2,640,418	2,406,551
Supplemental Cash Flow Information: [Abstract]
Cash paid for interest	54,881	40,213
Cash paid for taxes	60,654	14,671
Net loans and bank premises transferred to repossessed real estate and other assets	2,049	5,372
Residential mortgage loans guaranteed by U.S. government agencies that became eligible for repurchase during the period	59,171	49,325
Conveyance of other real estate owned guaranteed by U.S. government agencies	$ 22,602	$ 29,512

Significant Accounting Policies	6 Months Ended
Significant Accounting Policies	Jun. 30, 2017
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Significant Accounting Policies Basis of Presentation The accompanying unaudited consolidated financial statements of BOK Financial Corporation (“BOK Financial” or “the Company”) have been prepared in accordance with accounting principles for interim financial information generally accepted in the United States and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. The unaudited consolidated financial statements include accounts of BOK Financial and its subsidiaries, principally BOKF, NA (“the Bank”), BOK Financial Securities, Inc., The Milestone Group, Inc. and Cavanal Hill Investment Management Inc. Operating divisions of the Bank include Bank of Albuquerque, Bank of Arizona, Bank of Arkansas, Bank of Oklahoma, Bank of Texas, Colorado State Bank and Trust, Mobank, BOK Financial Mortgage and the TransFund electronic funds network. Certain reclassifications have been made to conform to the current period presentation. The financial information should be read in conjunction with BOK Financial’s 2016 Form 10-K filed with the Securities and Exchange Commission, which contains audited financial statements. Amounts presented as of December 31, 2016 have been derived from the audited financial statements included in BOK Financial’s 2016 Form 10-K but do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. Operating results for the six-month period ended June 30, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017. Newly Adopted and Pending Accounting Policies Financial Accounting Standards Board (“FASB”) FASB Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers ("ASU 2014-09") On May 28, 2014, the FASB issued ASU 2014-09 to clarify the principles for recognizing revenue by providing a more robust framework that will give greater consistency and comparability in revenue recognition practices. In the new framework, an entity recognizes revenue in an amount that reflects the consideration to which the entity expects to be entitled in exchange for goods or services. The new model requires the identification of performance obligations included in contracts with customers, a determination of the transaction price and an allocation of the price to those performance obligations. The entity recognizes revenue when performance obligations are satisfied. ASU 2014-09 is effective for the Company for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. Net interest revenue from financial assets and liabilities is explicitly excluded from the scope of ASU 2014-09. Management expects that most fees and commissions revenue will not be affected. The Company continues to evaluate the impact of ASU 2014-09 on Fiduciary and Asset Management Revenue and Transaction Card Revenue, which represents 19% of gross revenue and 43% of fees and commissions revenue for the first half of 2017. Timing of revenue recognition and gross versus net presentation may be affected. Management will adopt the standard in the first quarter of 2018 with a cumulative effect adjustment to opening retained earnings if such adjustment is significant. FASB Accounting Standards Update No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net) ("ASU 2016-08") On March 17, 2016, the FASB Issued ASU 2016-08 to amend the principal versus agent implementation guidance in ASU 2014-09. The ASU clarifies that an entity should evaluate whether it is the principal or the agent for each specified good or service promised in a contract with a customer. ASU 2016-08 is effective for the Company for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. The Company is evaluating the impact the adoption of ASU 2016-08 will have on the Company's financial statements along with ASU 2014-09. FASB Accounting Standards Update No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01") On January 5, 2016, the FASB issued ASU 2016-01 over the recognition and measurement of financial assets and liabilities. The update requires equity investments, in general, to be measured at fair value with changes in fair value recognized in earnings. It also eliminates the requirement to disclose the methods and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost, requires entities to use the exit price notion when measuring fair value, requires an entity to present separately in other comprehensive income the portion of the total change in fair value of a liability resulting from a change in the instrument-specific credit risk when the fair value option has been elected, requires separate presentation of financial assets and liabilities by measurement category and form on the balance sheet or accompanying notes, clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity's other deferred tax assets, and simplifies the impairment assessment of equity investments without readily determinable fair values. The ASU is effective for the Company for interim and annual periods beginning after December 15, 2017. Upon adoption, unrealized gains and losses from equity securities will be reclassified from other comprehensive income to retained earnings. At June 30, 2017, the Company had $3.2 million of unrealized gains included in accumulated other comprehensive income. 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. Lessees will be required to recognize an obligation for future lease payments measured on a discounted basis and a right-of-use asset. The ASU is effective for the Company for interim and annual periods beginning after December 15, 2018 and requires transition through a modified retrospective approach for leases existing at or entered into after January 1, 2017. The Company is evaluating the impact the adoption of ASU 2016-02 will have on the Company's financial statements. FASB Accounting Standards Update No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting ("ASU 2016-09") On March 30, 2016, the FASB issued ASU 2016-09 to simplify multiple aspects of accounting for employee share-based payment transactions including accounting income taxes, forfeitures, and statutory tax withholding requirements. The ASU became effective for annual reporting periods beginning after December 15, 2016, including interim periods within those annual reporting periods. Implementation of ASU 2016-09 decreased tax expense $2.3 million in the first six months of 2017. 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 in order to provide more timely recording of credit losses on loans and other financial instruments. The ASU adds an impairment model (known as the current expected credit loss ("CECL") model) that is based on expected credit losses rather than incurred credit losses. It requires measurement of all expected credit losses for financial assets carried at amortized cost, including loans and investment securities, based on historical experience, current conditions, and reasonable and supportable forecasts. ASU 2016-13 also changes the recognition of other-than-temporary impairment of available for sale securities to an allowance methodology from a direct write-down methodology. ASU 2016-13 will be effective for the Company for annual reporting periods beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for annual reporting periods beginning after December 15, 2018. ASU 2016-13 will be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The Company is evaluating the impact the adoption of ASU 2016-13 will have on the Company's financial statements. FASB Accounting Standards Update No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments ("ASU 2016-15") On August 26, 2016, the FASB issued ASU 2016-15, which amends guidance in ASC 230 on the classification of certain cash receipts and payments in the statement of cash flows. The amendments address eight cash flow issues. ASU 2016-15 is effective for the Company for interim and annual reporting periods beginning after December 15, 2017. Entities generally must apply the guidance retrospectively to all periods presented. Adoption of ASU 2016-15 is not expected to have a material impact on the Company's financial statements.

Securities

6 Months Ended

Jun. 30, 2017

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):



	June 30, 2017					December 31, 2016					June 30, 2016
	Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)
U.S. government agency debentures	$	20,954	$	(9	)	$	6,234	$	(4	)	$	18,909	$	(8	)
U.S. government agency residential mortgage-backed securities	365,171		(1,032		)	310,067		635			122,306		363
Municipal and other tax-exempt securities	45,444		230			14,427		50			52,721		262
Other trading securities	9,845		(175		)	6,900		57			17,686		169
Total trading securities	$	441,414	$	(986	)	$	337,628	$	738		$	211,622	$	786

Investment Securities

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



	June 30, 2017
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss
Municipal and other tax-exempt	$	267,375	$	270,531	$	3,384	$	(228	)
U.S. government agency residential mortgage-backed securities – Other	18,035		18,642		668		(61		)
Other debt securities	205,016		226,502		22,040		(554		)
Total investment securities	$	490,426	$	515,675	$	26,092	$	(843	)


¹	Gross unrealized gains and losses are not recognized in Accumulated Other Comprehensive Income "AOCI" in the Consolidated Balance Sheets.



	December 31, 2016
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss
Municipal and other tax-exempt	$	320,364	$	321,225	$	2,272	$	(1,411	)
U.S. government agency residential mortgage-backed securities – Other	20,777		21,473		767		(71		)
Other debt securities	205,004		222,795		18,115		(324		)
Total investment securities	$	546,145	$	565,493	$	21,154	$	(1,806	)


¹	Gross unrealized gains and losses are not recognized in AOCI in the Consolidated Balance Sheets.



	June 30, 2016
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss
Municipal and other tax-exempt	$	334,551	$	340,700	$	6,234	$	(85	)
U.S. government agency residential mortgage-backed securities – Other	23,750		25,233		1,483		—
Other debt securities	202,410		233,129		30,723		(4		)
Total investment securities	$	560,711	$	599,062	$	38,440	$	(89	)


¹	Gross unrealized gains and losses are not recognized in AOCI in the Consolidated Balance Sheets.

The amortized cost and fair values of investment securities at June 30, 2017, 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 Maturity²
Municipal and other tax-exempt:
Amortized cost	$	90,415		$	122,560		$	10,739		$	43,661		$	267,375		3.48
Fair value	90,436			122,914			11,220			45,961			270,531
Nominal yield¹	1.66		%	2.12		%	4.88		%	5.05		%	2.55		%
Other debt securities:
Amortized cost	14,286			45,638			130,279			14,813			205,016			6.59
Fair value	14,482			48,973			148,415			14,632			226,502
Nominal yield	3.84		%	4.95		%	5.75		%	4.46		%	5.35		%
Total fixed maturity securities:
Amortized cost	$	104,701		$	168,198		$	141,018		$	58,474		$	472,391		4.83
Fair value	104,918			171,887			159,635			60,593			497,033
Nominal yield	1.95		%	2.89		%	5.69		%	4.90		%	3.77		%
Residential mortgage-backed securities:
Amortized cost													$	18,035		³
Fair value													18,642
Nominal yield⁴													2.76		%
Total investment securities:
Amortized cost													$	490,426
Fair value													515,675
Nominal yield													3.73		%


¹	Calculated on a taxable equivalent basis using a 39 percent effective tax rate.


²	Expected maturities may differ from contractual maturities, because borrowers may have the right to call or prepay obligations with or without penalty.


³	The average expected lives of residential mortgage-backed securities were 4.7 years based upon current prepayment assumptions.


⁴	The nominal yield on residential mortgage-backed securities is based upon prepayment assumptions at the purchase date. Actual yields earned may differ significantly based upon actual prepayments. See Quarterly Financial Summary - Unaudited for current yields on the investment securities portfolio.

Available for Sale Securities

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



	June 30, 2017
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss			OTTI²
U.S. Treasury	$	1,000	$	998	$	—	$	(2	)	$	—
Municipal and other tax-exempt	32,885		32,765		293		(413		)	—
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	3,005,920		3,008,531		24,213		(21,602		)	—
FHLMC	1,412,376		1,412,472		7,785		(7,689		)	—
GNMA	938,086		936,365		3,641		(5,362		)	—
Other	25,000		25,009		52		(43		)	—
Total U.S. government agencies	5,381,382		5,382,377		35,691		(34,696		)	—
Private issue:
Alt-A loans	38,334		46,903		8,569		—			—
Jumbo-A loans	48,322		56,480		8,158		—			—
Total private issue	86,656		103,383		16,727		—			—
Total residential mortgage-backed securities	5,468,038		5,485,760		52,418		(34,696		)	—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,788,543		2,782,070		7,804		(14,277		)	—
Other debt securities	4,400		4,152		—		(248		)	—
Perpetual preferred stock	12,562		16,568		4,006		—			—
Equity securities and mutual funds	17,572		18,728		1,219		(63		)	—
Total available for sale securities	$	8,325,000	$	8,341,041	$	65,740	$	(49,699	)	$	—

¹ Gross unrealized gain/loss recognized in AOCI in the consolidated balance sheet.

² Amounts represent unrealized loss that remains in AOCI after an other-than-temporary credit loss has been recognized in income.



	December 31, 2016
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss			OTTI²
U.S. Treasury	$	1,000	$	999	$	—	$	(1	)	$	—
Municipal and other tax-exempt	41,050		40,993		343		(400		)	—
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	3,062,525		3,055,676		25,066		(31,915		)	—
FHLMC	1,534,451		1,531,116		8,475		(11,810		)	—
GNMA	878,375		873,594		2,259		(7,040		)	—
Total U.S. government agencies	5,475,351		5,460,386		35,800		(50,765		)	—
Private issue:
Alt-A loans	44,245		51,512		7,485		—			(218		)
Jumbo-A loans	56,947		64,023		7,092		(16		)	—
Total private issue	101,192		115,535		14,577		(16		)	(218		)
Total residential mortgage-backed securities	5,576,543		5,575,921		50,377		(50,781		)	(218		)
Commercial mortgage-backed securities guaranteed by U.S. government agencies	3,035,750		3,017,933		5,472		(23,289		)	—
Other debt securities	4,400		4,152		—		(248		)	—
Perpetual preferred stock	15,561		18,474		2,913		—			—
Equity securities and mutual funds	17,424		18,357		1,060		(127		)	—
Total available for sale securities	$	8,691,728	$	8,676,829	$	60,165	$	(74,846	)	$	(218	)

¹ Gross unrealized gain/loss recognized in AOCI in the consolidated balance sheet.

² Amounts represent unrealized loss that remains in AOCI after an other-than-temporary credit loss has been recognized in income.



	June 30, 2016
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss			OTTI²
U.S. Treasury	$	1,000	$	1,004	$	4	$	—		$	—
Municipal and other tax-exempt	50,170		50,262		805		(713		)	—
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	2,908,698		2,988,974		80,549		(273		)	—
FHLMC	1,746,661		1,785,332		38,869		(198		)	—
GNMA	921,928		925,962		4,646		(612		)	—
Total U.S. government agencies	5,577,287		5,700,268		124,064		(1,083		)	—
Private issue:
Alt-A loans	49,522		54,536		5,461		—			(447		)
Jumbo-A loans	65,787		71,777		6,355		(36		)	(329		)
Total private issue	115,309		126,313		11,816		(36		)	(776		)
Total residential mortgage-backed securities	5,692,596		5,826,581		135,880		(1,119		)	(776		)
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,854,306		2,911,946		57,762		(122		)	—
Other debt securities	4,400		4,151		—		(249		)	—
Perpetual preferred stock	15,562		17,931		2,369		—			—
Equity securities and mutual funds	17,270		18,814		1,558		(14		)	—
Total available for sale securities	$	8,635,304	$	8,830,689	$	198,378	$	(2,217	)	$	(776	)


¹	Gross unrealized gain/loss recognized in AOCI in the consolidated balance sheet.


²	Amounts represent unrealized loss that remains in AOCI after an other-than-temporary credit loss has been recognized in income.

The amortized cost and fair values of available for sale securities at June 30, 2017, 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 Maturity⁵
U.S. Treasuries:
Amortized cost	$	1,000		$	—		$	—		$	—			$	1,000		0.55
Fair value	998			—			—			—				998
Nominal yield	0.87		%	—		%	—		%	—		%		0.87		%
Municipal and other tax-exempt:
Amortized cost	$	8,981		$	6,380		$	1,028		$	16,496			$	32,885		8.87
Fair value	9,021			6,497			1,081			16,166				32,765
Nominal yield¹	4.24		%	3.91		%	6.72		%	2.28		%	⁶	3.27		%
Commercial mortgage-backed securities:
Amortized cost	$	58,263		$	880,459		$	1,571,735		$	278,086			$	2,788,543		6.98
Fair value	58,147			879,286			1,568,732			275,905				2,782,070
Nominal yield	1.20		%	1.83		%	1.84		%	1.88		%		1.82		%
Other debt securities:
Amortized cost	$	—		$	—		$	—		$	4,400			$	4,400		30.16
Fair value	—			—			—			4,152				4,152
Nominal yield	—		%	—		%	—		%	1.71		%	⁶	1.71		%
Total fixed maturity securities:
Amortized cost	$	68,244		$	886,839		$	1,572,763		$	298,982			$	2,826,828		7.03
Fair value	68,166			885,783			1,569,813			296,223				2,819,985
Nominal yield	1.60		%	1.85		%	1.85		%	1.90		%		1.83		%
Residential mortgage-backed securities:
Amortized cost														$	5,468,038		²
Fair value														5,485,760
Nominal yield⁴														1.94		%
Equity securities and mutual funds:
Amortized cost														$	30,134		³
Fair value														35,296
Nominal yield														—		%
Total available-for-sale securities:
Amortized cost														$	8,325,000
Fair value														8,341,041
Nominal yield														1.90		%


¹	Calculated on a taxable equivalent basis using a 39 percent effective tax rate.


²	The average expected lives of mortgage-backed securities were 3.9 years years based upon current prepayment assumptions.


³	Primarily common stock and preferred stock of corporate issuers with no stated maturity.


⁴	The nominal yield on mortgage-backed securities is based upon prepayment assumptions at the purchase date. Actual yields earned may differ significantly based upon actual prepayments. See Quarterly Financial Summary –– Unaudited following for current yields on available for sale securities portfolio.


⁵	Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty.


⁶	Nominal yield on municipal and other tax-exempt securities and other debt securities with contractual maturity dates over ten years are based on variable rates which generally are reset within 35 days.

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



	Three Months Ended June 30,					Six Months Ended June 30,
	2017			2016		2017			2016
Proceeds	$	460,402		$	325,758	$	700,412		$	795,140
Gross realized gains	2,763			5,326		4,855			9,290
Gross realized losses	(2,383		)	—		(2,426		)	—
Related federal and state income tax expense	148			2,072		945			3,614

A summary of investment and available for sale securities that have been pledged as collateral for repurchase agreements, public trust funds on deposit and for other purposes, as required by law was as follows (in thousands):



	June 30, 2017		Dec. 31, 2016		June 30, 2016
Investment:
Amortized cost	$	251,684	$	322,208	$	287,166
Fair value	255,097		323,808		293,625

Available for sale:
Amortized cost	6,327,666		7,353,116		7,502,361
Fair value	6,317,623		7,327,470		7,657,916

The secured parties do not have the right to sell or repledge these securities.

Temporarily Impaired Securities as of June 30, 2017

(in thousands):



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investment:
Municipal and other tax-exempt	82	$	111,078	$	149	$	3,000	$	79	$	114,078	$	228
U.S. government agency residential mortgage-backed securities – Other	1	3,810		61		—		—		3,810		61
Other debt securities	22	8,384		554		—		—		8,384		554
Total investment securities	105	$	123,272	$	764	$	3,000	$	79	$	126,272	$	843



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available for sale:
U.S. Treasury	1	$	997	$	2	$	—	$	—	$	997	$	2
Municipal and other tax-exempt	13	$	1,957	$	1	$	4,655	$	412	$	6,612	$	413
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	75	1,381,687		20,288		87,371		1,314		1,469,058		21,602
FHLMC	42	731,853		7,213		16,388		476		748,241		7,689
GNMA	21	291,806		3,766		76,605		1,596		368,411		5,362
Other	1	19,957		43		—		—		19,957		43
Total U.S. government agencies	139	2,425,303		31,310		180,364		3,386		2,605,667		34,696
Private issue:
Alt-A loans	—	—		—		—		—		—		—
Jumbo-A loans	—	—		—		—		—		—		—
Total private issue	—	—		—		—		—		—		—
Total residential mortgage-backed securities	139	2,425,303		31,310		180,364		3,386		2,605,667		34,696
Commercial mortgage-backed securities guaranteed by U.S. government agencies	121	1,388,406		12,690		78,828		1,587		1,467,234		14,277
Other debt securities	2	—		—		4,152		248		4,152		248
Perpetual preferred stocks	—	—		—		—		—		—		—
Equity securities and mutual funds	91	1,668		22		887		41		2,555		63
Total available for sale securities	367	$	3,818,331	$	44,025	$	268,886	$	5,674	$	4,087,217	$	49,699

Temporarily Impaired Securities as of December 31, 2016

(In thousands)



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investment:
Municipal and other tax-exempt	151	$	219,892	$	1,316	$	4,333	$	95	$	224,225	$	1,411
U.S. government agency residential mortgage-backed securities – Other	1	4,358		71		—		—		4,358		71
Other debt securities	41	11,820		322		855		2		12,675		324
Total investment securities	193	$	236,070	$	1,709	$	5,188	$	97	$	241,258	$	1,806



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available for sale:
U.S. Treasury	1	$	999	$	1	$	—	$	—	$	999	$	1
Municipal and other tax-exempt	24	$	15,666	$	22	$	4,689	$	378	$	20,355	$	400
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	91	1,787,644		30,238		72,105		1,677		1,859,749		31,915
FHLMC	58	964,017		11,210		18,307		600		982,324		11,810
GNMA	31	548,637		6,145		25,796		895		574,433		7,040
Total U.S. government agencies	180	3,300,298		47,593		116,208		3,172		3,416,506		50,765
Private issue¹:
Alt-A loans	5	7,931		174		7,410		44		15,341		218
Jumbo-A loans	1	—		—		6,098		16		6,098		16
Total private issue	6	7,931		174		13,508		60		21,439		234
Total residential mortgage-backed securities	186	3,308,229		47,767		129,716		3,232		3,437,945		50,999
Commercial mortgage-backed securities guaranteed by U.S. government agencies	171	1,904,584		22,987		38,875		302		1,943,459		23,289
Other debt securities	2	—		—		4,152		248		4,152		248
Perpetual preferred stocks	—	—		—		—		—		—		—
Equity securities and mutual funds	104	2,127		41		817		86		2,944		127
Total available for sale securities	488	$	5,231,605	$	70,818	$	178,249	$	4,246	$	5,409,854	$	75,064


¹	Includes securities for which an unrealized loss remains in AOCI after an other-than-temporary credit loss has been recognized in income.

Temporarily Impaired Securities as of June 30, 2016

(In thousands)



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investment:
Municipal and other tax-exempt	19	$	11,915	$	20	$	4,378	$	65	$	16,293	$	85
U.S. government agency residential mortgage-backed securities – Other	—	—		—		—		—		—		—
Other debt securities	1	—		—		858		4		858		4
Total investment securities	20	$	11,915	$	20	$	5,236	$	69	$	17,151	$	89



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available for sale:
U.S. Treasury	—	$	—	$	—	$	—	$	—	$	—	$	—
Municipal and other tax-exempt¹	17	$	375	$	—	$	10,289	$	713	$	10,664	$	713
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	4	97,910		267		15,401		6		113,311		273
FHLMC	1	—		—		22,338		198		22,338		198
GNMA	11	349,631		612		—		—		349,631		612
Total U.S. government agencies	16	447,541		879		37,739		204		485,280		1,083
Private issue¹:
Alt-A loans	5	8,513		241		8,291		206		16,804		447
Jumbo-A loans	9	7,076		36		7,877		329		14,953		365
Total private issue	14	15,589		277		16,168		535		31,757		812
Total residential mortgage-backed securities	30	463,130		1,156		53,907		739		517,037		1,895
Commercial mortgage-backed securities guaranteed by U.S. government agencies	11	103,955		37		65,857		85		169,812		122
Other debt securities	2	—		—		4,151		249		4,151		249
Perpetual preferred stocks	—	—		—		—		—		—		—
Equity securities and mutual funds	30	—		—		889		14		889		14
Total available for sale securities	90	$	567,460	$	1,193	$	135,093	$	1,800	$	702,553	$	2,993


¹	Includes securities for which an unrealized loss remains in AOCI after an other-than-temporary credit loss has been recognized in income.

For debt securities, 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, regulatory and capital requirements and securities portfolio management. Based on this evaluation as of June 30, 2017, 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. Changes in the fair value are recognized in earnings as they occur. Certain U.S. Treasury securities, 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):



	June 30, 2017				Dec. 31, 2016					June 30, 2016
	Fair Value		Net Unrealized Gain (Loss)		Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)
U.S. Treasury	$	—	$	—	$	—	$	—		$	25,306	$	(43	)
U.S. government agency residential mortgage-backed securities	445,169		1,247		77,046		(1,777		)	237,959		4,476
Total	$	445,169	$	1,247	$	77,046	$	(1,777	)	$	263,265	$	4,433

Restricted Equity Securities

Restricted equity securities primarily include stock we are required to hold as members of the Federal Reserve system and the 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 are restricted and they lack a market. A summary of restricted equity securities follows (in thousands):



	June 30, 2017		Dec. 31, 2016		June 30, 2016
Federal Reserve stock	$	36,676	$	36,498	$	36,283
Federal Home Loan Bank stock	274,113		270,541		283,155
Other	244		201		201
Total	$	311,033	$	307,240	$	319,639

The entire disclosure for investments in certain debt and equity securities.

Derivative Instrument Detail [Abstract]

Derivatives

6 Months Ended

Jun. 30, 2017

Derivatives [Text Block]

Derivatives

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 reported in earnings as they occur. Credit risk is also considered in determining fair value.

When bilateral netting agreements or similar arrangements 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 type by counterparty basis.

Derivative contracts may 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.

None of these derivative contracts have been designated as hedging instruments for accounting purposes.

Customer Risk Management Programs

BOK Financial offers programs to 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 borrowers to modify interest rate terms of their loans or to-be-announced securities used by mortgage banking customers to hedge their loan production. Derivative contracts are executed between the customers and BOK Financial. Offsetting contracts are executed between BOK Financial and other selected counterparties to minimize the risk of 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.

Internal Risk Management Programs

BOK Financial may use derivative contracts in managing its interest rate sensitivity, as part of its economic hedge of the change in the fair value of mortgage servicing rights and as an economic hedge of trading securities. As of June 30, 2017, derivative contracts under the internal risk management programs were primarily used as part of the economic hedges of the change in the fair value of the mortgage servicing rights and trading securities.

As discussed in Note 6, 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 6 for additional discussion of notional, fair value and impact on earnings of these contracts.

The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at June 30, 2017 (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
To-be-announced residential mortgage-backed securities	$	16,174,687	$	57,948	$	(29,034	)	$	28,914	$	—		$	28,914
Interest rate swaps	1,450,193		29,932		—			29,932		(2,206		)	27,726
Energy contracts	891,480		56,824		(20,546		)	36,278		(21,267		)	15,011
Agricultural contracts	45,250		3,541		(1,027		)	2,514		—			2,514
Foreign exchange contracts	169,529		162,429		—			162,429		(7		)	162,422
Equity option contracts	100,159		4,437		—			4,437		(920		)	3,517
Total customer risk management programs	18,831,298		315,111		(50,607		)	264,504		(24,400		)	240,104
Internal risk management programs	10,680,498		40,185		—			40,185		—			40,185
Total derivative contracts	$	29,511,796	$	355,296	$	(50,607	)	$	304,689	$	(24,400	)	$	280,289

	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
To-be-announced residential mortgage-backed securities	$	16,174,687	$	53,829	$	(29,034	)	$	24,795	$	—		$	24,795
Interest rate swaps	1,450,193		29,982		—			29,982		(15,396		)	14,586
Energy contracts	874,625		53,895		(20,546		)	33,349		—			33,349
Agricultural contracts	45,262		3,538		(1,027		)	2,511		(2,511		)	—
Foreign exchange contracts	169,553		162,276		—			162,276		(3,188		)	159,088
Equity option contracts	100,159		4,437		—			4,437		—			4,437
Total customer risk management programs	18,814,479		307,957		(50,607		)	257,350		(21,095		)	236,255
Internal risk management programs	8,310,950		49,564		—			49,564		—			49,564
Total derivative contracts	$	27,125,429	$	357,521	$	(50,607	)	$	306,914	$	(21,095	)	$	285,819


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, 2016 (in thousands):



	Assets
	Notional ¹		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
To-be-announced residential mortgage-backed securities	$	16,949,152	$	180,695	$	(60,555	)	$	120,140	$	—		$	120,140
Interest rate swaps	1,403,408		34,442		—			34,442		(4,567		)	29,875
Energy contracts	835,566		64,140		(28,298		)	35,842		(71		)	35,771
Agricultural contracts	53,209		1,382		(515		)	867		—			867
Foreign exchange contracts	580,886		494,349		—			494,349		(5,183		)	489,166
Equity option contracts	100,924		4,357		—			4,357		(730		)	3,627
Total customer risk management programs	19,923,145		779,365		(89,368		)	689,997		(10,551		)	679,446
Internal risk management programs	2,514,169		10,426		—			10,426		—			10,426
Total derivative contracts	$	22,437,314	$	789,791	$	(89,368	)	$	700,423	$	(10,551	)	$	689,872

	Liabilities
	Notional ¹		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
To-be-announced residential mortgage-backed securities	$	16,637,532	$	176,928	$	(60,555	)	$	116,373	$	—		$	116,373
Interest rate swaps	1,403,408		34,442		—			34,442		(11,977		)	22,465
Energy contracts	820,365		64,306		(28,298		)	36,008		(31,534		)	4,474
Agricultural contracts	53,216		1,365		(515		)	850		(769		)	81
Foreign exchange contracts	580,712		494,695		—			494,695		(3,630		)	491,065
Equity option contracts	100,924		4,357		—			4,357		—			4,357
Total customer risk management programs	19,596,157		776,093		(89,368		)	686,725		(47,910		)	638,815
Internal risk management programs	2,582,202		25,716		—			25,716		—			25,716
Total derivative contracts	$	22,178,359	$	801,809	$	(89,368	)	$	712,441	$	(47,910	)	$	664,531


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 June 30, 2016 (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
To-be-announced residential mortgage-backed securities	$	18,774,134	$	183,118	$	(67,383	)	$	115,735	$	—		$	115,735
Interest rate swaps	1,299,985		54,978		—			54,978		(1,100		)	53,878
Energy contracts	757,669		59,103		(33,996		)	25,107		(155		)	24,952
Agricultural contracts	50,848		2,488		(1,609		)	879		(37		)	842
Foreign exchange contracts	701,436		675,804		—			675,804		(5,054		)	670,750
Equity option contracts	116,901		4,236		—			4,236		(478		)	3,758
Total customer risk management programs	21,700,973		979,727		(102,988		)	876,739		(6,824		)	869,915
Internal risk management programs	1,337,000		13,758		—			13,758		—			13,758
Total derivative contracts	$	23,037,973	$	993,485	$	(102,988	)	$	890,497	$	(6,824	)	$	883,673

	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
To-be-announced residential mortgage-backed securities	$	18,662,334	$	179,443	$	(67,383	)	$	112,060	$	(103,724	)	$	8,336
Interest rate swaps	1,299,985		55,404		—			55,404		(32,597		)	22,807
Energy contracts	734,538		58,033		(33,996		)	24,037		(11,784		)	12,253
Agricultural contracts	50,843		2,476		(1,609		)	867		—			867
Foreign exchange contracts	701,219		675,383		—			675,383		(4,723		)	670,660
Equity option contracts	116,901		4,236		—			4,236		—			4,236
Total customer risk management programs	21,565,820		974,975		(102,988		)	871,987		(152,828		)	719,159
Internal risk management programs	—		—		—			—		—			—
Total derivative contracts	$	21,565,820	$	974,975	$	(102,988	)	$	871,987	$	(152,828	)	$	719,159


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 income statement (in thousands):



	Three Months Ended
	June 30, 2017				June 30, 2016
	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 residential mortgage-backed securities	$	9,205	$	—	$	9,862		$	—
Interest rate swaps	665		—		723			—
Energy contracts	1,666		—		2,749			—
Agricultural contracts	11		—		32			—
Foreign exchange contracts	90		—		134			—
Equity option contracts	—		—		—			—
Total customer risk management programs	11,637		—		13,500			—
Internal risk management programs	6,485		3,241		(9		)	10,766
Total derivative contracts	$	18,122	$	3,241	$	13,491		$	10,766



	Six Months Ended
	June 30, 2017				June 30, 2016
	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 residential mortgage-backed securities	$	17,232	$	—	$	17,302		$	—
Interest rate swaps	1,124		—		1,048			—
Energy contracts	4,539		—		3,445			—
Agricultural contracts	20		—		61			—
Foreign exchange contracts	360		—		512			—
Equity option contracts	—		—		—			—
Total customer risk management programs	23,275		—		22,368			—
Internal risk management programs	6,018		2,791		(9		)	17,904
Total derivative contracts	$	29,293	$	2,791	$	22,359		$	17,904

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

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Loans and Allowances for Credit Losses

6 Months Ended

Jun. 30, 2017

Loans Receivable, Net [Abstract]

Loans [Text Block]

Loans and Allowances for Credit Losses

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 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 principal amount outstanding. 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 more than 90 days 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 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.

Loans to borrowers experiencing financial difficulties may be modified in troubled debt restructurings ("TDRs"). All TDRs are 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. Generally, principal and accrued but unpaid interest is not voluntarily forgiven.

Performing loans may be renewed under the current collateral value, debt service ratio and other underwriting standards. Nonaccruing loans may be renewed and will remain classified as nonaccruing.

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 a quarterly evaluation of available cash resources and collateral value 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.

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 may have 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 impaired because we do not expect to receive all principal and interest based on the loan's contractual terms. 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 the 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 based on 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 a further disaggregation of portfolio segments based on the risk characteristics of the loans and the Company’s method for monitoring and assessing credit risk.

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



	June 30, 2017								December 31, 2016
	Fixed Rate		Variable Rate		Non-accrual		Total		Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	2,198,066	$	8,242,732	$	197,157	$	10,637,955	$	2,327,085	$	7,884,786	$	178,953	$	10,390,824
Commercial real estate	594,542		3,090,275		3,775		3,688,592		624,187		3,179,338		5,521		3,809,046
Residential mortgage	1,597,587		297,376		44,235		1,939,198		1,647,357		256,255		46,220		1,949,832
Personal	150,728		766,900		272		917,900		154,971		684,697		290		839,958
Total	$	4,540,923	$	12,397,283	$	245,439	$	17,183,645	$	4,753,600	$	12,005,076	$	230,984	$	16,989,660
Accruing loans past due (90 days)¹							$	1,414							$	5



	June 30, 2016
	Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	1,994,415	$	8,180,033	$	181,989	$	10,356,437
Commercial real estate	612,822		2,961,364		7,780		3,581,966
Residential mortgage	1,586,116		237,746		57,061		1,880,923
Personal	109,447		477,622		354		587,423
Total	$	4,302,800	$	11,856,765	$	247,184	$	16,406,749
Accruing loans past due (90 days)¹							$	2,899


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

At June 30, 2017, $5.7 billion or 33 percent of our total loan portfolio is to businesses and individuals attributed to the Texas market and $3.4 billion or 20 percent of the total loan portfolio is to businesses and individuals attributed to the Oklahoma market. These geographic concentrations subject the loan portfolio to the general economic conditions within these areas.

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 ongoing 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 ongoing 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 June 30, 2017, commercial loans attributed to the Texas market totaled $3.6 billion or 33 percent of the commercial loan portfolio segment and commercial loans attributed to the Oklahoma market totaled $2.1 billion or 19 percent of the commercial loan portfolio segment.

The commercial loan portfolio segment is further divided into loan classes. The energy loan class totaled $2.8 billion or 17 percent of total loans at June 30, 2017, including $2.4 billion of outstanding loans to energy producers. Approximately 58 percent of committed production loans are secured by properties primarily producing oil and 42 percent are secured by properties producing natural gas. The services loan class totaled $3.0 billion or 17 percent of total loans at June 30, 2017. Approximately $1.5 billion of loans in the services category consist of loans with individual balances of less than $10 million. Businesses included in the services class include governmental, finance and insurance, not-for-profit, educational services and loans to entities providing services for real estate and construction. The healthcare loan class totaled $2.2 billion or 13 percent of total loans at June 30, 2017. 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.

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 June 30, 2017, 32 percent of commercial real estate loans are secured by properties primarily located in the Dallas and Houston areas of Texas. An additional 12 percent of commercial real estate loans are secured by properties located primarily in the Tulsa and Oklahoma City metropolitan areas of Oklahoma.

Residential Mortgage and Personal

Residential mortgage loans provide funds for our customers to purchase or refinance their primary residence or to borrow against the equity in their home. Residential mortgage loans are secured by a first or second mortgage on the customer’s primary residence. Personal loans consist primarily of loans 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. Residential mortgage 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. Residential mortgage loans retained in the Company’s portfolio are primarily composed of various mortgage programs to support customer relationships including jumbo mortgage loans, non-builder construction loans and special loan programs for high net worth individuals and certain professionals. Jumbo loans may be fixed or variable rate and are fully amortizing. Jumbo loans generally conform to government sponsored entity standards, except that the loan size exceeds maximums required under these standards. These loans generally require a minimum FICO score of 720 and a maximum debt-to-income ratio (“DTI”) of 38 percent. Loan-to-value (“LTV”) ratios are tiered from 60 percent to 100 percent, depending on the market. Special mortgage programs include fixed and variable fully amortizing loans tailored to the needs of certain healthcare professionals. Variable rate loans are fully indexed at origination and may have fixed rates for three to ten years, then adjust annually thereafter.

At June 30, 2017, residential mortgage loans included $192 million of loans guaranteed by U.S. government agencies previously sold into GNMA mortgage pools. These loans either have been repurchased or are eligible to be repurchased by the Company when certain defined delinquency criteria are met. Although payments on these loans generally are past due more than 90 days, interest continues to accrue based on the government guarantee.

Home equity loans totaled $758 million at June 30, 2017. Approximately 65 percent of the home equity loan portfolio is comprised of first lien loans and 35 percent of the home equity portfolio is comprised of junior lien loans. Junior lien loans are distributed 49 percent to amortizing term loans and 51 percent to revolving lines of credit. Home equity loans generally require a minimum FICO score of 700 and a maximum DTI of 40 percent. The maximum loan amount available for our home equity loan products is generally $400 thousand. Revolving loans have a 5 year revolving period followed by a 15 year term of amortizing repayments. Interest-only home equity loans may not be extended for any additional revolving time. All other home equity loans may be extended at management's discretion for an additional 5 year revolving term, subject to an update of certain credit information.

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 June 30, 2017, outstanding commitments totaled $9.6 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 June 30, 2017, outstanding standby letters of credit totaled $615 million. Commercial letters of credit are used to facilitate customer trade transactions with the drafts being drawn when the underlying transaction is consummated. At June 30, 2017, outstanding commercial letters of credit totaled $3.2 million.

Allowances for Credit Losses

BOK Financial maintains an allowance for loan losses and an accrual for off-balance sheet credit risk. 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. As discussed in greater detail in Note 6, the Company also has separate accruals for off-balance sheet credit risk related to residential mortgage loans previously sold with full or partial recourse and for residential mortgage loans sold to government sponsored agencies under standard representations and warranties.

The appropriateness of the allowance for loan losses and accrual for off-balance sheet credit losses (collectively "allowance for credit losses") is assessed by management based on an ongoing quarterly evaluation of the probable estimated losses inherent in the portfolio, including probable losses on both outstanding loans and unused commitments.

The allowance for loan losses consists of specific allowances attributed to impaired loans that have not yet been charged down to amounts we expect to recover, general allowances for unimpaired loans based on estimated loss rates by loan class and nonspecific allowances based on general economic conditions, risk concentration and related factors. There have been no material changes in the approach or techniques utilized in developing the allowance for loan losses and the accrual for off-balance sheet credit losses for the three and six months ended June 30, 2017.

Loans are considered to be impaired when it becomes probable that BOK Financial will be unable to collect all amounts due according to the contractual terms of the loan agreements. Internally risk graded loans are evaluated individually for impairment. Substantially all commercial and commercial real estate loans and certain residential mortgage and consumer loans are risk graded based on evaluation of the borrowers' ability to repay. Certain commercial loans and most residential mortgage and consumer loans are small balance, homogeneous pools of loans that are not risk graded. Non-risk graded loans are identified as impaired based on performance status. Generally, non-risk graded loans 90 days or more past due or modified in a TDR or in bankruptcy are considered to be impaired.

Specific allowances for impaired loans are measured 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. Collateral value of real property is generally based on third party appraisals that conform to Uniform Standards of Professional Appraisal Practice, less estimated selling costs. Appraised values are on an "as-is" basis and are generally not adjusted by the Company. Updated appraisals are obtained at least annually or more frequently if market conditions indicate collateral values have declined. Collateral value of mineral rights is generally determined by our internal staff of engineers based on projected cash flows under current market conditions. Collateral values and available cash resources that support impaired loans are evaluated quarterly. Historical statistics may be used as a practical way to estimate impairment in limited situations, such as when a collateral dependent loan is identified as impaired at the end of a reporting period, until an updated appraisal of collateral value is received or a full assessment of future cash flows is completed. Estimates of future cash flows and collateral values require significant judgments and may be volatile.

General allowances for unimpaired loans are based on estimated loss rates by loan class. The gross loss rate for each loan class is determined by the greater of the current gross loss rate based on the most recent twelve months or a ten-year gross loss rate. Recoveries are not directly considered in the estimation of loss rates. Recoveries generally do not follow predictable patterns and are not received until well after the charge-off date as a result of protracted legal actions. For risk graded loans, gross loss rates are adjusted for changes in risk grading. For each loan class, the current weighted average risk grade is compared to the long-term average risk grade. This comparison determines whether credit risk in each loan class is increasing or decreasing. Loss rates are adjusted upward or downward in proportion to changes in average risk grading. General allowances for unimpaired loans also consider inherent risks identified for each loan class. Inherent risks consider loss rates that most appropriately represent the current credit cycle and other factors attributable to specific loan classes which have not yet been represented in the gross loss rates or risk grading. These factors include changes in commodity prices or engineering imprecision, which may affect the value of reserves that secure our energy loan portfolio, construction risk that may affect commercial real estate loans, changes in regulations and public policy that may disproportionately impact health care loans and changes in loan products.

Nonspecific allowances are maintained for risks beyond factors specific to a particular loan or loan class. These factors include trends in the economy of our primary lending areas, concentrations in large balance loans and other relevant factors.

An accrual for off-balance sheet credit losses is included in Other liabilities in the Consolidated Balance Sheets. The appropriateness of this accrual is determined in the same manner as the allowance for loan losses.

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.

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 for the three months ended June 30, 2017 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	137,616		$	58,343		$	18,177		$	7,247		$	27,327	$	248,710
Provision for loan losses	1,546			105			(47		)	1,358			47		3,009
Loans charged off	(1,703		)	(76		)	(40		)	(1,053		)	—		(2,872		)
Recoveries	283			208			169			554			—		1,214
Ending balance	$	137,742		$	58,580		$	18,259		$	8,106		$	27,374	$	250,061
Allowance for off-balance sheet credit losses:
Beginning balance	$	9,288		$	106		$	40		$	6		$	—	$	9,440
Provision for off-balance sheet credit losses	(2,987		)	(22		)	(2		)	2			—		(3,009		)
Ending balance	$	6,301		$	84		$	38		$	8		$	—	$	6,431

Total provision for credit losses	$	(1,441	)	$	83		$	(49	)	$	1,360		$	47	$	—

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 for the six months ended June 30, 2017 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance			Total
Allowance for loan losses:
Beginning balance	$	140,213		$	50,749		$	18,224		$	8,773		$	28,200		$	246,159
Provision for loan losses	(1,809		)	6,964			(86		)	570			(826		)	4,813
Loans charged off	(2,127		)	(76		)	(276		)	(2,546		)	—			(5,025		)
Recoveries	1,465			943			397			1,309			—			4,114
Ending balance	$	137,742		$	58,580		$	18,259		$	8,106		$	27,374		$	250,061
Allowance for off-balance sheet credit losses:
Beginning balance	$	11,063		$	123		$	50		$	8		$	—		$	11,244
Provision for off-balance sheet credit losses	(4,762		)	(39		)	(12		)	—			—			(4,813		)
Ending balance	$	6,301		$	84		$	38		$	8		$	—		$	6,431

Total provision for credit losses	$	(6,571	)	$	6,925		$	(98	)	$	570		$	(826	)	$	—

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 for the three months ended June 30, 2016 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	139,793		$	44,453		$	18,467		$	5,022		$	25,421	$	233,156
Provision for loan losses	12,478			2,010			368			1,443			1,263		17,562
Loans charged off	(7,355		)	—			(345		)	(1,145		)	—		(8,845		)
Recoveries	223			282			200			681			—		1,386
Ending balance	$	145,139		$	46,745		$	18,690		$	6,001		$	26,684	$	243,259
Allowance for off-balance sheet credit losses:
Beginning balance	$	6,319		$	228		$	58		$	2		$	—	$	6,607
Provision for off-balance sheet credit losses	2,433			(25		)	4			26			—		2,438
Ending balance	$	8,752		$	203		$	62		$	28		$	—	$	9,045

Total provision for credit losses	$	14,911		$	1,985		$	372		$	1,469		$	1,263	$	20,000

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 for the six months ended June 30, 2016 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate		Residential Mortgage			Personal			Nonspecific Allowance			Total
Allowance for loan losses:
Beginning balance	$	130,334		$	41,391	$	19,509		$	4,164		$	30,126		$	225,524
Provision for loan losses	43,575			4,987		(363		)	2,909			(3,442		)	47,666
Loans charged off	(29,481		)	—		(819		)	(2,536		)	—			(32,836		)
Recoveries	711			367		363			1,464			—			2,905
Ending balance	$	145,139		$	46,745	$	18,690		$	6,001		$	26,684		$	243,259
Allowance for off-balance sheet credit losses:
Beginning balance	$	1,506		$	153	$	30		$	22		$	—		$	1,711
Provision for off-balance sheet credit losses	7,246			50		32			6			—			7,334
Ending balance	$	8,752		$	203	$	62		$	28		$	—		$	9,045

Total provision for credit losses	$	50,821		$	5,037	$	(331	)	$	2,915		$	(3,442	)	$	55,000

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at June 30, 2017 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	$	10,440,798	$	128,049	$	197,157	$	9,693	$	10,637,955	$	137,742
Commercial real estate	3,684,817		58,580		3,775		—		3,688,592		58,580
Residential mortgage	1,894,963		18,259		44,235		—		1,939,198		18,259
Personal	917,628		8,106		272		—		917,900		8,106
Total	16,938,206		212,994		245,439		9,693		17,183,645		222,687

Nonspecific allowance	—		—		—		—		—		27,374

Total	$	16,938,206	$	212,994	$	245,439	$	9,693	$	17,183,645	$	250,061

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2016 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	$	10,211,871	$	139,416	$	178,953	$	797	$	10,390,824	$	140,213
Commercial real estate	3,803,525		50,749		5,521		—		3,809,046		50,749
Residential mortgage	1,903,612		18,178		46,220		46		1,949,832		18,224
Personal	839,668		8,773		290		—		839,958		8,773
Total	16,758,676		217,116		230,984		843		16,989,660		217,959

Nonspecific allowance	—		—		—		—		—		28,200

Total	$	16,758,676	$	217,116	$	230,984	$	843	$	16,989,660	$	246,159

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at June 30, 2016 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	$	10,174,448	$	140,911	$	181,989	$	4,228	$	10,356,437	$	145,139
Commercial real estate	3,574,186		46,727		7,780		18		3,581,966		46,745
Residential mortgage	1,823,862		18,626		57,061		64		1,880,923		18,690
Personal	587,069		6,001		354		—		587,423		6,001
Total	16,159,565		212,265		247,184		4,310		16,406,749		216,575

Nonspecific allowance	—		—		—		—		—		26,684

Total	$	16,159,565	$	212,265	$	247,184	$	4,310	$	16,406,749	$	243,259

Credit Quality Indicators

The Company utilizes loan class and risk grading as primary credit quality indicators. Substantially all commercial and commercial real estate loans and certain residential mortgage and consumer loans are risk graded based on a quarterly evaluation of the borrowers’ ability to repay the loans. Certain commercial loans and most residential mortgage and consumer loans are small, homogeneous pools that are not risk graded.

The allowance for loan losses and recorded investment of the related loans by portfolio segment for risk graded and non-risk graded loans at June 30, 2017 is as follows (in thousands):



	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,612,477	$	136,819	$	25,478	$	923	$	10,637,955	$	137,742
Commercial real estate	3,688,592		58,580		—		—		3,688,592		58,580
Residential mortgage	216,007		2,976		1,723,191		15,283		1,939,198		18,259
Personal	824,318		5,742		93,582		2,364		917,900		8,106
Total	15,341,394		204,117		1,842,251		18,570		17,183,645		222,687

Nonspecific allowance	—		—		—		—		—		27,374

Total	$	15,341,394	$	204,117	$	1,842,251	$	18,570	$	17,183,645	$	250,061

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, 2016 is as follows (in thousands):



	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,360,725	$	139,293	$	30,099	$	920	$	10,390,824	$	140,213
Commercial real estate	3,809,046		50,749		—		—		3,809,046		50,749
Residential mortgage	243,703		2,893		1,706,129		15,331		1,949,832		18,224
Personal	744,602		5,035		95,356		3,738		839,958		8,773
Total	15,158,076		197,970		1,831,584		19,989		16,989,660		217,959

Nonspecific allowance	—		—		—		—		—		28,200

Total	$	15,158,076	$	197,970	$	1,831,584	$	19,989	$	16,989,660	$	246,159

The allowance for loan losses and recorded investment of the related loans by portfolio segment for risk graded and non-risk graded loans at June 30, 2016 is as follows (in thousands):



	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,331,701	$	144,217	$	24,736	$	922	$	10,356,437	$	145,139
Commercial real estate	3,581,966		46,745		—		—		3,581,966		46,745
Residential mortgage	202,520		2,995		1,678,403		15,695		1,880,923		18,690
Personal	500,240		3,624		87,183		2,377		587,423		6,001
Total	14,616,427		197,581		1,790,322		18,994		16,406,749		216,575

Nonspecific allowance	—		—		—		—		—		26,684

Total	$	14,616,427	$	197,581	$	1,790,322	$	18,994	$	16,406,749	$	243,259

Loans are considered to be performing if they 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.” Performing loans also include 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 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.

The risk grading process identified certain loans that have a well-defined weakness (e.g. 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 were not placed in nonaccruing status.

Nonaccruing loans represent loans for which full collection of principal and interest is uncertain. This is substantially the same criteria used to determine whether a loan is impaired and includes certain loans considered “substandard” and all loans considered “doubtful” by regulatory guidelines.

The following table summarizes the Company’s loan portfolio at June 30, 2017 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	$	2,376,368	$	120,473	$	226,407	$	123,992	$	—	$	—	$	2,847,240
Services	2,921,510		12,452		17,111		7,754		—		—		2,958,827
Wholesale/retail	1,507,063		16,224		9,788		10,620		—		—		1,543,695
Manufacturing	513,442		6,540		16,499		9,656		—		—		546,137
Healthcare	2,130,339		33,554		33,120		24,505		—		—		2,221,518
Other commercial and industrial	453,712		2,961		17,861		20,526		25,374		104		520,538
Total commercial	9,902,434		192,204		320,786		197,053		25,374		104		10,637,955

Commercial real estate:
Residential construction and land development	138,790		—		751		2,051		—		—		141,592
Retail	720,730		1,774		—		301		—		—		722,805
Office	859,722		2,855		—		396		—		—		862,973
Multifamily	947,950		—		4,420		10		—		—		952,380
Industrial	693,635		—		—		—		—		—		693,635
Other commercial real estate	314,187		—		3		1,017		—		—		315,207
Total commercial real estate	3,675,014		4,629		5,174		3,775		—		—		3,688,592

Residential mortgage:
Permanent mortgage	212,563		1,693		478		1,273		750,891		22,142		989,040
Permanent mortgages guaranteed by U.S. government agencies	—		—		—		—		182,677		9,052		191,729
Home equity	—		—		—		—		746,661		11,768		758,429
Total residential mortgage	212,563		1,693		478		1,273		1,680,229		42,962		1,939,198

Personal	823,304		49		877		88		93,398		184		917,900

Total	$	14,613,315	$	198,575	$	327,315	$	202,189	$	1,799,001	$	43,250	$	17,183,645

The following table summarizes the Company’s loan portfolio at December 31, 2016 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	$	1,937,790	$	119,583	$	307,996	$	132,499	$	—	$	—	$	2,497,868
Services	3,052,002		10,960		37,855		8,173		—		—		3,108,990
Wholesale/retail	1,535,463		16,886		13,062		11,407		—		—		1,576,818
Manufacturing	468,314		26,532		15,198		4,931		—		—		514,975
Healthcare	2,140,458		44,472		16,161		825		—		—		2,201,916
Other commercial and industrial	433,789		5,309		—		21,060		30,041		58		490,257
Total commercial	9,567,816		223,742		390,272		178,895		30,041		58		10,390,824

Commercial real estate:
Residential construction and land development	131,630		—		470		3,433		—		—		135,533
Retail	756,418		4,745		399		326		—		—		761,888
Office	798,462		—		—		426		—		—		798,888
Multifamily	898,800		—		4,434		38		—		—		903,272
Industrial	871,673		—		—		76		—		—		871,749
Other commercial real estate	336,488		—		6		1,222		—		—		337,716
Total commercial real estate	3,793,471		4,745		5,309		5,521		—		—		3,809,046

Residential mortgage:
Permanent mortgage	238,769		1,186		2,331		1,417		741,679		21,438		1,006,820
Permanent mortgages guaranteed by U.S. government agencies	—		—		—		—		187,541		11,846		199,387
Home equity	—		—		—		—		732,106		11,519		743,625
Total residential mortgage	238,769		1,186		2,331		1,417		1,661,326		44,803		1,949,832

Personal	743,451		—		1,054		97		95,163		193		839,958

Total	$	14,343,507	$	229,673	$	398,966	$	185,930	$	1,786,530	$	45,054	$	16,989,660

The following table summarizes the Company’s loan portfolio at June 30, 2016 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	$	2,031,955	$	197,531	$	421,025	$	168,145	$	—	$	—	$	2,818,656
Services	2,805,307		6,253		9,916		9,388		—		—		2,830,864
Wholesale/retail	1,478,966		24,595		26,624		2,772		—		—		1,532,957
Manufacturing	556,741		18,757		19,612		293		—		—		595,403
Healthcare	2,011,934		29,420		8,917		875		—		—		2,051,146
Other commercial and industrial	478,169		24,053		—		453		24,673		63		527,411
Total commercial	9,363,072		300,609		486,094		181,926		24,673		63		10,356,437

Commercial real estate:
Residential construction and land development	152,343		—		972		4,261		—		—		157,576
Retail	787,779		5,962		413		1,265		—		—		795,419
Office	767,296		906		304		606		—		—		769,112
Multifamily	781,058		—		6,077		65		—		—		787,200
Industrial	645,510		—		—		76		—		—		645,586
Other commercial real estate	425,558		—		8		1,507		—		—		427,073
Total commercial real estate	3,559,544		6,868		7,774		7,780		—		—		3,581,966

Residential mortgage:
Permanent mortgage	194,962		1,197		3,406		2,955		742,214		24,273		969,007
Permanent mortgages guaranteed by U.S. government agencies	—		—		—		—		172,991		19,741		192,732
Home equity	—		—		—		—		709,092		10,092		719,184
Total residential mortgage	194,962		1,197		3,406		2,955		1,624,297		54,106		1,880,923

Personal	496,534		—		3,590		116		86,945		238		587,423

Total	$	13,614,112	$	308,674	$	500,864	$	192,777	$	1,735,915	$	54,407	$	16,406,749

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 includes all nonaccruing loans, all loans modified in a TDR and all loans repurchased from GNMA pools.

A summary of impaired loans follows (in thousands):



	As of										For the				For the
	June 30, 2017										Three Months Ended				Six Months Ended
			Recorded Investment								June 30, 2017				June 30, 2017
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance		Average Recorded Investment		Interest Income Recognized		Average Recorded Investment		Interest Income Recognized
Commercial:
Energy	$	141,091	$	123,992	$	56,988	$	67,004	$	8,874	$	117,209	$	—	$	128,246	$	—
Services	11,209		7,754		7,754		—		—		7,734		—		7,964		—
Wholesale/retail	17,392		10,620		10,620		—		—		10,855		—		11,013		—
Manufacturing	10,223		9,656		9,656		—		—		7,781		—		7,293		—
Healthcare	24,795		24,505		18,883		5,622		802		12,707		—		12,665		—
Other commercial and industrial	28,933		20,630		20,609		21		17		20,706		—		20,874		—
Total commercial	233,643		197,157		124,510		72,647		9,693		176,992		—		188,055		—

Commercial real estate:
Residential construction and land development	3,676		2,051		2,051		—		—		2,334		—		2,742		—
Retail	518		301		301		—		—		308		—		314		—
Office	499		396		396		—		—		404		—		411		—
Multifamily	1,000		10		10		—		—		17		—		24		—
Industrial	—		—		—		—		—		38		—		38		—
Other commercial real estate	1,212		1,017		1,017		—		—		1,024		—		1,119		—
Total commercial real estate	6,905		3,775		3,775		—		—		4,125		—		4,648		—

Residential mortgage:
Permanent mortgage	28,603		23,415		23,415		—		—		23,801		307		23,135		598
Permanent mortgage guaranteed by U.S. government agencies¹	197,659		191,729		191,729		—		—		202,946		2,021		205,159		3,925
Home equity	13,064		11,768		11,768		—		—		11,776		—		11,643		—
Total residential mortgage	239,326		226,912		226,912		—		—		238,523		2,328		239,937		4,523

Personal	307		272		272		—		—		253		—		281		—

Total	$	480,181	$	428,116	$	355,469	$	72,647	$	9,693	$	419,893	$	2,328	$	432,921	$	4,523


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 June 30, 2017, $9.1 million of these loans were nonaccruing and $183 million were accruing based on the guarantee by U.S. government agencies.

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, 2016 follows (in thousands):



			Recorded Investment
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance
Commercial:
Energy	$	146,897	$	132,499	$	121,418	$	11,081	$	762
Services	11,723		8,173		8,173		—		—
Wholesale/retail	17,669		11,407		11,407		—		—
Manufacturing	5,320		4,931		4,931		—		—
Healthcare	1,147		825		825		—		—
Other commercial and industrial	29,006		21,118		21,083		35		35
Total commercial	211,762		178,953		167,837		11,116		797

Commercial real estate:
Residential construction and land development	4,951		3,433		3,433		—		—
Retail	530		326		326		—		—
Office	521		426		426		—		—
Multifamily	1,000		38		38		—		—
Industrial	76		76		76		—		—
Other commercial real estate	7,349		1,222		1,222		—		—
Total commercial real estate	14,427		5,521		5,521		—		—

Residential mortgage:
Permanent mortgage	28,830		22,855		22,809		46		46
Permanent mortgage guaranteed by U.S. government agencies¹	205,564		199,387		199,387		—		—
Home equity	12,611		11,519		11,519		—		—
Total residential mortgage	247,005		233,761		233,715		46		46

Personal	332		290		290		—		—

Total	$	473,526	$	418,525	$	407,363	$	11,162	$	843


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, 2016, $12 million of these loans were nonaccruing and $188 million were accruing based on the guarantee by U.S. government agencies.

A summary of impaired loans at June 30, 2016 follows (in thousands):



											For the				For the
	As of June 30, 2016										Three Months Ended				Six Months Ended
			Recorded Investment								June 30, 2016				June 30, 2016
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance		Average Recorded Investment		Interest Income Recognized		Average Recorded Investment		Interest Income Recognized
Commercial:
Energy	$	202,369	$	168,145	$	136,264	$	31,881	$	4,228	$	163,849	$	—	$	97,923	$	—
Services	12,780		9,388		9,388		—		—		9,450		—		9,839		—
Wholesale/retail	8,697		2,772		2,772		—		—		3,229		—		2,846		—
Manufacturing	650		293		293		—		—		303		—		312		—
Healthcare	1,175		875		875		—		—		949		—		973		—
Other commercial and industrial	8,186		516		516		—		—		542		—		569		—
Total commercial	233,857		181,989		150,108		31,881		4,228		178,322		—		112,462		—

Commercial real estate:
Residential construction and land development	7,177		4,261		4,261		—		—		4,525		—		4,335		—
Retail	1,914		1,265		1,265		—		—		1,283		—		1,292		—
Office	907		606		606		—		—		618		—		628		—
Multifamily	1,000		65		65		—		—		157		—		169		—
Industrial	76		76		76		—		—		76		—		76		—
Other commercial real estate	7,445		1,507		1,355		152		18		1,865		—		1,890		—
Total commercial real estate	18,519		7,780		7,628		152		18		8,524		—		8,390		—

Residential mortgage:
Permanent mortgage	33,793		27,228		27,117		111		64		27,362		304		28,106		631
Permanent mortgage guaranteed by U.S. government agencies¹	198,534		192,732		192,732		—		—		191,430		2,023		195,563		3,795
Home equity	10,964		10,092		10,092		—		—		10,311		—		10,224		—
Total residential mortgage	243,291		230,052		229,941		111		64		229,103		2,327		233,893		4,426

Personal	1,174		354		354		—		—		342		—		409		—

Total	$	496,841	$	420,175	$	388,031	$	32,144	$	4,310	$	416,291	$	2,327	$	355,154	$	4,426


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 June 30, 2016, $20 million of these loans were nonaccruing and $173 million were accruing based on the guarantee by U.S. government agencies.

Troubled Debt Restructurings

A summary of troubled debt restructurings ("TDRs") by accruing status as of June 30, 2017 is as follows (in thousands):



	As of June 30, 2017								Amounts Charged Off During:
	Recorded Investment		Performing in Accordance With Modified Terms		Not Performing in Accordance With Modified Terms		Specific Allowance		Three Months Ended June 30, 2017		Six Months Ended June 30, 2017
Nonaccruing TDRs:

Commercial:
Energy	$	22,466	$	12,692	$	9,774	$	4,308	$	—	$	—
Services	7,208		6,561		647		—		3		3
Wholesale/retail	10,524		10,524		—		—		—		—
Manufacturing	195		195		—		—		—		—
Healthcare	—		—		—		—		—		—
Other commercial and industrial	20,531		35		20,496		—		—		—
Total commercial	60,924		30,007		30,917		4,308		3		3

Commercial real estate:
Residential construction and land development	381		145		236		—		—		—
Retail	301		301		—		—		—		—
Office	121		—		121		—		—		—
Multifamily	—		—		—		—		—		—
Industrial	—		—		—		—		—		—
Other commercial real estate	365		365		—		—		—		—
Total commercial real estate	1,168		811		357		—		—		—

Residential mortgage:
Permanent mortgage	14,284		9,939		4,345		—		—		—
Permanent mortgage guaranteed by U.S. government agencies	5,962		1,176		4,786		—		—		—
Home equity	5,549		4,239		1,310		—		—		31
Total residential mortgage	25,795		15,354		10,441		—		—		31

Personal	228		228		—		—		7		8

Total nonaccruing TDRs	$	88,115	$	46,400	$	41,715	$	4,308	$	10	$	42

Accruing TDRs:
Permanent mortgages guaranteed by U.S. government agencies	80,624		24,506		56,118		—		—		—

Total TDRs	$	168,739	$	70,906	$	97,833	$	4,308	$	10	$	42

A summary of troubled debt restructurings by accruing status as of December 31, 2016 is as follows (in thousands):



	As of
	December 31, 2016
	Recorded Investment		Performing in Accordance With Modified Terms		Not Performing in Accordance With Modified Terms		Specific Allowance
Nonaccruing TDRs:

Commercial:
Energy	$	16,893	$	10,867	$	6,026	$	—
Services	7,527		6,830		697		—
Wholesale/retail	11,291		11,251		40		—
Manufacturing	224		224		—		—
Healthcare	607		—		607		—
Other commercial and industrial	337		53		284		—
Total commercial	36,879		29,225		7,654		—

Commercial real estate:
Residential construction and land development	690		97		593		—
Retail	326		326		—		—
Office	143		143		—		—
Multifamily	—		—		—		—
Industrial	—		—		—		—
Other commercial real estate	548		548		—		—
Total commercial real estate	1,707		1,114		593		—

Residential mortgage:
Permanent mortgage	14,876		10,175		4,701		46
Permanent mortgage guaranteed by U.S. government agencies	6,702		2,241		4,461		—
Home equity	5,346		4,458		888		—
Total residential mortgage	26,924		16,874		10,050		46

Personal	237		236		1		—

Total nonaccuring TDRs	$	65,747	$	47,449	$	18,298	$	46

Accruing TDRs:
Permanent mortgages guaranteed by U.S. government agencies	81,370		27,289		54,081		—

Total TDRs	$	147,117	$	74,738	$	72,379	$	46

A summary of troubled debt restructurings by accruing status as of June 30, 2016 is as follows (in thousands):



	As of June 30, 2016								Amounts Charged Off During:
	Recorded Investment		Performing in Accordance With Modified Terms		Not Performing in Accordance With Modified Terms		Specific Allowance		Three Months Ended June 30, 2016		Six Months Ended June 30, 2016
Nonaccruing TDRs:

Commercial:
Energy	$	2,246	$	—	$	2,246	$	—	$	500	$	500
Services	8,610		7,853		757		—		—		—
Wholesale/retail	2,467		2,427		40		—		—		—
Manufacturing	253		253		—		—		—		—
Healthcare	640		640		—		—		—		—
Other commercial and industrial	516		63		453		—		—		57
Total commercial	14,732		11,236		3,496		—		500		557

Commercial real estate:
Residential construction and land development	1,601		1,079		522		—		—		—
Retail	1,264		907		357		—		—		—
Office	152		152		—		—		—		—
Multifamily	—		—		—		—		—		—
Industrial	—		—		—		—		—		—
Other commercial real estate	793		372		421		—		—		—
Total commercial real estate	3,810		2,510		1,300		—		—		—

Residential mortgage:
Permanent mortgage	17,367		12,462		4,905		64		37		52
Permanent mortgage guaranteed by U.S. government agencies	9,709		2,024		7,685		—		—		—
Home equity	4,763		4,139		624		—		60		126
Total residential mortgage	31,839		18,625		13,214		64		97		178

Personal	298		276		22		—		3		9

Total nonaccruing TDRs	$	50,679	$	32,647	$	18,032	$	64	$	600	$	744

Accruing TDRs:
Permanent mortgages guaranteed by U.S. government agencies	78,806		27,999		50,807		—		—		—

Total TDRs	$	129,485	$	60,646	$	68,839	$	64	$	600	$	744

Troubled debt restructurings generally consist of interest rate concessions, payment stream concessions or a combination of concessions to distressed borrowers. The following tables detail the recorded balance of loans at June 30, 2017 by class that were restructured during the three months ended June 30, 2017 by primary type of concession (in thousands):



	Three Months Ended June 30, 2017
	Accruing						Nonaccrual						Total
	Payment Stream		Combination & Other		Total		Payment Stream		Combination & Other		Total
Commercial:
Energy	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Services	—		—		—		—		—		—		—
Wholesale/retail	—		—		—		—		626		626		626
Manufacturing	—		—		—		—		—		—		—
Healthcare	—		—		—		—		—		—		—
Other commercial and industrial	—		—		—		20,242		—		20,242		20,242
Total commercial	—		—		—		20,242		626		20,868		20,868

Commercial real estate:
Residential construction and land development	—		—		—		—		—		—		—
Retail	—		—		—		—		—		—		—
Office	—		—		—		—		—		—		—
Multifamily	—		—		—		—		—		—		—
Industrial	—		—		—		—		—		—		—
Other commercial real estate	—		—		—		—		—		—		—
Total commercial real estate	—		—		—		—		—		—		—

Residential mortgage:
Permanent mortgage	—		—		—		138		53		191		191
Permanent mortgage guaranteed by U.S. government agencies	10,410		1,568		11,978		223		—		223		12,201
Home equity	—		—		—		26		559		585		585
Total residential mortgage	10,410		1,568		11,978		387		612		999		12,977

Personal	—		—		—		—		47		47		47

Total	$	10,410	$	1,568	$	11,978	$	20,629	$	1,285	$	21,914	$	33,892



	Six Months Ended June 30, 2017
	Accruing							Nonaccrual							Total
		Payment Stream		Combination & Other		Total			Payment Stream		Combination & Other		Total
Commercial:
Energy		$	—	$	—	$	—		$	13,010	$	—	$	13,010	$	13,010
Services		—		—		—			—		—		—		—
Wholesale/retail		—		—		—			—		626		626		626
Manufacturing		—		—		—			—		—		—		—
Healthcare		—		—		—			—		—		—		—
Other commercial and industrial		—		—		—			20,242		—		20,242		20,242
Total commercial		—		—		—			33,252		626		33,878		33,878

Commercial real estate:
Residential construction and land development		—		—		—			—		—		—		—
Retail		—		—		—			—		—		—		—
Office		—		—		—			—		—		—		—
Multifamily		—		—		—			—		—		—		—
Industrial		—		—		—			—		—		—		—
Other commercial real estate		—		—		—			—		—		—		—
Total commercial real estate		—		—		—			—		—		—		—

Residential mortgage:
Permanent mortgage		—		—		—			153		84		237		237
Permanent mortgage guaranteed by U.S. government agencies		14,883		2,586		17,469			224		85		309		17,778
Home equity		—		—		—			149		1,053		1,202		1,202
Total residential mortgage		14,883		2,586		17,469			526		1,222		1,748		19,217

Personal		—		—		—			—		51		51		51

Total		$	14,883	$	2,586	$	17,469		$	33,778	$	1,899	$	35,677	$	53,146

Troubled debt restructurings generally consist of interest rate concessions, payment stream concessions or a combination of concessions to distressed borrowers. The following tables detail the recorded balance of loans by class that were restructured during three months ended June 30, 2016 by primary type of concession (in thousands):



	Three Months Ended June 30, 2016
	Accruing						Nonaccrual						Total
	Payment Stream		Combination & Other		Total		Payment Stream		Combination & Other		Total
Commercial:
Energy	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Services	—		—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—		—
Healthcare	—		—		—		—		—		—		—
Other commercial and industrial	—		—		—		—		—		—		—
Total commercial	—		—		—		—		—		—		—

Commercial real estate:
Residential construction and land development	—		—		—		—		—		—		—
Retail	—		—		—		—		—		—		—
Office	—		—		—		—		—		—		—
Multifamily	—		—		—		—		—		—		—
Industrial	—		—		—		—		—		—		—
Other commercial real estate	—		—		—		—		—		—		—
Total commercial real estate	—		—		—		—		—		—		—

Residential mortgage:
Permanent mortgage	—		—		—		684		1,183		1,867		1,867
Permanent mortgage guaranteed by U.S. government agencies	2,783		4,455		7,238		—		625		625		7,863
Home equity	—		—		—		48		329		377		377
Total residential mortgage	2,783		4,455		7,238		732		2,137		2,869		10,107

Personal	—		—		—		—		65		65		65

Total	$	2,783	$	4,455	$	7,238	$	732	$	2,202	$	2,934	$	10,172



	Six Months Ended June 30, 2016
	Accruing						Nonaccrual						Total
	Payment Stream		Combination & Other		Total		Payment Stream		Combination & Other		Total
Commercial:
Energy	$	—	$	—	$	—	$	501	$	—	$	501	$	501
Services	—		—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—		—
Healthcare	—		—		—		—		—		—		—
Other commercial and industrial	—		—		—		—		—		—		—
Total commercial	—		—		—		501		—		501		501

Commercial real estate:
Residential construction and land development	—		—		—		—		—		—		—
Retail	—		—		—		—		—		—		—
Office	—		—		—		—		—		—		—
Multifamily	—		—		—		—		—		—		—
Industrial	—		—		—		—		—		—		—
Other commercial real estate	—		—		—		—		—		—		—
Total commercial real estate	—		—		—		—		—		—		—

Residential mortgage:
Permanent mortgage	—		—		—		1,046		1,244		2,290		2,290
Permanent mortgage guaranteed by U.S. government agencies	6,625		7,818		14,443		—		625		625		15,068
Home equity	—		—		—		48		791		839		839
Total residential mortgage	6,625		7,818		14,443		1,094		2,660		3,754		18,197

Personal	—		—		—		—		72		72		72

Total	$	6,625	$	7,818	$	14,443	$	1,595	$	2,732	$	4,327	$	18,770

The following table summarizes, by loan class, the recorded investment at June 30, 2017 and 2016, respectively, of loans modified as TDRs within the previous 12 months and for which there was a payment default during the three months ended June 30, 2017 and 2016, respectively (in thousands):



	Three Months Ended June 30, 2017						Six Months Ended June 30, 2017
	Accruing		Nonaccrual		Total		Accruing		Nonaccrual		Total
Commercial:
Energy	$	—	$	9,774	$	9,774	$	—	$	9,774	$	9,774
Services	—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—
Healthcare	—		—		—		—		—		—
Other commercial and industrial	—		20,242		20,242		—		20,242		20,242
Total commercial	—		30,016		30,016		—		30,016		30,016

Commercial real estate:
Residential construction and land development	—		—		—		—		—		—
Retail	—		—		—		—		—		—
Office	—		—		—		—		—		—
Multifamily	—		—		—		—		—		—
Industrial	—		—		—		—		—		—
Other commercial real estate	—		—		—		—		—		—
Total commercial real estate	—		—		—		—		—		—

Residential mortgage:
Permanent mortgage	—		161		161		—		161		161
Permanent mortgage guaranteed by U.S. government agencies	22,234		918		23,152		22,590		918		23,508
Home equity	—		1,113		1,113		—		1,262		1,262
Total residential mortgage	22,234		2,192		24,426		22,590		2,341		24,931

Personal	—		—		—		—		—		—

Total	$	22,234	$	32,208	$	54,442	$	22,590	$	32,357	$	54,947

A payment default is defined as being 30 days or more past due. The table above includes loans that experienced a payment default during the period, but may be performing in accordance with the modified terms as of the balance sheet date.



	Three Months Ended June 30, 2016						Six Months Ended June 30, 2016
	Accruing		Nonaccrual		Total		Accruing		Nonaccrual		Total
Commercial:
Energy	$	—	$	2,246	$	2,246	$	—	$	2,246	$	2,246
Services	—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—
Healthcare	—		—		—		—		—		—
Other commercial and industrial	—		—		—		—		—		—
Total commercial	—		2,246		2,246		—		2,246		2,246

Commercial real estate:
Residential construction and land development	—		—		—		—		—		—
Retail	—		—		—		—		—		—
Office	—		—		—		—		—		—
Multifamily	—		—		—		—		—		—
Industrial	—		—		—		—		—		—
Other commercial real estate	—		—		—		—		—		—
Total commercial real estate	—		—		—		—		—		—

Residential mortgage:
Permanent mortgage	—		788		788		—		1,806		1,806
Permanent mortgage guaranteed by U.S. government agencies	18,893		1,006		19,899		20,621		1,006		21,627
Home equity	—		232		232		—		232		232
Total residential mortgage	18,893		2,026		20,919		20,621		3,044		23,665

Personal	—		—		—		—		—		—

Total	$	18,893	$	4,272	$	23,165	$	20,621	$	5,290	$	25,911

Nonaccrual & 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.

A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of June 30, 2017 is as follows (in thousands):



			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	2,723,248	$	—	$	—	$	—	$	123,992	$	2,847,240
Services	2,949,562		50		180		1,281		7,754		2,958,827
Wholesale/retail	1,532,986		89		—		—		10,620		1,543,695
Manufacturing	536,481		—		—		—		9,656		546,137
Healthcare	2,196,088		925		—		—		24,505		2,221,518
Other commercial and industrial	499,743		45		119		1		20,630		520,538
Total commercial	10,438,108		1,109		299		1,282		197,157		10,637,955

Commercial real estate:
Residential construction and land development	139,070		471		—		—		2,051		141,592
Retail	722,504		—		—		—		301		722,805
Office	862,577		—		—		—		396		862,973
Multifamily	952,370		—		—		—		10		952,380
Industrial	693,635		—		—		—		—		693,635
Other commercial real estate	314,187		3		—		—		1,017		315,207
Total commercial real estate	3,684,343		474		—		—		3,775		3,688,592

Residential mortgage:
Permanent mortgage	962,443		2,024		1,026		132		23,415		989,040
Permanent mortgages guaranteed by U.S. government agencies	36,867		18,416		13,581		113,813		9,052		191,729
Home equity	744,735		1,564		362		—		11,768		758,429
Total residential mortgage	1,744,045		22,004		14,969		113,945		44,235		1,939,198

Personal	916,852		487		289		—		272		917,900

Total	$	16,783,348	$	24,074	$	15,557	$	115,227	$	245,439	$	17,183,645

A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of December 31, 2016 is as follows (in thousands):



			Past Due
	Current		30 to 59 Days		60 to 89 Days	90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	2,364,890	$	479	—	$	—	$	132,499	$	2,497,868
Services	3,099,605		191		1,021	—		8,173		3,108,990
Wholesale/retail	1,561,650		3,761		—	—		11,407		1,576,818
Manufacturing	509,662		382		—	—		4,931		514,975
Healthcare	2,201,050		—		41	—		825		2,201,916
Other commercial and industrial	468,981		155		3	—		21,118		490,257
Total commercial	10,205,838		4,968		1,065	—		178,953		10,390,824

Commercial real estate:
Residential construction and land development	132,100		—		—	—		3,433		135,533
Retail	761,562		—		—	—		326		761,888
Office	798,462		—		—	—		426		798,888
Multifamily	903,234		—		—	—		38		903,272
Industrial	871,673		—		—	—		76		871,749
Other commercial real estate	336,488		6		—	—		1,222		337,716
Total commercial real estate	3,803,519		6		—	—		5,521		3,809,046

Residential mortgage:
Permanent mortgage	979,386		3,299		1,280	—		22,855		1,006,820
Permanent mortgages guaranteed by U.S. government agencies	40,594		17,465		13,803	115,679		11,846		199,387
Home equity	729,493		2,276		337	—		11,519		743,625
Total residential mortgage	1,749,473		23,040		15,420	115,679		46,220		1,949,832

Personal	838,811		589		263	5		290		839,958

Total	$	16,597,641	$	28,603	16,748	$	115,684	$	230,984	$	16,989,660

A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of June 30, 2016 is as follows (in thousands):



			Past Due
	Current		30 to 59 Days		60 to 89 Days	90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	2,647,678	$	—	—	$	2,833	$	168,145	$	2,818,656
Services	2,817,217		494		3,765	—		9,388		2,830,864
Wholesale/retail	1,530,110		75		—	—		2,772		1,532,957
Manufacturing	595,110		—		—	—		293		595,403
Healthcare	2,050,271		—		—	—		875		2,051,146
Other commercial and industrial	526,691		76		82	46		516		527,411
Total commercial	10,167,077		645		3,847	2,879		181,989		10,356,437

Commercial real estate:
Residential construction and land development	153,315		—		—	—		4,261		157,576
Retail	794,154		—		—	—		1,265		795,419
Office	768,506		—		—	—		606		769,112
Multifamily	784,826		2,309		—	—		65		787,200
Industrial	645,510		—		—	—		76		645,586
Other commercial real estate	425,566		—		—	—		1,507		427,073
Total commercial real estate	3,571,877		2,309		—	—		7,780		3,581,966

Residential mortgage:
Permanent mortgage	935,857		5,798		124	—		27,228		969,007
Permanent mortgages guaranteed by U.S. government agencies	42,019		15,349		11,869	103,754		19,741		192,732
Home equity	707,024		1,889		159	20		10,092		719,184
Total residential mortgage	1,684,900		23,036		12,152	103,774		57,061		1,880,923

Personal	586,611		400		58	—		354		587,423

Total	$	16,010,465	$	26,390	16,057	$	106,653	$	247,184	$	16,406,749

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

Acquisitions	6 Months Ended
Acquisitions	Jun. 30, 2017
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	Acquisitions On December 1, 2016, the Company acquired MBT Bancshares (“MBT”), parent company of Missouri Bank and Trust of Kansas City (“Mobank”) following regulatory approval of the transaction. Mobank operated four banking branches in the Kansas City, Mo. area. BOK Financial paid $102.5 million in an all-cash deal for all outstanding shares of MBT stock. MBT was merged into BOK Financial and Mobank became a wholly owned subsidiary of BOK Financial on December 1, 2016. On February 21, 2017, Mobank was merged with the Bank of Kansas City division of BOKF, NA. All branches in the Kansas City market will operate under the Mobank name. The preliminary purchase price allocation was updated in the first quarter of 2017 resulting in a $2.0 million increase in identifiable intangibles, $1.5 million decrease in premises and equipment and other repossessed assets, and a $526 thousand decrease in goodwill.

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Mortgage Banking Activities [Text Block]

Mortgage Banking Activities

6 Months Ended

Jun. 30, 2017

Mortgage Banking [Abstract]

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 retained for investment. Residential mortgage loans originated for sale by the Company are carried at fair value based on sales commitments and market quotes. Changes in the fair value of mortgage loans held for sale are included in Other operating revenue – Mortgage banking revenue. Residential mortgage loans held for sale also includes the fair value of residential mortgage loan commitments and forward sale commitments which are considered derivative contracts that have not been designated as hedging instruments for accounting purposes. 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):



	June 30, 2017				Dec. 31, 2016				June 30, 2016
	Unpaid Principal Balance/ Notional		Fair Value		Unpaid Principal Balance/ Notional		Fair Value		Unpaid Principal Balance/ Notional		Fair Value
Residential mortgage loans held for sale	$	269,772	$	275,179	$	286,414	$	286,971	$	404,507	$	417,542
Residential mortgage loan commitments	362,088		10,993		318,359		9,733		965,631		25,499
Forward sales contracts	587,595		1,087		569,543		5,193		1,216,966		(12,313		)
			$	287,259			$	301,897			$	430,728

No residential mortgage loans held for sale were 90 days or more past due or considered impaired as of June 30, 2017, December 31, 2016 or June 30, 2016. No credit losses were recognized on residential mortgage loans held for sale for the three and six month periods ended June 30, 2017 and 2016.

Mortgage banking revenue was as follows (in thousands):



	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Production revenue:
Net realized gains on sale of mortgage loans	$	11,787		$	15,865		$	20,402		$	24,314
Net change in unrealized gain on mortgage loans held for sale	985			3,884			4,827			7,167
Net change in the fair value of mortgage loan commitments	(3,274		)	5,329			1,260			17,365
Net change in the fair value of forward sales contracts	4,342			(5,992		)	(4,106		)	(13,113		)
Total production revenue	13,840			19,086			22,383			35,733
Servicing revenue	16,436			15,798			33,084			31,251
Total mortgage banking revenue	$	30,276		$	34,884		$	55,467		$	66,984

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 for accounting purposes 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

Mortgage servicing rights may be originated or purchased. Both originated and purchased mortgage servicing rights are initially recognized at fair value. The Company has elected to carry all mortgage servicing rights at fair value. Changes in the fair value are recognized in earnings as they occur. 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):



	June 30, 2017			Dec. 31, 2016			June 30, 2016
Number of residential mortgage loans serviced for others	138,335			139,340			137,210
Outstanding principal balance of residential mortgage loans serviced for others	$	22,095,232		$	21,997,568		$	21,178,387
Weighted average interest rate	3.95		%	3.97		%	4.06		%
Remaining term (in months)	299			301			301

Activity in capitalized mortgage servicing rights during the three months ended June 30, 2017 was as follows (in thousands):



	Purchased			Originated			Total
Balance, March 31, 2017	$	8,316		$	241,087		$	249,403
Additions, net	—			11,078			11,078
Change in fair value due to scheduled payments and full-balance payoffs	(464		)	(7,835		)	(8,299		)
Change in fair value due to market assumption changes	143			(7,086		)	(6,943		)
Balance, June 30, 2017	$	7,995		$	237,244		$	245,239



	Purchased			Originated			Total
Balance, Dec. 31, 2016	$	8,909		$	238,164		$	247,073
Additions, net	—			19,514			19,514
Change in fair value due to scheduled payments and full-balance payoffs	(973		)	(15,288		)	(16,261		)
Change in fair value due to market assumption changes	59			(5,146		)	(5,087		)
Balance, June 30, 2017	$	7,995		$	237,244		$	245,239

Activity in capitalized mortgage servicing rights during the three months ended June 30, 2016 was as follows (in thousands):



	Purchased			Originated			Total
Balance, March 31, 2016	$	5,949		$	190,106		$	196,055
Additions, net	—			20,773			20,773
Change in fair value due to scheduled payments and full-balance payoffs	(730		)	(9,068		)	(9,798		)
Change in fair value due to market assumption changes	(1,152		)	(15,131		)	(16,283		)
Balance, June 30, 2016	$	4,067		$	186,680		$	190,747



	Purchased			Originated			Total
Balance, Dec. 31, 2015	$	9,911		$	208,694		$	218,605
Additions, net	—			34,355			34,355
Change in fair value due to scheduled payments and full-balance payoffs	(1,356		)	(16,586		)	(17,942		)
Change in fair value due to market assumption changes	(4,488		)	(39,783		)	(44,271		)
Balance, June 30, 2016	$	4,067		$	186,680		$	190,747

Changes in the fair value of mortgage servicing rights are included in Other operating revenue in the Consolidated Statements of Earnings. Changes in fair value due to actual loan payments are included in Mortgage banking costs. Changes in fair value due to market assumption changes are reported separately. Changes in fair value due to market assumption changes during the period relate to assets held at the reporting date.

There is no active market for trading in mortgage servicing rights after origination. Fair value is determined by discounting the projected net cash flows. Significant assumptions used to determine fair value based on significant unobservable inputs were as follows:



	June 30, 2017	Dec. 31, 2016	June 30, 2016
Discount rate – risk-free rate plus a market premium	9.84%	10.08%	10.09%
Prepayment rate - based upon loan interest rate, original term and loan type	8.61%-15.91%	8.98%-16.91%	9.26%-42.77%
Loan servicing costs – annually per loan based upon loan type:
Performing loans	$65-$120	$63 - $120	$63 - $120
Delinquent loans	$150-$500	$150 - $500	$150 - $500
Loans in foreclosure	$1,000-$4,250	$650 - $4,250	$650 - $4,250
Escrow earnings rate – indexed to rates paid on deposit accounts with comparable average life	1.95%	1.98%	0.99%
Primary/secondary mortgage rate spread	105 bps	105 bps	115 bps

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.

The aging status of our mortgage loans serviced for others by investor at June 30, 2017 follows (in thousands):



			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Total
FHLMC	$	8,083,330	$	48,659	$	12,294	$	27,338	$	8,171,621
FNMA	6,756,211		46,918		10,679		23,981		6,837,789
GNMA	6,331,439		170,889		47,335		16,082		6,565,745
Other	514,272		3,278		932		1,595		520,077
Total	$	21,685,252	$	269,744	$	71,240	$	68,996	$	22,095,232

The Company has obligations to repurchase or provide indemnification for residential mortgage loans sold to government sponsored entities due to standard representations and warranties made under contractual agreements and to service loans in accordance with investor guidelines. The Company has established accruals for losses related to these obligations that are included in Other liabilities in the Consolidated Balance Sheets and in Mortgage banking costs in the Consolidated Statements of Earnings.

The Company repurchased five loans from the agencies for $1.3 million during the second quarter of 2017. There were four indemnifications on loans paid during the second quarter of 2017. Losses recognized on repurchases were insignificant.

A summary of unresolved deficiency requests from the agencies follows (in thousands, except for number of unresolved deficiency requests):



	June 30,
	2017		2016
Number of unresolved deficiency requests	206		211
Aggregate outstanding principal balance subject to unresolved deficiency requests	$	13,370	$	15,920
Unpaid principal balance subject to indemnification by the Company	5,074		5,519

The activity in the accruals for mortgage losses related to repurchases is summarized as follows (in thousands).



	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Beginning balance	$	2,587		$	2,974		$	2,788		$	3,359
Provision for losses	(895		)	368			(1,094		)	250
Charge-offs, net	(45		)	(89		)	(47		)	(356		)
Ending balance	$	1,647		$	3,253		$	1,647		$	3,253

Commitments and Contingent Liabilities

6 Months Ended

Jun. 30, 2017

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 415,755 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. Therefore, no value has been currently assigned to the Class B shares and no value may be assigned until the Class B shares are converted into a known number of Class A shares.

On March 3, 2015, BOKF, NA and the Company were named as defendants in a class action alleging (1) that the manner in which the Bank posted charges to its consumer deposit accounts was improper from September 1, 2011 through July 8, 2014, the period after which the Bank and BOK Financial had settled a class action respecting a similar claim, and before it made changes to its posting order and (2) that the manner in which the Bank posted charges to its small business deposit accounts was improper from July 9, 2009 through July 8, 2014. Following mediation of the case in August 2016, the Class Representatives and the Bank reached a settlement of the action for $7.8 million. The Settlement was approved by the Court in a final order, the Company funded the settlement, and the settlement has been implemented.

On June 24, 2015, the Bank 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 the Bank 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 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 (estimated to be approximately $73 million, less the value of the facilities securing repayment of the bonds), subject to oversight by a court appointed monitor. On September 7, 2016, the Bank agreed, and the SEC entered, a consent order finding that the Bank had violated Section 17(a) of the Securities Act of 1933 and Section 10(b) of the Securities Exchange Act and requiring the Bank to disgorge $1,067,721 of fees and pay a civil penalty of $600,000. The Bank has disgorged the fees and paid the penalty. On August 26, 2016, the Bank 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 the Bank participated in the fraudulent sale of securities by the principals. On September 14, 2016, the Bank was sued in the District Court of Tulsa County, Oklahoma by 19 bondholders alleging the Bank participated in the fraudulent sale of securities by the principals. Management has been advised by counsel that the Bank has valid defenses to the claims. The Bank expects the Court ordered payment plan will result in the payment of the bonds by the principals. Accordingly, no loss is probable at this time and no provision for loss has been made. If the payment plan does not result in payment of the bonds, a loss could become probable. A reasonable estimate cannot be made at this time though the amount could be material to the Company.

On March 14, 2017, the Bank was sued in the United States District Court for the Northern District of Oklahoma by bondholders in a second putative class action. The bondholders in this second action allege 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 the Bank also served as indenture trustee. The bondholders allege the Bank failed to disclose that the seller of the purchased facilities had engaged in the conduct complained of in the New Jersey action. The Bank properly performed all duties as indenture trustee of this second set of municipal securities, timely commenced proceedings against the issuer of the securities when default occurred, is cooperating with the SEC in actions against the two principals, is not a target of the SEC proceedings, and has been advised by counsel that the Bank has valid defenses to the claims of these bondholders. It is the opinion of management that no loss is probable at this time.

The County of Bernalillo, New Mexico, commenced arbitration pursuant to the Arbitration Rules of FINRA seeking recovery of $5.6 million alleging that various municipal bonds purchased by the elected County Treasurer of Bernalillo County, New Mexico, from BOK Financial Securities, Inc. were unsuitable. The arbitration was conducted in July 2017. Management has been advised by counsel that a loss is not probable.

On March 30, 2017, two deposit customers of the Bank sued the Bank in the District Court of Harris County, Texas. A judgment creditor had served a garnishment summons on the Bank. The deposit customers allege that, because the Bank was unable to produce adequate documentation of ownership of a series of deposit accounts at the Bank owned by them, they were compelled to enter into a settlement agreement with the judgment creditor pursuant to which the Bank paid $4.2 million from the accounts to the judgment creditor. The two deposit customers seek $7 million. Management has been advised by counsel that a loss is not probable and that the amount of the liability, if any, cannot be quantified at this time.

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. BOKF, NA was previously sued in a class action in the United States District Court for the Northern District of Oklahoma making the same allegations. Pursuant to a motion to dismiss, the Northern District of Oklahoma Court action was dismissed. Other courts considering the question whether extended overdraft fees are interest have likewise determined such fees are not interest. BOKF, NA has moved to dismiss the action. Management is advised by counsel that a loss is not probable and that the loss, if any, cannot be reasonably estimated.

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 two private equity funds 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 determined by the nature of the entity. 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. Variable interest entities are consolidated based on the determination that the Company is the primary beneficiary including 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.

BOKF Equity, LLC, an indirect wholly-owned subsidiary, is the general partner of two consolidated private equity funds (“the Funds”). The Funds provide alternative investment opportunities to certain customers, some of which are related parties, through unaffiliated limited partnerships. These unaffiliated limited partnerships generally invest in distressed assets, asset buy-outs or venture capital companies. As general partner, BOKF Equity, LLC has the power to direct activities that most significantly affect the Funds' performance and contingent obligations to make additional investments totaling $4.0 million at June 30, 2017. Substantially all of the obligations are offset by limited partner commitments. The Company does not accrue its contingent liability to fund investments. The Volcker Rule in Title VI of the Dodd-Frank Act will limit both the amount and structure of these types of investments.

Consolidated tax credit investment entities represent the Company's interest in entities earning federal new market tax credits related to qualifying loans. The Company has the power to direct the activities that most significantly impact the variable interest's economic performance of the entity including being the primary beneficiary of or the obligation to absorb losses of the variable interest that could be significant to the variable interest.

Other consolidated alternative investments include entities held under merchant banking authority. While the Company owns a majority of the voting interest in these entities, its ability to manage daily operations is limited by applicable banking regulations. Consolidated other assets includes total tangible assets, identifiable intangible assets and goodwill held by these entities.

The Company also has interests in various unrelated alternative investments generally consisting of unconsolidated limited partnership interests in or loans to entities for which investment return is primarily in the form of tax credits or that invest in distressed real estate loans and properties, energy development, venture capital and other activities. The Company is prohibited by banking regulations from controlling or actively managing the activities of these investments and the Company's maximum exposure to loss is restricted to its investment balance. The Company's obligation to fund alternative investments is included in Other liabilities in the Consolidated Balance Sheets.

A summary of consolidated and unconsolidated alternative investments as of June 30, 2017, December 31, 2016 and June 30, 2016 is as follows (in thousands):



	June 30, 2017
	Loans		Other assets		Other liabilities		Other borrowings		Non-controlling interests
Consolidated:
Private equity funds	$	—	$	16,905	$	—	$	—	$	14,199
Tax credit entities	10,000		11,274		—		10,964		10,000
Other	—		15,894		1,621		878		2,877
Total consolidated	$	10,000	$	44,073	$	1,621	$	11,842	$	27,076

Unconsolidated:
Tax credit entities	$	59,744	$	148,525	$	63,822	$	—	$	—
Other	—		33,155		13,680		—		—
Total unconsolidated	$	59,744	$	181,680	$	77,502	$	—	$	—



	Dec. 31, 2016
	Loans		Other assets		Other liabilities		Other borrowings		Non-controlling interests
Consolidated:
Private equity funds	$	—	$	17,357	$	—	$	—	$	13,237
Tax credit entities	10,000		11,585		—		10,964		10,000
Other	—		29,783		3,189		1,092		8,266
Total consolidated	$	10,000	$	58,725	$	3,189	$	12,056	$	31,503

Unconsolidated:
Tax credit entities	$	44,488	$	143,715	$	63,329	$	—	$	—
Other	—		31,675		15,028		—		—
Total unconsolidated	$	44,488	$	175,390	$	78,357	$	—	$	—



	June 30, 2016
	Loans		Other assets		Other liabilities		Other borrowings		Non-controlling interests
Consolidated:
Private equity funds	$	—	$	20,469	$	—	$	—	$	16,316
Tax credit entities	10,000		11,895		—		10,964		10,000
Other	—		35,387		2,004		2,272		7,589
Total consolidated	$	10,000	$	67,751	$	2,004	$	13,236	$	33,905

Unconsolidated:
Tax credit entities	$	32,679	$	102,138	$	30,953	$	—	$	—
Other	—		23,439		13,767		—		—
Total unconsolidated	$	32,679	$	125,577	$	44,720	$	—	$	—

Other Commitments and Contingencies

At June 30, 2017, Cavanal Hill Funds’ assets included U.S. Treasury, cash management and tax-free money market funds. Assets of these funds consist of highly-rated, short-term obligations of the U.S. Treasury, corporate issuers and U.S. states and municipalities. The net asset value of units in these funds was $1.00 at June 30, 2017. 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 2017 or 2016.

Shareholders' Equity

6 Months Ended

Jun. 30, 2017

Stockholders' Equity Note [Abstract]

Shareholders' Equity [Text Block]

Shareholders' Equity

On July 25, 2017, the Company declared a quarterly cash dividend of $0.44 per common share on or about August 25, 2017 to shareholders of record as of August 11, 2017.

Dividends declared were $0.44 per share and $0.88 per share during the three and six months ended June 30, 2017 and $0.43 per share and $0.86 per share during the three and six months ended June 30, 2016.

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. AOCI also includes unrealized gains on AFS securities that were transferred from AFS to investment securities in the third quarter of 2011. Such amounts are being amortized over the estimated remaining life of the security as an adjustment to yield, offsetting the related amortization of premium on the transferred securities. 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			Investment Securities Transferred from AFS			Employee Benefit Plans			Total
Balance, Dec. 31, 2015	$	23,284		$	68		$	(1,765	)	$	21,587
Net change in unrealized gain (loss)	166,566			—			—			166,566
Reclassification adjustments included in earnings:
Interest revenue, Investment securities, Taxable securities	—			(112		)	—			(112		)
Gain on available for sale securities, net	(9,290		)	—			—			(9,290		)
Other comprehensive income (loss), before income taxes	157,276			(112		)	—			157,164
Federal and state income taxes¹	61,163			(44		)	—			61,119
Other comprehensive income (loss), net of income taxes	96,113			(68		)	—			96,045
Balance, June 30, 2016	$	119,397		$	—		$	(1,765	)	$	117,632

Balance, Dec. 31, 2016	$	(9,087	)	$	—		$	(1,880	)	$	(10,967	)
Net change in unrealized gain (loss)	33,369			—			—			33,369
Reclassification adjustments included in earnings:
Gain on available for sale securities, net	(2,429		)	—			—			(2,429		)
Other comprehensive income, before income taxes	30,940			—			—			30,940
Federal and state income taxes¹	12,009						—			12,009
Other comprehensive income, net of income taxes	18,931			—			—			18,931
Balance, June 30, 2017	$	9,844		$	—		$	(1,880	)	$	7,964


¹	Calculated using a 39 percent effective tax rate.

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

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Earnings Per Share [Text Block]

Earnings Per Share

6 Months Ended

Jun. 30, 2017

Earnings Per Share [Abstract]

Earnings Per Share



(In thousands, except share and per share amounts)	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Numerator:
Net income attributable to BOK Financial Corp. shareholders	$	88,147	$	65,801	$	176,503	$	108,365
Less: Earnings allocated to participating securities	926		821		1,929		1,359
Numerator for basic earnings per share – income available to common shareholders	87,221		64,980		174,574		107,006
Effect of reallocating undistributed earnings of participating securities	1		—		1		—
Numerator for diluted earnings per share – income available to common shareholders	$	87,222	$	64,980	$	174,575	$	107,006

Denominator:
Weighted average shares outstanding	65,416,274		66,069,392		65,436,909		66,100,279
Less: Participating securities included in weighted average shares outstanding	686,522		823,505		714,165		829,065
Denominator for basic earnings per common share	64,729,752		65,245,887		64,722,744		65,271,214
Dilutive effect of employee stock compensation plans¹	63,382		57,039		65,578		45,963
Denominator for diluted earnings per common share	64,793,134		65,302,926		64,788,322		65,317,177

Basic earnings per share	$	1.35	$	1.00	$	2.70	$	1.64
Diluted earnings per share	$	1.35	$	1.00	$	2.69	$	1.64
¹ Excludes employee stock options with exercise prices greater than current market price.	—		—		—		145,247

Reportable Segments

6 Months Ended

Jun. 30, 2017

Segment Reporting [Abstract]

Reportable Segments [Text Block]

Reportable Segments

Reportable segments reconciliation to the Consolidated Financial Statements for the three months ended June 30, 2017 is as follows (in thousands):



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	144,164		$	23,503		$	10,474		$	27,063		$	205,204
Net interest revenue (expense) from internal sources	(20,347		)	11,837			10,325			(1,815		)	—
Net interest revenue	123,817			35,340			20,799			25,248			205,204
Provision for credit losses	1,228			926			(93		)	(2,061		)	—
Net interest revenue after provision for credit losses	122,589			34,414			20,892			27,309			205,204
Other operating revenue	55,778			52,102			75,569			(1,197		)	182,252
Other operating expense	59,128			55,709			60,615			75,433			250,885
Net direct contribution	119,239			30,807			35,846			(49,321		)	136,571
Gain on financial instruments, net	3			5,224			—			(5,227		)	—
Change in fair value of mortgage servicing rights	—			(6,943		)	—			6,943			—
Gain on repossessed assets, net	1,403			98			—			(1,501		)	—
Corporate expense allocations	8,862			17,039			9,947			(35,848		)	—
Net income before taxes	111,783			12,147			25,899			(13,258		)	136,571
Federal and state income taxes	43,484			4,725			10,075			(10,579		)	47,705
Net income	68,299			7,422			15,824			(2,679		)	88,866
Net income attributable to non-controlling interests	—			—			—			719			719
Net income attributable to BOK Financial Corp. shareholders	$	68,299		$	7,422		$	15,824		$	(3,398	)	$	88,147

Average assets	$	17,596,273		$	8,845,398		$	6,763,093		$	(836,193	)	$	32,368,571

Reportable segments reconciliation to the Consolidated Financial Statements for the six months ended June 30, 2017 is as follows (in thousands):



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	278,868		$	44,632		$	21,960		$	60,926		$	406,386
Net interest revenue (expense) from internal sources	(37,140		)	22,789			19,181			(4,830		)	—
Net interest revenue	241,728			67,421			41,141			56,096			406,386
Provision for credit losses	(234		)	2,198			(53		)	(1,911		)	—
Net interest revenue after provision for credit losses	241,962			65,223			41,194			58,007			406,386
Other operating revenue	102,048			99,408			149,727			1,365			352,548
Other operating expense	111,565			109,242			121,025			153,764			495,596
Net direct contribution	232,445			55,389			69,896			(94,392		)	263,338
Gain on financial instruments, net	41			3,557			—			(3,598		)	—
Change in fair value of mortgage servicing rights	—			(5,087		)	—			5,087			—
Gain (loss) on repossessed assets, net	1,398			(39		)	—			(1,359		)	—
Corporate expense allocations	17,493			33,908			20,619			(72,020		)	—
Net income before taxes	216,391			19,912			49,277			(22,242		)	263,338
Federal and state income taxes	84,176			7,746			19,169			(25,283		)	85,808
Net income	132,215			12,166			30,108			3,041			177,530
Net income attributable to non-controlling interests	—			—			—			1,027			1,027
Net income attributable to BOK Financial Corp. shareholders	$	132,215		$	12,166		$	30,108		$	2,014		$	176,503

Average assets	$	17,517,960		$	8,747,524		$	6,960,872		$	(566,196	)	$	32,660,160

Reportable segments reconciliation to the Consolidated Financial Statements for the three months ended June 30, 2016 is as follows (in thousands):



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	118,480		$	22,349		$	6,271		$	35,512		$	182,612
Net interest revenue (expense) from internal sources	(14,575		)	8,876			$	7,193		(1,494		)	—
Net interest revenue	103,905			31,225			13,464			34,018			182,612
Provision for credit losses	6,852			1,318			(239		)	12,069			20,000
Net interest revenue after provision for credit losses	97,053			29,907			13,703			21,949			162,612
Other operating revenue	51,497			57,440			75,772			833			185,542
Other operating expense	52,594			62,806			61,414			74,571			251,385
Net direct contribution	95,956			24,541			28,061			(51,789		)	96,769
Gain on financial instruments, net	—			15,045			—			(15,045		)	—
Change in fair value of mortgage servicing rights	—			(16,283		)	—			16,283			—
Gain (loss) on repossessed assets, net	(598		)	252			—			346			—
Corporate expense allocations	8,883			16,630			10,417			(35,930		)	—
Net income before taxes	86,475			6,925			17,644			(14,275		)	96,769
Federal and state income taxes	33,639			2,694			6,864			(12,700		)	30,497
Net income	52,836			4,231			10,780			(1,575		)	66,272
Net gain attributable to non-controlling interests	—			—			—			471			471
Net income attributable to BOK Financial Corp. shareholders	$	52,836		$	4,231		$	10,780		$	(2,046	)	$	65,801

Average assets	$	16,973,663		$	8,774,881		$	5,765,390		$	472,108		$	31,986,042

Reportable segments reconciliation to the Consolidated Financial Statements for the six months ended June 30, 2016 is as follows (in thousands):



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	235,116		$	43,799		$	12,349		$	73,920		$	365,184
Net interest revenue (expense) from internal sources	(29,208		)	18,229			$	14,857		(3,878		)	—
Net interest revenue	205,908			62,028			27,206			70,042			365,184
Provision for credit losses	28,423			3,020			(390		)	23,947			55,000
Net interest revenue after provision for credit losses	177,485			59,008			27,596			46,095			310,184
Other operating revenue	96,605			111,469			144,518			(9,636		)	342,956
Other operating expense	108,663			118,524			122,098			144,670			493,955
Net direct contribution	165,427			51,953			50,016			(108,211		)	159,185
Gain on financial instruments, net	—			31,626			—			(31,626		)	—
Change in fair value of mortgage servicing rights	—			(44,271		)	—			44,271			—
Gain (loss) on repossessed assets, net	(680		)	406			—			274			—
Corporate expense allocations	17,627			32,608			20,952			(71,187		)	—
Net income before taxes	147,120			7,106			29,064			(24,105		)	159,185
Federal and state income taxes	57,230			2,764			11,306			(19,375		)	51,925
Net income	89,890			4,342			17,758			(4,730		)	107,260
Net loss attributable to non-controlling interests	—			—			—			(1,105		)	(1,105		)
Net income attributable to BOK Financial Corp. shareholders	$	89,890		$	4,342		$	17,758		$	(3,625	)	$	108,365

Average assets	$	16,971,339		$	8,731,085		$	5,665,218		$	379,615		$	31,747,257

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.

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Fair Value Measurements [Text Block]

Fair Value Measurements

6 Months Ended

Jun. 30, 2017

Fair Value Disclosures [Abstract]

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. 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 three and six months ended June 30, 2017 and 2016, respectively. Transfers between significant other observable inputs and significant unobservable inputs during the three and six months ended June 30, 2017 and 2016 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 June 30, 2017, December 31, 2016 or June 30, 2016.

Assets and Liabilities Measured at Fair Value on a Recurring Basis

The fair value of financial assets and liabilities measured on a recurring basis was as follows as of June 30, 2017 (in thousands):



	Total		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Trading securities:
U.S. government agency debentures	$	20,954	$	—	$	20,954	$	—
U.S. government agency residential mortgage-backed securities	365,171		—		365,171		—
Municipal and other tax-exempt securities	45,444		—		45,444		—
Other trading securities	9,845		—		9,845		—
Total trading securities	441,414		—		441,414		—
Available for sale securities:
U.S. Treasury	998		998		—		—
Municipal and other tax-exempt securities	32,765		—		28,110		4,655
U.S. government agency residential mortgage-backed securities	5,382,377		—		5,382,377		—
Privately issued residential mortgage-backed securities	103,383		—		103,383		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,782,070		—		2,782,070		—
Other debt securities	4,152		—		—		4,152
Perpetual preferred stock	16,568		—		16,568		—
Equity securities and mutual funds	18,728		3,516		15,212		—
Total available for sale securities	8,341,041		4,514		8,327,720		8,807
Fair value option securities – U.S. government agency residential mortgage-backed securities	445,169		—		445,169		—
Residential mortgage loans held for sale	287,259		—		274,524		12,735
Mortgage servicing rights¹	245,239		—		—		245,239
Derivative contracts, net of cash collateral²	280,289		20,213		260,076		—
Liabilities:
Derivative contracts, net of cash collateral²	285,819		5,919		279,900		—


¹	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 6, Mortgage Banking Activities.

²

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 energy and interest rate derivative contacts. Derivative contacts in liability positions that were valued using quoted prices in active markets for identical instruments are exchange-traded interest rate and agricultural derivative contracts, net of cash margin.

The fair value of financial assets and liabilities measured on a recurring basis was as follows as of December 31, 2016 (in thousands):



	Total		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Trading securities:
U.S. government agency debentures	$	6,234	$	—	$	6,234	$	—
U.S. government agency residential mortgage-backed securities	310,067		—		310,067		—
Municipal and other tax-exempt securities	14,427		—		14,427		—
Other trading securities	6,900		—		6,900		—
Total trading securities	337,628		—		337,628		—
Available for sale securities:
U.S. Treasury	999		999		—		—
Municipal and other tax-exempt securities	40,993		—		35,204		5,789
U.S. government agency residential mortgage-backed securities	5,460,386		—		5,460,386		—
Privately issued residential mortgage-backed securities	115,535		—		115,535		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	3,017,933		—		3,017,933		—
Other debt securities	4,152		—		—		4,152
Perpetual preferred stock	18,474		—		18,474		—
Equity securities and mutual funds	18,357		3,495		14,862		—
Total available for sale securities	8,676,829		4,494		8,662,394		9,941
Fair value option securities – U.S. government agency residential mortgage-backed securities	77,046		—		77,046		—
Residential mortgage loans held for sale	301,897		—		290,280		11,617
Mortgage servicing rights¹	247,073		—		—		247,073
Derivative contracts, net of cash collateral²	689,872		7,541		682,331		—
Liabilities:
Derivative contracts, net of cash collateral²	664,531		6,972		657,559		—


¹	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 6, Mortgage Banking Activities.

²

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 contacts, 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, energy and agricultural derivative contracts, net of cash margin.

The fair value of financial assets and liabilities measured on a recurring basis was as follows as of June 30, 2016 (in thousands):



	Total		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Trading securities:
U.S. government agency debentures	$	18,909	$	—	$	18,909	$	—
U.S. government agency residential mortgage-backed securities	122,306		—		122,306		—
Municipal and other tax-exempt securities	52,721		—		52,721		—
Other trading securities	17,686		—		17,686		—
Total trading securities	211,622		—		211,622		—
Available for sale securities:
U.S. Treasury	1,004		1,004		—		—
Municipal and other tax-exempt securities	50,262		—		40,662		9,600
U.S. government agency residential mortgage-backed securities	5,700,268		—		5,700,268		—
Privately issued residential mortgage-backed securities	126,313		—		126,313		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,911,946		—		2,911,946		—
Other debt securities	4,151		—		—		4,151
Perpetual preferred stock	17,931		—		17,931		—
Equity securities and mutual funds	18,814		3,785		15,029		—
Total available for sale securities	8,830,689		4,789		8,812,149		13,751
Fair value option securities:
U.S. Treasury	25,306		25,306		—		—
U.S. government agency residential mortgage-backed securities	237,959		—		237,959		—
Total fair value option securities	263,265		25,306		237,959		—
Residential mortgage loans held for sale	430,728		—		420,979		9,749
Mortgage servicing rights¹	190,747		—		—		190,747
Derivative contracts, net of cash collateral²	883,673		7,246		876,427		—
Liabilities:
Derivative contracts, net of cash collateral²	719,159		4,808		714,351		—


¹	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 6, Mortgage Banking Activities.

²

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 energy and agricultural derivative contacts, 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 energy derivative contracts, net 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 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 references 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 assesses 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. The reduction in fair value is recognized in earnings during the current period.

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. The change in the fair value would be recognized in earnings in the current period.

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 residential mortgage loans held for sale are based upon quoted market prices of such loans sold in securitization transactions, including related unfunded loan commitments and forward sales contracts. The fair value of mortgage loans that were unable to be sold to U.S. government agencies were determined using quoted prices of loans that are sold in securitization transactions with a liquidity discount applied.

Other Assets - Private Equity Funds

The fair value of the portfolio investments of the Company's two private equity funds is based upon net asset value reported by the underlying funds, as adjusted by the general partner when necessary, as a practical expedient to measure the fair value of the investments in the underlying funds. The Company's private equity funds provide customers alternative investment opportunities as limited partners of the funds. As fund of funds, the private equity funds invest in other limited partnerships or limited liability companies that invest substantially all of their assets in U.S. companies pursuing diversified investment strategies including early-stage venture capital, distressed securities and corporate or asset buy-outs. Private equity fund assets are long-term, illiquid investments. No secondary market exists for these assets. The private equity funds typically invest in funds that provide no redemption rights to investors. The fair value of the private equity investments may only be realized through cash distributions from the underlying funds.

See Note 7 for disclosure of the fair value of the private equity funds using the net asset value per share of the underlying investments, as a practical expedient, included in Other assets in the Consolidated Balance Sheets of the Company.

The following represents the changes for the three and six months ended June 30, 2017 related to assets measured at fair value on a recurring basis using significant unobservable inputs (in thousands):



	Available for Sale Securities
	Municipal and other tax-exempt securities			Other debt securities			Residential mortgage loans held for sale
Balance, March 31, 2017	$	5,722		$	4,153		$	12,679
Transfer to Level 3 from Level 2¹	—			—			853
Purchases	—			—			—
Proceeds from sales	—			—			(1,030		)
Redemptions and distributions	(1,100		)	—			—
Gain (loss) recognized in earnings:
Mortgage banking revenue	—			—			233
Other comprehensive income (loss):
Net change in unrealized gain (loss)	33			(1		)	—
Balance, June 30, 2017	$	4,655		$	4,152		$	12,735


¹	Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.



	Available for Sale Securities
	Municipal and other tax-exempt			Other debt securities		Residential mortgage loans held for sale
Balance, Dec. 31, 2016	$	5,789		$	4,152	$	11,617
Transfer to Level 3 from Level 2¹	—			—		2,740
Purchases	—			—		—
Proceeds from sales	—			—		(1,702		)
Redemptions and distributions	(1,100		)	—		—
Gain (loss) recognized in earnings:
Mortgage banking revenue	—			—		80
Other comprehensive income (loss):
Net change in unrealized gain (loss)	(34		)	—		—
Balance, June 30, 2017	$	4,655		$	4,152	$	12,735


¹	Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.

The following represents the changes for the three and six months ended June 30, 2016 related to assets measured at fair value on a recurring basis using significant unobservable inputs (in thousands):



	Available for Sale Securities
	Municipal and other tax-exempt securities			Other debt securities		Residential mortgage loans held for sale
Balance, March 31, 2016	$	9,614		$	4,151	$	8,099
Transfer to Level 3 from Level 2¹	—			—		3,080
Purchases	—			—		—
Proceeds from sales	—			—		(1,249		)
Redemptions and distributions	—			—		—
Gain (loss) recognized in earnings:
Mortgage banking revenue	—			—		(181		)
Other comprehensive income (loss):
Net change in unrealized gain (loss)	(14		)	—		—
Balance, June 30, 2016	$	9,600		$	4,151	$	9,749


¹	Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.



	Available for Sale Securities
	Municipal and other tax-exempt			Other debt securities		Residential mortgage loans held for sale
Balance, Dec. 31, 2015	$	9,610		$	4,151	$	7,874
Transfer to Level 3 from Level 2¹	—			—		3,540
Purchases	—			—		—
Proceeds from sales	—			—		(1,362		)
Redemptions and distributions	—			—		—
Gain (loss) recognized in earnings
Mortgage banking revenue	—			—		(303		)
Other comprehensive income (loss):
Net change in unrealized gain (loss)	(10		)	—		—
Balance, June 30, 2016	$	9,600		$	4,151	$	9,749


¹	Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.

A summary of quantitative information about assets measured at fair value on a recurring basis using Significant Unobservable Inputs (Level 3) as of June 30, 2017 follows (in thousands):



	Par Value		Amortized Cost/Unpaid Principal Balance		Fair Value		Valuation Technique(s)		Unobservable Input	Range (Weighted Average)

Available for sale securities
Municipal and other tax-exempt securities	$	5,095	$	5,067	$	4,655	Discounted cash flows	¹	Interest rate spread	5.98%-5.98% (5.98%)	²
										90.00%-94.90% (92.93%)	³
Other debt securities	4,400		4,400		4,152		Discounted cash flows	¹	Interest rate spread	5.41%-6.72% (6.57%)	⁴
										94.31% - 94.38 (94.37%)	³

Residential mortgage loans held for sale	N/A		13,274		12,563		Quoted prices of loans sold in securitization transactions, with a liquidity discount applied		Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.	94.64%


¹	Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume.


²	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 360 to 446 basis points over average yields for comparable tax-exempt securities.


³	Represents fair value as a percentage of par value.


⁴	Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 3 percent.

A summary of quantitative information about Recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of December 31, 2016 follows (in thousands):



	Par Value		Amortized Cost/Unpaid Principal Balance		Fair Value		Valuation Technique(s)		Unobservable Input	Range (Weighted Average)

Available for sale securities
Municipal and other tax-exempt securities	$	6,195	$	6,163	$	5,789	Discounted cash flows	¹	Interest rate spread	5.91%-6.21% (6.16%)	²
										90.00%-93.40% (92.20%)	³
Other debt securities	4,400		4,400		4,152		Discounted cash flows	¹	Interest rate spread	6.01%-6.26% (6.23%)	⁴
										94.34% - 94.36 (94.36%)	³
Residential mortgage loans held for sale	N/A		12,431		11,617		Quoted prices of loans sold in securitization transactions, with a liquidity discount applied		Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.	93.45%


¹	Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume.


²	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 467 to 525 basis points over average yields for comparable tax-exempt securities.


³	Represents fair value as a percentage of par value.


⁴	Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 1 percent.

A summary of quantitative information about Recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of June 30, 2016 follows (in thousands):



	Par Value		Amortized Cost		Fair Value		Valuation Technique(s)		Unobservable Input	Range (Weighted Average)

Available for sale securities
Municipal and other tax-exempt securities	$	10,370	$	10,312	$	9,600	Discounted cash flows	¹	Interest rate spread	5.34%-5.64% (5.60%)	²
										90.00%-93.28% (92.58%)	³
Other debt securities	4,400		4,400		4,151		Discounted cash flows	¹	Interest rate spread	5.51%-5.96% (5.91%)	⁴
										94.32% - 94.34 (94.34%)	³

Residential mortgage loans held for sale	N/A		10,518		9,749		Quoted prices of loans sold in securitization transactions, with a liquidity discount applied		Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.	92.69%


¹	Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume.


²	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 474 to 513 basis points over average yields for comparable tax-exempt securities.


³	Represents fair value as a percentage of par value.


⁴	Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 1 percent.

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

Assets measured at fair value on a non-recurring basis include 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) during the period. The carrying value represents only those assets with a balance at June 30, 2017 for which the fair value was adjusted during the six months ended June 30, 2017:



							Fair Value Adjustments for the
	Carrying Value at June 30, 2017						Three Months Ended June 30, 2017 Recognized in:				Six Months Ended June 30, 2017 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 and expenses of repossessed assets, net		Gross charge-offs against allowance for loan losses		Net losses and expenses of repossessed assets, net
Impaired loans	$	—	$	464	$	3,570	$	232	$	—	$	676	$	—
Real estate and other repossessed assets	—		3,488		530		—		772		—		906

The following represents the carrying value of assets measured at fair value on a non-recurring basis (and related losses) during the period. The carrying value represents only those assets with a balance at June 30, 2016 for which the fair value was adjusted during the six months ended June 30, 2016:



	Carrying Value at June 30, 2016						Fair Value Adjustments for the Three Months Ended June 30, 2016 Recognized in:				Six Months Ended June 30, 2016 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 and expenses of repossessed assets, net		Gross charge-offs against allowance for loan losses		Net losses and expenses of repossessed assets, net
Impaired loans	$	—	$	634	$	42,342	$	7,041	$	—	$	29,186	$	—
Real estate and other repossessed assets	—		5,709		1,693		—		751		—		1,068

The fair value of collateral-dependent impaired loans secured by real estate 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 impaired 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 the same or 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 June 30, 2017 follows (in thousands):



	Fair Value		Valuation Technique(s)	Unobservable Input	Range (Weighted Average)
Impaired loans	$	3,570	Discounted cash flows	Recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs	75% - 90% (83%)¹
Real estate and other repossessed assets	530		Appraised value, as adjusted	Marketability adjustment off appraised value²	65% - 88% (80%)


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.

A summary of quantitative information about Non-recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of June 30, 2016 follows (in thousands):



	Fair Value		Valuation Technique(s)	Unobservable Input	Range (Weighted Average)
Impaired loans	$	42,342	Discounted cash flows	Recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs	25% - 71% (58%)¹
Real estate and other repossessed assets	1,693		Appraised value, as adjusted	Marketability adjustments off appraised value2	68% - 80% (71%)


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

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 basis as of June 30, 2017 (dollars in thousands):



	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	$	561,587		$	561,587	$	561,587	$	—	$	—
Interest-bearing cash and cash equivalents	2,078,831			2,078,831		2,078,831		—		—
Trading securities:								—
U.S. government agency debentures	20,954			20,954		—		20,954		—
U.S. government agency residential mortgage-backed securities	365,171			365,171		—		365,171		—
Municipal and other tax-exempt securities	45,444			45,444		—		45,444		—
Other trading securities	9,845			9,845		—		9,845		—
Total trading securities	441,414			441,414		—		441,414		—
Investment securities:
Municipal and other tax-exempt securities	267,375			270,531		—		270,531		—
U.S. government agency residential mortgage-backed securities	18,035			18,642		—		18,642		—
Other debt securities	205,016			226,502		—		226,502		—
Total investment securities	490,426			515,675		—		515,675		—
Available for sale securities:
U.S. Treasury	998			998		998		—		—
Municipal and other tax-exempt securities	32,765			32,765		—		28,110		4,655
U.S. government agency residential mortgage-backed securities	5,382,377			5,382,377		—		5,382,377		—
Privately issued residential mortgage-backed securities	103,383			103,383		—		103,383		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,782,070			2,782,070		—		2,782,070		—
Other debt securities	4,152			4,152		—		—		4,152
Perpetual preferred stock	16,568			16,568		—		16,568		—
Equity securities and mutual funds	18,728			18,728		3,516		15,212		—
Total available for sale securities	8,341,041			8,341,041		4,514		8,327,720		8,807
Fair value option securities – U.S. government agency residential mortgage-backed securities	445,169			445,169		—		445,169		—
Residential mortgage loans held for sale	287,259			287,259		—		274,524		12,735
Loans:
Commercial	10,637,955			10,413,704		—		—		10,413,704
Commercial real estate	3,688,592			3,636,365		—		—		3,636,365
Residential mortgage	1,939,198			1,950,577		—		—		1,950,577
Personal	917,900			909,055		—		—		909,055
Total loans	17,183,645			16,909,701		—		—		16,909,701
Allowance for loan losses	(250,061		)	—		—		—		—
Loans, net of allowance	16,933,584			16,909,701		—		—		16,909,701
Mortgage servicing rights	245,239			245,239		—		—		245,239
Derivative instruments with positive fair value, net of cash collateral	280,289			280,289		46,366		233,923		—
Deposits with no stated maturity	20,120,352			20,120,352		—		—		20,120,352
Time deposits	2,196,122			2,164,115		—		—		2,164,115
Other borrowed funds	5,696,666			5,664,273		—		—		5,664,273
Subordinated debentures	144,658			147,204		—		147,204		—
Derivative instruments with negative fair value, net of cash collateral	285,819			285,819		20,915		264,904		—

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 basis as of December 31, 2016 (dollars in thousands):



	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	$	620,846		$	620,846	$	620,846	$	—	$	—
Interest-bearing cash and cash equivalents	1,916,651			1,916,651		1,916,651		—		—
Trading securities:								—
U.S. government agency debentures	6,234			6,234		—		6,234		—
U.S. government agency residential mortgage-backed securities	310,067			310,067		—		310,067		—
Municipal and other tax-exempt securities	14,427			14,427		—		14,427		—
Other trading securities	6,900			6,900		—		6,900		—
Total trading securities	337,628			337,628		—		337,628		—
Investment securities:
Municipal and other tax-exempt securities	320,364			321,225		—		321,225		—
U.S. government agency residential mortgage-backed securities	20,777			21,473		—		21,473		—
Other debt securities	205,004			222,795		—		222,795		—
Total investment securities	546,145			565,493		—		565,493		—
Available for sale securities:
U.S. Treasury	999			999		999		—		—
Municipal and other tax-exempt securities	40,993			40,993		—		35,204		5,789
U.S. government agency residential mortgage-backed securities	5,460,386			5,460,386		—		5,460,386		—
Privately issued residential mortgage-backed securities	115,535			115,535		—		115,535		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	3,017,933			3,017,933		—		3,017,933		—
Other debt securities	4,152			4,152		—		—		4,152
Perpetual preferred stock	18,474			18,474		—		18,474		—
Equity securities and mutual funds	18,357			18,357		3,495		14,862		—
Total available for sale securities	8,676,829			8,676,829		4,494		8,662,394		9,941
Fair value option securities – U.S. government agency residential mortgage-backed securities	77,046			77,046		—		77,046		—
Residential mortgage loans held for sale	301,897			301,897		—		290,280		11,617
Loans:
Commercial	10,390,824			10,437,016		—		—		10,437,016
Commercial real estate	3,809,046			3,850,981		—		—		3,850,981
Residential mortgage	1,949,832			2,025,159		—		—		2,025,159
Personal	839,958			864,904		—		—		864,904
Total loans	16,989,660			17,178,060		—		—		17,178,060
Allowance for loan losses	(246,159		)	—		—		—		—
Loans, net of allowance	16,743,501			17,178,060		—		—		17,178,060
Mortgage servicing rights	247,073			247,073		—		—		247,073
Derivative instruments with positive fair value, net of cash collateral	689,872			689,872		7,541		682,331		—
Deposits with no stated maturity	20,526,295			20,526,295		—		—		20,526,295
Time deposits	2,221,800			2,218,303		—		—		2,218,303
Other borrowed funds	5,572,662			5,556,327		—		—		5,556,327
Subordinated debentures	144,640			128,903		—		128,903		—
Derivative instruments with negative fair value, net of cash collateral	664,531			664,531		6,972		657,559		—

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 basis as of June 30, 2016 (dollars in thousands):



	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	$	498,713		$	498,713	$	498,713	$	—	$	—
Interest-bearing cash and cash equivalents	1,907,838			1,907,838		1,907,838		—		—
Trading securities:								—
U.S. government agency debentures	18,909			18,909		—		18,909		—
U.S. government agency residential mortgage-backed securities	122,306			122,306		—		122,306		—
Municipal and other tax-exempt securities	52,721			52,721		—		52,721		—
Other trading securities	17,686			17,686		—		17,686		—
Total trading securities	211,622			211,622		—		211,622		—
Investment securities:
Municipal and other tax-exempt securities	334,551			340,700		—		340,700		—
U.S. government agency residential mortgage-backed securities	23,750			25,233		—		25,233		—
Other debt securities	202,410			233,129		—		233,129		—
Total investment securities	560,711			599,062		—		599,062		—
Available for sale securities:
U.S. Treasury	1,004			1,004		1,004		—		—
Municipal and other tax-exempt securities	50,262			50,262		—		40,662		9,600
U.S. government agency residential mortgage-backed securities	5,700,268			5,700,268		—		5,700,268		—
Privately issued residential mortgage-backed securities	126,313			126,313		—		126,313		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,911,946			2,911,946		—		2,911,946		—
Other debt securities	4,151			4,151		—		—		4,151
Perpetual preferred stock	17,931			17,931		—		17,931		—
Equity securities and mutual funds	18,814			18,814		3,785		15,029		—
Total available for sale securities	8,830,689			8,830,689		4,789		8,812,149		13,751
Fair value option securities:
U.S. Treasury	25,306			25,306		25,306		—		—
U.S. government agency residential mortgage-backed securities	237,959			237,959		—		237,959		—
Total fair value option securities	263,265			263,265		25,306		237,959		—
Residential mortgage loans held for sale	430,728			430,728		—		420,979		9,749
Loans:
Commercial	10,356,437			10,172,701		—		—		10,172,701
Commercial real estate	3,581,966			3,563,378		—		—		3,563,378
Residential mortgage	1,880,923			1,913,208		—		—		1,913,208
Personal	587,423			582,353		—		—		582,353
Total loans	16,406,749			16,231,640		—		—		16,231,640
Allowance for loan losses	(243,259		)	—		—		—		—
Loans, net of allowance	16,163,490			16,231,640		—		—		16,231,640
Mortgage servicing rights	190,747			190,747		—		—		190,747
Derivative instruments with positive fair value, net of cash collateral	883,673			883,673		7,246		876,427		—
Deposits with no stated maturity	18,512,740			18,512,740		—		—		18,512,740
Time deposits	2,247,061			2,252,212		—		—		2,252,212
Other borrowed funds	6,360,199			6,342,885		—		—		6,342,885
Subordinated debentures	371,812			371,808		—		150,234		221,574
Derivative instruments with negative fair value, net of cash collateral	719,159			719,159		4,808		714,351		—

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.

The following methods and assumptions were used in estimating the fair value of these financial instruments:

Cash and Cash Equivalents

The book value reported in the consolidated balance sheets for cash and short-term instruments approximates those assets’ fair values.

Securities

The fair values of securities are generally based on Significant Other Observable Inputs such as quoted prices for comparable instruments or interest rates and credit spreads, yield curves, volatilities, prepayment speeds and loss severities.

Loans

The fair value of loans, excluding loans held for sale, are based on discounted cash flow analyses using interest rates and credit and liquidity spreads currently being offered for loans with similar remaining terms to maturity and risk, adjusted for the impact of interest rate floors and ceilings, which are classified as Significant Unobservable Inputs. The fair values of loans were estimated to approximate their discounted cash flows less loan loss allowances allocated to these loans of $223 million at June 30, 2017, $218 million at December 31, 2016 and $217 million at June 30, 2016. A summary of assumptions used in determining the fair value of loans follows:



	Range of Contractual Yields	Average Re-pricing (in years)	Discount Rate
June 30, 2017:
Commercial	0.38% - 30.00%	0.64	0.71% - 4.56%
Commercial real estate	0.38% - 18.00%	0.77	1.03% - 4.31%
Residential mortgage	1.74% - 18.00%	2.18	1.75% - 4.19%
Personal	0.25% - 21.00%	0.28	0.70% - 4.68%

December 31, 2016:
Commercial	0.38% - 30.00%	0.70	0.64% - 4.60%
Commercial real estate	0.38% - 18.00%	0.71	0.94% - 4.27%
Residential mortgage	1.74% - 18.00%	2.27	1.71% - 4.26%
Personal	0.25% - 21.00%	0.40	1.03% - 4.59%

June 30, 2016:
Commercial	0.38% - 30.00%	0.69	0.55% - 3.68%
Commercial real estate	0.38% - 18.00%	0.73	0.80% - 3.65%
Residential mortgage	1.70% - 18.00%	1.97	1.25% - 3.75%
Personal	0.25% - 21.00%	0.35	0.71% - 3.91%

Deposits

The fair values of time deposits are based on discounted cash flow analyses using interest rates currently being offered on similar transactions which are considered Significant Unobservable Inputs. Estimated fair value of deposits with no stated maturity, which includes demand deposits, transaction deposits, money market deposits and savings accounts, is equal to the amount payable on demand. Although market premiums paid reflect an additional value for these low cost deposits, adjusting fair value for the expected benefit of these deposits is prohibited. Accordingly, the positive effect of such deposits is not included in the tables above.

A summary of assumptions used in determining the fair value of time deposits follows:



	Range of Contractual Yields	Average Re-pricing (in years)	Discount Rate
June 30, 2017	0.03% - 10.00%	1.91	1.81% - 2.12%
December 31, 2016	0.02% - 9.65%	1.96	1.57% - 2.00%
June 30, 2016	0.03% - 9.64%	2.15	1.16% - 1.43%

Other Borrowings and Subordinated Debentures

The fair values of these instruments are based upon discounted cash flow analyses using interest rates currently being offered on similar instruments, which are considered Significant Unobservable Inputs. A summary of assumptions used in determining the fair value of other borrowings and subordinated debentures follows:



	Range of Contractual Yields	Average Re-pricing (in years)	Discount Rate
June 30, 2017:
Other borrowed funds	0.25% - 3.58%	0.02	1.06% - 3.69%
Subordinated debentures	5.38%	16.90	4.89%

December 31, 2016:
Other borrowed funds	0.25% - 3.50%	0.00	0.55% - 3.22%
Subordinated debentures	5.38%	16.86	6.11%

June 30, 2016:
Other borrowed funds	0.25% - 3.28%	0.02	0.30% - 2.92%
Subordinated debentures	1.32% - 5.38%	8.35	2.16% - 5.38%

Off-Balance Sheet Instruments

The fair values of commercial loan commitments are based on fees currently charged to enter into similar agreements, taking into account the remaining terms of the agreements. The fair values of these off-balance sheet instruments were not significant at June 30, 2017, December 31, 2016 or June 30, 2016.

Fair Value Election

As more fully disclosed in Note 2 and Note 6 to the Consolidated Financial Statements, the Company has elected to carry all residential mortgage-backed securities guaranteed by U.S. government agencies and U.S. Treasury 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.

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.

Income Tax Disclosure [Text Block]

Federal and State Income Taxes Federal and State Income Taxes

6 Months Ended

Jun. 30, 2017

Income Tax Disclosure [Abstract]

Federal and State Income Taxes

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



	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Amount:
Federal statutory tax	$	47,800		$	33,869		$	92,168		$	55,715
Tax exempt revenue	(3,224		)	(2,568		)	(6,335		)	(5,100		)
Effect of state income taxes, net of federal benefit	2,944			1,557			5,389			3,858
Utilization of tax credits:
Low-income housing tax credit, net of amortization	(526		)	(572		)	(2,249		)	(1,882		)
Other tax credits	(363		)	(521		)	(727		)	(1,042		)
Bank-owned life insurance	(775		)	(810		)	(1,547		)	(1,601		)
Share-based compensation	1,636			—			(2,301		)	—
Other, net	213			(458		)	1,410			1,977
Total income tax expense	$	47,705		$	30,497		$	85,808		$	51,925



	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Percent of pretax income:
Federal statutory tax	35.0	%	35.0	%	35.0	%	35.0	%
Tax exempt revenue	(2.4	)	(2.7	)	(2.4	)	(3.2	)
Effect of state income taxes, net of federal benefit	2.2		1.6		2.0		2.4
Utilization of tax credits:
Low-income housing tax credit, net of amortization	(0.4	)	(0.6	)	(0.8	)	(1.2	)
Other tax credits	(0.3	)	(0.5	)	(0.3	)	(0.6	)
Bank-owned life insurance	(0.6	)	(0.8	)	(0.6	)	(1.0	)
Share-based compensation	1.2		—		(0.9	)	—
Other, net	0.2		(0.5	)	0.6		1.2
Total	34.9	%	31.5	%	32.6	%	32.6	%

Subsequent Events	6 Months Ended
Subsequent Events	Jun. 30, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company evaluated events from the date of the consolidated financial statements on June 30, 2017 through the issuance of those consolidated financial statements included in this Quarterly Report on Form 10-Q. No events were identified requiring recognition in and/or disclosure in the consolidated financial statements.

Significant Accounting Policies (Policies)	6 Months Ended
Significant Accounting Policies (Policies)	Jun. 30, 2017
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	The accompanying unaudited consolidated financial statements of BOK Financial Corporation (“BOK Financial” or “the Company”) have been prepared in accordance with accounting principles for interim financial information generally accepted in the United States and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included.
Principles of Consolidation [Policy Text Block]	The unaudited consolidated financial statements include accounts of BOK Financial and its subsidiaries, principally BOKF, NA (“the Bank”), BOK Financial Securities, Inc., The Milestone Group, Inc. and Cavanal Hill Investment Management Inc. Operating divisions of the Bank include Bank of Albuquerque, Bank of Arizona, Bank of Arkansas, Bank of Oklahoma, Bank of Texas, Colorado State Bank and Trust, Mobank, BOK Financial Mortgage and the TransFund electronic funds network.
Reclassification, Policy [Policy Text Block]	Certain reclassifications have been made to conform to the current period presentation.
Newly Adopted and Pending Accounting Policies [Policy Text Block]	Newly Adopted and Pending Accounting Policies Financial Accounting Standards Board (“FASB”) FASB Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers ("ASU 2014-09") On May 28, 2014, the FASB issued ASU 2014-09 to clarify the principles for recognizing revenue by providing a more robust framework that will give greater consistency and comparability in revenue recognition practices. In the new framework, an entity recognizes revenue in an amount that reflects the consideration to which the entity expects to be entitled in exchange for goods or services. The new model requires the identification of performance obligations included in contracts with customers, a determination of the transaction price and an allocation of the price to those performance obligations. The entity recognizes revenue when performance obligations are satisfied. ASU 2014-09 is effective for the Company for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. Net interest revenue from financial assets and liabilities is explicitly excluded from the scope of ASU 2014-09. Management expects that most fees and commissions revenue will not be affected. The Company continues to evaluate the impact of ASU 2014-09 on Fiduciary and Asset Management Revenue and Transaction Card Revenue, which represents 19% of gross revenue and 43% of fees and commissions revenue for the first half of 2017. Timing of revenue recognition and gross versus net presentation may be affected. Management will adopt the standard in the first quarter of 2018 with a cumulative effect adjustment to opening retained earnings if such adjustment is significant. FASB Accounting Standards Update No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net) ("ASU 2016-08") On March 17, 2016, the FASB Issued ASU 2016-08 to amend the principal versus agent implementation guidance in ASU 2014-09. The ASU clarifies that an entity should evaluate whether it is the principal or the agent for each specified good or service promised in a contract with a customer. ASU 2016-08 is effective for the Company for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. The Company is evaluating the impact the adoption of ASU 2016-08 will have on the Company's financial statements along with ASU 2014-09. FASB Accounting Standards Update No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01") On January 5, 2016, the FASB issued ASU 2016-01 over the recognition and measurement of financial assets and liabilities. The update requires equity investments, in general, to be measured at fair value with changes in fair value recognized in earnings. It also eliminates the requirement to disclose the methods and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost, requires entities to use the exit price notion when measuring fair value, requires an entity to present separately in other comprehensive income the portion of the total change in fair value of a liability resulting from a change in the instrument-specific credit risk when the fair value option has been elected, requires separate presentation of financial assets and liabilities by measurement category and form on the balance sheet or accompanying notes, clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity's other deferred tax assets, and simplifies the impairment assessment of equity investments without readily determinable fair values. The ASU is effective for the Company for interim and annual periods beginning after December 15, 2017. Upon adoption, unrealized gains and losses from equity securities will be reclassified from other comprehensive income to retained earnings. At June 30, 2017, the Company had $3.2 million of unrealized gains included in accumulated other comprehensive income. 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. Lessees will be required to recognize an obligation for future lease payments measured on a discounted basis and a right-of-use asset. The ASU is effective for the Company for interim and annual periods beginning after December 15, 2018 and requires transition through a modified retrospective approach for leases existing at or entered into after January 1, 2017. The Company is evaluating the impact the adoption of ASU 2016-02 will have on the Company's financial statements. FASB Accounting Standards Update No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting ("ASU 2016-09") On March 30, 2016, the FASB issued ASU 2016-09 to simplify multiple aspects of accounting for employee share-based payment transactions including accounting income taxes, forfeitures, and statutory tax withholding requirements. The ASU became effective for annual reporting periods beginning after December 15, 2016, including interim periods within those annual reporting periods. Implementation of ASU 2016-09 decreased tax expense $2.3 million in the first six months of 2017. 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 in order to provide more timely recording of credit losses on loans and other financial instruments. The ASU adds an impairment model (known as the current expected credit loss ("CECL") model) that is based on expected credit losses rather than incurred credit losses. It requires measurement of all expected credit losses for financial assets carried at amortized cost, including loans and investment securities, based on historical experience, current conditions, and reasonable and supportable forecasts. ASU 2016-13 also changes the recognition of other-than-temporary impairment of available for sale securities to an allowance methodology from a direct write-down methodology. ASU 2016-13 will be effective for the Company for annual reporting periods beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for annual reporting periods beginning after December 15, 2018. ASU 2016-13 will be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The Company is evaluating the impact the adoption of ASU 2016-13 will have on the Company's financial statements. FASB Accounting Standards Update No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments ("ASU 2016-15") On August 26, 2016, the FASB issued ASU 2016-15, which amends guidance in ASC 230 on the classification of certain cash receipts and payments in the statement of cash flows. The amendments address eight cash flow issues. ASU 2016-15 is effective for the Company for interim and annual reporting periods beginning after December 15, 2017. Entities generally must apply the guidance retrospectively to all periods presented. Adoption of ASU 2016-15 is not expected to have a material impact on the Company's financial statements.
Derivatives, Policy [Policy Text Block]	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 reported in earnings as they occur. Credit risk is also considered in determining fair value. When bilateral netting agreements or similar arrangements 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 type by counterparty basis. Derivative contracts may 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. None of these derivative contracts have been designated as hedging instruments for accounting purposes. Customer Risk Management Programs BOK Financial offers programs to 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 borrowers to modify interest rate terms of their loans or to-be-announced securities used by mortgage banking customers to hedge their loan production. Derivative contracts are executed between the customers and BOK Financial. Offsetting contracts are executed between BOK Financial and other selected counterparties to minimize the risk of 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. Internal Risk Management Programs BOK Financial may use derivative contracts in managing its interest rate sensitivity, as part of its economic hedge of the change in the fair value of mortgage servicing rights and as an economic hedge of trading securities. As of June 30, 2017, derivative contracts under the internal risk management programs were primarily used as part of the economic hedges of the change in the fair value of the mortgage servicing rights and trading securities. As discussed in Note 6, 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 6 for additional discussion of notional, fair value and impact on earnings of these contracts.
Loans and Allowances for Credit Losses, 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 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 principal amount outstanding. 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 more than 90 days 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 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. Loans to borrowers experiencing financial difficulties may be modified in troubled debt restructurings ("TDRs"). All TDRs are 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. Generally, principal and accrued but unpaid interest is not voluntarily forgiven. Performing loans may be renewed under the current collateral value, debt service ratio and other underwriting standards. Nonaccruing loans may be renewed and will remain classified as nonaccruing. 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 a quarterly evaluation of available cash resources and collateral value 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. 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 may have 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 impaired because we do not expect to receive all principal and interest based on the loan's contractual terms. 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 the 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 based on 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 a further disaggregation of portfolio segments based on the risk characteristics of the loans and the Company’s method for monitoring and assessing credit risk.
Loans and Allowances for Credit Losses, Allowances for Credit Losses [Policy Text Block]	Allowances for Credit Losses BOK Financial maintains an allowance for loan losses and an accrual for off-balance sheet credit risk. 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. As discussed in greater detail in Note 6, the Company also has separate accruals for off-balance sheet credit risk related to residential mortgage loans previously sold with full or partial recourse and for residential mortgage loans sold to government sponsored agencies under standard representations and warranties. The appropriateness of the allowance for loan losses and accrual for off-balance sheet credit losses (collectively "allowance for credit losses") is assessed by management based on an ongoing quarterly evaluation of the probable estimated losses inherent in the portfolio, including probable losses on both outstanding loans and unused commitments. The allowance for loan losses consists of specific allowances attributed to impaired loans that have not yet been charged down to amounts we expect to recover, general allowances for unimpaired loans based on estimated loss rates by loan class and nonspecific allowances based on general economic conditions, risk concentration and related factors. There have been no material changes in the approach or techniques utilized in developing the allowance for loan losses and the accrual for off-balance sheet credit losses for the three and six months ended June 30, 2017. Loans are considered to be impaired when it becomes probable that BOK Financial will be unable to collect all amounts due according to the contractual terms of the loan agreements. Internally risk graded loans are evaluated individually for impairment. Substantially all commercial and commercial real estate loans and certain residential mortgage and consumer loans are risk graded based on evaluation of the borrowers' ability to repay. Certain commercial loans and most residential mortgage and consumer loans are small balance, homogeneous pools of loans that are not risk graded. Non-risk graded loans are identified as impaired based on performance status. Generally, non-risk graded loans 90 days or more past due or modified in a TDR or in bankruptcy are considered to be impaired. Specific allowances for impaired loans are measured 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. Collateral value of real property is generally based on third party appraisals that conform to Uniform Standards of Professional Appraisal Practice, less estimated selling costs. Appraised values are on an "as-is" basis and are generally not adjusted by the Company. Updated appraisals are obtained at least annually or more frequently if market conditions indicate collateral values have declined. Collateral value of mineral rights is generally determined by our internal staff of engineers based on projected cash flows under current market conditions. Collateral values and available cash resources that support impaired loans are evaluated quarterly. Historical statistics may be used as a practical way to estimate impairment in limited situations, such as when a collateral dependent loan is identified as impaired at the end of a reporting period, until an updated appraisal of collateral value is received or a full assessment of future cash flows is completed. Estimates of future cash flows and collateral values require significant judgments and may be volatile. General allowances for unimpaired loans are based on estimated loss rates by loan class. The gross loss rate for each loan class is determined by the greater of the current gross loss rate based on the most recent twelve months or a ten-year gross loss rate. Recoveries are not directly considered in the estimation of loss rates. Recoveries generally do not follow predictable patterns and are not received until well after the charge-off date as a result of protracted legal actions. For risk graded loans, gross loss rates are adjusted for changes in risk grading. For each loan class, the current weighted average risk grade is compared to the long-term average risk grade. This comparison determines whether credit risk in each loan class is increasing or decreasing. Loss rates are adjusted upward or downward in proportion to changes in average risk grading. General allowances for unimpaired loans also consider inherent risks identified for each loan class. Inherent risks consider loss rates that most appropriately represent the current credit cycle and other factors attributable to specific loan classes which have not yet been represented in the gross loss rates or risk grading. These factors include changes in commodity prices or engineering imprecision, which may affect the value of reserves that secure our energy loan portfolio, construction risk that may affect commercial real estate loans, changes in regulations and public policy that may disproportionately impact health care loans and changes in loan products. Nonspecific allowances are maintained for risks beyond factors specific to a particular loan or loan class. These factors include trends in the economy of our primary lending areas, concentrations in large balance loans and other relevant factors. An accrual for off-balance sheet credit losses is included in Other liabilities in the Consolidated Balance Sheets. The appropriateness of this accrual is determined in the same manner as the allowance for loan losses. 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.

Securities (Tables)

6 Months Ended

Jun. 30, 2017

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):



	June 30, 2017					December 31, 2016					June 30, 2016
	Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)
U.S. government agency debentures	$	20,954	$	(9	)	$	6,234	$	(4	)	$	18,909	$	(8	)
U.S. government agency residential mortgage-backed securities	365,171		(1,032		)	310,067		635			122,306		363
Municipal and other tax-exempt securities	45,444		230			14,427		50			52,721		262
Other trading securities	9,845		(175		)	6,900		57			17,686		169
Total trading securities	$	441,414	$	(986	)	$	337,628	$	738		$	211,622	$	786

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

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



	June 30, 2017
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss
Municipal and other tax-exempt	$	267,375	$	270,531	$	3,384	$	(228	)
U.S. government agency residential mortgage-backed securities – Other	18,035		18,642		668		(61		)
Other debt securities	205,016		226,502		22,040		(554		)
Total investment securities	$	490,426	$	515,675	$	26,092	$	(843	)


¹	Gross unrealized gains and losses are not recognized in Accumulated Other Comprehensive Income "AOCI" in the Consolidated Balance Sheets.



	December 31, 2016
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss
Municipal and other tax-exempt	$	320,364	$	321,225	$	2,272	$	(1,411	)
U.S. government agency residential mortgage-backed securities – Other	20,777		21,473		767		(71		)
Other debt securities	205,004		222,795		18,115		(324		)
Total investment securities	$	546,145	$	565,493	$	21,154	$	(1,806	)


¹	Gross unrealized gains and losses are not recognized in AOCI in the Consolidated Balance Sheets.



	June 30, 2016
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss
Municipal and other tax-exempt	$	334,551	$	340,700	$	6,234	$	(85	)
U.S. government agency residential mortgage-backed securities – Other	23,750		25,233		1,483		—
Other debt securities	202,410		233,129		30,723		(4		)
Total investment securities	$	560,711	$	599,062	$	38,440	$	(89	)


¹	Gross unrealized gains and losses are not recognized in AOCI in the Consolidated Balance Sheets.

The amortized cost and fair values of investment securities at June 30, 2017, 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 Maturity²
Municipal and other tax-exempt:
Amortized cost	$	90,415		$	122,560		$	10,739		$	43,661		$	267,375		3.48
Fair value	90,436			122,914			11,220			45,961			270,531
Nominal yield¹	1.66		%	2.12		%	4.88		%	5.05		%	2.55		%
Other debt securities:
Amortized cost	14,286			45,638			130,279			14,813			205,016			6.59
Fair value	14,482			48,973			148,415			14,632			226,502
Nominal yield	3.84		%	4.95		%	5.75		%	4.46		%	5.35		%
Total fixed maturity securities:
Amortized cost	$	104,701		$	168,198		$	141,018		$	58,474		$	472,391		4.83
Fair value	104,918			171,887			159,635			60,593			497,033
Nominal yield	1.95		%	2.89		%	5.69		%	4.90		%	3.77		%
Residential mortgage-backed securities:
Amortized cost													$	18,035		³
Fair value													18,642
Nominal yield⁴													2.76		%
Total investment securities:
Amortized cost													$	490,426
Fair value													515,675
Nominal yield													3.73		%


¹	Calculated on a taxable equivalent basis using a 39 percent effective tax rate.


²	Expected maturities may differ from contractual maturities, because borrowers may have the right to call or prepay obligations with or without penalty.


³	The average expected lives of residential mortgage-backed securities were 4.7 years based upon current prepayment assumptions.


⁴	The nominal yield on residential mortgage-backed securities is based upon prepayment assumptions at the purchase date. Actual yields earned may differ significantly based upon actual prepayments. See Quarterly Financial Summary - Unaudited for current yields on the investment securities portfolio.

Available For Sale Securities [Table Text Block]

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



	June 30, 2017
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss			OTTI²
U.S. Treasury	$	1,000	$	998	$	—	$	(2	)	$	—
Municipal and other tax-exempt	32,885		32,765		293		(413		)	—
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	3,005,920		3,008,531		24,213		(21,602		)	—
FHLMC	1,412,376		1,412,472		7,785		(7,689		)	—
GNMA	938,086		936,365		3,641		(5,362		)	—
Other	25,000		25,009		52		(43		)	—
Total U.S. government agencies	5,381,382		5,382,377		35,691		(34,696		)	—
Private issue:
Alt-A loans	38,334		46,903		8,569		—			—
Jumbo-A loans	48,322		56,480		8,158		—			—
Total private issue	86,656		103,383		16,727		—			—
Total residential mortgage-backed securities	5,468,038		5,485,760		52,418		(34,696		)	—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,788,543		2,782,070		7,804		(14,277		)	—
Other debt securities	4,400		4,152		—		(248		)	—
Perpetual preferred stock	12,562		16,568		4,006		—			—
Equity securities and mutual funds	17,572		18,728		1,219		(63		)	—
Total available for sale securities	$	8,325,000	$	8,341,041	$	65,740	$	(49,699	)	$	—

¹ Gross unrealized gain/loss recognized in AOCI in the consolidated balance sheet.

² Amounts represent unrealized loss that remains in AOCI after an other-than-temporary credit loss has been recognized in income.



	December 31, 2016
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss			OTTI²
U.S. Treasury	$	1,000	$	999	$	—	$	(1	)	$	—
Municipal and other tax-exempt	41,050		40,993		343		(400		)	—
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	3,062,525		3,055,676		25,066		(31,915		)	—
FHLMC	1,534,451		1,531,116		8,475		(11,810		)	—
GNMA	878,375		873,594		2,259		(7,040		)	—
Total U.S. government agencies	5,475,351		5,460,386		35,800		(50,765		)	—
Private issue:
Alt-A loans	44,245		51,512		7,485		—			(218		)
Jumbo-A loans	56,947		64,023		7,092		(16		)	—
Total private issue	101,192		115,535		14,577		(16		)	(218		)
Total residential mortgage-backed securities	5,576,543		5,575,921		50,377		(50,781		)	(218		)
Commercial mortgage-backed securities guaranteed by U.S. government agencies	3,035,750		3,017,933		5,472		(23,289		)	—
Other debt securities	4,400		4,152		—		(248		)	—
Perpetual preferred stock	15,561		18,474		2,913		—			—
Equity securities and mutual funds	17,424		18,357		1,060		(127		)	—
Total available for sale securities	$	8,691,728	$	8,676,829	$	60,165	$	(74,846	)	$	(218	)

¹ Gross unrealized gain/loss recognized in AOCI in the consolidated balance sheet.

² Amounts represent unrealized loss that remains in AOCI after an other-than-temporary credit loss has been recognized in income.



	June 30, 2016
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss			OTTI²
U.S. Treasury	$	1,000	$	1,004	$	4	$	—		$	—
Municipal and other tax-exempt	50,170		50,262		805		(713		)	—
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	2,908,698		2,988,974		80,549		(273		)	—
FHLMC	1,746,661		1,785,332		38,869		(198		)	—
GNMA	921,928		925,962		4,646		(612		)	—
Total U.S. government agencies	5,577,287		5,700,268		124,064		(1,083		)	—
Private issue:
Alt-A loans	49,522		54,536		5,461		—			(447		)
Jumbo-A loans	65,787		71,777		6,355		(36		)	(329		)
Total private issue	115,309		126,313		11,816		(36		)	(776		)
Total residential mortgage-backed securities	5,692,596		5,826,581		135,880		(1,119		)	(776		)
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,854,306		2,911,946		57,762		(122		)	—
Other debt securities	4,400		4,151		—		(249		)	—
Perpetual preferred stock	15,562		17,931		2,369		—			—
Equity securities and mutual funds	17,270		18,814		1,558		(14		)	—
Total available for sale securities	$	8,635,304	$	8,830,689	$	198,378	$	(2,217	)	$	(776	)


¹	Gross unrealized gain/loss recognized in AOCI in the consolidated balance sheet.


²	Amounts represent unrealized loss that remains in AOCI after an other-than-temporary credit loss has been recognized in income.

The amortized cost and fair values of available for sale securities at June 30, 2017, 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 Maturity⁵
U.S. Treasuries:
Amortized cost	$	1,000		$	—		$	—		$	—			$	1,000		0.55
Fair value	998			—			—			—				998
Nominal yield	0.87		%	—		%	—		%	—		%		0.87		%
Municipal and other tax-exempt:
Amortized cost	$	8,981		$	6,380		$	1,028		$	16,496			$	32,885		8.87
Fair value	9,021			6,497			1,081			16,166				32,765
Nominal yield¹	4.24		%	3.91		%	6.72		%	2.28		%	⁶	3.27		%
Commercial mortgage-backed securities:
Amortized cost	$	58,263		$	880,459		$	1,571,735		$	278,086			$	2,788,543		6.98
Fair value	58,147			879,286			1,568,732			275,905				2,782,070
Nominal yield	1.20		%	1.83		%	1.84		%	1.88		%		1.82		%
Other debt securities:
Amortized cost	$	—		$	—		$	—		$	4,400			$	4,400		30.16
Fair value	—			—			—			4,152				4,152
Nominal yield	—		%	—		%	—		%	1.71		%	⁶	1.71		%
Total fixed maturity securities:
Amortized cost	$	68,244		$	886,839		$	1,572,763		$	298,982			$	2,826,828		7.03
Fair value	68,166			885,783			1,569,813			296,223				2,819,985
Nominal yield	1.60		%	1.85		%	1.85		%	1.90		%		1.83		%
Residential mortgage-backed securities:
Amortized cost														$	5,468,038		²
Fair value														5,485,760
Nominal yield⁴														1.94		%
Equity securities and mutual funds:
Amortized cost														$	30,134		³
Fair value														35,296
Nominal yield														—		%
Total available-for-sale securities:
Amortized cost														$	8,325,000
Fair value														8,341,041
Nominal yield														1.90		%


¹	Calculated on a taxable equivalent basis using a 39 percent effective tax rate.


²	The average expected lives of mortgage-backed securities were 3.9 years years based upon current prepayment assumptions.


³	Primarily common stock and preferred stock of corporate issuers with no stated maturity.


⁴	The nominal yield on mortgage-backed securities is based upon prepayment assumptions at the purchase date. Actual yields earned may differ significantly based upon actual prepayments. See Quarterly Financial Summary –– Unaudited following for current yields on available for sale securities portfolio.


⁵	Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty.


⁶	Nominal yield on municipal and other tax-exempt securities and other debt securities with contractual maturity dates over ten years are based on variable rates which generally are reset within 35 days.

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



	Three Months Ended June 30,					Six Months Ended June 30,
	2017			2016		2017			2016
Proceeds	$	460,402		$	325,758	$	700,412		$	795,140
Gross realized gains	2,763			5,326		4,855			9,290
Gross realized losses	(2,383		)	—		(2,426		)	—
Related federal and state income tax expense	148			2,072		945			3,614

Securities Pledged As Collateral [Table Text Block]

A summary of investment and available for sale securities that have been pledged as collateral for repurchase agreements, public trust funds on deposit and for other purposes, as required by law was as follows (in thousands):



	June 30, 2017		Dec. 31, 2016		June 30, 2016
Investment:
Amortized cost	$	251,684	$	322,208	$	287,166
Fair value	255,097		323,808		293,625

Available for sale:
Amortized cost	6,327,666		7,353,116		7,502,361
Fair value	6,317,623		7,327,470		7,657,916

Schedule of Unrealized Loss on Investments [Table Text Block]

Temporarily Impaired Securities as of June 30, 2017

(in thousands):



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investment:
Municipal and other tax-exempt	82	$	111,078	$	149	$	3,000	$	79	$	114,078	$	228
U.S. government agency residential mortgage-backed securities – Other	1	3,810		61		—		—		3,810		61
Other debt securities	22	8,384		554		—		—		8,384		554
Total investment securities	105	$	123,272	$	764	$	3,000	$	79	$	126,272	$	843



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available for sale:
U.S. Treasury	1	$	997	$	2	$	—	$	—	$	997	$	2
Municipal and other tax-exempt	13	$	1,957	$	1	$	4,655	$	412	$	6,612	$	413
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	75	1,381,687		20,288		87,371		1,314		1,469,058		21,602
FHLMC	42	731,853		7,213		16,388		476		748,241		7,689
GNMA	21	291,806		3,766		76,605		1,596		368,411		5,362
Other	1	19,957		43		—		—		19,957		43
Total U.S. government agencies	139	2,425,303		31,310		180,364		3,386		2,605,667		34,696
Private issue:
Alt-A loans	—	—		—		—		—		—		—
Jumbo-A loans	—	—		—		—		—		—		—
Total private issue	—	—		—		—		—		—		—
Total residential mortgage-backed securities	139	2,425,303		31,310		180,364		3,386		2,605,667		34,696
Commercial mortgage-backed securities guaranteed by U.S. government agencies	121	1,388,406		12,690		78,828		1,587		1,467,234		14,277
Other debt securities	2	—		—		4,152		248		4,152		248
Perpetual preferred stocks	—	—		—		—		—		—		—
Equity securities and mutual funds	91	1,668		22		887		41		2,555		63
Total available for sale securities	367	$	3,818,331	$	44,025	$	268,886	$	5,674	$	4,087,217	$	49,699

Temporarily Impaired Securities as of December 31, 2016

(In thousands)



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investment:
Municipal and other tax-exempt	151	$	219,892	$	1,316	$	4,333	$	95	$	224,225	$	1,411
U.S. government agency residential mortgage-backed securities – Other	1	4,358		71		—		—		4,358		71
Other debt securities	41	11,820		322		855		2		12,675		324
Total investment securities	193	$	236,070	$	1,709	$	5,188	$	97	$	241,258	$	1,806



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available for sale:
U.S. Treasury	1	$	999	$	1	$	—	$	—	$	999	$	1
Municipal and other tax-exempt	24	$	15,666	$	22	$	4,689	$	378	$	20,355	$	400
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	91	1,787,644		30,238		72,105		1,677		1,859,749		31,915
FHLMC	58	964,017		11,210		18,307		600		982,324		11,810
GNMA	31	548,637		6,145		25,796		895		574,433		7,040
Total U.S. government agencies	180	3,300,298		47,593		116,208		3,172		3,416,506		50,765
Private issue¹:
Alt-A loans	5	7,931		174		7,410		44		15,341		218
Jumbo-A loans	1	—		—		6,098		16		6,098		16
Total private issue	6	7,931		174		13,508		60		21,439		234
Total residential mortgage-backed securities	186	3,308,229		47,767		129,716		3,232		3,437,945		50,999
Commercial mortgage-backed securities guaranteed by U.S. government agencies	171	1,904,584		22,987		38,875		302		1,943,459		23,289
Other debt securities	2	—		—		4,152		248		4,152		248
Perpetual preferred stocks	—	—		—		—		—		—		—
Equity securities and mutual funds	104	2,127		41		817		86		2,944		127
Total available for sale securities	488	$	5,231,605	$	70,818	$	178,249	$	4,246	$	5,409,854	$	75,064


¹	Includes securities for which an unrealized loss remains in AOCI after an other-than-temporary credit loss has been recognized in income.

Temporarily Impaired Securities as of June 30, 2016

(In thousands)



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investment:
Municipal and other tax-exempt	19	$	11,915	$	20	$	4,378	$	65	$	16,293	$	85
U.S. government agency residential mortgage-backed securities – Other	—	—		—		—		—		—		—
Other debt securities	1	—		—		858		4		858		4
Total investment securities	20	$	11,915	$	20	$	5,236	$	69	$	17,151	$	89



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available for sale:
U.S. Treasury	—	$	—	$	—	$	—	$	—	$	—	$	—
Municipal and other tax-exempt¹	17	$	375	$	—	$	10,289	$	713	$	10,664	$	713
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	4	97,910		267		15,401		6		113,311		273
FHLMC	1	—		—		22,338		198		22,338		198
GNMA	11	349,631		612		—		—		349,631		612
Total U.S. government agencies	16	447,541		879		37,739		204		485,280		1,083
Private issue¹:
Alt-A loans	5	8,513		241		8,291		206		16,804		447
Jumbo-A loans	9	7,076		36		7,877		329		14,953		365
Total private issue	14	15,589		277		16,168		535		31,757		812
Total residential mortgage-backed securities	30	463,130		1,156		53,907		739		517,037		1,895
Commercial mortgage-backed securities guaranteed by U.S. government agencies	11	103,955		37		65,857		85		169,812		122
Other debt securities	2	—		—		4,151		249		4,151		249
Perpetual preferred stocks	—	—		—		—		—		—		—
Equity securities and mutual funds	30	—		—		889		14		889		14
Total available for sale securities	90	$	567,460	$	1,193	$	135,093	$	1,800	$	702,553	$	2,993


¹	Includes securities for which an unrealized loss remains in AOCI after an other-than-temporary credit loss has been recognized in income.

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):



	June 30, 2017				Dec. 31, 2016					June 30, 2016
	Fair Value		Net Unrealized Gain (Loss)		Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)
U.S. Treasury	$	—	$	—	$	—	$	—		$	25,306	$	(43	)
U.S. government agency residential mortgage-backed securities	445,169		1,247		77,046		(1,777		)	237,959		4,476
Total	$	445,169	$	1,247	$	77,046	$	(1,777	)	$	263,265	$	4,433

Schedule of Restricted Equity Securities [Table Text Block]



	June 30, 2017		Dec. 31, 2016		June 30, 2016
Federal Reserve stock	$	36,676	$	36,498	$	36,283
Federal Home Loan Bank stock	274,113		270,541		283,155
Other	244		201		201
Total	$	311,033	$	307,240	$	319,639

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

Tabular disclosure of all investments in certain debt and equity securities for which the entity has the positive intent and ability to hold until maturity.

Derivative Instrument Detail [Abstract]

Derivatives (Tables)

6 Months Ended

Jun. 30, 2017

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 June 30, 2017 (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
To-be-announced residential mortgage-backed securities	$	16,174,687	$	57,948	$	(29,034	)	$	28,914	$	—		$	28,914
Interest rate swaps	1,450,193		29,932		—			29,932		(2,206		)	27,726
Energy contracts	891,480		56,824		(20,546		)	36,278		(21,267		)	15,011
Agricultural contracts	45,250		3,541		(1,027		)	2,514		—			2,514
Foreign exchange contracts	169,529		162,429		—			162,429		(7		)	162,422
Equity option contracts	100,159		4,437		—			4,437		(920		)	3,517
Total customer risk management programs	18,831,298		315,111		(50,607		)	264,504		(24,400		)	240,104
Internal risk management programs	10,680,498		40,185		—			40,185		—			40,185
Total derivative contracts	$	29,511,796	$	355,296	$	(50,607	)	$	304,689	$	(24,400	)	$	280,289

	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
To-be-announced residential mortgage-backed securities	$	16,174,687	$	53,829	$	(29,034	)	$	24,795	$	—		$	24,795
Interest rate swaps	1,450,193		29,982		—			29,982		(15,396		)	14,586
Energy contracts	874,625		53,895		(20,546		)	33,349		—			33,349
Agricultural contracts	45,262		3,538		(1,027		)	2,511		(2,511		)	—
Foreign exchange contracts	169,553		162,276		—			162,276		(3,188		)	159,088
Equity option contracts	100,159		4,437		—			4,437		—			4,437
Total customer risk management programs	18,814,479		307,957		(50,607		)	257,350		(21,095		)	236,255
Internal risk management programs	8,310,950		49,564		—			49,564		—			49,564
Total derivative contracts	$	27,125,429	$	357,521	$	(50,607	)	$	306,914	$	(21,095	)	$	285,819


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, 2016 (in thousands):



	Assets
	Notional ¹		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
To-be-announced residential mortgage-backed securities	$	16,949,152	$	180,695	$	(60,555	)	$	120,140	$	—		$	120,140
Interest rate swaps	1,403,408		34,442		—			34,442		(4,567		)	29,875
Energy contracts	835,566		64,140		(28,298		)	35,842		(71		)	35,771
Agricultural contracts	53,209		1,382		(515		)	867		—			867
Foreign exchange contracts	580,886		494,349		—			494,349		(5,183		)	489,166
Equity option contracts	100,924		4,357		—			4,357		(730		)	3,627
Total customer risk management programs	19,923,145		779,365		(89,368		)	689,997		(10,551		)	679,446
Internal risk management programs	2,514,169		10,426		—			10,426		—			10,426
Total derivative contracts	$	22,437,314	$	789,791	$	(89,368	)	$	700,423	$	(10,551	)	$	689,872

	Liabilities
	Notional ¹		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
To-be-announced residential mortgage-backed securities	$	16,637,532	$	176,928	$	(60,555	)	$	116,373	$	—		$	116,373
Interest rate swaps	1,403,408		34,442		—			34,442		(11,977		)	22,465
Energy contracts	820,365		64,306		(28,298		)	36,008		(31,534		)	4,474
Agricultural contracts	53,216		1,365		(515		)	850		(769		)	81
Foreign exchange contracts	580,712		494,695		—			494,695		(3,630		)	491,065
Equity option contracts	100,924		4,357		—			4,357		—			4,357
Total customer risk management programs	19,596,157		776,093		(89,368		)	686,725		(47,910		)	638,815
Internal risk management programs	2,582,202		25,716		—			25,716		—			25,716
Total derivative contracts	$	22,178,359	$	801,809	$	(89,368	)	$	712,441	$	(47,910	)	$	664,531


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 June 30, 2016 (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
To-be-announced residential mortgage-backed securities	$	18,774,134	$	183,118	$	(67,383	)	$	115,735	$	—		$	115,735
Interest rate swaps	1,299,985		54,978		—			54,978		(1,100		)	53,878
Energy contracts	757,669		59,103		(33,996		)	25,107		(155		)	24,952
Agricultural contracts	50,848		2,488		(1,609		)	879		(37		)	842
Foreign exchange contracts	701,436		675,804		—			675,804		(5,054		)	670,750
Equity option contracts	116,901		4,236		—			4,236		(478		)	3,758
Total customer risk management programs	21,700,973		979,727		(102,988		)	876,739		(6,824		)	869,915
Internal risk management programs	1,337,000		13,758		—			13,758		—			13,758
Total derivative contracts	$	23,037,973	$	993,485	$	(102,988	)	$	890,497	$	(6,824	)	$	883,673

	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
To-be-announced residential mortgage-backed securities	$	18,662,334	$	179,443	$	(67,383	)	$	112,060	$	(103,724	)	$	8,336
Interest rate swaps	1,299,985		55,404		—			55,404		(32,597		)	22,807
Energy contracts	734,538		58,033		(33,996		)	24,037		(11,784		)	12,253
Agricultural contracts	50,843		2,476		(1,609		)	867		—			867
Foreign exchange contracts	701,219		675,383		—			675,383		(4,723		)	670,660
Equity option contracts	116,901		4,236		—			4,236		—			4,236
Total customer risk management programs	21,565,820		974,975		(102,988		)	871,987		(152,828		)	719,159
Internal risk management programs	—		—		—			—		—			—
Total derivative contracts	$	21,565,820	$	974,975	$	(102,988	)	$	871,987	$	(152,828	)	$	719,159


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 income statement (in thousands):



	Three Months Ended
	June 30, 2017				June 30, 2016
	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 residential mortgage-backed securities	$	9,205	$	—	$	9,862		$	—
Interest rate swaps	665		—		723			—
Energy contracts	1,666		—		2,749			—
Agricultural contracts	11		—		32			—
Foreign exchange contracts	90		—		134			—
Equity option contracts	—		—		—			—
Total customer risk management programs	11,637		—		13,500			—
Internal risk management programs	6,485		3,241		(9		)	10,766
Total derivative contracts	$	18,122	$	3,241	$	13,491		$	10,766



	Six Months Ended
	June 30, 2017				June 30, 2016
	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 residential mortgage-backed securities	$	17,232	$	—	$	17,302		$	—
Interest rate swaps	1,124		—		1,048			—
Energy contracts	4,539		—		3,445			—
Agricultural contracts	20		—		61			—
Foreign exchange contracts	360		—		512			—
Equity option contracts	—		—		—			—
Total customer risk management programs	23,275		—		22,368			—
Internal risk management programs	6,018		2,791		(9		)	17,904
Total derivative contracts	$	29,293	$	2,791	$	22,359		$	17,904

Loans and Allowances for Credit Losses (Tables)

6 Months Ended

Jun. 30, 2017

Loans Receivable, Net [Abstract]

Schedule of Loans by Portfolio Segment [Table Text Block]

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



	June 30, 2017								December 31, 2016
	Fixed Rate		Variable Rate		Non-accrual		Total		Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	2,198,066	$	8,242,732	$	197,157	$	10,637,955	$	2,327,085	$	7,884,786	$	178,953	$	10,390,824
Commercial real estate	594,542		3,090,275		3,775		3,688,592		624,187		3,179,338		5,521		3,809,046
Residential mortgage	1,597,587		297,376		44,235		1,939,198		1,647,357		256,255		46,220		1,949,832
Personal	150,728		766,900		272		917,900		154,971		684,697		290		839,958
Total	$	4,540,923	$	12,397,283	$	245,439	$	17,183,645	$	4,753,600	$	12,005,076	$	230,984	$	16,989,660
Accruing loans past due (90 days)¹							$	1,414							$	5



	June 30, 2016
	Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	1,994,415	$	8,180,033	$	181,989	$	10,356,437
Commercial real estate	612,822		2,961,364		7,780		3,581,966
Residential mortgage	1,586,116		237,746		57,061		1,880,923
Personal	109,447		477,622		354		587,423
Total	$	4,302,800	$	11,856,765	$	247,184	$	16,406,749
Accruing loans past due (90 days)¹							$	2,899


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

Rollforward of Allowance For Loan Losses And Accrual for Off-Balance 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 for the three months ended June 30, 2017 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	137,616		$	58,343		$	18,177		$	7,247		$	27,327	$	248,710
Provision for loan losses	1,546			105			(47		)	1,358			47		3,009
Loans charged off	(1,703		)	(76		)	(40		)	(1,053		)	—		(2,872		)
Recoveries	283			208			169			554			—		1,214
Ending balance	$	137,742		$	58,580		$	18,259		$	8,106		$	27,374	$	250,061
Allowance for off-balance sheet credit losses:
Beginning balance	$	9,288		$	106		$	40		$	6		$	—	$	9,440
Provision for off-balance sheet credit losses	(2,987		)	(22		)	(2		)	2			—		(3,009		)
Ending balance	$	6,301		$	84		$	38		$	8		$	—	$	6,431

Total provision for credit losses	$	(1,441	)	$	83		$	(49	)	$	1,360		$	47	$	—

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 for the six months ended June 30, 2017 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance			Total
Allowance for loan losses:
Beginning balance	$	140,213		$	50,749		$	18,224		$	8,773		$	28,200		$	246,159
Provision for loan losses	(1,809		)	6,964			(86		)	570			(826		)	4,813
Loans charged off	(2,127		)	(76		)	(276		)	(2,546		)	—			(5,025		)
Recoveries	1,465			943			397			1,309			—			4,114
Ending balance	$	137,742		$	58,580		$	18,259		$	8,106		$	27,374		$	250,061
Allowance for off-balance sheet credit losses:
Beginning balance	$	11,063		$	123		$	50		$	8		$	—		$	11,244
Provision for off-balance sheet credit losses	(4,762		)	(39		)	(12		)	—			—			(4,813		)
Ending balance	$	6,301		$	84		$	38		$	8		$	—		$	6,431

Total provision for credit losses	$	(6,571	)	$	6,925		$	(98	)	$	570		$	(826	)	$	—

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 for the three months ended June 30, 2016 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	139,793		$	44,453		$	18,467		$	5,022		$	25,421	$	233,156
Provision for loan losses	12,478			2,010			368			1,443			1,263		17,562
Loans charged off	(7,355		)	—			(345		)	(1,145		)	—		(8,845		)
Recoveries	223			282			200			681			—		1,386
Ending balance	$	145,139		$	46,745		$	18,690		$	6,001		$	26,684	$	243,259
Allowance for off-balance sheet credit losses:
Beginning balance	$	6,319		$	228		$	58		$	2		$	—	$	6,607
Provision for off-balance sheet credit losses	2,433			(25		)	4			26			—		2,438
Ending balance	$	8,752		$	203		$	62		$	28		$	—	$	9,045

Total provision for credit losses	$	14,911		$	1,985		$	372		$	1,469		$	1,263	$	20,000

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 for the six months ended June 30, 2016 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate		Residential Mortgage			Personal			Nonspecific Allowance			Total
Allowance for loan losses:
Beginning balance	$	130,334		$	41,391	$	19,509		$	4,164		$	30,126		$	225,524
Provision for loan losses	43,575			4,987		(363		)	2,909			(3,442		)	47,666
Loans charged off	(29,481		)	—		(819		)	(2,536		)	—			(32,836		)
Recoveries	711			367		363			1,464			—			2,905
Ending balance	$	145,139		$	46,745	$	18,690		$	6,001		$	26,684		$	243,259
Allowance for off-balance sheet credit losses:
Beginning balance	$	1,506		$	153	$	30		$	22		$	—		$	1,711
Provision for off-balance sheet credit losses	7,246			50		32			6			—			7,334
Ending balance	$	8,752		$	203	$	62		$	28		$	—		$	9,045

Total provision for credit losses	$	50,821		$	5,037	$	(331	)	$	2,915		$	(3,442	)	$	55,000

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at June 30, 2017 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	$	10,440,798	$	128,049	$	197,157	$	9,693	$	10,637,955	$	137,742
Commercial real estate	3,684,817		58,580		3,775		—		3,688,592		58,580
Residential mortgage	1,894,963		18,259		44,235		—		1,939,198		18,259
Personal	917,628		8,106		272		—		917,900		8,106
Total	16,938,206		212,994		245,439		9,693		17,183,645		222,687

Nonspecific allowance	—		—		—		—		—		27,374

Total	$	16,938,206	$	212,994	$	245,439	$	9,693	$	17,183,645	$	250,061

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2016 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	$	10,211,871	$	139,416	$	178,953	$	797	$	10,390,824	$	140,213
Commercial real estate	3,803,525		50,749		5,521		—		3,809,046		50,749
Residential mortgage	1,903,612		18,178		46,220		46		1,949,832		18,224
Personal	839,668		8,773		290		—		839,958		8,773
Total	16,758,676		217,116		230,984		843		16,989,660		217,959

Nonspecific allowance	—		—		—		—		—		28,200

Total	$	16,758,676	$	217,116	$	230,984	$	843	$	16,989,660	$	246,159

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at June 30, 2016 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	$	10,174,448	$	140,911	$	181,989	$	4,228	$	10,356,437	$	145,139
Commercial real estate	3,574,186		46,727		7,780		18		3,581,966		46,745
Residential mortgage	1,823,862		18,626		57,061		64		1,880,923		18,690
Personal	587,069		6,001		354		—		587,423		6,001
Total	16,159,565		212,265		247,184		4,310		16,406,749		216,575

Nonspecific allowance	—		—		—		—		—		26,684

Total	$	16,159,565	$	212,265	$	247,184	$	4,310	$	16,406,749	$	243,259

Schedule of Allowance for Loan Losses and Recorded Investment by Portfolio Segment for Risk Graded and Non-Risk Graded Loans [Table Text Block]

The allowance for loan losses and recorded investment of the related loans by portfolio segment for risk graded and non-risk graded loans at June 30, 2017 is as follows (in thousands):



	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,612,477	$	136,819	$	25,478	$	923	$	10,637,955	$	137,742
Commercial real estate	3,688,592		58,580		—		—		3,688,592		58,580
Residential mortgage	216,007		2,976		1,723,191		15,283		1,939,198		18,259
Personal	824,318		5,742		93,582		2,364		917,900		8,106
Total	15,341,394		204,117		1,842,251		18,570		17,183,645		222,687

Nonspecific allowance	—		—		—		—		—		27,374

Total	$	15,341,394	$	204,117	$	1,842,251	$	18,570	$	17,183,645	$	250,061

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, 2016 is as follows (in thousands):



	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,360,725	$	139,293	$	30,099	$	920	$	10,390,824	$	140,213
Commercial real estate	3,809,046		50,749		—		—		3,809,046		50,749
Residential mortgage	243,703		2,893		1,706,129		15,331		1,949,832		18,224
Personal	744,602		5,035		95,356		3,738		839,958		8,773
Total	15,158,076		197,970		1,831,584		19,989		16,989,660		217,959

Nonspecific allowance	—		—		—		—		—		28,200

Total	$	15,158,076	$	197,970	$	1,831,584	$	19,989	$	16,989,660	$	246,159

The allowance for loan losses and recorded investment of the related loans by portfolio segment for risk graded and non-risk graded loans at June 30, 2016 is as follows (in thousands):



	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,331,701	$	144,217	$	24,736	$	922	$	10,356,437	$	145,139
Commercial real estate	3,581,966		46,745		—		—		3,581,966		46,745
Residential mortgage	202,520		2,995		1,678,403		15,695		1,880,923		18,690
Personal	500,240		3,624		87,183		2,377		587,423		6,001
Total	14,616,427		197,581		1,790,322		18,994		16,406,749		216,575

Nonspecific allowance	—		—		—		—		—		26,684

Total	$	14,616,427	$	197,581	$	1,790,322	$	18,994	$	16,406,749	$	243,259

Schedule of Credit Quality Indicators [Table Text Block]

The following table summarizes the Company’s loan portfolio at June 30, 2017 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	$	2,376,368	$	120,473	$	226,407	$	123,992	$	—	$	—	$	2,847,240
Services	2,921,510		12,452		17,111		7,754		—		—		2,958,827
Wholesale/retail	1,507,063		16,224		9,788		10,620		—		—		1,543,695
Manufacturing	513,442		6,540		16,499		9,656		—		—		546,137
Healthcare	2,130,339		33,554		33,120		24,505		—		—		2,221,518
Other commercial and industrial	453,712		2,961		17,861		20,526		25,374		104		520,538
Total commercial	9,902,434		192,204		320,786		197,053		25,374		104		10,637,955

Commercial real estate:
Residential construction and land development	138,790		—		751		2,051		—		—		141,592
Retail	720,730		1,774		—		301		—		—		722,805
Office	859,722		2,855		—		396		—		—		862,973
Multifamily	947,950		—		4,420		10		—		—		952,380
Industrial	693,635		—		—		—		—		—		693,635
Other commercial real estate	314,187		—		3		1,017		—		—		315,207
Total commercial real estate	3,675,014		4,629		5,174		3,775		—		—		3,688,592

Residential mortgage:
Permanent mortgage	212,563		1,693		478		1,273		750,891		22,142		989,040
Permanent mortgages guaranteed by U.S. government agencies	—		—		—		—		182,677		9,052		191,729
Home equity	—		—		—		—		746,661		11,768		758,429
Total residential mortgage	212,563		1,693		478		1,273		1,680,229		42,962		1,939,198

Personal	823,304		49		877		88		93,398		184		917,900

Total	$	14,613,315	$	198,575	$	327,315	$	202,189	$	1,799,001	$	43,250	$	17,183,645

The following table summarizes the Company’s loan portfolio at December 31, 2016 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	$	1,937,790	$	119,583	$	307,996	$	132,499	$	—	$	—	$	2,497,868
Services	3,052,002		10,960		37,855		8,173		—		—		3,108,990
Wholesale/retail	1,535,463		16,886		13,062		11,407		—		—		1,576,818
Manufacturing	468,314		26,532		15,198		4,931		—		—		514,975
Healthcare	2,140,458		44,472		16,161		825		—		—		2,201,916
Other commercial and industrial	433,789		5,309		—		21,060		30,041		58		490,257
Total commercial	9,567,816		223,742		390,272		178,895		30,041		58		10,390,824

Commercial real estate:
Residential construction and land development	131,630		—		470		3,433		—		—		135,533
Retail	756,418		4,745		399		326		—		—		761,888
Office	798,462		—		—		426		—		—		798,888
Multifamily	898,800		—		4,434		38		—		—		903,272
Industrial	871,673		—		—		76		—		—		871,749
Other commercial real estate	336,488		—		6		1,222		—		—		337,716
Total commercial real estate	3,793,471		4,745		5,309		5,521		—		—		3,809,046

Residential mortgage:
Permanent mortgage	238,769		1,186		2,331		1,417		741,679		21,438		1,006,820
Permanent mortgages guaranteed by U.S. government agencies	—		—		—		—		187,541		11,846		199,387
Home equity	—		—		—		—		732,106		11,519		743,625
Total residential mortgage	238,769		1,186		2,331		1,417		1,661,326		44,803		1,949,832

Personal	743,451		—		1,054		97		95,163		193		839,958

Total	$	14,343,507	$	229,673	$	398,966	$	185,930	$	1,786,530	$	45,054	$	16,989,660

The following table summarizes the Company’s loan portfolio at June 30, 2016 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	$	2,031,955	$	197,531	$	421,025	$	168,145	$	—	$	—	$	2,818,656
Services	2,805,307		6,253		9,916		9,388		—		—		2,830,864
Wholesale/retail	1,478,966		24,595		26,624		2,772		—		—		1,532,957
Manufacturing	556,741		18,757		19,612		293		—		—		595,403
Healthcare	2,011,934		29,420		8,917		875		—		—		2,051,146
Other commercial and industrial	478,169		24,053		—		453		24,673		63		527,411
Total commercial	9,363,072		300,609		486,094		181,926		24,673		63		10,356,437

Commercial real estate:
Residential construction and land development	152,343		—		972		4,261		—		—		157,576
Retail	787,779		5,962		413		1,265		—		—		795,419
Office	767,296		906		304		606		—		—		769,112
Multifamily	781,058		—		6,077		65		—		—		787,200
Industrial	645,510		—		—		76		—		—		645,586
Other commercial real estate	425,558		—		8		1,507		—		—		427,073
Total commercial real estate	3,559,544		6,868		7,774		7,780		—		—		3,581,966

Residential mortgage:
Permanent mortgage	194,962		1,197		3,406		2,955		742,214		24,273		969,007
Permanent mortgages guaranteed by U.S. government agencies	—		—		—		—		172,991		19,741		192,732
Home equity	—		—		—		—		709,092		10,092		719,184
Total residential mortgage	194,962		1,197		3,406		2,955		1,624,297		54,106		1,880,923

Personal	496,534		—		3,590		116		86,945		238		587,423

Total	$	13,614,112	$	308,674	$	500,864	$	192,777	$	1,735,915	$	54,407	$	16,406,749

Summary of Impaired Loans [Table Text Block]

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 includes all nonaccruing loans, all loans modified in a TDR and all loans repurchased from GNMA pools.

A summary of impaired loans follows (in thousands):



	As of										For the				For the
	June 30, 2017										Three Months Ended				Six Months Ended
			Recorded Investment								June 30, 2017				June 30, 2017
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance		Average Recorded Investment		Interest Income Recognized		Average Recorded Investment		Interest Income Recognized
Commercial:
Energy	$	141,091	$	123,992	$	56,988	$	67,004	$	8,874	$	117,209	$	—	$	128,246	$	—
Services	11,209		7,754		7,754		—		—		7,734		—		7,964		—
Wholesale/retail	17,392		10,620		10,620		—		—		10,855		—		11,013		—
Manufacturing	10,223		9,656		9,656		—		—		7,781		—		7,293		—
Healthcare	24,795		24,505		18,883		5,622		802		12,707		—		12,665		—
Other commercial and industrial	28,933		20,630		20,609		21		17		20,706		—		20,874		—
Total commercial	233,643		197,157		124,510		72,647		9,693		176,992		—		188,055		—

Commercial real estate:
Residential construction and land development	3,676		2,051		2,051		—		—		2,334		—		2,742		—
Retail	518		301		301		—		—		308		—		314		—
Office	499		396		396		—		—		404		—		411		—
Multifamily	1,000		10		10		—		—		17		—		24		—
Industrial	—		—		—		—		—		38		—		38		—
Other commercial real estate	1,212		1,017		1,017		—		—		1,024		—		1,119		—
Total commercial real estate	6,905		3,775		3,775		—		—		4,125		—		4,648		—

Residential mortgage:
Permanent mortgage	28,603		23,415		23,415		—		—		23,801		307		23,135		598
Permanent mortgage guaranteed by U.S. government agencies¹	197,659		191,729		191,729		—		—		202,946		2,021		205,159		3,925
Home equity	13,064		11,768		11,768		—		—		11,776		—		11,643		—
Total residential mortgage	239,326		226,912		226,912		—		—		238,523		2,328		239,937		4,523

Personal	307		272		272		—		—		253		—		281		—

Total	$	480,181	$	428,116	$	355,469	$	72,647	$	9,693	$	419,893	$	2,328	$	432,921	$	4,523


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 June 30, 2017, $9.1 million of these loans were nonaccruing and $183 million were accruing based on the guarantee by U.S. government agencies.

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, 2016 follows (in thousands):



			Recorded Investment
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance
Commercial:
Energy	$	146,897	$	132,499	$	121,418	$	11,081	$	762
Services	11,723		8,173		8,173		—		—
Wholesale/retail	17,669		11,407		11,407		—		—
Manufacturing	5,320		4,931		4,931		—		—
Healthcare	1,147		825		825		—		—
Other commercial and industrial	29,006		21,118		21,083		35		35
Total commercial	211,762		178,953		167,837		11,116		797

Commercial real estate:
Residential construction and land development	4,951		3,433		3,433		—		—
Retail	530		326		326		—		—
Office	521		426		426		—		—
Multifamily	1,000		38		38		—		—
Industrial	76		76		76		—		—
Other commercial real estate	7,349		1,222		1,222		—		—
Total commercial real estate	14,427		5,521		5,521		—		—

Residential mortgage:
Permanent mortgage	28,830		22,855		22,809		46		46
Permanent mortgage guaranteed by U.S. government agencies¹	205,564		199,387		199,387		—		—
Home equity	12,611		11,519		11,519		—		—
Total residential mortgage	247,005		233,761		233,715		46		46

Personal	332		290		290		—		—

Total	$	473,526	$	418,525	$	407,363	$	11,162	$	843


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, 2016, $12 million of these loans were nonaccruing and $188 million were accruing based on the guarantee by U.S. government agencies.

A summary of impaired loans at June 30, 2016 follows (in thousands):



											For the				For the
	As of June 30, 2016										Three Months Ended				Six Months Ended
			Recorded Investment								June 30, 2016				June 30, 2016
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance		Average Recorded Investment		Interest Income Recognized		Average Recorded Investment		Interest Income Recognized
Commercial:
Energy	$	202,369	$	168,145	$	136,264	$	31,881	$	4,228	$	163,849	$	—	$	97,923	$	—
Services	12,780		9,388		9,388		—		—		9,450		—		9,839		—
Wholesale/retail	8,697		2,772		2,772		—		—		3,229		—		2,846		—
Manufacturing	650		293		293		—		—		303		—		312		—
Healthcare	1,175		875		875		—		—		949		—		973		—
Other commercial and industrial	8,186		516		516		—		—		542		—		569		—
Total commercial	233,857		181,989		150,108		31,881		4,228		178,322		—		112,462		—

Commercial real estate:
Residential construction and land development	7,177		4,261		4,261		—		—		4,525		—		4,335		—
Retail	1,914		1,265		1,265		—		—		1,283		—		1,292		—
Office	907		606		606		—		—		618		—		628		—
Multifamily	1,000		65		65		—		—		157		—		169		—
Industrial	76		76		76		—		—		76		—		76		—
Other commercial real estate	7,445		1,507		1,355		152		18		1,865		—		1,890		—
Total commercial real estate	18,519		7,780		7,628		152		18		8,524		—		8,390		—

Residential mortgage:
Permanent mortgage	33,793		27,228		27,117		111		64		27,362		304		28,106		631
Permanent mortgage guaranteed by U.S. government agencies¹	198,534		192,732		192,732		—		—		191,430		2,023		195,563		3,795
Home equity	10,964		10,092		10,092		—		—		10,311		—		10,224		—
Total residential mortgage	243,291		230,052		229,941		111		64		229,103		2,327		233,893		4,426

Personal	1,174		354		354		—		—		342		—		409		—

Total	$	496,841	$	420,175	$	388,031	$	32,144	$	4,310	$	416,291	$	2,327	$	355,154	$	4,426


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 June 30, 2016, $20 million of these loans were nonaccruing and $173 million were accruing based on the guarantee by U.S. government agencies.

Troubled Debt Restructurings [Table Text Block]

Troubled Debt Restructurings

A summary of troubled debt restructurings ("TDRs") by accruing status as of June 30, 2017 is as follows (in thousands):



	As of June 30, 2017								Amounts Charged Off During:
	Recorded Investment		Performing in Accordance With Modified Terms		Not Performing in Accordance With Modified Terms		Specific Allowance		Three Months Ended June 30, 2017		Six Months Ended June 30, 2017
Nonaccruing TDRs:

Commercial:
Energy	$	22,466	$	12,692	$	9,774	$	4,308	$	—	$	—
Services	7,208		6,561		647		—		3		3
Wholesale/retail	10,524		10,524		—		—		—		—
Manufacturing	195		195		—		—		—		—
Healthcare	—		—		—		—		—		—
Other commercial and industrial	20,531		35		20,496		—		—		—
Total commercial	60,924		30,007		30,917		4,308		3		3

Commercial real estate:
Residential construction and land development	381		145		236		—		—		—
Retail	301		301		—		—		—		—
Office	121		—		121		—		—		—
Multifamily	—		—		—		—		—		—
Industrial	—		—		—		—		—		—
Other commercial real estate	365		365		—		—		—		—
Total commercial real estate	1,168		811		357		—		—		—

Residential mortgage:
Permanent mortgage	14,284		9,939		4,345		—		—		—
Permanent mortgage guaranteed by U.S. government agencies	5,962		1,176		4,786		—		—		—
Home equity	5,549		4,239		1,310		—		—		31
Total residential mortgage	25,795		15,354		10,441		—		—		31

Personal	228		228		—		—		7		8

Total nonaccruing TDRs	$	88,115	$	46,400	$	41,715	$	4,308	$	10	$	42

Accruing TDRs:
Permanent mortgages guaranteed by U.S. government agencies	80,624		24,506		56,118		—		—		—

Total TDRs	$	168,739	$	70,906	$	97,833	$	4,308	$	10	$	42

A summary of troubled debt restructurings by accruing status as of December 31, 2016 is as follows (in thousands):



	As of
	December 31, 2016
	Recorded Investment		Performing in Accordance With Modified Terms		Not Performing in Accordance With Modified Terms		Specific Allowance
Nonaccruing TDRs:

Commercial:
Energy	$	16,893	$	10,867	$	6,026	$	—
Services	7,527		6,830		697		—
Wholesale/retail	11,291		11,251		40		—
Manufacturing	224		224		—		—
Healthcare	607		—		607		—
Other commercial and industrial	337		53		284		—
Total commercial	36,879		29,225		7,654		—

Commercial real estate:
Residential construction and land development	690		97		593		—
Retail	326		326		—		—
Office	143		143		—		—
Multifamily	—		—		—		—
Industrial	—		—		—		—
Other commercial real estate	548		548		—		—
Total commercial real estate	1,707		1,114		593		—

Residential mortgage:
Permanent mortgage	14,876		10,175		4,701		46
Permanent mortgage guaranteed by U.S. government agencies	6,702		2,241		4,461		—
Home equity	5,346		4,458		888		—
Total residential mortgage	26,924		16,874		10,050		46

Personal	237		236		1		—

Total nonaccuring TDRs	$	65,747	$	47,449	$	18,298	$	46

Accruing TDRs:
Permanent mortgages guaranteed by U.S. government agencies	81,370		27,289		54,081		—

Total TDRs	$	147,117	$	74,738	$	72,379	$	46

A summary of troubled debt restructurings by accruing status as of June 30, 2016 is as follows (in thousands):



	As of June 30, 2016								Amounts Charged Off During:
	Recorded Investment		Performing in Accordance With Modified Terms		Not Performing in Accordance With Modified Terms		Specific Allowance		Three Months Ended June 30, 2016		Six Months Ended June 30, 2016
Nonaccruing TDRs:

Commercial:
Energy	$	2,246	$	—	$	2,246	$	—	$	500	$	500
Services	8,610		7,853		757		—		—		—
Wholesale/retail	2,467		2,427		40		—		—		—
Manufacturing	253		253		—		—		—		—
Healthcare	640		640		—		—		—		—
Other commercial and industrial	516		63		453		—		—		57
Total commercial	14,732		11,236		3,496		—		500		557

Commercial real estate:
Residential construction and land development	1,601		1,079		522		—		—		—
Retail	1,264		907		357		—		—		—
Office	152		152		—		—		—		—
Multifamily	—		—		—		—		—		—
Industrial	—		—		—		—		—		—
Other commercial real estate	793		372		421		—		—		—
Total commercial real estate	3,810		2,510		1,300		—		—		—

Residential mortgage:
Permanent mortgage	17,367		12,462		4,905		64		37		52
Permanent mortgage guaranteed by U.S. government agencies	9,709		2,024		7,685		—		—		—
Home equity	4,763		4,139		624		—		60		126
Total residential mortgage	31,839		18,625		13,214		64		97		178

Personal	298		276		22		—		3		9

Total nonaccruing TDRs	$	50,679	$	32,647	$	18,032	$	64	$	600	$	744

Accruing TDRs:
Permanent mortgages guaranteed by U.S. government agencies	78,806		27,999		50,807		—		—		—

Total TDRs	$	129,485	$	60,646	$	68,839	$	64	$	600	$	744

Troubled debt restructurings generally consist of interest rate concessions, payment stream concessions or a combination of concessions to distressed borrowers. The following tables detail the recorded balance of loans at June 30, 2017 by class that were restructured during the three months ended June 30, 2017 by primary type of concession (in thousands):



	Three Months Ended June 30, 2017
	Accruing						Nonaccrual						Total
	Payment Stream		Combination & Other		Total		Payment Stream		Combination & Other		Total
Commercial:
Energy	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Services	—		—		—		—		—		—		—
Wholesale/retail	—		—		—		—		626		626		626
Manufacturing	—		—		—		—		—		—		—
Healthcare	—		—		—		—		—		—		—
Other commercial and industrial	—		—		—		20,242		—		20,242		20,242
Total commercial	—		—		—		20,242		626		20,868		20,868

Commercial real estate:
Residential construction and land development	—		—		—		—		—		—		—
Retail	—		—		—		—		—		—		—
Office	—		—		—		—		—		—		—
Multifamily	—		—		—		—		—		—		—
Industrial	—		—		—		—		—		—		—
Other commercial real estate	—		—		—		—		—		—		—
Total commercial real estate	—		—		—		—		—		—		—

Residential mortgage:
Permanent mortgage	—		—		—		138		53		191		191
Permanent mortgage guaranteed by U.S. government agencies	10,410		1,568		11,978		223		—		223		12,201
Home equity	—		—		—		26		559		585		585
Total residential mortgage	10,410		1,568		11,978		387		612		999		12,977

Personal	—		—		—		—		47		47		47

Total	$	10,410	$	1,568	$	11,978	$	20,629	$	1,285	$	21,914	$	33,892



	Six Months Ended June 30, 2017
	Accruing							Nonaccrual							Total
		Payment Stream		Combination & Other		Total			Payment Stream		Combination & Other		Total
Commercial:
Energy		$	—	$	—	$	—		$	13,010	$	—	$	13,010	$	13,010
Services		—		—		—			—		—		—		—
Wholesale/retail		—		—		—			—		626		626		626
Manufacturing		—		—		—			—		—		—		—
Healthcare		—		—		—			—		—		—		—
Other commercial and industrial		—		—		—			20,242		—		20,242		20,242
Total commercial		—		—		—			33,252		626		33,878		33,878

Commercial real estate:
Residential construction and land development		—		—		—			—		—		—		—
Retail		—		—		—			—		—		—		—
Office		—		—		—			—		—		—		—
Multifamily		—		—		—			—		—		—		—
Industrial		—		—		—			—		—		—		—
Other commercial real estate		—		—		—			—		—		—		—
Total commercial real estate		—		—		—			—		—		—		—

Residential mortgage:
Permanent mortgage		—		—		—			153		84		237		237
Permanent mortgage guaranteed by U.S. government agencies		14,883		2,586		17,469			224		85		309		17,778
Home equity		—		—		—			149		1,053		1,202		1,202
Total residential mortgage		14,883		2,586		17,469			526		1,222		1,748		19,217

Personal		—		—		—			—		51		51		51

Total		$	14,883	$	2,586	$	17,469		$	33,778	$	1,899	$	35,677	$	53,146

Troubled debt restructurings generally consist of interest rate concessions, payment stream concessions or a combination of concessions to distressed borrowers. The following tables detail the recorded balance of loans by class that were restructured during three months ended June 30, 2016 by primary type of concession (in thousands):



	Three Months Ended June 30, 2016
	Accruing						Nonaccrual						Total
	Payment Stream		Combination & Other		Total		Payment Stream		Combination & Other		Total
Commercial:
Energy	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Services	—		—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—		—
Healthcare	—		—		—		—		—		—		—
Other commercial and industrial	—		—		—		—		—		—		—
Total commercial	—		—		—		—		—		—		—

Commercial real estate:
Residential construction and land development	—		—		—		—		—		—		—
Retail	—		—		—		—		—		—		—
Office	—		—		—		—		—		—		—
Multifamily	—		—		—		—		—		—		—
Industrial	—		—		—		—		—		—		—
Other commercial real estate	—		—		—		—		—		—		—
Total commercial real estate	—		—		—		—		—		—		—

Residential mortgage:
Permanent mortgage	—		—		—		684		1,183		1,867		1,867
Permanent mortgage guaranteed by U.S. government agencies	2,783		4,455		7,238		—		625		625		7,863
Home equity	—		—		—		48		329		377		377
Total residential mortgage	2,783		4,455		7,238		732		2,137		2,869		10,107

Personal	—		—		—		—		65		65		65

Total	$	2,783	$	4,455	$	7,238	$	732	$	2,202	$	2,934	$	10,172



	Six Months Ended June 30, 2016
	Accruing						Nonaccrual						Total
	Payment Stream		Combination & Other		Total		Payment Stream		Combination & Other		Total
Commercial:
Energy	$	—	$	—	$	—	$	501	$	—	$	501	$	501
Services	—		—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—		—
Healthcare	—		—		—		—		—		—		—
Other commercial and industrial	—		—		—		—		—		—		—
Total commercial	—		—		—		501		—		501		501

Commercial real estate:
Residential construction and land development	—		—		—		—		—		—		—
Retail	—		—		—		—		—		—		—
Office	—		—		—		—		—		—		—
Multifamily	—		—		—		—		—		—		—
Industrial	—		—		—		—		—		—		—
Other commercial real estate	—		—		—		—		—		—		—
Total commercial real estate	—		—		—		—		—		—		—

Residential mortgage:
Permanent mortgage	—		—		—		1,046		1,244		2,290		2,290
Permanent mortgage guaranteed by U.S. government agencies	6,625		7,818		14,443		—		625		625		15,068
Home equity	—		—		—		48		791		839		839
Total residential mortgage	6,625		7,818		14,443		1,094		2,660		3,754		18,197

Personal	—		—		—		—		72		72		72

Total	$	6,625	$	7,818	$	14,443	$	1,595	$	2,732	$	4,327	$	18,770

The following table summarizes, by loan class, the recorded investment at June 30, 2017 and 2016, respectively, of loans modified as TDRs within the previous 12 months and for which there was a payment default during the three months ended June 30, 2017 and 2016, respectively (in thousands):



	Three Months Ended June 30, 2017						Six Months Ended June 30, 2017
	Accruing		Nonaccrual		Total		Accruing		Nonaccrual		Total
Commercial:
Energy	$	—	$	9,774	$	9,774	$	—	$	9,774	$	9,774
Services	—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—
Healthcare	—		—		—		—		—		—
Other commercial and industrial	—		20,242		20,242		—		20,242		20,242
Total commercial	—		30,016		30,016		—		30,016		30,016

Commercial real estate:
Residential construction and land development	—		—		—		—		—		—
Retail	—		—		—		—		—		—
Office	—		—		—		—		—		—
Multifamily	—		—		—		—		—		—
Industrial	—		—		—		—		—		—
Other commercial real estate	—		—		—		—		—		—
Total commercial real estate	—		—		—		—		—		—

Residential mortgage:
Permanent mortgage	—		161		161		—		161		161
Permanent mortgage guaranteed by U.S. government agencies	22,234		918		23,152		22,590		918		23,508
Home equity	—		1,113		1,113		—		1,262		1,262
Total residential mortgage	22,234		2,192		24,426		22,590		2,341		24,931

Personal	—		—		—		—		—		—

Total	$	22,234	$	32,208	$	54,442	$	22,590	$	32,357	$	54,947

A payment default is defined as being 30 days or more past due. The table above includes loans that experienced a payment default during the period, but may be performing in accordance with the modified terms as of the balance sheet date.

Summary of Loans by Aging Status [Table Text Block]

Nonaccrual & 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.

A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of June 30, 2017 is as follows (in thousands):



			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	2,723,248	$	—	$	—	$	—	$	123,992	$	2,847,240
Services	2,949,562		50		180		1,281		7,754		2,958,827
Wholesale/retail	1,532,986		89		—		—		10,620		1,543,695
Manufacturing	536,481		—		—		—		9,656		546,137
Healthcare	2,196,088		925		—		—		24,505		2,221,518
Other commercial and industrial	499,743		45		119		1		20,630		520,538
Total commercial	10,438,108		1,109		299		1,282		197,157		10,637,955

Commercial real estate:
Residential construction and land development	139,070		471		—		—		2,051		141,592
Retail	722,504		—		—		—		301		722,805
Office	862,577		—		—		—		396		862,973
Multifamily	952,370		—		—		—		10		952,380
Industrial	693,635		—		—		—		—		693,635
Other commercial real estate	314,187		3		—		—		1,017		315,207
Total commercial real estate	3,684,343		474		—		—		3,775		3,688,592

Residential mortgage:
Permanent mortgage	962,443		2,024		1,026		132		23,415		989,040
Permanent mortgages guaranteed by U.S. government agencies	36,867		18,416		13,581		113,813		9,052		191,729
Home equity	744,735		1,564		362		—		11,768		758,429
Total residential mortgage	1,744,045		22,004		14,969		113,945		44,235		1,939,198

Personal	916,852		487		289		—		272		917,900

Total	$	16,783,348	$	24,074	$	15,557	$	115,227	$	245,439	$	17,183,645

A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of December 31, 2016 is as follows (in thousands):



			Past Due
	Current		30 to 59 Days		60 to 89 Days	90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	2,364,890	$	479	—	$	—	$	132,499	$	2,497,868
Services	3,099,605		191		1,021	—		8,173		3,108,990
Wholesale/retail	1,561,650		3,761		—	—		11,407		1,576,818
Manufacturing	509,662		382		—	—		4,931		514,975
Healthcare	2,201,050		—		41	—		825		2,201,916
Other commercial and industrial	468,981		155		3	—		21,118		490,257
Total commercial	10,205,838		4,968		1,065	—		178,953		10,390,824

Commercial real estate:
Residential construction and land development	132,100		—		—	—		3,433		135,533
Retail	761,562		—		—	—		326		761,888
Office	798,462		—		—	—		426		798,888
Multifamily	903,234		—		—	—		38		903,272
Industrial	871,673		—		—	—		76		871,749
Other commercial real estate	336,488		6		—	—		1,222		337,716
Total commercial real estate	3,803,519		6		—	—		5,521		3,809,046

Residential mortgage:
Permanent mortgage	979,386		3,299		1,280	—		22,855		1,006,820
Permanent mortgages guaranteed by U.S. government agencies	40,594		17,465		13,803	115,679		11,846		199,387
Home equity	729,493		2,276		337	—		11,519		743,625
Total residential mortgage	1,749,473		23,040		15,420	115,679		46,220		1,949,832

Personal	838,811		589		263	5		290		839,958

Total	$	16,597,641	$	28,603	16,748	$	115,684	$	230,984	$	16,989,660

A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of June 30, 2016 is as follows (in thousands):



			Past Due
	Current		30 to 59 Days		60 to 89 Days	90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	2,647,678	$	—	—	$	2,833	$	168,145	$	2,818,656
Services	2,817,217		494		3,765	—		9,388		2,830,864
Wholesale/retail	1,530,110		75		—	—		2,772		1,532,957
Manufacturing	595,110		—		—	—		293		595,403
Healthcare	2,050,271		—		—	—		875		2,051,146
Other commercial and industrial	526,691		76		82	46		516		527,411
Total commercial	10,167,077		645		3,847	2,879		181,989		10,356,437

Commercial real estate:
Residential construction and land development	153,315		—		—	—		4,261		157,576
Retail	794,154		—		—	—		1,265		795,419
Office	768,506		—		—	—		606		769,112
Multifamily	784,826		2,309		—	—		65		787,200
Industrial	645,510		—		—	—		76		645,586
Other commercial real estate	425,566		—		—	—		1,507		427,073
Total commercial real estate	3,571,877		2,309		—	—		7,780		3,581,966

Residential mortgage:
Permanent mortgage	935,857		5,798		124	—		27,228		969,007
Permanent mortgages guaranteed by U.S. government agencies	42,019		15,349		11,869	103,754		19,741		192,732
Home equity	707,024		1,889		159	20		10,092		719,184
Total residential mortgage	1,684,900		23,036		12,152	103,774		57,061		1,880,923

Personal	586,611		400		58	—		354		587,423

Total	$	16,010,465	$	26,390	16,057	$	106,653	$	247,184	$	16,406,749

Mortgage Banking Activities (Tables)

6 Months Ended

Jun. 30, 2017

Mortgage Banking [Abstract]

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



	June 30, 2017				Dec. 31, 2016				June 30, 2016
	Unpaid Principal Balance/ Notional		Fair Value		Unpaid Principal Balance/ Notional		Fair Value		Unpaid Principal Balance/ Notional		Fair Value
Residential mortgage loans held for sale	$	269,772	$	275,179	$	286,414	$	286,971	$	404,507	$	417,542
Residential mortgage loan commitments	362,088		10,993		318,359		9,733		965,631		25,499
Forward sales contracts	587,595		1,087		569,543		5,193		1,216,966		(12,313		)
			$	287,259			$	301,897			$	430,728

Mortgage Banking Revenue [Table Text Block]

Mortgage banking revenue was as follows (in thousands):



	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Production revenue:
Net realized gains on sale of mortgage loans	$	11,787		$	15,865		$	20,402		$	24,314
Net change in unrealized gain on mortgage loans held for sale	985			3,884			4,827			7,167
Net change in the fair value of mortgage loan commitments	(3,274		)	5,329			1,260			17,365
Net change in the fair value of forward sales contracts	4,342			(5,992		)	(4,106		)	(13,113		)
Total production revenue	13,840			19,086			22,383			35,733
Servicing revenue	16,436			15,798			33,084			31,251
Total mortgage banking revenue	$	30,276		$	34,884		$	55,467		$	66,984

Summary of Mortgage Servicing Rights [Table Text Block]

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



	June 30, 2017			Dec. 31, 2016			June 30, 2016
Number of residential mortgage loans serviced for others	138,335			139,340			137,210
Outstanding principal balance of residential mortgage loans serviced for others	$	22,095,232		$	21,997,568		$	21,178,387
Weighted average interest rate	3.95		%	3.97		%	4.06		%
Remaining term (in months)	299			301			301

Activity in Capitalized Mortgage Servicing Rights [Table Text Block]

Activity in capitalized mortgage servicing rights during the three months ended June 30, 2017 was as follows (in thousands):



	Purchased			Originated			Total
Balance, March 31, 2017	$	8,316		$	241,087		$	249,403
Additions, net	—			11,078			11,078
Change in fair value due to scheduled payments and full-balance payoffs	(464		)	(7,835		)	(8,299		)
Change in fair value due to market assumption changes	143			(7,086		)	(6,943		)
Balance, June 30, 2017	$	7,995		$	237,244		$	245,239



	Purchased			Originated			Total
Balance, Dec. 31, 2016	$	8,909		$	238,164		$	247,073
Additions, net	—			19,514			19,514
Change in fair value due to scheduled payments and full-balance payoffs	(973		)	(15,288		)	(16,261		)
Change in fair value due to market assumption changes	59			(5,146		)	(5,087		)
Balance, June 30, 2017	$	7,995		$	237,244		$	245,239

Activity in capitalized mortgage servicing rights during the three months ended June 30, 2016 was as follows (in thousands):



	Purchased			Originated			Total
Balance, March 31, 2016	$	5,949		$	190,106		$	196,055
Additions, net	—			20,773			20,773
Change in fair value due to scheduled payments and full-balance payoffs	(730		)	(9,068		)	(9,798		)
Change in fair value due to market assumption changes	(1,152		)	(15,131		)	(16,283		)
Balance, June 30, 2016	$	4,067		$	186,680		$	190,747



	Purchased			Originated			Total
Balance, Dec. 31, 2015	$	9,911		$	208,694		$	218,605
Additions, net	—			34,355			34,355
Change in fair value due to scheduled payments and full-balance payoffs	(1,356		)	(16,586		)	(17,942		)
Change in fair value due to market assumption changes	(4,488		)	(39,783		)	(44,271		)
Balance, June 30, 2016	$	4,067		$	186,680		$	190,747

Assumptions to Value Mortgage Servicing Rights [Table Text Block]

There is no active market for trading in mortgage servicing rights after origination. Fair value is determined by discounting the projected net cash flows. Significant assumptions used to determine fair value based on significant unobservable inputs were as follows:



	June 30, 2017	Dec. 31, 2016	June 30, 2016
Discount rate – risk-free rate plus a market premium	9.84%	10.08%	10.09%
Prepayment rate - based upon loan interest rate, original term and loan type	8.61%-15.91%	8.98%-16.91%	9.26%-42.77%
Loan servicing costs – annually per loan based upon loan type:
Performing loans	$65-$120	$63 - $120	$63 - $120
Delinquent loans	$150-$500	$150 - $500	$150 - $500
Loans in foreclosure	$1,000-$4,250	$650 - $4,250	$650 - $4,250
Escrow earnings rate – indexed to rates paid on deposit accounts with comparable average life	1.95%	1.98%	0.99%
Primary/secondary mortgage rate spread	105 bps	105 bps	115 bps

Aging Status of Mortgage Loans Serviced For Others [Table Text Block]

The aging status of our mortgage loans serviced for others by investor at June 30, 2017 follows (in thousands):



			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Total
FHLMC	$	8,083,330	$	48,659	$	12,294	$	27,338	$	8,171,621
FNMA	6,756,211		46,918		10,679		23,981		6,837,789
GNMA	6,331,439		170,889		47,335		16,082		6,565,745
Other	514,272		3,278		932		1,595		520,077
Total	$	21,685,252	$	269,744	$	71,240	$	68,996	$	22,095,232

Summary of Unresolved Deficiency Requests and Related Accrual for Credit Losses [Table Text Block]

A summary of unresolved deficiency requests from the agencies follows (in thousands, except for number of unresolved deficiency requests):



	June 30,
	2017		2016
Number of unresolved deficiency requests	206		211
Aggregate outstanding principal balance subject to unresolved deficiency requests	$	13,370	$	15,920
Unpaid principal balance subject to indemnification by the Company	5,074		5,519

Activity in Accruals for Mortgage Losses [Table Text Block]

The activity in the accruals for mortgage losses related to repurchases is summarized as follows (in thousands).



	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Beginning balance	$	2,587		$	2,974		$	2,788		$	3,359
Provision for losses	(895		)	368			(1,094		)	250
Charge-offs, net	(45		)	(89		)	(47		)	(356		)
Ending balance	$	1,647		$	3,253		$	1,647		$	3,253

Commitments and Contingent Liabilities Commitments and Contingent Liabilities - Variable Interest Entities (Tables)

6 Months Ended

Jun. 30, 2017

Commitments and Contingencies Disclosure [Abstract]

Schedule of Variable Interest Entities [Table Text Block]

A summary of consolidated and unconsolidated alternative investments as of June 30, 2017, December 31, 2016 and June 30, 2016 is as follows (in thousands):



	June 30, 2017
	Loans		Other assets		Other liabilities		Other borrowings		Non-controlling interests
Consolidated:
Private equity funds	$	—	$	16,905	$	—	$	—	$	14,199
Tax credit entities	10,000		11,274		—		10,964		10,000
Other	—		15,894		1,621		878		2,877
Total consolidated	$	10,000	$	44,073	$	1,621	$	11,842	$	27,076

Unconsolidated:
Tax credit entities	$	59,744	$	148,525	$	63,822	$	—	$	—
Other	—		33,155		13,680		—		—
Total unconsolidated	$	59,744	$	181,680	$	77,502	$	—	$	—



	Dec. 31, 2016
	Loans		Other assets		Other liabilities		Other borrowings		Non-controlling interests
Consolidated:
Private equity funds	$	—	$	17,357	$	—	$	—	$	13,237
Tax credit entities	10,000		11,585		—		10,964		10,000
Other	—		29,783		3,189		1,092		8,266
Total consolidated	$	10,000	$	58,725	$	3,189	$	12,056	$	31,503

Unconsolidated:
Tax credit entities	$	44,488	$	143,715	$	63,329	$	—	$	—
Other	—		31,675		15,028		—		—
Total unconsolidated	$	44,488	$	175,390	$	78,357	$	—	$	—



	June 30, 2016
	Loans		Other assets		Other liabilities		Other borrowings		Non-controlling interests
Consolidated:
Private equity funds	$	—	$	20,469	$	—	$	—	$	16,316
Tax credit entities	10,000		11,895		—		10,964		10,000
Other	—		35,387		2,004		2,272		7,589
Total consolidated	$	10,000	$	67,751	$	2,004	$	13,236	$	33,905

Unconsolidated:
Tax credit entities	$	32,679	$	102,138	$	30,953	$	—	$	—
Other	—		23,439		13,767		—		—
Total unconsolidated	$	32,679	$	125,577	$	44,720	$	—	$	—

Tabular disclosure of the significant judgments and assumptions made in determining whether a variable interest (as defined) held by the entity requires the variable interest entity (VIE) (as defined) to be consolidated and (or) disclose information about its involvement with the VIE, individually or in aggregate (as applicable); the nature of restrictions, if any, on the consolidated VIE's assets and on the settlement of its liabilities reported by an entity in its statement of financial position, including the carrying amounts of such assets and liabilities; the nature of, and changes in, the risks associated with involvement in the VIE; how involvement with the VIE affects the entity's financial position, financial performance, and cash flows; the lack of recourse if creditors (or beneficial interest holders) of the consolidated VIE have no recourse to the general credit of the primary beneficiary (if applicable); the terms of arrangements, giving consideration to both explicit arrangements and implicit variable interests, if any, that could require the entity to provide financial support to the VIE, including events or circumstances that could expose the entity to a loss; the methodology used by the entity for determining whether or not it is the primary beneficiary of the variable interest entity; the significant factors considered and judgments made in determining that the power to direct the activities of a VIE that most significantly impact the VIE's economic performance are shared (as defined); the carrying amounts and classification of assets and liabilities of the VIE included in the statement of financial position; the entity's maximum exposure to loss, if any, as a result of its involvement with the VIE, including how the maximum exposure is determined and significant sources of the entity's exposure to the VIE; a comparison of the carrying amounts of the assets and liabilities and the entity's maximum exposure to loss; information about any liquidity arrangements, guarantees, and (or) other commitments by third parties that may affect the fair value or risk of the entity's variable interest in the VIE; whether or not the entity has provided financial support or other support (explicitly or implicitly) to the VIE that it was not previously contractually required to provide or whether the entity intends to provide that support, including the type and amount of the support and the primary reasons for providing the support; and supplemental information the entity determines necessary to provide.

Stockholders' Equity Note [Abstract]

Shareholders' Equity (Tables)

6 Months Ended

Jun. 30, 2017

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			Investment Securities Transferred from AFS			Employee Benefit Plans			Total
Balance, Dec. 31, 2015	$	23,284		$	68		$	(1,765	)	$	21,587
Net change in unrealized gain (loss)	166,566			—			—			166,566
Reclassification adjustments included in earnings:
Interest revenue, Investment securities, Taxable securities	—			(112		)	—			(112		)
Gain on available for sale securities, net	(9,290		)	—			—			(9,290		)
Other comprehensive income (loss), before income taxes	157,276			(112		)	—			157,164
Federal and state income taxes¹	61,163			(44		)	—			61,119
Other comprehensive income (loss), net of income taxes	96,113			(68		)	—			96,045
Balance, June 30, 2016	$	119,397		$	—		$	(1,765	)	$	117,632

Balance, Dec. 31, 2016	$	(9,087	)	$	—		$	(1,880	)	$	(10,967	)
Net change in unrealized gain (loss)	33,369			—			—			33,369
Reclassification adjustments included in earnings:
Gain on available for sale securities, net	(2,429		)	—			—			(2,429		)
Other comprehensive income, before income taxes	30,940			—			—			30,940
Federal and state income taxes¹	12,009						—			12,009
Other comprehensive income, net of income taxes	18,931			—			—			18,931
Balance, June 30, 2017	$	9,844		$	—		$	(1,880	)	$	7,964


¹	Calculated using a 39 percent effective tax rate.

Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2017

Earnings Per Share [Abstract]

Earnings Per Share [Table Text Block]



(In thousands, except share and per share amounts)	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Numerator:
Net income attributable to BOK Financial Corp. shareholders	$	88,147	$	65,801	$	176,503	$	108,365
Less: Earnings allocated to participating securities	926		821		1,929		1,359
Numerator for basic earnings per share – income available to common shareholders	87,221		64,980		174,574		107,006
Effect of reallocating undistributed earnings of participating securities	1		—		1		—
Numerator for diluted earnings per share – income available to common shareholders	$	87,222	$	64,980	$	174,575	$	107,006

Denominator:
Weighted average shares outstanding	65,416,274		66,069,392		65,436,909		66,100,279
Less: Participating securities included in weighted average shares outstanding	686,522		823,505		714,165		829,065
Denominator for basic earnings per common share	64,729,752		65,245,887		64,722,744		65,271,214
Dilutive effect of employee stock compensation plans¹	63,382		57,039		65,578		45,963
Denominator for diluted earnings per common share	64,793,134		65,302,926		64,788,322		65,317,177

Basic earnings per share	$	1.35	$	1.00	$	2.70	$	1.64
Diluted earnings per share	$	1.35	$	1.00	$	2.69	$	1.64
¹ Excludes employee stock options with exercise prices greater than current market price.	—		—		—		145,247

Reportable Segments (Tables)

6 Months Ended

Jun. 30, 2017

Segment Reporting [Abstract]

Reportable Segments [Table Text Block]

Reportable segments reconciliation to the Consolidated Financial Statements for the three months ended June 30, 2017 is as follows (in thousands):



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	144,164		$	23,503		$	10,474		$	27,063		$	205,204
Net interest revenue (expense) from internal sources	(20,347		)	11,837			10,325			(1,815		)	—
Net interest revenue	123,817			35,340			20,799			25,248			205,204
Provision for credit losses	1,228			926			(93		)	(2,061		)	—
Net interest revenue after provision for credit losses	122,589			34,414			20,892			27,309			205,204
Other operating revenue	55,778			52,102			75,569			(1,197		)	182,252
Other operating expense	59,128			55,709			60,615			75,433			250,885
Net direct contribution	119,239			30,807			35,846			(49,321		)	136,571
Gain on financial instruments, net	3			5,224			—			(5,227		)	—
Change in fair value of mortgage servicing rights	—			(6,943		)	—			6,943			—
Gain on repossessed assets, net	1,403			98			—			(1,501		)	—
Corporate expense allocations	8,862			17,039			9,947			(35,848		)	—
Net income before taxes	111,783			12,147			25,899			(13,258		)	136,571
Federal and state income taxes	43,484			4,725			10,075			(10,579		)	47,705
Net income	68,299			7,422			15,824			(2,679		)	88,866
Net income attributable to non-controlling interests	—			—			—			719			719
Net income attributable to BOK Financial Corp. shareholders	$	68,299		$	7,422		$	15,824		$	(3,398	)	$	88,147

Average assets	$	17,596,273		$	8,845,398		$	6,763,093		$	(836,193	)	$	32,368,571

Reportable segments reconciliation to the Consolidated Financial Statements for the six months ended June 30, 2017 is as follows (in thousands):



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	278,868		$	44,632		$	21,960		$	60,926		$	406,386
Net interest revenue (expense) from internal sources	(37,140		)	22,789			19,181			(4,830		)	—
Net interest revenue	241,728			67,421			41,141			56,096			406,386
Provision for credit losses	(234		)	2,198			(53		)	(1,911		)	—
Net interest revenue after provision for credit losses	241,962			65,223			41,194			58,007			406,386
Other operating revenue	102,048			99,408			149,727			1,365			352,548
Other operating expense	111,565			109,242			121,025			153,764			495,596
Net direct contribution	232,445			55,389			69,896			(94,392		)	263,338
Gain on financial instruments, net	41			3,557			—			(3,598		)	—
Change in fair value of mortgage servicing rights	—			(5,087		)	—			5,087			—
Gain (loss) on repossessed assets, net	1,398			(39		)	—			(1,359		)	—
Corporate expense allocations	17,493			33,908			20,619			(72,020		)	—
Net income before taxes	216,391			19,912			49,277			(22,242		)	263,338
Federal and state income taxes	84,176			7,746			19,169			(25,283		)	85,808
Net income	132,215			12,166			30,108			3,041			177,530
Net income attributable to non-controlling interests	—			—			—			1,027			1,027
Net income attributable to BOK Financial Corp. shareholders	$	132,215		$	12,166		$	30,108		$	2,014		$	176,503

Average assets	$	17,517,960		$	8,747,524		$	6,960,872		$	(566,196	)	$	32,660,160

Reportable segments reconciliation to the Consolidated Financial Statements for the three months ended June 30, 2016 is as follows (in thousands):



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	118,480		$	22,349		$	6,271		$	35,512		$	182,612
Net interest revenue (expense) from internal sources	(14,575		)	8,876			$	7,193		(1,494		)	—
Net interest revenue	103,905			31,225			13,464			34,018			182,612
Provision for credit losses	6,852			1,318			(239		)	12,069			20,000
Net interest revenue after provision for credit losses	97,053			29,907			13,703			21,949			162,612
Other operating revenue	51,497			57,440			75,772			833			185,542
Other operating expense	52,594			62,806			61,414			74,571			251,385
Net direct contribution	95,956			24,541			28,061			(51,789		)	96,769
Gain on financial instruments, net	—			15,045			—			(15,045		)	—
Change in fair value of mortgage servicing rights	—			(16,283		)	—			16,283			—
Gain (loss) on repossessed assets, net	(598		)	252			—			346			—
Corporate expense allocations	8,883			16,630			10,417			(35,930		)	—
Net income before taxes	86,475			6,925			17,644			(14,275		)	96,769
Federal and state income taxes	33,639			2,694			6,864			(12,700		)	30,497
Net income	52,836			4,231			10,780			(1,575		)	66,272
Net gain attributable to non-controlling interests	—			—			—			471			471
Net income attributable to BOK Financial Corp. shareholders	$	52,836		$	4,231		$	10,780		$	(2,046	)	$	65,801

Average assets	$	16,973,663		$	8,774,881		$	5,765,390		$	472,108		$	31,986,042

Reportable segments reconciliation to the Consolidated Financial Statements for the six months ended June 30, 2016 is as follows (in thousands):



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	235,116		$	43,799		$	12,349		$	73,920		$	365,184
Net interest revenue (expense) from internal sources	(29,208		)	18,229			$	14,857		(3,878		)	—
Net interest revenue	205,908			62,028			27,206			70,042			365,184
Provision for credit losses	28,423			3,020			(390		)	23,947			55,000
Net interest revenue after provision for credit losses	177,485			59,008			27,596			46,095			310,184
Other operating revenue	96,605			111,469			144,518			(9,636		)	342,956
Other operating expense	108,663			118,524			122,098			144,670			493,955
Net direct contribution	165,427			51,953			50,016			(108,211		)	159,185
Gain on financial instruments, net	—			31,626			—			(31,626		)	—
Change in fair value of mortgage servicing rights	—			(44,271		)	—			44,271			—
Gain (loss) on repossessed assets, net	(680		)	406			—			274			—
Corporate expense allocations	17,627			32,608			20,952			(71,187		)	—
Net income before taxes	147,120			7,106			29,064			(24,105		)	159,185
Federal and state income taxes	57,230			2,764			11,306			(19,375		)	51,925
Net income	89,890			4,342			17,758			(4,730		)	107,260
Net loss attributable to non-controlling interests	—			—			—			(1,105		)	(1,105		)
Net income attributable to BOK Financial Corp. shareholders	$	89,890		$	4,342		$	17,758		$	(3,625	)	$	108,365

Average assets	$	16,971,339		$	8,731,085		$	5,665,218		$	379,615		$	31,747,257

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2017

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 measured on a recurring basis was as follows as of June 30, 2017 (in thousands):



	Total		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Trading securities:
U.S. government agency debentures	$	20,954	$	—	$	20,954	$	—
U.S. government agency residential mortgage-backed securities	365,171		—		365,171		—
Municipal and other tax-exempt securities	45,444		—		45,444		—
Other trading securities	9,845		—		9,845		—
Total trading securities	441,414		—		441,414		—
Available for sale securities:
U.S. Treasury	998		998		—		—
Municipal and other tax-exempt securities	32,765		—		28,110		4,655
U.S. government agency residential mortgage-backed securities	5,382,377		—		5,382,377		—
Privately issued residential mortgage-backed securities	103,383		—		103,383		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,782,070		—		2,782,070		—
Other debt securities	4,152		—		—		4,152
Perpetual preferred stock	16,568		—		16,568		—
Equity securities and mutual funds	18,728		3,516		15,212		—
Total available for sale securities	8,341,041		4,514		8,327,720		8,807
Fair value option securities – U.S. government agency residential mortgage-backed securities	445,169		—		445,169		—
Residential mortgage loans held for sale	287,259		—		274,524		12,735
Mortgage servicing rights¹	245,239		—		—		245,239
Derivative contracts, net of cash collateral²	280,289		20,213		260,076		—
Liabilities:
Derivative contracts, net of cash collateral²	285,819		5,919		279,900		—


¹	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 6, Mortgage Banking Activities.

²

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 energy and interest rate derivative contacts. Derivative contacts in liability positions that were valued using quoted prices in active markets for identical instruments are exchange-traded interest rate and agricultural derivative contracts, net of cash margin.

The fair value of financial assets and liabilities measured on a recurring basis was as follows as of December 31, 2016 (in thousands):



	Total		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Trading securities:
U.S. government agency debentures	$	6,234	$	—	$	6,234	$	—
U.S. government agency residential mortgage-backed securities	310,067		—		310,067		—
Municipal and other tax-exempt securities	14,427		—		14,427		—
Other trading securities	6,900		—		6,900		—
Total trading securities	337,628		—		337,628		—
Available for sale securities:
U.S. Treasury	999		999		—		—
Municipal and other tax-exempt securities	40,993		—		35,204		5,789
U.S. government agency residential mortgage-backed securities	5,460,386		—		5,460,386		—
Privately issued residential mortgage-backed securities	115,535		—		115,535		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	3,017,933		—		3,017,933		—
Other debt securities	4,152		—		—		4,152
Perpetual preferred stock	18,474		—		18,474		—
Equity securities and mutual funds	18,357		3,495		14,862		—
Total available for sale securities	8,676,829		4,494		8,662,394		9,941
Fair value option securities – U.S. government agency residential mortgage-backed securities	77,046		—		77,046		—
Residential mortgage loans held for sale	301,897		—		290,280		11,617
Mortgage servicing rights¹	247,073		—		—		247,073
Derivative contracts, net of cash collateral²	689,872		7,541		682,331		—
Liabilities:
Derivative contracts, net of cash collateral²	664,531		6,972		657,559		—


¹	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 6, Mortgage Banking Activities.

²

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 contacts, 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, energy and agricultural derivative contracts, net of cash margin.

The fair value of financial assets and liabilities measured on a recurring basis was as follows as of June 30, 2016 (in thousands):



	Total		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Trading securities:
U.S. government agency debentures	$	18,909	$	—	$	18,909	$	—
U.S. government agency residential mortgage-backed securities	122,306		—		122,306		—
Municipal and other tax-exempt securities	52,721		—		52,721		—
Other trading securities	17,686		—		17,686		—
Total trading securities	211,622		—		211,622		—
Available for sale securities:
U.S. Treasury	1,004		1,004		—		—
Municipal and other tax-exempt securities	50,262		—		40,662		9,600
U.S. government agency residential mortgage-backed securities	5,700,268		—		5,700,268		—
Privately issued residential mortgage-backed securities	126,313		—		126,313		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,911,946		—		2,911,946		—
Other debt securities	4,151		—		—		4,151
Perpetual preferred stock	17,931		—		17,931		—
Equity securities and mutual funds	18,814		3,785		15,029		—
Total available for sale securities	8,830,689		4,789		8,812,149		13,751
Fair value option securities:
U.S. Treasury	25,306		25,306		—		—
U.S. government agency residential mortgage-backed securities	237,959		—		237,959		—
Total fair value option securities	263,265		25,306		237,959		—
Residential mortgage loans held for sale	430,728		—		420,979		9,749
Mortgage servicing rights¹	190,747		—		—		190,747
Derivative contracts, net of cash collateral²	883,673		7,246		876,427		—
Liabilities:
Derivative contracts, net of cash collateral²	719,159		4,808		714,351		—


¹	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 6, Mortgage Banking Activities.

²

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 energy and agricultural derivative contacts, 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 energy derivative contracts, net cash margin.

Fair Value Assets Measured On Recurring Basis, Significant Unobservable Inputs [Table Text Block]

The following represents the changes for the three and six months ended June 30, 2017 related to assets measured at fair value on a recurring basis using significant unobservable inputs (in thousands):



	Available for Sale Securities
	Municipal and other tax-exempt securities			Other debt securities			Residential mortgage loans held for sale
Balance, March 31, 2017	$	5,722		$	4,153		$	12,679
Transfer to Level 3 from Level 2¹	—			—			853
Purchases	—			—			—
Proceeds from sales	—			—			(1,030		)
Redemptions and distributions	(1,100		)	—			—
Gain (loss) recognized in earnings:
Mortgage banking revenue	—			—			233
Other comprehensive income (loss):
Net change in unrealized gain (loss)	33			(1		)	—
Balance, June 30, 2017	$	4,655		$	4,152		$	12,735


¹	Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.



	Available for Sale Securities
	Municipal and other tax-exempt			Other debt securities		Residential mortgage loans held for sale
Balance, Dec. 31, 2016	$	5,789		$	4,152	$	11,617
Transfer to Level 3 from Level 2¹	—			—		2,740
Purchases	—			—		—
Proceeds from sales	—			—		(1,702		)
Redemptions and distributions	(1,100		)	—		—
Gain (loss) recognized in earnings:
Mortgage banking revenue	—			—		80
Other comprehensive income (loss):
Net change in unrealized gain (loss)	(34		)	—		—
Balance, June 30, 2017	$	4,655		$	4,152	$	12,735


¹	Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.

The following represents the changes for the three and six months ended June 30, 2016 related to assets measured at fair value on a recurring basis using significant unobservable inputs (in thousands):



	Available for Sale Securities
	Municipal and other tax-exempt securities			Other debt securities		Residential mortgage loans held for sale
Balance, March 31, 2016	$	9,614		$	4,151	$	8,099
Transfer to Level 3 from Level 2¹	—			—		3,080
Purchases	—			—		—
Proceeds from sales	—			—		(1,249		)
Redemptions and distributions	—			—		—
Gain (loss) recognized in earnings:
Mortgage banking revenue	—			—		(181		)
Other comprehensive income (loss):
Net change in unrealized gain (loss)	(14		)	—		—
Balance, June 30, 2016	$	9,600		$	4,151	$	9,749


¹	Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.



	Available for Sale Securities
	Municipal and other tax-exempt			Other debt securities		Residential mortgage loans held for sale
Balance, Dec. 31, 2015	$	9,610		$	4,151	$	7,874
Transfer to Level 3 from Level 2¹	—			—		3,540
Purchases	—			—		—
Proceeds from sales	—			—		(1,362		)
Redemptions and distributions	—			—		—
Gain (loss) recognized in earnings
Mortgage banking revenue	—			—		(303		)
Other comprehensive income (loss):
Net change in unrealized gain (loss)	(10		)	—		—
Balance, June 30, 2016	$	9,600		$	4,151	$	9,749


¹	Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.

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

A summary of quantitative information about assets measured at fair value on a recurring basis using Significant Unobservable Inputs (Level 3) as of June 30, 2017 follows (in thousands):



	Par Value		Amortized Cost/Unpaid Principal Balance		Fair Value		Valuation Technique(s)		Unobservable Input	Range (Weighted Average)

Available for sale securities
Municipal and other tax-exempt securities	$	5,095	$	5,067	$	4,655	Discounted cash flows	¹	Interest rate spread	5.98%-5.98% (5.98%)	²
										90.00%-94.90% (92.93%)	³
Other debt securities	4,400		4,400		4,152		Discounted cash flows	¹	Interest rate spread	5.41%-6.72% (6.57%)	⁴
										94.31% - 94.38 (94.37%)	³

Residential mortgage loans held for sale	N/A		13,274		12,563		Quoted prices of loans sold in securitization transactions, with a liquidity discount applied		Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.	94.64%


¹	Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume.


²	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 360 to 446 basis points over average yields for comparable tax-exempt securities.


³	Represents fair value as a percentage of par value.


⁴	Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 3 percent.

A summary of quantitative information about Recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of December 31, 2016 follows (in thousands):



	Par Value		Amortized Cost/Unpaid Principal Balance		Fair Value		Valuation Technique(s)		Unobservable Input	Range (Weighted Average)

Available for sale securities
Municipal and other tax-exempt securities	$	6,195	$	6,163	$	5,789	Discounted cash flows	¹	Interest rate spread	5.91%-6.21% (6.16%)	²
										90.00%-93.40% (92.20%)	³
Other debt securities	4,400		4,400		4,152		Discounted cash flows	¹	Interest rate spread	6.01%-6.26% (6.23%)	⁴
										94.34% - 94.36 (94.36%)	³
Residential mortgage loans held for sale	N/A		12,431		11,617		Quoted prices of loans sold in securitization transactions, with a liquidity discount applied		Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.	93.45%


¹	Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume.


²	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 467 to 525 basis points over average yields for comparable tax-exempt securities.


³	Represents fair value as a percentage of par value.


⁴	Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 1 percent.

A summary of quantitative information about Recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of June 30, 2016 follows (in thousands):



	Par Value		Amortized Cost		Fair Value		Valuation Technique(s)		Unobservable Input	Range (Weighted Average)

Available for sale securities
Municipal and other tax-exempt securities	$	10,370	$	10,312	$	9,600	Discounted cash flows	¹	Interest rate spread	5.34%-5.64% (5.60%)	²
										90.00%-93.28% (92.58%)	³
Other debt securities	4,400		4,400		4,151		Discounted cash flows	¹	Interest rate spread	5.51%-5.96% (5.91%)	⁴
										94.32% - 94.34 (94.34%)	³

Residential mortgage loans held for sale	N/A		10,518		9,749		Quoted prices of loans sold in securitization transactions, with a liquidity discount applied		Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.	92.69%


¹	Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume.


²	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 474 to 513 basis points over average yields for comparable tax-exempt securities.


³	Represents fair value as a percentage of par value.


⁴	Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 1 percent.

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) during the period. The carrying value represents only those assets with a balance at June 30, 2017 for which the fair value was adjusted during the six months ended June 30, 2017:



							Fair Value Adjustments for the
	Carrying Value at June 30, 2017						Three Months Ended June 30, 2017 Recognized in:				Six Months Ended June 30, 2017 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 and expenses of repossessed assets, net		Gross charge-offs against allowance for loan losses		Net losses and expenses of repossessed assets, net
Impaired loans	$	—	$	464	$	3,570	$	232	$	—	$	676	$	—
Real estate and other repossessed assets	—		3,488		530		—		772		—		906

The following represents the carrying value of assets measured at fair value on a non-recurring basis (and related losses) during the period. The carrying value represents only those assets with a balance at June 30, 2016 for which the fair value was adjusted during the six months ended June 30, 2016:



	Carrying Value at June 30, 2016						Fair Value Adjustments for the Three Months Ended June 30, 2016 Recognized in:				Six Months Ended June 30, 2016 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 and expenses of repossessed assets, net		Gross charge-offs against allowance for loan losses		Net losses and expenses of repossessed assets, net
Impaired loans	$	—	$	634	$	42,342	$	7,041	$	—	$	29,186	$	—
Real estate and other repossessed assets	—		5,709		1,693		—		751		—		1,068

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 June 30, 2017 follows (in thousands):



	Fair Value		Valuation Technique(s)	Unobservable Input	Range (Weighted Average)
Impaired loans	$	3,570	Discounted cash flows	Recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs	75% - 90% (83%)¹
Real estate and other repossessed assets	530		Appraised value, as adjusted	Marketability adjustment off appraised value²	65% - 88% (80%)


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.

A summary of quantitative information about Non-recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of June 30, 2016 follows (in thousands):



	Fair Value		Valuation Technique(s)	Unobservable Input	Range (Weighted Average)
Impaired loans	$	42,342	Discounted cash flows	Recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs	25% - 71% (58%)¹
Real estate and other repossessed assets	1,693		Appraised value, as adjusted	Marketability adjustments off appraised value2	68% - 80% (71%)


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 basis as of June 30, 2017 (dollars in thousands):



	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	$	561,587		$	561,587	$	561,587	$	—	$	—
Interest-bearing cash and cash equivalents	2,078,831			2,078,831		2,078,831		—		—
Trading securities:								—
U.S. government agency debentures	20,954			20,954		—		20,954		—
U.S. government agency residential mortgage-backed securities	365,171			365,171		—		365,171		—
Municipal and other tax-exempt securities	45,444			45,444		—		45,444		—
Other trading securities	9,845			9,845		—		9,845		—
Total trading securities	441,414			441,414		—		441,414		—
Investment securities:
Municipal and other tax-exempt securities	267,375			270,531		—		270,531		—
U.S. government agency residential mortgage-backed securities	18,035			18,642		—		18,642		—
Other debt securities	205,016			226,502		—		226,502		—
Total investment securities	490,426			515,675		—		515,675		—
Available for sale securities:
U.S. Treasury	998			998		998		—		—
Municipal and other tax-exempt securities	32,765			32,765		—		28,110		4,655
U.S. government agency residential mortgage-backed securities	5,382,377			5,382,377		—		5,382,377		—
Privately issued residential mortgage-backed securities	103,383			103,383		—		103,383		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,782,070			2,782,070		—		2,782,070		—
Other debt securities	4,152			4,152		—		—		4,152
Perpetual preferred stock	16,568			16,568		—		16,568		—
Equity securities and mutual funds	18,728			18,728		3,516		15,212		—
Total available for sale securities	8,341,041			8,341,041		4,514		8,327,720		8,807
Fair value option securities – U.S. government agency residential mortgage-backed securities	445,169			445,169		—		445,169		—
Residential mortgage loans held for sale	287,259			287,259		—		274,524		12,735
Loans:
Commercial	10,637,955			10,413,704		—		—		10,413,704
Commercial real estate	3,688,592			3,636,365		—		—		3,636,365
Residential mortgage	1,939,198			1,950,577		—		—		1,950,577
Personal	917,900			909,055		—		—		909,055
Total loans	17,183,645			16,909,701		—		—		16,909,701
Allowance for loan losses	(250,061		)	—		—		—		—
Loans, net of allowance	16,933,584			16,909,701		—		—		16,909,701
Mortgage servicing rights	245,239			245,239		—		—		245,239
Derivative instruments with positive fair value, net of cash collateral	280,289			280,289		46,366		233,923		—
Deposits with no stated maturity	20,120,352			20,120,352		—		—		20,120,352
Time deposits	2,196,122			2,164,115		—		—		2,164,115
Other borrowed funds	5,696,666			5,664,273		—		—		5,664,273
Subordinated debentures	144,658			147,204		—		147,204		—
Derivative instruments with negative fair value, net of cash collateral	285,819			285,819		20,915		264,904		—

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 basis as of December 31, 2016 (dollars in thousands):



	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	$	620,846		$	620,846	$	620,846	$	—	$	—
Interest-bearing cash and cash equivalents	1,916,651			1,916,651		1,916,651		—		—
Trading securities:								—
U.S. government agency debentures	6,234			6,234		—		6,234		—
U.S. government agency residential mortgage-backed securities	310,067			310,067		—		310,067		—
Municipal and other tax-exempt securities	14,427			14,427		—		14,427		—
Other trading securities	6,900			6,900		—		6,900		—
Total trading securities	337,628			337,628		—		337,628		—
Investment securities:
Municipal and other tax-exempt securities	320,364			321,225		—		321,225		—
U.S. government agency residential mortgage-backed securities	20,777			21,473		—		21,473		—
Other debt securities	205,004			222,795		—		222,795		—
Total investment securities	546,145			565,493		—		565,493		—
Available for sale securities:
U.S. Treasury	999			999		999		—		—
Municipal and other tax-exempt securities	40,993			40,993		—		35,204		5,789
U.S. government agency residential mortgage-backed securities	5,460,386			5,460,386		—		5,460,386		—
Privately issued residential mortgage-backed securities	115,535			115,535		—		115,535		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	3,017,933			3,017,933		—		3,017,933		—
Other debt securities	4,152			4,152		—		—		4,152
Perpetual preferred stock	18,474			18,474		—		18,474		—
Equity securities and mutual funds	18,357			18,357		3,495		14,862		—
Total available for sale securities	8,676,829			8,676,829		4,494		8,662,394		9,941
Fair value option securities – U.S. government agency residential mortgage-backed securities	77,046			77,046		—		77,046		—
Residential mortgage loans held for sale	301,897			301,897		—		290,280		11,617
Loans:
Commercial	10,390,824			10,437,016		—		—		10,437,016
Commercial real estate	3,809,046			3,850,981		—		—		3,850,981
Residential mortgage	1,949,832			2,025,159		—		—		2,025,159
Personal	839,958			864,904		—		—		864,904
Total loans	16,989,660			17,178,060		—		—		17,178,060
Allowance for loan losses	(246,159		)	—		—		—		—
Loans, net of allowance	16,743,501			17,178,060		—		—		17,178,060
Mortgage servicing rights	247,073			247,073		—		—		247,073
Derivative instruments with positive fair value, net of cash collateral	689,872			689,872		7,541		682,331		—
Deposits with no stated maturity	20,526,295			20,526,295		—		—		20,526,295
Time deposits	2,221,800			2,218,303		—		—		2,218,303
Other borrowed funds	5,572,662			5,556,327		—		—		5,556,327
Subordinated debentures	144,640			128,903		—		128,903		—
Derivative instruments with negative fair value, net of cash collateral	664,531			664,531		6,972		657,559		—

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 basis as of June 30, 2016 (dollars in thousands):



	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	$	498,713		$	498,713	$	498,713	$	—	$	—
Interest-bearing cash and cash equivalents	1,907,838			1,907,838		1,907,838		—		—
Trading securities:								—
U.S. government agency debentures	18,909			18,909		—		18,909		—
U.S. government agency residential mortgage-backed securities	122,306			122,306		—		122,306		—
Municipal and other tax-exempt securities	52,721			52,721		—		52,721		—
Other trading securities	17,686			17,686		—		17,686		—
Total trading securities	211,622			211,622		—		211,622		—
Investment securities:
Municipal and other tax-exempt securities	334,551			340,700		—		340,700		—
U.S. government agency residential mortgage-backed securities	23,750			25,233		—		25,233		—
Other debt securities	202,410			233,129		—		233,129		—
Total investment securities	560,711			599,062		—		599,062		—
Available for sale securities:
U.S. Treasury	1,004			1,004		1,004		—		—
Municipal and other tax-exempt securities	50,262			50,262		—		40,662		9,600
U.S. government agency residential mortgage-backed securities	5,700,268			5,700,268		—		5,700,268		—
Privately issued residential mortgage-backed securities	126,313			126,313		—		126,313		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,911,946			2,911,946		—		2,911,946		—
Other debt securities	4,151			4,151		—		—		4,151
Perpetual preferred stock	17,931			17,931		—		17,931		—
Equity securities and mutual funds	18,814			18,814		3,785		15,029		—
Total available for sale securities	8,830,689			8,830,689		4,789		8,812,149		13,751
Fair value option securities:
U.S. Treasury	25,306			25,306		25,306		—		—
U.S. government agency residential mortgage-backed securities	237,959			237,959		—		237,959		—
Total fair value option securities	263,265			263,265		25,306		237,959		—
Residential mortgage loans held for sale	430,728			430,728		—		420,979		9,749
Loans:
Commercial	10,356,437			10,172,701		—		—		10,172,701
Commercial real estate	3,581,966			3,563,378		—		—		3,563,378
Residential mortgage	1,880,923			1,913,208		—		—		1,913,208
Personal	587,423			582,353		—		—		582,353
Total loans	16,406,749			16,231,640		—		—		16,231,640
Allowance for loan losses	(243,259		)	—		—		—		—
Loans, net of allowance	16,163,490			16,231,640		—		—		16,231,640
Mortgage servicing rights	190,747			190,747		—		—		190,747
Derivative instruments with positive fair value, net of cash collateral	883,673			883,673		7,246		876,427		—
Deposits with no stated maturity	18,512,740			18,512,740		—		—		18,512,740
Time deposits	2,247,061			2,252,212		—		—		2,252,212
Other borrowed funds	6,360,199			6,342,885		—		—		6,342,885
Subordinated debentures	371,812			371,808		—		150,234		221,574
Derivative instruments with negative fair value, net of cash collateral	719,159			719,159		4,808		714,351		—

Fair Value Inputs, Financial Instruments, Quantitative Information [Table Text Block]



	Range of Contractual Yields				Average Re-pricing (in years)	Discount Rate
	Minimum		Maximum		Average	Minimum		Maximum
June 30, 2017
Commercial	0.38	%	30.00	%	0.64	0.71	%	4.56	%
Commercial real estate	0.38	%	18.00	%	0.77	1.03	%	4.31	%
Residential mortgage	1.74	%	18.00	%	2.18	1.75	%	4.19	%
Consumer	0.25	%	21.00	%	0.28	0.70	%	4.68	%

Time deposits	0.03	%	10.00	%	1.91	1.81	%	2.12	%
Other borrowings	0.25	%	3.58	%	0.02	1.06	%	3.69	%
Subordinated debentures	5.38	%	5.38	%	16.90	4.89	%	4.89	%

December 31, 2016
Commercial	0.38	%	30.00	%	0.70	0.64	%	4.60	%
Commercial real estate	0.38	%	18.00	%	0.71	0.94	%	4.27	%
Residential mortgage	1.74	%	18.00	%	2.27	1.71	%	4.26	%
Consumer	0.25	%	21.00	%	0.40	1.03	%	4.59	%

Time deposits	0.02	%	9.65	%	1.96	1.57	%	2.00	%
Other borrowings	0.25	%	3.50	%	0.00	0.55	%	3.22	%
Subordinated debentures	5.38	%	5.38	%	16.86	6.11	%	6.11	%

June 30, 2016
Commercial	0.38	%	30.00	%	0.69	0.55	%	3.68	%
Commercial real estate	0.38	%	18.00	%	0.73	0.80	%	3.65	%
Residential mortgage	1.70	%	18.00	%	1.97	1.25	%	3.75	%
Consumer	0.25	%	21.00	%	0.35	0.71	%	3.91	%

Time deposits	0.03	%	9.64	%	2.15	1.16	%	1.43	%
Other borrowings	0.25	%	3.28	%	0.02	0.30	%	2.92	%
Subordinated debentures	1.32	%	5.38	%	8.35	2.16	%	5.38	%

Federal and State Income Taxes Federal and State Income Taes (Tables)

6 Months Ended

Jun. 30, 2017

Income Tax Disclosure [Abstract]

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

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



	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Amount:
Federal statutory tax	$	47,800		$	33,869		$	92,168		$	55,715
Tax exempt revenue	(3,224		)	(2,568		)	(6,335		)	(5,100		)
Effect of state income taxes, net of federal benefit	2,944			1,557			5,389			3,858
Utilization of tax credits:
Low-income housing tax credit, net of amortization	(526		)	(572		)	(2,249		)	(1,882		)
Other tax credits	(363		)	(521		)	(727		)	(1,042		)
Bank-owned life insurance	(775		)	(810		)	(1,547		)	(1,601		)
Share-based compensation	1,636			—			(2,301		)	—
Other, net	213			(458		)	1,410			1,977
Total income tax expense	$	47,705		$	30,497		$	85,808		$	51,925



	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Percent of pretax income:
Federal statutory tax	35.0	%	35.0	%	35.0	%	35.0	%
Tax exempt revenue	(2.4	)	(2.7	)	(2.4	)	(3.2	)
Effect of state income taxes, net of federal benefit	2.2		1.6		2.0		2.4
Utilization of tax credits:
Low-income housing tax credit, net of amortization	(0.4	)	(0.6	)	(0.8	)	(1.2	)
Other tax credits	(0.3	)	(0.5	)	(0.3	)	(0.6	)
Bank-owned life insurance	(0.6	)	(0.8	)	(0.6	)	(1.0	)
Share-based compensation	1.2		—		(0.9	)	—
Other, net	0.2		(0.5	)	0.6		1.2
Total	34.9	%	31.5	%	32.6	%	32.6	%

Significant Accounting Policies Loans and Allowance for Credit Losses (Details)	6 Months Ended
	Jun. 30, 2017
Loans and Allowance for Credit Losses [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 and Allowances for Credit Losses, Minimum No of Days After Which Past Due Non-Risk Graded Loans Are Charged Off	60 days
Loans and Allowances for Credit Losses, Maximum No 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 Newly Adopted and Pending Accounting Pronouncements (Details)	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Percentage of gross revenue of Transaction Card Revenue and Fiduciary and Asset Management Revenue	19.00%
Percentage of fees and commission revenue composed of Transaction Card Revenue and Fiduciary and Asset Management Revenue	43.00%

Trading Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	$ 441,414	$ 337,628	$ 211,622
Trading Securities, Net Unrealized Gain (Loss)	(986)	738	786
U.S. government agency debentures
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	20,954	6,234	18,909
Trading Securities, Net Unrealized Gain (Loss)	(9)	(4)	(8)
U.S. government agency residential mortgage-backed securities
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	365,171	310,067	122,306
Trading Securities, Net Unrealized Gain (Loss)	(1,032)	635	363
Municipal and other tax-exempt securities
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	45,444	14,427	52,721
Trading Securities, Net Unrealized Gain (Loss)	230	50	262
Other trading securities
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	9,845	6,900	17,686
Trading Securities, Net Unrealized Gain (Loss)	$ (175)	$ 57	$ 169

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

6 Months Ended

Jun. 30, 2017

USD ($)

Dec. 31, 2016

USD ($)

Jun. 30, 2016

USD ($)

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

$ 490,426

$ 546,145

$ 560,711

515,675

565,493

599,062

26,092

^[1]

21,154

^[2]

38,440

^[3]

Investment Securities, Debt Maturities, Net Carrying Value [Abstract]

(843)

^[1]

(1,806)

^[2]

(89)

^[3]

Investments Securities, Debt Maturities, Amortized Cost

490,426

546,145

560,711

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

Investment Securities, Debt Maturities, Nominal Yield [Abstract]

$ 515,675

565,493

599,062

Investment Securities, Debt Maturities, Nominal Yield

3.73%

Investment Securities, Pledged as Collateral [Abstract]

Investment Securities, Pledged as Collateral, Amortized Cost

$ 251,684

322,208

287,166

Investment Securities, Pledged as Collateral, Fair Value

$ 255,097

$ 323,808

$ 293,625

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

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

105

193

20

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

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

$ 123,272

$ 236,070

$ 11,915

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

3,000

5,188

5,236

Investment Securities, Continuous Unrealized Loss Position, Fair Value

126,272

241,258

17,151

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

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

764

1,709

20

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

79

97

69

Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss

843

1,806

89

Fixed Maturity Securities [Member]

Investment Securities, Debt Maturities, Net Carrying Value [Abstract]

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

104,701

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

168,198

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

141,018

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

58,474

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

472,391

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

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

104,918

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

171,887

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

159,635

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

60,593

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

$ 497,033

Investment Securities, Debt Maturities, Nominal Yield [Abstract]

Investment Securities, Debt Maturities, Less Than One Year, Nominal Yield

1.95%

Investment Securities, Debt Maturities, One to Five Years, Nominal Yield

2.89%

Investment Securities, Debt Maturities, Six to Ten Years, Nominal Yield

5.69%

Investment Securities, Debt Maturities, Over Ten Years, Nominal Yield

4.90%

Investment Securities, Debt Maturities, Nominal Yield

3.77%

Investment Securities, Debt Maturities, Weighted Average Maturity

^[4]

4.83

Municipal and other tax-exempt securities

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

$ 267,375

320,364

334,551

270,531

321,225

340,700

3,384

^[1]

2,272

^[2]

6,234

^[3]

Investment Securities, Debt Maturities, Net Carrying Value [Abstract]

(228)

^[1]

(1,411)

^[2]

(85)

^[3]

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

90,415

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

122,560

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

10,739

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

43,661

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

267,375

Investments Securities, Debt Maturities, Amortized Cost

267,375

320,364

334,551

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

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

90,436

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

122,914

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

11,220

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

45,961

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

270,531

Investment Securities, Debt Maturities, Nominal Yield [Abstract]

$ 270,531

$ 321,225

$ 340,700

Investment Securities, Debt Maturities, Less Than One Year, Nominal Yield

^[5]

1.66%

Investment Securities, Debt Maturities, One to Five Years, Nominal Yield

^[5]

2.12%

Investment Securities, Debt Maturities, Six to Ten Years, Nominal Yield

^[5]

4.88%

Investment Securities, Debt Maturities, Over Ten Years, Nominal Yield

^[5]

5.05%

Investment Securities, Debt Maturities, Nominal Yield

^[5]

2.55%

Investment Securities, Debt Maturities, Weighted Average Maturity

^[4]

3.48

Investment Securities,Debt Maturities, Effective tax rate for nominal yield calculation

39.00%

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

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

82

151

19

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

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

$ 111,078

$ 219,892

$ 11,915

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

3,000

4,333

4,378

Investment Securities, Continuous Unrealized Loss Position, Fair Value

114,078

224,225

16,293

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

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

149

1,316

20

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

79

95

65

Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss

228

1,411

85

Other debt securities

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

205,016

205,004

202,410

226,502

222,795

233,129

22,040

^[1]

18,115

^[2]

30,723

^[3]

Investment Securities, Debt Maturities, Net Carrying Value [Abstract]

(554)

^[1]

(324)

^[2]

(4)

^[3]

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

14,286

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

45,638

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

130,279

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

14,813

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

205,016

Investments Securities, Debt Maturities, Amortized Cost

205,016

205,004

202,410

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

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

14,482

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

48,973

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

148,415

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

14,632

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

226,502

Investment Securities, Debt Maturities, Nominal Yield [Abstract]

$ 226,502

$ 222,795

$ 233,129

Investment Securities, Debt Maturities, Less Than One Year, Nominal Yield

3.84%

Investment Securities, Debt Maturities, One to Five Years, Nominal Yield

4.95%

Investment Securities, Debt Maturities, Six to Ten Years, Nominal Yield

5.75%

Investment Securities, Debt Maturities, Over Ten Years, Nominal Yield

4.46%

Investment Securities, Debt Maturities, Nominal Yield

5.35%

Investment Securities, Debt Maturities, Weighted Average Maturity

^[4]

6.59

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

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

22

41

1

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

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

$ 8,384

$ 11,820

$ 0

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

0

855

858

Investment Securities, Continuous Unrealized Loss Position, Fair Value

8,384

12,675

858

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

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

554

322

0

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

0

2

4

Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss

554

324

4

U.S. government agency residential mortgage-backed securities

Investment Securities, Debt Maturities, Net Carrying Value [Abstract]

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

18,035

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

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

$ 18,642

Investment Securities, Debt Maturities, Nominal Yield [Abstract]

Investment Securities, Debt Maturities, Nominal Yield

^[6]

2.76%

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

4 years 255 days

U.S. government agency residential mortgage-backed securities | Other

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

$ 18,035

20,777

23,750

18,642

21,473

25,233

668

^[1]

767

^[2]

1,483

^[3]

Investment Securities, Debt Maturities, Net Carrying Value [Abstract]

(61)

^[1]

(71)

^[2]

0

^[3]

Investments Securities, Debt Maturities, Amortized Cost

18,035

20,777

23,750

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

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

$ 18,642

$ 21,473

$ 25,233

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

1

0

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

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

$ 3,810

$ 4,358

$ 0

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

0

Investment Securities, Continuous Unrealized Loss Position, Fair Value

3,810

4,358

0

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

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

61

71

0

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

0

Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss

$ 61

$ 71

$ 0

[1]	Gross unrealized gains and losses are not recognized in Accumulated Other Comprehensive Income "AOCI" in the Consolidated Balance Sheets.
[2]	Gross unrealized gains and losses are not recognized in AOCI in the Consolidated Balance Sheets.
[3]	Gross unrealized gains and losses are not recognized in AOCI in the Consolidated Balance Sheets.
[4]	Expected maturities may differ from contractual maturities, because borrowers may have the right to call or prepay obligations with or without penalty.
[5]	Calculated on a taxable equivalent basis using a 39 percent effective tax rate.
[6]	The nominal yield on residential mortgage-backed securities is based upon prepayment assumptions at the purchase date. Actual yields earned may differ significantly based upon actual prepayments. See Quarterly Financial Summary - Unaudited for current yields on the investment securities portfolio.

Available for Sale Securities (Details)
$ in Thousands

3 Months Ended

6 Months Ended

Jun. 30, 2017

USD ($)

Jun. 30, 2016

USD ($)

Jun. 30, 2017

USD ($)

Jun. 30, 2016

USD ($)

Dec. 31, 2016

USD ($)

Schedule of Available-for-sale Securities [Line Items]

$ 8,325,000

$ 8,635,304

$ 8,325,000

$ 8,635,304

$ 8,691,728

Available-for-sale Securities, Gross Unrealized Gain

8,341,041

8,830,689

8,341,041

8,830,689

8,676,829

65,740

^[1]

198,378

^[2]

65,740

^[1]

198,378

^[2]

60,165

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(49,699)

^[1]

(2,217)

^[2]

(49,699)

^[1]

(2,217)

^[2]

(74,846)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

(776)

^[5]

0

^[4]

(776)

^[5]

(218)

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Amortized Cost

8,325,000

8,635,304

8,325,000

8,635,304

8,691,728

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Fair Value

$ 8,341,041

8,830,689

$ 8,341,041

8,830,689

8,676,829

Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]

Available-for-sale Securities, Debt Maturities, Nominal Yield

1.90%

Available-for-sale Securities, Gross Realized Gain (Loss), Disclosures [Abstract]

Available-for-sale Securities, Proceeds

$ 460,402

325,758

$ 700,412

795,140

Available-for-sale Securities, Gross realized gains

2,763

5,326

4,855

9,290

Available-for-sale Securities, Gross realized losses

(2,383)

0

(2,426)

0

Available-for-sale Securities, Related federal and state income tax expense

148

2,072

945

3,614

Available-for-sale Securities, Pledged as Collateral [Abstract]

Available-for-sale Securities, Pledged As Collateral, Amortized cost

6,327,666

7,502,361

6,327,666

7,502,361

7,353,116

Available-for-sale Securities, Pledged As Collateral, Fair value

$ 6,317,623

$ 7,657,916

$ 6,317,623

$ 7,657,916

$ 7,327,470

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

367

90

367

90

488

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 3,818,331

$ 567,460

$ 3,818,331

$ 567,460

$ 5,231,605

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

268,886

135,093

268,886

135,093

178,249

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

4,087,217

702,553

4,087,217

702,553

5,409,854

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

44,025

1,193

44,025

1,193

70,818

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

5,674

1,800

5,674

1,800

4,246

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

49,699

2,993

49,699

2,993

75,064

Fixed Maturity Securities [Member]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Amortized Cost Basis

68,244

Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis

886,839

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis

1,572,763

Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis

298,982

Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis

2,826,828

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value

68,166

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

885,783

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

1,569,813

Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value

296,223

Available-for-sale Securities, Debt Maturities, Single Maturity Date

$ 2,819,985

Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield

1.60%

Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield

1.85%

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield

1.85%

Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield

1.90%

Available-for-sale Securities, Debt Maturities, Nominal Yield

1.83%

Available-for-sale Securities, Debt Maturities, Weighted Average Maturity

^[7]

7.03

U.S. Treasury

Schedule of Available-for-sale Securities [Line Items]

$ 1,000

1,000

$ 1,000

1,000

Available-for-sale Securities, Gross Unrealized Gain

998

1,004

998

1,004

999

0

^[1]

4

^[2]

0

^[1]

4

^[2]

0

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(2)

^[1]

0

^[2]

(2)

^[1]

0

^[2]

(1)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Amortized Cost Basis

1,000

Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis

0

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis

0

Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis

0

Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis

1,000

Available-for-sale Securities, Debt Maturities, Amortized Cost

1,000

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value

998

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

0

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

0

Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value

0

Available-for-sale Securities, Debt Maturities, Single Maturity Date

998

Available-for-sale Securities, Debt Maturities, Fair Value

$ 998

$ 1,004

$ 998

$ 1,004

$ 999

Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield

0.87%

Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield

0.00%

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield

0.00%

Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield

0.00%

Available-for-sale Securities, Debt Maturities, Nominal Yield

0.87%

Available-for-sale Securities, Debt Maturities, Weighted Average Maturity

^[7]

0.55

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

1

0

1

0

1

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 997

$ 0

$ 997

$ 0

$ 999

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

0

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

997

0

997

0

999

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

2

0

2

0

1

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

0

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

2

0

2

0

1

Municipal and other tax-exempt securities

Schedule of Available-for-sale Securities [Line Items]

32,885

50,170

32,885

50,170

41,050

Available-for-sale Securities, Gross Unrealized Gain

32,765

50,262

32,765

50,262

40,993

293

^[1]

805

^[2]

293

^[1]

805

^[2]

343

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(413)

^[1]

(713)

^[2]

(413)

^[1]

(713)

^[2]

(400)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Amortized Cost Basis

8,981

Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis

6,380

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis

1,028

Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis

16,496

Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis

32,885

Available-for-sale Securities, Debt Maturities, Amortized Cost

32,885

50,170

32,885

50,170

41,050

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value

9,021

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

6,497

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

1,081

Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value

16,166

Available-for-sale Securities, Debt Maturities, Single Maturity Date

32,765

Available-for-sale Securities, Debt Maturities, Fair Value

$ 32,765

$ 50,262

$ 32,765

$ 50,262

$ 40,993

Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield

^[8]

4.24%

Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield

^[8]

3.91%

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield

^[8]

6.72%

Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield

^[8],[9]

2.28%

Available-for-sale Securities, Debt Maturities, Nominal Yield

^[8]

3.27%

Available-for-sale Securities, Debt Maturities, Weighted Average Maturity

^[7]

8.87

Available-for-sale Securities, Debt Maturities, Effective tax rate for nominal yield calculation

39.00%

Available-for-sale Securities, Debt Maturities, Number of days for interest rates to reset

35 days

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

13

17

13

17

24

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 1,957

$ 375

$ 1,957

$ 375

$ 15,666

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

4,655

10,289

4,655

10,289

4,689

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

6,612

10,664

6,612

10,664

20,355

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

1

0

1

0

22

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

412

713

412

713

378

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

413

713

413

713

400

Commercial mortgage-backed securities guaranteed by U.S. government agencies

Schedule of Available-for-sale Securities [Line Items]

2,788,543

2,854,306

2,788,543

2,854,306

3,035,750

Available-for-sale Securities, Gross Unrealized Gain

2,782,070

2,911,946

2,782,070

2,911,946

3,017,933

7,804

^[1]

57,762

^[2]

7,804

^[1]

57,762

^[2]

5,472

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(14,277)

^[1]

(122)

^[2]

(14,277)

^[1]

(122)

^[2]

(23,289)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Amortized Cost Basis

58,263

Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis

880,459

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis

1,571,735

Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis

278,086

Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis

2,788,543

Available-for-sale Securities, Debt Maturities, Amortized Cost

2,788,543

2,854,306

2,788,543

2,854,306

3,035,750

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value

58,147

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

879,286

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

1,568,732

Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value

275,905

Available-for-sale Securities, Debt Maturities, Single Maturity Date

2,782,070

Available-for-sale Securities, Debt Maturities, Fair Value

$ 2,782,070

$ 2,911,946

$ 2,782,070

$ 2,911,946

$ 3,017,933

Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield

1.20%

Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield

1.83%

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield

1.84%

Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield

1.88%

Available-for-sale Securities, Debt Maturities, Nominal Yield

1.82%

Available-for-sale Securities, Debt Maturities, Weighted Average Maturity

^[7]

6.98

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

121

11

121

11

171

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 1,388,406

$ 103,955

$ 1,388,406

$ 103,955

$ 1,904,584

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

78,828

65,857

78,828

65,857

38,875

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

1,467,234

169,812

1,467,234

169,812

1,943,459

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

12,690

37

12,690

37

22,987

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

1,587

85

1,587

85

302

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

14,277

122

14,277

122

23,289

Other debt securities

Schedule of Available-for-sale Securities [Line Items]

4,400

Available-for-sale Securities, Gross Unrealized Gain

4,152

4,151

4,152

4,151

4,152

0

^[1]

0

^[2]

0

^[1]

0

^[2]

0

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(248)

^[1]

(249)

^[2]

(248)

^[1]

(249)

^[2]

(248)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Amortized Cost Basis

0

Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis

0

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis

0

Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis

4,400

Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis

4,400

Available-for-sale Securities, Debt Maturities, Amortized Cost

4,400

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value

0

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

0

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

0

Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value

4,152

Available-for-sale Securities, Debt Maturities, Single Maturity Date

4,152

Available-for-sale Securities, Debt Maturities, Fair Value

$ 4,152

$ 4,151

$ 4,152

$ 4,151

$ 4,152

Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]

Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield

0.00%

Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield

0.00%

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield

0.00%

Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield

^[9]

1.71%

Available-for-sale Securities, Debt Maturities, Nominal Yield

1.71%

Available-for-sale Securities, Debt Maturities, Weighted Average Maturity

^[7]

30.16

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

2

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 0

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

4,152

4,151

4,152

4,151

4,152

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

4,152

4,151

4,152

4,151

4,152

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

0

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

248

249

248

249

248

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

248

249

248

249

248

Residential Mortgage Backed Securities [Member]

Schedule of Available-for-sale Securities [Line Items]

5,468,038

5,692,596

5,468,038

5,692,596

5,576,543

Available-for-sale Securities, Gross Unrealized Gain

5,485,760

5,826,581

5,485,760

5,826,581

5,575,921

52,418

^[1]

135,880

^[2]

52,418

^[1]

135,880

^[2]

50,377

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(34,696)

^[1]

(1,119)

^[2]

(34,696)

^[1]

(1,119)

^[2]

(50,781)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

(776)

^[5]

0

^[4]

(776)

^[5]

(218)

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis

5,468,038

Available-for-sale Securities, Debt Maturities, Amortized Cost

5,468,038

5,692,596

5,468,038

5,692,596

5,576,543

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value

5,485,760

Available-for-sale Securities, Debt Maturities, Fair Value

$ 5,485,760

$ 5,826,581

$ 5,485,760

$ 5,826,581

$ 5,575,921

Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]

Available-for-sale Securities, Debt Maturities, Nominal Yield

^[10]

1.94%

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

3 years 329 days

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

139

30

139

30

186

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 2,425,303

$ 463,130

$ 2,425,303

$ 463,130

$ 3,308,229

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

180,364

53,907

180,364

53,907

129,716

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

2,605,667

517,037

2,605,667

517,037

3,437,945

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

31,310

1,156

31,310

1,156

47,767

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

3,386

739

3,386

739

3,232

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

34,696

1,895

34,696

1,895

50,999

U.S. government agency residential mortgage-backed securities

Schedule of Available-for-sale Securities [Line Items]

5,381,382

5,577,287

5,381,382

5,577,287

5,475,351

Available-for-sale Securities, Gross Unrealized Gain

5,382,377

5,700,268

5,382,377

5,700,268

5,460,386

35,691

^[1]

124,064

^[2]

35,691

^[1]

124,064

^[2]

35,800

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(34,696)

^[1]

(1,083)

^[2]

(34,696)

^[1]

(1,083)

^[2]

(50,765)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Amortized Cost

5,381,382

5,577,287

5,381,382

5,577,287

5,475,351

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Fair Value

$ 5,382,377

$ 5,700,268

$ 5,382,377

$ 5,700,268

$ 5,460,386

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

139

16

139

16

180

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 2,425,303

$ 447,541

$ 2,425,303

$ 447,541

$ 3,300,298

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

180,364

37,739

180,364

37,739

116,208

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

2,605,667

485,280

2,605,667

485,280

3,416,506

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

31,310

879

31,310

879

47,593

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

3,386

204

3,386

204

3,172

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

34,696

1,083

34,696

1,083

50,765

U.S. government agency residential mortgage-backed securities | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]

Schedule of Available-for-sale Securities [Line Items]

3,005,920

2,908,698

3,005,920

2,908,698

3,062,525

Available-for-sale Securities, Gross Unrealized Gain

3,008,531

2,988,974

3,008,531

2,988,974

3,055,676

24,213

^[1]

80,549

^[2]

24,213

^[1]

80,549

^[2]

25,066

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(21,602)

^[1]

(273)

^[2]

(21,602)

^[1]

(273)

^[2]

(31,915)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Amortized Cost

3,005,920

2,908,698

3,005,920

2,908,698

3,062,525

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Fair Value

$ 3,008,531

$ 2,988,974

$ 3,008,531

$ 2,988,974

$ 3,055,676

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

75

4

75

4

91

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 1,381,687

$ 97,910

$ 1,381,687

$ 97,910

$ 1,787,644

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

87,371

15,401

87,371

15,401

72,105

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

1,469,058

113,311

1,469,058

113,311

1,859,749

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

20,288

267

20,288

267

30,238

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

1,314

6

1,314

6

1,677

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

21,602

273

21,602

273

31,915

U.S. government agency residential mortgage-backed securities | Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]

Schedule of Available-for-sale Securities [Line Items]

1,412,376

1,746,661

1,412,376

1,746,661

1,534,451

Available-for-sale Securities, Gross Unrealized Gain

1,412,472

1,785,332

1,412,472

1,785,332

1,531,116

7,785

^[1]

38,869

^[2]

7,785

^[1]

38,869

^[2]

8,475

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(7,689)

^[1]

(198)

^[2]

(7,689)

^[1]

(198)

^[2]

(11,810)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Amortized Cost

1,412,376

1,746,661

1,412,376

1,746,661

1,534,451

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Fair Value

$ 1,412,472

$ 1,785,332

$ 1,412,472

$ 1,785,332

$ 1,531,116

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

42

1

42

1

58

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 731,853

$ 0

$ 731,853

$ 0

$ 964,017

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

16,388

22,338

16,388

22,338

18,307

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

748,241

22,338

748,241

22,338

982,324

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

7,213

0

7,213

0

11,210

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

476

198

476

198

600

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

7,689

198

7,689

198

11,810

U.S. government agency residential mortgage-backed securities | Government National Mortgage Association Certificates and Obligations (GNMA) [Member]

Schedule of Available-for-sale Securities [Line Items]

938,086

921,928

938,086

921,928

878,375

Available-for-sale Securities, Gross Unrealized Gain

936,365

925,962

936,365

925,962

873,594

3,641

^[1]

4,646

^[2]

3,641

^[1]

4,646

^[2]

2,259

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(5,362)

^[1]

(612)

^[2]

(5,362)

^[1]

(612)

^[2]

(7,040)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Amortized Cost

938,086

921,928

938,086

921,928

878,375

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Fair Value

$ 936,365

$ 925,962

$ 936,365

$ 925,962

$ 873,594

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

21

11

21

11

31

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 291,806

$ 349,631

$ 291,806

$ 349,631

$ 548,637

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

76,605

0

76,605

0

25,796

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

368,411

349,631

368,411

349,631

574,433

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

3,766

612

3,766

612

6,145

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

1,596

0

1,596

0

895

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

5,362

612

5,362

612

7,040

U.S. government agency residential mortgage-backed securities | Other

Schedule of Available-for-sale Securities [Line Items]

25,000

Available-for-sale Securities, Gross Unrealized Gain

25,009

^[1]

52

Available-for-sale Securities, Gross Unrealized Loss

^[1]

(43)

Available-for-Sale Securities, Other Than Temporary Impairments

0

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Amortized Cost

25,000

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Fair Value

$ 25,009

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

1

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 19,957

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

0

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

19,957

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

43

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

0

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

43

Privately issued residential mortgage-backed securities

Schedule of Available-for-sale Securities [Line Items]

86,656

115,309

86,656

115,309

101,192

Available-for-sale Securities, Gross Unrealized Gain

103,383

126,313

103,383

126,313

115,535

16,727

^[1]

11,816

^[2]

16,727

^[1]

11,816

^[2]

14,577

^[3]

Available-for-sale Securities, Gross Unrealized Loss

0

^[1]

(36)

^[2]

0

^[1]

(36)

^[2]

(16)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

(776)

^[5]

0

^[4]

(776)

^[5]

(218)

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Amortized Cost

86,656

115,309

86,656

115,309

101,192

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Fair Value

$ 103,383

$ 126,313

$ 103,383

$ 126,313

$ 115,535

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

0

14

^[11]

0

14

^[11]

6

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 0

$ 15,589

^[11]

$ 0

$ 15,589

^[11]

$ 7,931

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

0

16,168

^[11]

0

16,168

^[11]

13,508

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

0

31,757

^[11]

0

31,757

^[11]

21,439

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

0

277

^[11]

0

277

^[11]

174

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

0

535

^[11]

0

535

^[11]

60

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

0

812

^[11]

0

812

^[11]

234

^[12]

Privately issued residential mortgage-backed securities | Alt A loans Member]

Schedule of Available-for-sale Securities [Line Items]

38,334

49,522

38,334

49,522

44,245

Available-for-sale Securities, Gross Unrealized Gain

46,903

54,536

46,903

54,536

51,512

8,569

^[1]

5,461

^[2]

8,569

^[1]

5,461

^[2]

7,485

^[3]

Available-for-sale Securities, Gross Unrealized Loss

0

^[1]

0

^[2]

0

^[1]

0

^[2]

0

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

(447)

^[5]

0

^[4]

(447)

^[5]

(218)

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Amortized Cost

38,334

49,522

38,334

49,522

44,245

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Fair Value

$ 46,903

$ 54,536

$ 46,903

$ 54,536

$ 51,512

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

0

5

^[11]

0

5

^[11]

5

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 0

$ 8,513

^[11]

$ 0

$ 8,513

^[11]

$ 7,931

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

0

8,291

^[11]

0

8,291

^[11]

7,410

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

0

16,804

^[11]

0

16,804

^[11]

15,341

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

0

241

^[11]

0

241

^[11]

174

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

0

206

^[11]

0

206

^[11]

44

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

0

447

^[11]

0

447

^[11]

218

^[12]

Privately issued residential mortgage-backed securities | Jumbo A loans [Member]

Schedule of Available-for-sale Securities [Line Items]

48,322

65,787

48,322

65,787

56,947

Available-for-sale Securities, Gross Unrealized Gain

56,480

71,777

56,480

71,777

64,023

8,158

^[1]

6,355

^[2]

8,158

^[1]

6,355

^[2]

7,092

^[3]

Available-for-sale Securities, Gross Unrealized Loss

0

^[1]

(36)

^[2]

0

^[1]

(36)

^[2]

(16)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

(329)

^[5]

0

^[4]

(329)

^[5]

0

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Amortized Cost

48,322

65,787

48,322

65,787

56,947

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Fair Value

$ 56,480

$ 71,777

$ 56,480

$ 71,777

$ 64,023

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

0

9

^[11]

0

9

^[11]

1

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 0

$ 7,076

^[11]

$ 0

$ 7,076

^[11]

$ 0

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

0

7,877

^[11]

0

7,877

^[11]

6,098

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

0

14,953

^[11]

0

14,953

^[11]

6,098

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

0

36

^[11]

0

36

^[11]

0

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

0

329

^[11]

0

329

^[11]

16

^[12]

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

0

365

^[11]

0

365

^[11]

16

^[12]

Perpetual Preferred, Equity Securities and Mutual Funds [Member]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis

30,134

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value

$ 35,296

Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]

Available-for-sale Securities, Debt Maturities, Nominal Yield

0.00%

Perpetual preferred stock

Schedule of Available-for-sale Securities [Line Items]

$ 12,562

15,562

$ 12,562

15,562

15,561

Available-for-sale Securities, Gross Unrealized Gain

16,568

17,931

16,568

17,931

18,474

4,006

^[1]

2,369

^[2]

4,006

^[1]

2,369

^[2]

2,913

^[3]

Available-for-sale Securities, Gross Unrealized Loss

0

^[1]

0

^[2]

0

^[1]

0

^[2]

0

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Amortized Cost

12,562

15,562

12,562

15,562

15,561

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Fair Value

$ 16,568

$ 17,931

$ 16,568

$ 17,931

$ 18,474

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

0

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 0

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

0

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

0

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

0

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

0

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

0

Equity securities and mutual funds

Schedule of Available-for-sale Securities [Line Items]

17,572

17,270

17,572

17,270

17,424

Available-for-sale Securities, Gross Unrealized Gain

18,728

18,814

18,728

18,814

18,357

1,219

^[1]

1,558

^[2]

1,219

^[1]

1,558

^[2]

1,060

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(63)

^[1]

(14)

^[2]

(63)

^[1]

(14)

^[2]

(127)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Amortized Cost

17,572

17,270

17,572

17,270

17,424

Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]

Available-for-sale Securities, Debt Maturities, Fair Value

$ 18,728

$ 18,814

$ 18,728

$ 18,814

$ 18,357

Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]

Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions

91

30

91

30

104

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

$ 1,668

$ 0

$ 1,668

$ 0

$ 2,127

Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

887

889

887

889

817

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

2,555

889

2,555

889

2,944

Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]

Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

22

0

22

0

41

Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

41

14

41

14

86

Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss

$ 63

$ 14

$ 63

$ 14

$ 127

[1]	Gross unrealized gain/loss recognized in AOCI in the consolidated balance sheet.
[2]	Gross unrealized gain/loss recognized in AOCI in the consolidated balance sheet.
[3]	Gross unrealized gain/loss recognized in AOCI in the consolidated balance sheet.
[4]	Amounts represent unrealized loss that remains in AOCI after an other-than-temporary credit loss has been recognized in income.
[5]	Amounts represent unrealized loss that remains in AOCI after an other-than-temporary credit loss has been recognized in income.
[6]	Amounts represent unrealized loss that remains in AOCI after an other-than-temporary credit loss has been recognized in income.
[7]	Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty.
[8]	Calculated on a taxable equivalent basis using a 39 percent effective tax rate.
[9]	Nominal yield on municipal and other tax-exempt securities and other debt securities with contractual maturity dates over ten years are based on variable rates which generally are reset within 35 days.
[10]	The nominal yield on mortgage-backed securities is based upon prepayment assumptions at the purchase date. Actual yields earned may differ significantly based upon actual prepayments. See Quarterly Financial Summary –– Unaudited following for current yields on available for sale securities portfolio.
[11]	Includes securities for which an unrealized loss remains in AOCI after an other-than-temporary credit loss has been recognized in income.
[12]	Includes securities for which an unrealized loss remains in AOCI after an other-than-temporary credit loss has been recognized in income.

Securities Fair Value Option Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Schedule of Fair Value Option Securities [Line Items]
Fair Value Option Securities, Fair Value	$ 445,169	$ 77,046	$ 263,265
Fair Value Option Securities, Net Unrealized Gain or Loss	1,247	(1,777)	4,433
U.S. Treasury
Schedule of Fair Value Option Securities [Line Items]
Fair Value Option Securities, Fair Value	0	0	25,306
Fair Value Option Securities, Net Unrealized Gain or Loss	0	0	(43)
U.S. government agency residential mortgage-backed securities
Schedule of Fair Value Option Securities [Line Items]
Fair Value Option Securities, Fair Value	445,169	77,046	237,959
Fair Value Option Securities, Net Unrealized Gain or Loss	$ 1,247	$ (1,777)	$ 4,476

Securities Restricted Equity Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Restricted Equity Securities [Abstract]
Federal Reserve stock	$ 36,676	$ 36,498	$ 36,283
Federal Home Loan Bank stock	274,113	270,541	283,155
Other	244	201	201
Total	$ 311,033	$ 307,240	$ 319,639

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

Jun. 30, 2017

Dec. 31, 2016

Jun. 30, 2016

Derviative contracts, net of cash collateral, Assets, Fair value

$ 280,289

$ 689,872

$ 883,673

Derivative Liabilities, Fair Value, Net [Abstract]

Derivative Liabilities, Fair Value, Net of Cash Collateral

285,819

664,531

719,159

Not Designated as Hedging Instrument [Member]

29,511,796

^[1]

22,437,314

^[2]

23,037,973

^[3]

27,125,429

^[1]

22,178,359

^[2]

21,565,820

^[3]

355,296

789,791

993,485

Derivative Assets, Net Fair Value Before Cash Collateral

(50,607)

(89,368)

(102,988)

304,689

700,423

890,497

Derviative contracts, net of cash collateral, Assets, Fair value

(24,400)

(10,551)

(6,824)

280,289

689,872

883,673

Derivative Liabilities, Fair Value, Net [Abstract]

357,521

801,809

974,975

Derivative Liabilities, Net Fair Value Before Cash Collateral

(50,607)

(89,368)

(102,988)

306,914

712,441

871,987

Derivative Liabilities, Fair Value, Net of Cash Collateral

(21,095)

(47,910)

(152,828)

285,819

664,531

719,159

Not Designated as Hedging Instrument [Member] | To-be-announced residential mortgage-backed securities

16,174,687

^[1]

16,949,152

^[2]

18,774,134

^[3]

16,174,687

^[1]

16,637,532

^[2]

18,662,334

^[3]

57,948

180,695

183,118

Derivative Assets, Net Fair Value Before Cash Collateral

(29,034)

(60,555)

(67,383)

28,914

120,140

115,735

Derviative contracts, net of cash collateral, Assets, Fair value

0

28,914

120,140

115,735

Derivative Liabilities, Fair Value, Net [Abstract]

53,829

176,928

179,443

Derivative Liabilities, Net Fair Value Before Cash Collateral

(29,034)

(60,555)

(67,383)

24,795

116,373

112,060

Derivative Liabilities, Fair Value, Net of Cash Collateral

0

(103,724)

24,795

116,373

8,336

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

1,450,193

^[1]

1,403,408

^[2]

1,299,985

^[3]

1,450,193

^[1]

1,403,408

^[2]

1,299,985

^[3]

29,932

34,442

54,978

Derivative Assets, Net Fair Value Before Cash Collateral

0

29,932

34,442

54,978

Derviative contracts, net of cash collateral, Assets, Fair value

(2,206)

(4,567)

(1,100)

27,726

29,875

53,878

Derivative Liabilities, Fair Value, Net [Abstract]

29,982

34,442

55,404

Derivative Liabilities, Net Fair Value Before Cash Collateral

0

29,982

34,442

55,404

Derivative Liabilities, Fair Value, Net of Cash Collateral

(15,396)

(11,977)

(32,597)

14,586

22,465

22,807

Not Designated as Hedging Instrument [Member] | Energy contracts

891,480

^[1]

835,566

^[2]

757,669

^[3]

874,625

^[1]

820,365

^[2]

734,538

^[3]

56,824

64,140

59,103

Derivative Assets, Net Fair Value Before Cash Collateral

(20,546)

(28,298)

(33,996)

36,278

35,842

25,107

Derviative contracts, net of cash collateral, Assets, Fair value

(21,267)

(71)

(155)

15,011

35,771

24,952

Derivative Liabilities, Fair Value, Net [Abstract]

53,895

64,306

58,033

Derivative Liabilities, Net Fair Value Before Cash Collateral

(20,546)

(28,298)

(33,996)

33,349

36,008

24,037

Derivative Liabilities, Fair Value, Net of Cash Collateral

0

(31,534)

(11,784)

33,349

4,474

12,253

Not Designated as Hedging Instrument [Member] | Agricultural contracts

45,250

^[1]

53,209

^[2]

50,848

^[3]

45,262

^[1]

53,216

^[2]

50,843

^[3]

3,541

1,382

2,488

Derivative Assets, Net Fair Value Before Cash Collateral

(1,027)

(515)

(1,609)

2,514

867

879

Derviative contracts, net of cash collateral, Assets, Fair value

0

(37)

2,514

867

842

Derivative Liabilities, Fair Value, Net [Abstract]

3,538

1,365

2,476

Derivative Liabilities, Net Fair Value Before Cash Collateral

(1,027)

(515)

(1,609)

2,511

850

867

Derivative Liabilities, Fair Value, Net of Cash Collateral

(2,511)

(769)

0

0

81

867

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

169,529

^[1]

580,886

^[2]

701,436

^[3]

169,553

^[1]

580,712

^[2]

701,219

^[3]

162,429

494,349

675,804

Derivative Assets, Net Fair Value Before Cash Collateral

0

162,429

494,349

675,804

Derviative contracts, net of cash collateral, Assets, Fair value

(7)

(5,183)

(5,054)

162,422

489,166

670,750

Derivative Liabilities, Fair Value, Net [Abstract]

162,276

494,695

675,383

Derivative Liabilities, Net Fair Value Before Cash Collateral

0

162,276

494,695

675,383

Derivative Liabilities, Fair Value, Net of Cash Collateral

(3,188)

(3,630)

(4,723)

159,088

491,065

670,660

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

100,159

^[1]

100,924

^[2]

116,901

^[3]

100,159

^[1]

100,924

^[2]

116,901

^[3]

4,437

4,357

4,236

Derivative Assets, Net Fair Value Before Cash Collateral

0

4,437

4,357

4,236

Derviative contracts, net of cash collateral, Assets, Fair value

(920)

(730)

(478)

3,517

3,627

3,758

Derivative Liabilities, Fair Value, Net [Abstract]

4,437

4,357

4,236

Derivative Liabilities, Net Fair Value Before Cash Collateral

0

4,437

4,357

4,236

Derivative Liabilities, Fair Value, Net of Cash Collateral

0

4,437

4,357

4,236

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

18,831,298

^[1]

19,923,145

^[2]

21,700,973

^[3]

18,814,479

^[1]

19,596,157

^[2]

21,565,820

^[3]

315,111

779,365

979,727

Derivative Assets, Net Fair Value Before Cash Collateral

(50,607)

(89,368)

(102,988)

264,504

689,997

876,739

Derviative contracts, net of cash collateral, Assets, Fair value

(24,400)

(10,551)

(6,824)

240,104

679,446

869,915

Derivative Liabilities, Fair Value, Net [Abstract]

307,957

776,093

974,975

Derivative Liabilities, Net Fair Value Before Cash Collateral

(50,607)

(89,368)

(102,988)

257,350

686,725

871,987

Derivative Liabilities, Fair Value, Net of Cash Collateral

(21,095)

(47,910)

(152,828)

236,255

638,815

719,159

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

10,680,498

^[1]

2,514,169

^[2]

1,337,000

^[3]

8,310,950

^[1]

2,582,202

^[2]

0

^[3]

40,185

10,426

13,758

Derivative Assets, Net Fair Value Before Cash Collateral

0

40,185

10,426

13,758

Derviative contracts, net of cash collateral, Assets, Fair value

0

40,185

10,426

13,758

Derivative Liabilities, Fair Value, Net [Abstract]

49,564

25,716

0

Derivative Liabilities, Net Fair Value Before Cash Collateral

0

49,564

25,716

0

Derivative Liabilities, Fair Value, Net of Cash Collateral

0

$ 49,564

$ 25,716

$ 0

[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.
[3]	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	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	$ 18,122	$ 13,491	$ 29,293	$ 22,359
Gain (Loss) on Derivatives, Net	3,241	10,766	2,791	17,904
To-be-announced residential mortgage-backed securities
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	9,205	9,862	17,232	17,302
Gain (Loss) on Derivatives, Net	0	0	0	0
Interest rate swaps
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	665	723	1,124	1,048
Gain (Loss) on Derivatives, Net	0	0	0	0
Energy contracts
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	1,666	2,749	4,539	3,445
Gain (Loss) on Derivatives, Net	0	0	0	0
Agricultural contracts
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	11	32	20	61
Gain (Loss) on Derivatives, Net	0	0	0	0
Foreign exchange contracts
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	90	134	360	512
Gain (Loss) on Derivatives, Net	0	0	0	0
Equity option contracts
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	0	0	0	0
Gain (Loss) on Derivatives, Net	0	0	0	0
Total customer risk management programs
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	11,637	13,500	23,275	22,368
Gain (Loss) on Derivatives, Net	0	0	0	0
Internal risk management programs
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	6,485	(9)	6,018	(9)
Gain (Loss) on Derivatives, Net	$ 3,241	$ 10,766	$ 2,791	$ 17,904

Loans and Allowance for Credit Losses, Loans by Portfolio Type (Details) - USD ($)
$ in Thousands

6 Months Ended

Jun. 30, 2017

Dec. 31, 2016

Jun. 30, 2016

$ 4,540,923

$ 4,753,600

$ 4,302,800

12,397,283

12,005,076

11,856,765

245,439

230,984

247,184

Accruing loans past due (90 days)

17,183,645

16,989,660

16,406,749

^[1]

1,414

5

2,899

Credit Commitments [Abstract]

Outstanding commitments to extend credit

9,600,000

Outstanding standby letters of credit

615,000

Outstanding commercial letters of credit

3,200

Texas [Member] | Geographic Concentration Risk [Member]

$ 5,700,000

Percentage of loan portfolio attributed to Texas (in hundredths)

33.00%

Oklahoma [Member] | Geographic Concentration Risk [Member]

$ 3,400,000

Percentage of loan portfolio attributed to Oklahoma (in hundredths)

20.00%

Commercial

$ 2,198,066

2,327,085

1,994,415

8,242,732

7,884,786

8,180,033

197,157

178,953

181,989

Commercial | Texas [Member] | Geographic Concentration Risk [Member]

10,637,955

10,390,824

10,356,437

$ 3,600,000

Percentage of loan portfolio attributed to Texas (in hundredths)

33.00%

Commercial | Oklahoma [Member] | Geographic Concentration Risk [Member]

$ 2,100,000

Percentage of loan portfolio attributed to Oklahoma (in hundredths)

19.00%

Commercial | Energy [Member]

Commercial | Energy [Member] | Credit Concentration Risk [Member]

$ 2,847,240

2,497,868

2,818,656

$ 2,800,000

Percentage of loan class to total loans

17.00%

Commercial | Energy Producers [Member] | Credit Concentration Risk [Member]

$ 2,400,000

Percentage of committed energy production loans secured by oil

58.00%

Percentage of committed energy production loans secured by natural gas

42.00%

Commercial | Services [Member]

Commercial | Services [Member] | Credit Concentration Risk [Member]

$ 2,958,827

3,108,990

2,830,864

$ 3,000,000

Percentage of loan class to total loans

17.00%

Amount of loans with individual balances less than $10 million

$ 1,500,000

Maximum loan amount for certain individual loans in category

10,000

Commercial | Healthcare [Member]

Commercial | Healthcare [Member] | Credit Concentration Risk [Member]

2,221,518

2,201,916

2,051,146

$ 2,200,000

Percentage of loan class to total loans

13.00%

Commercial real estate

$ 594,542

624,187

612,822

3,090,275

3,179,338

2,961,364

3,775

5,521

7,780

Commercial real estate | Texas [Member] | Geographic Concentration Risk [Member]

$ 3,688,592

3,809,046

3,581,966

Percentage of loan portfolio secured by property in Texas (in hundredths)

32.00%

Commercial real estate | Oklahoma [Member] | Geographic Concentration Risk [Member]

Percentage of loan portfolio secured by property in Oklahoma (in hundredths)

12.00%

Residential mortgage

$ 1,597,587

1,647,357

1,586,116

297,376

256,255

237,746

44,235

46,220

57,061

Residential mortgage | Permanent mortgage [Member]

1,939,198

1,949,832

1,880,923

$ 989,040

1,006,820

969,007

Minimum FICO required for jumbo loan approval

720

Maximum debt-to-income ratio on jumbo loans (in hundredths)

38.00%

Minimum loan-to-value ratio on jumbo loans (in hundredths)

60.00%

Maximum loan-to-value ratio on jumbo loans (in hundredths)

100.00%

Minimum period for fixed rate on variable rate jumbo loans (in years)

3 years

Maximum period for fixed rate on variable rate jumbo loans (in years)

10 years

Residential mortgage | Permanent mortgages guaranteed by US government agencies [Member]

$ 191,729

199,387

192,732

Amount of loans guaranteed by US government and previously sold into GNMA mortgage pools

192,000

Residential mortgage | Home equity [Member]

$ 758,429

743,625

719,184

Percentage of home equity portfolio comprised of first lien loans

65.00%

Percentage of home equity portfolio comprised of junior lien loans

35.00%

Percentage of junior lien home equity loans that are amortizing term loans

49.00%

Percentage of junior lien home equity loans that are revolving lines of credit

51.00%

Home equity loans, description

Home equity loans generally require a minimum FICO score of 700 and a maximum DTI of 40 percent.

Home equity loans, maximum

$ 400

Home equity loans, revolving period

5 years

Home equity loans, amortization period following revolving period

15 years

Home equity loans, discretionary additional revolving period

5 years

Personal

$ 150,728

154,971

109,447

766,900

684,697

477,622

272

290

354

$ 917,900

$ 839,958

$ 587,423

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

Loans and Allowances for Credit Losses, Activity in Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Allowance for loan losses [Roll Forward]
Beginning balance	$ 248,710	$ 233,156	$ 246,159	$ 225,524
Provision for loan losses	3,009	17,562	4,813	47,666
Loans charged off	(2,872)	(8,845)	(5,025)	(32,836)
Recoveries	1,214	1,386	4,114	2,905
Ending balance	250,061	243,259	250,061	243,259
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	9,440	6,607	11,244	1,711
Provision for off-balance sheet credit losses	(3,009)	2,438	(4,813)	7,334
Ending balance	6,431	9,045	6,431	9,045
Total provision for credit losses	0	20,000	0	55,000
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					$ 16,938,206	$ 16,758,676	$ 16,159,565
Individually measured for impairment, recorded investment					245,439	230,984	247,184
Total					17,183,645	16,989,660	16,406,749
Related allowance [Abstract]
Collectively measured for impairment, related allowance					212,994	217,116	212,265
Individually measured for impairment, related allowance					9,693	843	4,310
Total	248,710	233,156	246,159	225,524	250,061	246,159	243,259
Commercial
Allowance for loan losses [Roll Forward]
Beginning balance	137,616	139,793	140,213	130,334
Provision for loan losses	1,546	12,478	(1,809)	43,575
Loans charged off	(1,703)	(7,355)	(2,127)	(29,481)
Recoveries	283	223	1,465	711
Ending balance	137,742	145,139	137,742	145,139
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	9,288	6,319	11,063	1,506
Provision for off-balance sheet credit losses	(2,987)	2,433	(4,762)	7,246
Ending balance	6,301	8,752	6,301	8,752
Total provision for credit losses	(1,441)	14,911	(6,571)	50,821
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					10,440,798	10,211,871	10,174,448
Individually measured for impairment, recorded investment					197,157	178,953	181,989
Total					10,637,955	10,390,824	10,356,437
Related allowance [Abstract]
Collectively measured for impairment, related allowance					128,049	139,416	140,911
Individually measured for impairment, related allowance					9,693	797	4,228
Total	137,616	139,793	140,213	130,334	137,742	140,213	145,139
Commercial real estate
Allowance for loan losses [Roll Forward]
Beginning balance	58,343	44,453	50,749	41,391
Provision for loan losses	105	2,010	6,964	4,987
Loans charged off	(76)	0	(76)	0
Recoveries	208	282	943	367
Ending balance	58,580	46,745	58,580	46,745
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	106	228	123	153
Provision for off-balance sheet credit losses	(22)	(25)	(39)	50
Ending balance	84	203	84	203
Total provision for credit losses	83	1,985	6,925	5,037
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					3,684,817	3,803,525	3,574,186
Individually measured for impairment, recorded investment					3,775	5,521	7,780
Total					3,688,592	3,809,046	3,581,966
Related allowance [Abstract]
Collectively measured for impairment, related allowance					58,580	50,749	46,727
Individually measured for impairment, related allowance					0	0	18
Total	58,343	44,453	50,749	41,391	58,580	50,749	46,745
Residential mortgage
Allowance for loan losses [Roll Forward]
Beginning balance	18,177	18,467	18,224	19,509
Provision for loan losses	(47)	368	(86)	(363)
Loans charged off	(40)	(345)	(276)	(819)
Recoveries	169	200	397	363
Ending balance	18,259	18,690	18,259	18,690
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	40	58	50	30
Provision for off-balance sheet credit losses	(2)	4	(12)	32
Ending balance	38	62	38	62
Total provision for credit losses	(49)	372	(98)	(331)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					1,894,963	1,903,612	1,823,862
Individually measured for impairment, recorded investment					44,235	46,220	57,061
Total					1,939,198	1,949,832	1,880,923
Related allowance [Abstract]
Collectively measured for impairment, related allowance					18,259	18,178	18,626
Individually measured for impairment, related allowance					0	46	64
Total	18,177	18,467	18,224	19,509	18,259	18,224	18,690
Personal
Allowance for loan losses [Roll Forward]
Beginning balance	7,247	5,022	8,773	4,164
Provision for loan losses	1,358	1,443	570	2,909
Loans charged off	(1,053)	(1,145)	(2,546)	(2,536)
Recoveries	554	681	1,309	1,464
Ending balance	8,106	6,001	8,106	6,001
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	6	2	8	22
Provision for off-balance sheet credit losses	2	26	0	6
Ending balance	8	28	8	28
Total provision for credit losses	1,360	1,469	570	2,915
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					917,628	839,668	587,069
Individually measured for impairment, recorded investment					272	290	354
Total					917,900	839,958	587,423
Related allowance [Abstract]
Collectively measured for impairment, related allowance					8,106	8,773	6,001
Individually measured for impairment, related allowance					0	0	0
Total	7,247	5,022	8,773	4,164	8,106	8,773	6,001
Specific Allowance [Member]
Allowance for loan losses [Roll Forward]
Beginning balance			217,959
Ending balance	222,687	216,575	222,687	216,575
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					16,938,206	16,758,676	16,159,565
Individually measured for impairment, recorded investment					245,439	230,984	247,184
Total					17,183,645	16,989,660	16,406,749
Related allowance [Abstract]
Collectively measured for impairment, related allowance					212,994	217,116	212,265
Individually measured for impairment, related allowance					9,693	843	4,310
Total	222,687	216,575	217,959	216,575	222,687	217,959	216,575
Nonspecific Allowance [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	27,327	25,421	28,200	30,126
Provision for loan losses	47	1,263	(826)	(3,442)
Loans charged off	0	0	0	0
Recoveries	0	0	0	0
Ending balance	27,374	26,684	27,374	26,684
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	0	0	0	0
Provision for off-balance sheet credit losses	0	0	0	0
Ending balance	0	0	0	0
Total provision for credit losses	47	1,263	(826)	(3,442)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					0	0	0
Individually measured for impairment, recorded investment					0	0	0
Total					0	0	0
Related allowance [Abstract]
Collectively measured for impairment, related allowance					0	0	0
Individually measured for impairment, related allowance					0	0	0
Total	$ 27,327	$ 25,421	$ 28,200	$ 30,126	$ 27,374	$ 28,200	$ 26,684

Loans and Allowances for Credit Losses, Credit Quality Indicators (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	$ 15,341,394		$ 15,158,076	$ 14,616,427
Non-Graded, Recorded Investment	1,842,251		1,831,584	1,790,322
Total	17,183,645		16,989,660	16,406,749
Related Allowance [Abstract]
Internally Risk Graded, Allowance	204,117		197,970	197,581
Non-Graded, Allowance	18,570		19,989	18,994
Total	250,061	$ 248,710	246,159	243,259	$ 233,156	$ 225,524
Commercial
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	10,612,477		10,360,725	10,331,701
Non-Graded, Recorded Investment	25,478		30,099	24,736
Total	10,637,955		10,390,824	10,356,437
Related Allowance [Abstract]
Internally Risk Graded, Allowance	136,819		139,293	144,217
Non-Graded, Allowance	923		920	922
Total	137,742	137,616	140,213	145,139	139,793	130,334
Commercial \| Energy [Member]
Recorded Investment [Abstract]
Total	2,847,240		2,497,868	2,818,656
Commercial \| Services [Member]
Recorded Investment [Abstract]
Total	2,958,827		3,108,990	2,830,864
Commercial \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Total	1,543,695		1,576,818	1,532,957
Commercial \| Manufacturing [Member]
Recorded Investment [Abstract]
Total	546,137		514,975	595,403
Commercial \| Healthcare [Member]
Recorded Investment [Abstract]
Total	2,221,518		2,201,916	2,051,146
Commercial \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Total	520,538		490,257	527,411
Commercial real estate
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	3,688,592		3,809,046	3,581,966
Non-Graded, Recorded Investment	0		0	0
Total	3,688,592		3,809,046	3,581,966
Related Allowance [Abstract]
Internally Risk Graded, Allowance	58,580		50,749	46,745
Non-Graded, Allowance	0		0	0
Total	58,580	58,343	50,749	46,745	44,453	41,391
Commercial real estate \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Total	141,592		135,533	157,576
Commercial real estate \| Retail [Member]
Recorded Investment [Abstract]
Total	722,805		761,888	795,419
Commercial real estate \| Office [Member]
Recorded Investment [Abstract]
Total	862,973		798,888	769,112
Commercial real estate \| Multifamily [Member]
Recorded Investment [Abstract]
Total	952,380		903,272	787,200
Commercial real estate \| Industrial [Member]
Recorded Investment [Abstract]
Total	693,635		871,749	645,586
Commercial real estate \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Total	315,207		337,716	427,073
Residential mortgage
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	216,007		243,703	202,520
Non-Graded, Recorded Investment	1,723,191		1,706,129	1,678,403
Total	1,939,198		1,949,832	1,880,923
Related Allowance [Abstract]
Internally Risk Graded, Allowance	2,976		2,893	2,995
Non-Graded, Allowance	15,283		15,331	15,695
Total	18,259	18,177	18,224	18,690	18,467	19,509
Residential mortgage \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Total	989,040		1,006,820	969,007
Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Recorded Investment [Abstract]
Total	191,729		199,387	192,732
Residential mortgage \| Home equity [Member]
Recorded Investment [Abstract]
Total	758,429		743,625	719,184
Personal
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	824,318		744,602	500,240
Non-Graded, Recorded Investment	93,582		95,356	87,183
Total	917,900		839,958	587,423
Related Allowance [Abstract]
Internally Risk Graded, Allowance	5,742		5,035	3,624
Non-Graded, Allowance	2,364		3,738	2,377
Total	8,106	7,247	8,773	6,001	5,022	4,164
Specific Allowance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	15,341,394		15,158,076	14,616,427
Non-Graded, Recorded Investment	1,842,251		1,831,584	1,790,322
Total	17,183,645		16,989,660	16,406,749
Related Allowance [Abstract]
Internally Risk Graded, Allowance	204,117		197,970	197,581
Non-Graded, Allowance	18,570		19,989	18,994
Total	222,687		217,959	216,575
Nonspecific Allowance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Non-Graded, Recorded Investment	0		0	0
Total	0		0	0
Related Allowance [Abstract]
Internally Risk Graded, Allowance	0		0	0
Non-Graded, Allowance	0		0	0
Total	27,374	$ 27,327	28,200	26,684	$ 25,421	$ 30,126
Performing [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	1,799,001		1,786,530	1,735,915
Performing [Member] \| Commercial
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	25,374		30,041	24,673
Performing [Member] \| Commercial \| Energy [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial \| Services [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial \| Manufacturing [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial \| Healthcare [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	25,374		30,041	24,673
Performing [Member] \| Commercial real estate
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial real estate \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial real estate \| Retail [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial real estate \| Office [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial real estate \| Multifamily [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial real estate \| Industrial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial real estate \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Residential mortgage
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	1,680,229		1,661,326	1,624,297
Performing [Member] \| Residential mortgage \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	750,891		741,679	742,214
Performing [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	183,000		188,000	173,000
Performing [Member] \| Residential mortgage \| Home equity [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	746,661		732,106	709,092
Performing [Member] \| Personal
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	93,398		95,163	86,945
Performing [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	14,613,315		14,343,507	13,614,112
Performing [Member] \| Pass [Member] \| Commercial
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	9,902,434		9,567,816	9,363,072
Performing [Member] \| Pass [Member] \| Commercial \| Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,376,368		1,937,790	2,031,955
Performing [Member] \| Pass [Member] \| Commercial \| Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,921,510		3,052,002	2,805,307
Performing [Member] \| Pass [Member] \| Commercial \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,507,063		1,535,463	1,478,966
Performing [Member] \| Pass [Member] \| Commercial \| Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	513,442		468,314	556,741
Performing [Member] \| Pass [Member] \| Commercial \| Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,130,339		2,140,458	2,011,934
Performing [Member] \| Pass [Member] \| Commercial \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	453,712		433,789	478,169
Performing [Member] \| Pass [Member] \| Commercial real estate
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	3,675,014		3,793,471	3,559,544
Performing [Member] \| Pass [Member] \| Commercial real estate \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	138,790		131,630	152,343
Performing [Member] \| Pass [Member] \| Commercial real estate \| Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	720,730		756,418	787,779
Performing [Member] \| Pass [Member] \| Commercial real estate \| Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	859,722		798,462	767,296
Performing [Member] \| Pass [Member] \| Commercial real estate \| Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	947,950		898,800	781,058
Performing [Member] \| Pass [Member] \| Commercial real estate \| Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	693,635		871,673	645,510
Performing [Member] \| Pass [Member] \| Commercial real estate \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	314,187		336,488	425,558
Performing [Member] \| Pass [Member] \| Residential mortgage
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	212,563		238,769	194,962
Performing [Member] \| Pass [Member] \| Residential mortgage \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	212,563		238,769	194,962
Performing [Member] \| Pass [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Pass [Member] \| Residential mortgage \| Home equity [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Pass [Member] \| Personal
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	823,304		743,451	496,534
Performing [Member] \| Other Loans Especially Mentioned [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	198,575		229,673	308,674
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	192,204		223,742	300,609
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial \| Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	120,473		119,583	197,531
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial \| Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	12,452		10,960	6,253
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	16,224		16,886	24,595
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial \| Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	6,540		26,532	18,757
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial \| Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	33,554		44,472	29,420
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,961		5,309	24,053
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial real estate
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	4,629		4,745	6,868
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial real estate \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial real estate \| Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,774		4,745	5,962
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial real estate \| Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,855		0	906
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial real estate \| Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial real estate \| Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial real estate \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Residential mortgage
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,693		1,186	1,197
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Residential mortgage \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,693		1,186	1,197
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Residential mortgage \| Home equity [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Personal
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	49		0	0
Performing [Member] \| Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	327,315		398,966	500,864
Performing [Member] \| Substandard [Member] \| Commercial
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	320,786		390,272	486,094
Performing [Member] \| Substandard [Member] \| Commercial \| Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	226,407		307,996	421,025
Performing [Member] \| Substandard [Member] \| Commercial \| Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	17,111		37,855	9,916
Performing [Member] \| Substandard [Member] \| Commercial \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	9,788		13,062	26,624
Performing [Member] \| Substandard [Member] \| Commercial \| Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	16,499		15,198	19,612
Performing [Member] \| Substandard [Member] \| Commercial \| Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	33,120		16,161	8,917
Performing [Member] \| Substandard [Member] \| Commercial \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	17,861		0	0
Performing [Member] \| Substandard [Member] \| Commercial real estate
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	5,174		5,309	7,774
Performing [Member] \| Substandard [Member] \| Commercial real estate \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	751		470	972
Performing [Member] \| Substandard [Member] \| Commercial real estate \| Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		399	413
Performing [Member] \| Substandard [Member] \| Commercial real estate \| Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	304
Performing [Member] \| Substandard [Member] \| Commercial real estate \| Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	4,420		4,434	6,077
Performing [Member] \| Substandard [Member] \| Commercial real estate \| Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Substandard [Member] \| Commercial real estate \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	3		6	8
Performing [Member] \| Substandard [Member] \| Residential mortgage
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	478		2,331	3,406
Performing [Member] \| Substandard [Member] \| Residential mortgage \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	478		2,331	3,406
Performing [Member] \| Substandard [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Substandard [Member] \| Residential mortgage \| Home equity [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Substandard [Member] \| Personal
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	877		1,054	3,590
Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	202,189		185,930	192,777
Non-Graded, Recorded Investment	43,250		45,054	54,407
Nonaccrual [Member] \| Commercial
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	197,053		178,895	181,926
Non-Graded, Recorded Investment	104		58	63
Nonaccrual [Member] \| Commercial \| Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	123,992		132,499	168,145
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial \| Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	7,754		8,173	9,388
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	10,620		11,407	2,772
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial \| Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	9,656		4,931	293
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial \| Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	24,505		825	875
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	20,526		21,060	453
Non-Graded, Recorded Investment	104		58	63
Nonaccrual [Member] \| Commercial real estate
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	3,775		5,521	7,780
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial real estate \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,051		3,433	4,261
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial real estate \| Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	301		326	1,265
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial real estate \| Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	396		426	606
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial real estate \| Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	10		38	65
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial real estate \| Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		76	76
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial real estate \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,017		1,222	1,507
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Residential mortgage
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,273		1,417	2,955
Non-Graded, Recorded Investment	42,962		44,803	54,106
Nonaccrual [Member] \| Residential mortgage \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,273		1,417	2,955
Non-Graded, Recorded Investment	22,142		21,438	24,273
Nonaccrual [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Non-Graded, Recorded Investment	9,100		12,000	20,000
Nonaccrual [Member] \| Residential mortgage \| Home equity [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Non-Graded, Recorded Investment	11,768		11,519	10,092
Nonaccrual [Member] \| Personal
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	88		97	116
Non-Graded, Recorded Investment	$ 184		$ 193	$ 238

Loans and Allowance for Credit Losses, Impaired Loans (Details) - USD ($)
$ in Thousands

3 Months Ended

6 Months Ended

Jun. 30, 2017

Jun. 30, 2016

Jun. 30, 2017

Jun. 30, 2016

Dec. 31, 2016

$ 480,181

$ 496,841

$ 480,181

$ 496,841

$ 473,526

Impaired loans, recorded investment with no related allowance

428,116

420,175

428,116

420,175

418,525

355,469

388,031

355,469

388,031

407,363

Impaired loans, recorded investment with related allowance

72,647

32,144

72,647

32,144

11,162

9,693

4,310

9,693

4,310

843

419,893

416,291

432,921

355,154

2,328

2,327

4,523

4,426

Commercial

233,643

233,857

233,643

233,857

211,762

Impaired loans, recorded investment with no related allowance

197,157

181,989

197,157

181,989

178,953

124,510

150,108

124,510

150,108

167,837

Impaired loans, recorded investment with related allowance

72,647

31,881

72,647

31,881

11,116

9,693

4,228

9,693

4,228

797

176,992

178,322

188,055

112,462

Commercial | Energy [Member]

0

141,091

202,369

141,091

202,369

146,897

Impaired loans, recorded investment with no related allowance

123,992

168,145

123,992

168,145

132,499

56,988

136,264

56,988

136,264

121,418

Impaired loans, recorded investment with related allowance

67,004

31,881

67,004

31,881

11,081

8,874

4,228

8,874

4,228

762

117,209

163,849

128,246

97,923

Commercial | Services [Member]

0

11,209

12,780

11,209

12,780

11,723

Impaired loans, recorded investment with no related allowance

7,754

9,388

7,754

9,388

8,173

7,754

9,388

7,754

9,388

8,173

Impaired loans, recorded investment with related allowance

0

0

7,734

9,450

7,964

9,839

Commercial | Wholesale/retail [Member]

0

17,392

8,697

17,392

8,697

17,669

Impaired loans, recorded investment with no related allowance

10,620

2,772

10,620

2,772

11,407

10,620

2,772

10,620

2,772

11,407

Impaired loans, recorded investment with related allowance

0

0

10,855

3,229

11,013

2,846

Commercial | Manufacturing [Member]

0

10,223

650

10,223

650

5,320

Impaired loans, recorded investment with no related allowance

9,656

293

9,656

293

4,931

9,656

293

9,656

293

4,931

Impaired loans, recorded investment with related allowance

0

0

7,781

303

7,293

312

Commercial | Healthcare [Member]

0

24,795

1,175

24,795

1,175

1,147

Impaired loans, recorded investment with no related allowance

24,505

875

24,505

875

825

18,883

875

18,883

875

825

Impaired loans, recorded investment with related allowance

5,622

0

5,622

0

802

0

802

0

12,707

949

12,665

973

Commercial | Other commercial and industrial [Member]

0

28,933

8,186

28,933

8,186

29,006

Impaired loans, recorded investment with no related allowance

20,630

516

20,630

516

21,118

20,609

516

20,609

516

21,083

Impaired loans, recorded investment with related allowance

21

0

21

0

35

17

0

17

0

35

20,706

542

20,874

569

0

Commercial real estate

6,905

18,519

6,905

18,519

14,427

Impaired loans, recorded investment with no related allowance

3,775

7,780

3,775

7,780

5,521

3,775

7,628

3,775

7,628

5,521

Impaired loans, recorded investment with related allowance

0

152

0

152

0

0

18

0

18

0

4,125

8,524

4,648

8,390

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

0

3,676

7,177

3,676

7,177

4,951

Impaired loans, recorded investment with no related allowance

2,051

4,261

2,051

4,261

3,433

2,051

4,261

2,051

4,261

3,433

Impaired loans, recorded investment with related allowance

0

0

2,334

4,525

2,742

4,335

Commercial real estate | Retail [Member]

0

518

1,914

518

1,914

530

Impaired loans, recorded investment with no related allowance

301

1,265

301

1,265

326

301

1,265

301

1,265

326

Impaired loans, recorded investment with related allowance

0

0

308

1,283

314

1,292

Commercial real estate | Office [Member]

0

499

907

499

907

521

Impaired loans, recorded investment with no related allowance

396

606

396

606

426

396

606

396

606

426

Impaired loans, recorded investment with related allowance

0

0

404

618

411

628

Commercial real estate | Multifamily [Member]

0

1,000

Impaired loans, recorded investment with no related allowance

10

65

10

65

38

10

65

10

65

38

Impaired loans, recorded investment with related allowance

0

0

17

157

24

169

Commercial real estate | Industrial [Member]

0

0

76

0

76

Impaired loans, recorded investment with no related allowance

0

76

0

76

0

76

0

76

Impaired loans, recorded investment with related allowance

0

0

38

76

38

76

Commercial real estate | Other commercial real estate [Member]

0

1,212

7,445

1,212

7,445

7,349

Impaired loans, recorded investment with no related allowance

1,017

1,507

1,017

1,507

1,222

1,017

1,355

1,017

1,355

1,222

Impaired loans, recorded investment with related allowance

0

152

0

152

0

0

18

0

18

0

1,024

1,865

1,119

1,890

0

Residential mortgage

239,326

243,291

239,326

243,291

247,005

Impaired loans, recorded investment with no related allowance

226,912

230,052

226,912

230,052

233,761

226,912

229,941

226,912

229,941

233,715

Impaired loans, recorded investment with related allowance

0

111

0

111

46

0

64

0

64

46

238,523

229,103

239,937

233,893

Residential mortgage | Permanent mortgage [Member]

2,328

2,327

4,523

4,426

28,603

33,793

28,603

33,793

28,830

Impaired loans, recorded investment with no related allowance

23,415

27,228

23,415

27,228

22,855

23,415

27,117

23,415

27,117

22,809

Impaired loans, recorded investment with related allowance

0

111

0

111

46

0

64

0

64

46

23,801

27,362

23,135

28,106

Residential mortgage | Permanent mortgages guaranteed by US government agencies [Member]

307

304

598

631

197,659

^[1]

198,534

^[2]

197,659

^[1]

198,534

^[2]

205,564

^[3]

Impaired loans, recorded investment with no related allowance

191,729

^[1]

192,732

^[2]

191,729

^[1]

192,732

^[2]

199,387

^[3]

191,729

^[1]

192,732

^[2]

191,729

^[1]

192,732

^[2]

199,387

^[3]

Impaired loans, recorded investment with related allowance

0

^[1]

0

^[2]

0

^[1]

0

^[2]

0

^[3]

0

^[1]

0

^[2]

0

^[1]

0

^[2]

0

^[3]

202,946

^[1]

191,430

^[2]

205,159

^[1]

195,563

^[2]

Residential mortgage | Home equity [Member]

2,021

^[1]

2,023

^[2]

3,925

^[1]

3,795

^[2]

13,064

10,964

13,064

10,964

12,611

Impaired loans, recorded investment with no related allowance

11,768

10,092

11,768

10,092

11,519

11,768

10,092

11,768

10,092

11,519

Impaired loans, recorded investment with related allowance

0

0

11,776

10,311

11,643

10,224

0

Personal

307

1,174

307

1,174

332

Impaired loans, recorded investment with no related allowance

272

354

272

354

290

272

354

272

354

290

Impaired loans, recorded investment with related allowance

0

0

$ 0

253

342

281

409

Dividends declared (in dollars per share)

$ 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 June 30, 2017, $9.1 million of these loans were nonaccruing and $183 million were accruing based on the guarantee by U.S. government agencies.
[2]	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 June 30, 2016, $20 million of these loans were nonaccruing and $173 million were accruing based on the guarantee by U.S. government agencies.
[3]	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, 2016, $12 million of these loans were nonaccruing and $188 million were accruing based on the guarantee by U.S. government agencies.

Loans and Allowances for Credit Losses, Troubled Debt Restructurings (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	$ 168,739	$ 129,485	$ 168,739	$ 129,485	$ 147,117
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	70,906	60,646	70,906	60,646	74,738
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	97,833	68,839	97,833	68,839	72,379
Troubled Debt Restructuring, Specific allowance	4,308	64	4,308	64	46
Troubled Debt Restructuring, Charge-offs	10	600	42	744
Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	88,115	50,679	88,115	50,679	65,747
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	46,400	32,647	46,400	32,647	47,449
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	41,715	18,032	41,715	18,032	18,298
Troubled Debt Restructuring, Specific allowance	4,308	64	4,308	64	46
Troubled Debt Restructuring, Charge-offs	10	600	42	744
Nonaccrual [Member] \| Commercial
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	60,924	14,732	60,924	14,732	36,879
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	30,007	11,236	30,007	11,236	29,225
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	30,917	3,496	30,917	3,496	7,654
Troubled Debt Restructuring, Specific allowance	4,308	0	4,308	0	0
Troubled Debt Restructuring, Charge-offs	3	500	3	557
Nonaccrual [Member] \| Commercial \| Energy [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	22,466	2,246	22,466	2,246	16,893
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	12,692	0	12,692	0	10,867
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	9,774	2,246	9,774	2,246	6,026
Troubled Debt Restructuring, Specific allowance	4,308	0	4,308	0	0
Troubled Debt Restructuring, Charge-offs	0	500	0	500
Nonaccrual [Member] \| Commercial \| Services [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	7,208	8,610	7,208	8,610	7,527
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	6,561	7,853	6,561	7,853	6,830
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	647	757	647	757	697
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	3	0	3	0
Nonaccrual [Member] \| Commercial \| Wholesale/retail [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	10,524	2,467	10,524	2,467	11,291
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	10,524	2,427	10,524	2,427	11,251
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	40	0	40	40
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial \| Manufacturing [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	195	253	195	253	224
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	195	253	195	253	224
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial \| Healthcare [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	0	640	0	640	607
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	0	640	0	640	0
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	0	0	0	607
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial \| Other commercial and industrial [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	20,531	516	20,531	516	337
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	35	63	35	63	53
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	20,496	453	20,496	453	284
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	57
Nonaccrual [Member] \| Commercial real estate
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	1,168	3,810	1,168	3,810	1,707
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	811	2,510	811	2,510	1,114
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	357	1,300	357	1,300	593
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Residential construction and land development [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	381	1,601	381	1,601	690
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	145	1,079	145	1,079	97
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	236	522	236	522	593
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Retail [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	301	1,264	301	1,264	326
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	301	907	301	907	326
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	357	0	357	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Office [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	121	152	121	152	143
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	0	152	0	152	143
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	121	0	121	0	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Multifamily [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	0	0	0	0	0
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Industrial [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	0	0	0	0	0
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Other commercial real estate [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	365	793	365	793	548
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	365	372	365	372	548
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	421	0	421	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Residential mortgage
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	25,795	31,839	25,795	31,839	26,924
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	15,354	18,625	15,354	18,625	16,874
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	10,441	13,214	10,441	13,214	10,050
Troubled Debt Restructuring, Specific allowance	0	64	0	64	46
Troubled Debt Restructuring, Charge-offs	0	97	31	178
Nonaccrual [Member] \| Residential mortgage \| Permanent mortgage [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	14,284	17,367	14,284	17,367	14,876
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	9,939	12,462	9,939	12,462	10,175
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	4,345	4,905	4,345	4,905	4,701
Troubled Debt Restructuring, Specific allowance	0	64	0	64	46
Troubled Debt Restructuring, Charge-offs	0	37	0	52
Nonaccrual [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	5,962	9,709	5,962	9,709	6,702
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	1,176	2,024	1,176	2,024	2,241
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	4,786	7,685	4,786	7,685	4,461
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Residential mortgage \| Home equity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	5,549	4,763	5,549	4,763	5,346
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	4,239	4,139	4,239	4,139	4,458
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	1,310	624	1,310	624	888
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	60	31	126
Nonaccrual [Member] \| Personal
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	228	298	228	298	237
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	228	276	228	276	236
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	22	0	22	1
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	7	3	8	9
Accruing [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	80,624	78,806	80,624	78,806	81,370
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	24,506	27,999	24,506	27,999	27,289
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	56,118	50,807	56,118	50,807	54,081
Troubled Debt Restructuring, Specific allowance	0	0	0	0	$ 0
Troubled Debt Restructuring, Charge-offs	$ 0	$ 0	$ 0	$ 0

Loans and Allowances for Credit Losses, Troubled Debt Restructurings, Modifications (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	$ 33,892	$ 10,172	$ 53,146	$ 18,770
Troubled Debt Restructurings, Recorded Balance With Payment Default	54,442	23,165	54,947	25,911
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	20,868	0	33,878	501
Troubled Debt Restructurings, Recorded Balance With Payment Default	30,016	2,246	30,016	2,246
Commercial \| Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	13,010	501
Troubled Debt Restructurings, Recorded Balance With Payment Default	9,774	2,246	9,774	2,246
Commercial \| Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial \| Wholesale/retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	626	0	626	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial \| Manufacturing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial \| Healthcare [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial \| Other commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	20,242	0	20,242	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	20,242	0	20,242	0
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial real estate \| Residential construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial real estate \| Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial real estate \| Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial real estate \| Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial real estate \| Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial real estate \| Other commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	12,977	10,107	19,217	18,197
Troubled Debt Restructurings, Recorded Balance With Payment Default	24,426	20,919	24,931	23,665
Residential mortgage \| Permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	191	1,867	237	2,290
Troubled Debt Restructurings, Recorded Balance With Payment Default	161	788	161	1,806
Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	12,201	7,863	17,778	15,068
Troubled Debt Restructurings, Recorded Balance With Payment Default	23,152	19,899	23,508	21,627
Residential mortgage \| Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	585	377	1,202	839
Troubled Debt Restructurings, Recorded Balance With Payment Default	1,113	232	1,262	232
Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	47	65	51	72
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	11,978	7,238	17,469	14,443
Troubled Debt Restructurings, Recorded Balance With Payment Default	22,234	18,893	22,590	20,621
Accruing [Member] \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial \| Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial \| Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial \| Wholesale/retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial \| Manufacturing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial \| Healthcare [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial \| Other commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial real estate \| Residential construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Accruing [Member] \| Commercial real estate \| Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Accruing [Member] \| Commercial real estate \| Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Accruing [Member] \| Commercial real estate \| Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Accruing [Member] \| Commercial real estate \| Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Accruing [Member] \| Commercial real estate \| Other commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Accruing [Member] \| Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	11,978	7,238	17,469	14,443
Troubled Debt Restructurings, Recorded Balance With Payment Default	22,234	18,893	22,590	20,621
Accruing [Member] \| Residential mortgage \| Permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	11,978	7,238	17,469	14,443
Troubled Debt Restructurings, Recorded Balance With Payment Default	22,234	18,893	22,590	20,621
Accruing [Member] \| Residential mortgage \| Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Accruing [Member] \| Payment Stream [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	10,410	2,783	14,883	6,625
Accruing [Member] \| Payment Stream [Member] \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial \| Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial \| Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial \| Wholesale/retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial \| Manufacturing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial \| Healthcare [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial \| Other commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial real estate \| Residential construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial real estate \| Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial real estate \| Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial real estate \| Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial real estate \| Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial real estate \| Other commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	10,410	2,783	14,883	6,625
Accruing [Member] \| Payment Stream [Member] \| Residential mortgage \| Permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	10,410	2,783	14,883	6,625
Accruing [Member] \| Payment Stream [Member] \| Residential mortgage \| Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	1,568	4,455	2,586	7,818
Accruing [Member] \| Combination & Other [Member] \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial \| Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial \| Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial \| Wholesale/retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial \| Manufacturing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial \| Healthcare [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial \| Other commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial real estate \| Residential construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial real estate \| Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial real estate \| Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial real estate \| Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial real estate \| Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial real estate \| Other commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	1,568	4,455	2,586	7,818
Accruing [Member] \| Combination & Other [Member] \| Residential mortgage \| Permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	1,568	4,455	2,586	7,818
Accruing [Member] \| Combination & Other [Member] \| Residential mortgage \| Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	21,914	2,934	35,677	4,327
Troubled Debt Restructurings, Recorded Balance With Payment Default	32,208	4,272	32,357	5,290
Nonaccrual [Member] \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	20,868	0	33,878	501
Troubled Debt Restructurings, Recorded Balance With Payment Default	30,016	2,246	30,016	2,246
Nonaccrual [Member] \| Commercial \| Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	13,010	501
Troubled Debt Restructurings, Recorded Balance With Payment Default	9,774	2,246	9,774	2,246
Nonaccrual [Member] \| Commercial \| Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial \| Wholesale/retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	626	0	626	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial \| Manufacturing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial \| Healthcare [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial \| Other commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	20,242	0	20,242	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	20,242	0	20,242	0
Nonaccrual [Member] \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Residential construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Nonaccrual [Member] \| Commercial real estate \| Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Nonaccrual [Member] \| Commercial real estate \| Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Nonaccrual [Member] \| Commercial real estate \| Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Nonaccrual [Member] \| Commercial real estate \| Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Nonaccrual [Member] \| Commercial real estate \| Other commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Nonaccrual [Member] \| Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	999	2,869	1,748	3,754
Troubled Debt Restructurings, Recorded Balance With Payment Default	2,192	2,026	2,341	3,044
Nonaccrual [Member] \| Residential mortgage \| Permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	191	1,867	237	2,290
Troubled Debt Restructurings, Recorded Balance With Payment Default	161	788	161	1,806
Nonaccrual [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	223	625	309	625
Troubled Debt Restructurings, Recorded Balance With Payment Default	918	1,006	918	1,006
Nonaccrual [Member] \| Residential mortgage \| Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	585	377	1,202	839
Troubled Debt Restructurings, Recorded Balance With Payment Default	1,113	232	1,262	232
Nonaccrual [Member] \| Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	47	65	51	72
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0		0
Nonaccrual [Member] \| Payment Stream [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	20,629	732	33,778	1,595
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	20,242	0	33,252	501
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial \| Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	13,010	501
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial \| Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial \| Wholesale/retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial \| Manufacturing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial \| Healthcare [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial \| Other commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	20,242	0	20,242	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial real estate \| Residential construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial real estate \| Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial real estate \| Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial real estate \| Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial real estate \| Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial real estate \| Other commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	387	732	526	1,094
Nonaccrual [Member] \| Payment Stream [Member] \| Residential mortgage \| Permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	138	684	153	1,046
Nonaccrual [Member] \| Payment Stream [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	223	0	224	0
Nonaccrual [Member] \| Payment Stream [Member] \| Residential mortgage \| Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	26	48	149	48
Nonaccrual [Member] \| Payment Stream [Member] \| Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	1,285	2,202	1,899	2,732
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	626	0	626	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial \| Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial \| Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial \| Wholesale/retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	626	0	626	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial \| Manufacturing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial \| Healthcare [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial \| Other commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial real estate \| Residential construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial real estate \| Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial real estate \| Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial real estate \| Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial real estate \| Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial real estate \| Other commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	612	2,137	1,222	2,660
Nonaccrual [Member] \| Combination & Other [Member] \| Residential mortgage \| Permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	53	1,183	84	1,244
Nonaccrual [Member] \| Combination & Other [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	625	85	625
Nonaccrual [Member] \| Combination & Other [Member] \| Residential mortgage \| Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	559	329	1,053	791
Nonaccrual [Member] \| Combination & Other [Member] \| Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	$ 47	$ 65	$ 51	$ 72

Loans and Allowances for Credit Losses, By Aging Category (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Financing receivable, recorded investment, aging [Abstract]
Current	$ 16,783,348	$ 16,597,641	$ 16,010,465
Nonaccrual	245,439	230,984	247,184
Total	17,183,645	16,989,660	16,406,749
Commercial
Financing receivable, recorded investment, aging [Abstract]
Current	10,438,108	10,205,838	10,167,077
Nonaccrual	197,157	178,953	181,989
Total	10,637,955	10,390,824	10,356,437
Commercial \| Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	2,723,248	2,364,890	2,647,678
Nonaccrual	123,992	132,499	168,145
Total	2,847,240	2,497,868	2,818,656
Commercial \| Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	2,949,562	3,099,605	2,817,217
Nonaccrual	7,754	8,173	9,388
Total	2,958,827	3,108,990	2,830,864
Commercial \| Wholesale/retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,532,986	1,561,650	1,530,110
Nonaccrual	10,620	11,407	2,772
Total	1,543,695	1,576,818	1,532,957
Commercial \| Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	536,481	509,662	595,110
Nonaccrual	9,656	4,931	293
Total	546,137	514,975	595,403
Commercial \| Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	2,196,088	2,201,050	2,050,271
Nonaccrual	24,505	825	875
Total	2,221,518	2,201,916	2,051,146
Commercial \| Other commercial and industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	499,743	468,981	526,691
Nonaccrual	20,630	21,118	516
Total	520,538	490,257	527,411
Commercial real estate
Financing receivable, recorded investment, aging [Abstract]
Current	3,684,343	3,803,519	3,571,877
Nonaccrual	3,775	5,521	7,780
Total	3,688,592	3,809,046	3,581,966
Commercial real estate \| Residential construction and land development [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	139,070	132,100	153,315
Nonaccrual	2,051	3,433	4,261
Total	141,592	135,533	157,576
Commercial real estate \| Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	722,504	761,562	794,154
Nonaccrual	301	326	1,265
Total	722,805	761,888	795,419
Commercial real estate \| Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	862,577	798,462	768,506
Nonaccrual	396	426	606
Total	862,973	798,888	769,112
Commercial real estate \| Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	952,370	903,234	784,826
Nonaccrual	10	38	65
Total	952,380	903,272	787,200
Commercial real estate \| Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	693,635	871,673	645,510
Nonaccrual	0	76	76
Total	693,635	871,749	645,586
Commercial real estate \| Other commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	314,187	336,488	425,566
Nonaccrual	1,017	1,222	1,507
Total	315,207	337,716	427,073
Residential mortgage
Financing receivable, recorded investment, aging [Abstract]
Current	1,744,045	1,749,473	1,684,900
Nonaccrual	44,235	46,220	57,061
Total	1,939,198	1,949,832	1,880,923
Residential mortgage \| Permanent mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	962,443	979,386	935,857
Nonaccrual	23,415	22,855	27,228
Total	989,040	1,006,820	969,007
Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	36,867	40,594	42,019
Nonaccrual	9,052	11,846	19,741
Total	191,729	199,387	192,732
Residential mortgage \| Home equity [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	744,735	729,493	707,024
Nonaccrual	11,768	11,519	10,092
Total	758,429	743,625	719,184
Personal
Financing receivable, recorded investment, aging [Abstract]
Current	916,852	838,811	586,611
Nonaccrual	272	290	354
Total	917,900	839,958	587,423
30 to 59 Days [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	24,074	28,603	26,390
30 to 59 Days [Member] \| Commercial
Financing receivable, recorded investment, aging [Abstract]
Past Due	1,109	4,968	645
30 to 59 Days [Member] \| Commercial \| Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	479	0
30 to 59 Days [Member] \| Commercial \| Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	50	191	494
30 to 59 Days [Member] \| Commercial \| Wholesale/retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	89	3,761	75
30 to 59 Days [Member] \| Commercial \| Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	382	0
30 to 59 Days [Member] \| Commercial \| Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	925	0	0
30 to 59 Days [Member] \| Commercial \| Other commercial and industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	45	155	76
30 to 59 Days [Member] \| Commercial real estate
Financing receivable, recorded investment, aging [Abstract]
Past Due	474	6	2,309
30 to 59 Days [Member] \| Commercial real estate \| Residential construction and land development [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	471	0	0
30 to 59 Days [Member] \| Commercial real estate \| Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
30 to 59 Days [Member] \| Commercial real estate \| Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
30 to 59 Days [Member] \| Commercial real estate \| Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	2,309
30 to 59 Days [Member] \| Commercial real estate \| Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
30 to 59 Days [Member] \| Commercial real estate \| Other commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	3	6	0
30 to 59 Days [Member] \| Residential mortgage
Financing receivable, recorded investment, aging [Abstract]
Past Due	22,004	23,040	23,036
30 to 59 Days [Member] \| Residential mortgage \| Permanent mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	2,024	3,299	5,798
30 to 59 Days [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	18,416	17,465	15,349
30 to 59 Days [Member] \| Residential mortgage \| Home equity [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	1,564	2,276	1,889
30 to 59 Days [Member] \| Personal
Financing receivable, recorded investment, aging [Abstract]
Past Due	487	589	400
60 to 89 Days [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	15,557	16,748	16,057
60 to 89 Days [Member] \| Commercial
Financing receivable, recorded investment, aging [Abstract]
Past Due	299	1,065	3,847
60 to 89 Days [Member] \| Commercial \| Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Commercial \| Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	180	1,021	3,765
60 to 89 Days [Member] \| Commercial \| Wholesale/retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Commercial \| Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Commercial \| Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	41	0
60 to 89 Days [Member] \| Commercial \| Other commercial and industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	119	3	82
60 to 89 Days [Member] \| Commercial real estate
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Commercial real estate \| Residential construction and land development [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Commercial real estate \| Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Commercial real estate \| Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Commercial real estate \| Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Commercial real estate \| Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Commercial real estate \| Other commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Residential mortgage
Financing receivable, recorded investment, aging [Abstract]
Past Due	14,969	15,420	12,152
60 to 89 Days [Member] \| Residential mortgage \| Permanent mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	1,026	1,280	124
60 to 89 Days [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	13,581	13,803	11,869
60 to 89 Days [Member] \| Residential mortgage \| Home equity [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	362	337	159
60 to 89 Days [Member] \| Personal
Financing receivable, recorded investment, aging [Abstract]
Past Due	289	263	58
90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	115,227	115,684	106,653
90 Days or More [Member] \| Commercial
Financing receivable, recorded investment, aging [Abstract]
Past Due	1,282	0	2,879
90 Days or More [Member] \| Commercial \| Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	2,833
90 Days or More [Member] \| Commercial \| Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	1,281	0	0
90 Days or More [Member] \| Commercial \| Wholesale/retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial \| Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial \| Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial \| Other commercial and industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	1	0	46
90 Days or More [Member] \| Commercial real estate
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial real estate \| Residential construction and land development [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial real estate \| Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial real estate \| Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial real estate \| Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial real estate \| Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial real estate \| Other commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Residential mortgage
Financing receivable, recorded investment, aging [Abstract]
Past Due	113,945	115,679	103,774
90 Days or More [Member] \| Residential mortgage \| Permanent mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	132	0	0
90 Days or More [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	113,813	115,679	103,754
90 Days or More [Member] \| Residential mortgage \| Home equity [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	20
90 Days or More [Member] \| Personal
Financing receivable, recorded investment, aging [Abstract]
Past Due	$ 0	$ 5	$ 0

Acquisitions (Details) - MBT Bancshares [Member] - USD ($) $ in Thousands		6 Months Ended
	Dec. 01, 2016	Jun. 30, 2017
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Dec. 01, 2016
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	$ 102,500
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles		$ 2,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment		1,500
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Goodwill		$ 526

Mortgage Banking Activities, Components of Loans Held For Sale (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Schedule of Residential Mortgage Loans Held For Sale [Line Items]
Number of days for past due for loan to be considered nonperforming (in days)	90 days	90 days	90 days
Residential mortgage loans held for sale, nonperforming	$ 0	$ 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	269,772	404,507	286,414
Residential mortgage loans held for sale, Fair value	275,179	417,542	286,971
Total residential mortgage loans held for sale and mortgage loan commitments, net of forward sales contracts	$ 287,259	$ 430,728	$ 301,897
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 days	60 days	60 days
General number of days outstanding for residential mortgage commitments, maximum (in days)	90 days	90 days	90 days
Components of Residential Mortgage Loans Held for Sale [Abstract]
Notional	$ 362,088	$ 965,631	$ 318,359
Derivative, Net fair value	$ 10,993	$ 25,499	$ 9,733
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 days	60 days	60 days
General number of days for delivery for loans, for which the price is set by forward sales contracts, maximum (in days)	90 days	90 days	90 days
Components of Residential Mortgage Loans Held for Sale [Abstract]
Notional	$ 587,595	$ 1,216,966	$ 569,543
Derivative, Net fair value	$ 1,087	$ (12,313)	$ 5,193

Mortgage Banking Activities Mortgage Banking Activities, Mortgage Banking Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Mortgage Banking Revenue [Abstract]
Net realized gains on sale of mortgage loans	$ 11,787	$ 15,865	$ 20,402	$ 24,314
Net change in unrealized gain on mortgage loans held for sale	985	3,884	4,827	7,167
Net change in the fair value of mortgage loan commitments	(3,274)	5,329	1,260	17,365
Net change in the fair value of forward sales contracts	4,342	(5,992)	(4,106)	(13,113)
Total production revenue	13,840	19,086	22,383	35,733
Servicing revenue	16,436	15,798	33,084	31,251
Total mortgage banking revenue	$ 30,276	$ 34,884	$ 55,467	$ 66,984

Mortgage Banking Activities, Mortgage Servicing Rights (Details)	3 Months Ended			6 Months Ended
	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)
Summary of Mortgage Servicing Rights [Abstract]
Number of residential mortgage loans serviced for others	138,335	139,340	137,210	138,335	137,210
Outstanding principal balance of residential mortgage loans serviced for others	$ 22,095,232,000	$ 21,997,568,000	$ 21,178,387,000	$ 22,095,232,000	$ 21,178,387,000
Weighted average interest rate	3.95%	3.97%	4.06%	3.95%	4.06%
Remaining term (in months)	299 months	301 months	301 months
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance	$ 249,403,000		$ 196,055,000	$ 247,073,000	$ 218,605,000
Additions, net	11,078,000		20,773,000	19,514,000	34,355,000
Change in fair value due to scheduled payments and full-balance payoffs	(8,299,000)		(9,798,000)	(16,261,000)	(17,942,000)
Change in fair value due to market assumption changes	(6,943,000)		(16,283,000)	(5,087,000)	(44,271,000)
Ending balance	$ 245,239,000	$ 247,073,000	$ 190,747,000	$ 245,239,000	$ 190,747,000
Servicing Assets at Fair Value, Assumptions Used to Estimate Fair Value [Abstract]
Discount rate - risk-free rate plus a market premium (in hundredths)	9.84%	10.08%	10.09%
Prepayment rate - based upon loan interest rate, original term and loan type, minimum	8.61%	8.98%	9.26%
Prepayment rate - based upon loan interest rate, original term and loan type, maximum	15.91%	16.91%	42.77%
Loan servicing costs - annually per loan based upon loan type, performing, minimum (in dollars per loan)	$ 65	$ 63	$ 63
Loan servicing costs - annually per loan based upon loan type, performing, maximum (in dollars per loan)	120	120	120
Loan servicing costs - annually per loan based upon loan type, delinquent, minimum (in dollars per loan)	150	150	150
Loan servicing costs - annually per loan based upon loan type, delinquent, maximum (in dollars per loan)	500	500	500
Loan servicing costs - annually per loan based upon loan type, foreclosure, minimum (in dollars per loan)	1,000	650	650
Loan servicing costs - annually per loan based upon loan type, foreclosure, maximum (in dollars per loan)	$ 4,250	$ 4,250	$ 4,250
Escrow earnings rate - indexed to rates paid on deposit accounts with comparable average life (in hundredths)	1.95%	1.98%	0.99%
Primary secondary mortgage rate spread (in basis points)	105	105	115	105	115
Purchased [Member]
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance	$ 8,316,000		$ 5,949,000	$ 8,909,000	$ 9,911,000
Additions, net	0		0	0	0
Change in fair value due to scheduled payments and full-balance payoffs	(464,000)		(730,000)	(973,000)	(1,356,000)
Change in fair value due to market assumption changes	143,000		(1,152,000)	59,000	(4,488,000)
Ending balance	7,995,000	$ 8,909,000	4,067,000	7,995,000	4,067,000
Originated [Member]
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance	241,087,000		190,106,000	238,164,000	208,694,000
Additions, net	11,078,000		20,773,000	19,514,000	34,355,000
Change in fair value due to scheduled payments and full-balance payoffs	(7,835,000)		(9,068,000)	(15,288,000)	(16,586,000)
Change in fair value due to market assumption changes	(7,086,000)		(15,131,000)	(5,146,000)	(39,783,000)
Ending balance	$ 237,244,000	$ 238,164,000	$ 186,680,000	$ 237,244,000	$ 186,680,000

Mortgage Banking Activities Mortgage Banking Activities, Loans Serviced for Others (Details) $ in Thousands	Jun. 30, 2017 USD ($)
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	$ 21,685,252
30 to 59 Days Past Due	269,744
60 to 89 Days Past Due	71,240
90 Days or More Past Due	68,996
Total	22,095,232
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	8,083,330
30 to 59 Days Past Due	48,659
60 to 89 Days Past Due	12,294
90 Days or More Past Due	27,338
Total	8,171,621
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	6,756,211
30 to 59 Days Past Due	46,918
60 to 89 Days Past Due	10,679
90 Days or More Past Due	23,981
Total	6,837,789
Government National Mortgage Association Certificates and Obligations (GNMA) [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	6,331,439
30 to 59 Days Past Due	170,889
60 to 89 Days Past Due	47,335
90 Days or More Past Due	16,082
Total	6,565,745
Other Investor Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	514,272
30 to 59 Days Past Due	3,278
60 to 89 Days Past Due	932
90 Days or More Past Due	1,595
Total	$ 520,077

Mortgage Banking Activities, Loans Sold With Recourse (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)
Residential Mortgage Loan Repurchase and Servicing Losses [Abstract]
Number of mortgages purchased under repurchase agreement with government sponsored entities.	5
Purchase price of loans purchased under repurchase agreement with government sponsored entities	$ 1,315
Number of loans sold under standard representations and warranties indemnified	4
Number of unresolved deficiency requests	206	211	206	211
Aggregate outstanding principal balance subject to unresolved deficiency requests	$ 13,370	$ 15,920	$ 13,370	$ 15,920
Unpaid principal balance subject to indemnification by the Company	5,074	5,519	5,074	5,519
Activity in accrual for mortgage losses [Rollforward]
Beginning balance	2,587	2,974	2,788	3,359
Provision for losses	(895)	368	(1,094)	250
Charge-offs, net	(45)	(89)	(47)	(356)
Ending balance	$ 1,647	$ 3,253	$ 1,647	$ 3,253

Commitments and Contingent Liabilities (Details)	6 Months Ended	12 Months Ended
Commitments and Contingent Liabilities (Details)	Jun. 30, 2017 USD ($) shares	Dec. 31, 2016 USD ($)
BOKF Equity, LLC [Member]
Litigation Settlement [Abstract]
Number of Private Equity Funds of which the Entity is a General Partner	2
Contingent Obligations For Additional Investments in Private Equity Funds	$ 4,000,000
Cavanal Hill Funds [Member]
Litigation Settlement [Abstract]
The Net Asset Value of Units in Mutual Funds (per unit)	1.00
Settled Litigation [Member] \| Deposit Account Posting Class Action [Member]
Litigation Settlement [Abstract]
Litigation Settlement, Amount		$ 7,800,000
Judicial Ruling [Member] \| Misuse of Revenues Pledged to Municipal Bonds [Member]
Litigation Settlement [Abstract]
Litigation Settlement, Amount	$ 600,000
Outstanding principal, accrued interest and other amounts required by bond documents	73,000,000
Disgorged fees	$ 1,067,721
Pending Litigation [Member] \| Misuse of Revenues Pledged to Municipal Bonds [Member]
Litigation Settlement [Abstract]
Loss Contingency, Number of Plaintiffs	2
Pending Litigation [Member] \| Bank Participation in Fraudulent Sale of Securities by Principals [Member]
Litigation Settlement [Abstract]
Loss Contingency, Number of Plaintiffs	19
Pending Litigation [Member] \| Purchase of facilities from principals subject to SEC New Jersey proceedings [Member]
Litigation Settlement [Abstract]
Outstanding principal, accrued interest and other amounts required by bond documents	$ 60,000,000
Number of individuals who purchased facilities from the principals subject to SEC New Jersey proceedings	2
Number of principals in SEC New Jersey proceedings	2
Pending Litigation [Member] \| Ownership of deposit accounts [Member]
Litigation Settlement [Abstract]
Loss Contingency, Number of Plaintiffs	2
Amount paid by the bank from creditor accounts to judgment creditor	$ 4,200,000
Loss Contingency, Damages Sought, Value	$ 7,000,000
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	415,755

Commitments and Contingent Liabilities Variable Interest Entities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Loans Receivable [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	$ 10,000	$ 10,000	$ 10,000
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	59,744	44,488	32,679
Loans Receivable [Member] \| Private equity funds [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Loans Receivable [Member] \| Tax credit entities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	10,000	10,000	10,000
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	59,744	44,488	32,679
Loans Receivable [Member] \| Other [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Other Assets [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	44,073	58,725	67,751
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	181,680	175,390	125,577
Other Assets [Member] \| Private equity funds [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	16,905	17,357	20,469
Other Assets [Member] \| Tax credit entities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	11,274	11,585	11,895
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	148,525	143,715	102,138
Other Assets [Member] \| Other [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	15,894	29,783	35,387
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	33,155	31,675	23,439
Other Liabilities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	1,621	3,189	2,004
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	77,502	78,357	44,720
Other Liabilities [Member] \| Private equity funds [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Other Liabilities [Member] \| Tax credit entities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	63,822	63,329	30,953
Other Liabilities [Member] \| Other [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	1,621	3,189	2,004
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	13,680	15,028	13,767
Other borrowings [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	11,842	12,056	13,236
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Other borrowings [Member] \| Private equity funds [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Other borrowings [Member] \| Tax credit entities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	10,964	10,964	10,964
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Other borrowings [Member] \| Other [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	878	1,092	2,272
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Non-Controlling Interests [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	27,076	31,503	33,905
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Non-Controlling Interests [Member] \| Private equity funds [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	14,199	13,237	16,316
Non-Controlling Interests [Member] \| Tax credit entities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	10,000	10,000	10,000
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Non-Controlling Interests [Member] \| Other [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	2,877	8,266	7,589
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	$ 0	$ 0	$ 0

Shareholders' Equity (Details) - USD ($)
$ / shares in Units, $ in Thousands

3 Months Ended

6 Months Ended

Jul. 25, 2017

Jun. 30, 2017

Jun. 30, 2016

Jun. 30, 2017

Jun. 30, 2016

$ 0.44

$ 0.43

$ 0.88

$ 0.86

Schedule of Accumulated Other Income (Loss) [Abstract]

$ (10,967)

$ 21,587

Reclassification adjustments included in earnings:

$ 21,958

$ 45,475

33,369

166,566

Interest revenue, Investment securities, Taxable securities

0

(43)

0

(112)

Other comprehensive income (loss), before income taxes

(380)

(5,326)

(2,429)

(9,290)

21,578

40,106

30,940

157,164

Other comprehensive income (loss), net of income taxes

8,393

15,583

12,009

^[1]

61,119

^[1]

13,185

24,523

18,931

96,045

Accumulated Net Unrealized Gain (Loss) on Available for Sale Securities [Member]

7,964

117,632

7,964

117,632

Schedule of Accumulated Other Income (Loss) [Abstract]

(9,087)

23,284

Reclassification adjustments included in earnings:

33,369

166,566

Interest revenue, Investment securities, Taxable securities

0

Other comprehensive income (loss), before income taxes

(2,429)

(9,290)

30,940

157,276

Other comprehensive income (loss), net of income taxes

^[1]

12,009

61,163

18,931

96,113

Accumulated Unrealized Gain on Investment Securities Transferred from AFS [Member]

9,844

119,397

9,844

119,397

Schedule of Accumulated Other Income (Loss) [Abstract]

0

68

Reclassification adjustments included in earnings:

0

Interest revenue, Investment securities, Taxable securities

(112)

Other comprehensive income (loss), before income taxes

0

0

(112)

Other comprehensive income (loss), net of income taxes

^[1]

(44)

0

(68)

Accumulated Unrealized Gain (Loss) on Employee Benefit Plans [Member]

0

Schedule of Accumulated Other Income (Loss) [Abstract]

(1,880)

(1,765)

Reclassification adjustments included in earnings:

0

Interest revenue, Investment securities, Taxable securities

0

Other comprehensive income (loss), before income taxes

0

0

Other comprehensive income (loss), net of income taxes

^[1]

0

0

Subsequent Event [Member]

(1,880)

$ (1,765)

(1,880)

$ (1,765)

Dividends Payable, Date Declared

Jul. 25, 2017

Dividends declared (in dollars per share)

$ 0.44

Dividends Payable, Date to be Paid

Aug. 25, 2017

Dividends Payable, Date of Record

Aug. 11, 2017

Perpetual Preferred, Equity Securities and Mutual Funds [Member] | Accumulated Net Unrealized Gain (Loss) on Available for Sale Securities [Member]

Reclassification adjustments included in earnings:

$ 3,200

[1]	Calculated using a 39 percent effective tax rate.

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator: [Abstract]
Net income attributable to BOK Financial Corp. shareholders	$ 88,147	$ 65,801	$ 176,503	$ 108,365
Less: Earnings allocated to participating securities	926	821	1,929	1,359
Numerator for basic earnings per share – income available to common shareholders	87,221	64,980	174,574	107,006
Effect of reallocating undistributed earnings of participating securities	1	0	1	0
Numerator for diluted earnings per share – income available to common shareholders	$ 87,222	$ 64,980	$ 174,575	$ 107,006
Denominator: [Abstract]
Weighted average shares outstanding (in shares)	65,416,274	66,069,392	65,436,909	66,100,279
Less: Participating securities included in weighted average shares (in shares)	686,522	823,505	714,165	829,065
Denominator for basic earnings per common share (in shares)	64,729,752	65,245,887	64,722,744	65,271,214
Dilutive effect of employee stock compensation plans (in shares)	63,382	57,039	65,578	45,963
Denominator for diluted earnings per common share (in shares)	64,793,134	65,302,926	64,788,322	65,317,177
Basic earnings per share (per share)	$ 1.35	$ 1.00	$ 2.70	$ 1.64
Diluted earnings per share (per share)	$ 1.35	$ 1.00	$ 2.69	$ 1.64
Excludes employee stock options with exercise prices greater than current market price.	0	0	0	145,247,000

Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Reportable Segments (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
NIR (expense) from external sources	$ 205,204	$ 182,612	$ 406,386	$ 365,184
NIR (expense) from internal sources	0	0	0	0
Net interest revenue	205,204	182,612	406,386	365,184
Provision for credit losses	0	20,000	0	55,000
Net interest revenue after provision for credit losses	205,204	162,612	406,386	310,184
Other operating revenue	182,252	185,542	352,548	342,956
Other operating expense	250,885	251,385	495,596	493,955
Net direct contribution	136,571	96,769	263,338	159,185
Gain (loss) on financial instruments, net	0	0	0	0
Change in fair value of mortgage servicing rights	0	0	0	0
Gain (loss) on repossessed assets, net	0	0	0	0
Corporate expense allocations	0	0	0	0
Net income before taxes	136,571	96,769	263,338	159,185
Federal and state income taxes	47,705	30,497	85,808	51,925
Net income	88,866	66,272	177,530	107,260
Net income (loss) attributable to non-controlling interests	719	471	1,027	(1,105)
Net income attributable to BOK Financial Corp. shareholders	88,147	65,801	176,503	108,365
Average assets	32,368,571	31,986,042	32,660,160	31,747,257
Operating Segments [Member] \| Commercial [Member]
Segment Reporting Information [Line Items]
NIR (expense) from external sources	144,164	118,480	278,868	235,116
NIR (expense) from internal sources	(20,347)	(14,575)	(37,140)	(29,208)
Net interest revenue	123,817	103,905	241,728	205,908
Provision for credit losses	1,228	6,852	(234)	28,423
Net interest revenue after provision for credit losses	122,589	97,053	241,962	177,485
Other operating revenue	55,778	51,497	102,048	96,605
Other operating expense	59,128	52,594	111,565	108,663
Net direct contribution	119,239	95,956	232,445	165,427
Gain (loss) on financial instruments, net	3	0	41	0
Change in fair value of mortgage servicing rights	0	0	0	0
Gain (loss) on repossessed assets, net	1,403	(598)	1,398	(680)
Corporate expense allocations	8,862	8,883	17,493	17,627
Net income before taxes	111,783	86,475	216,391	147,120
Federal and state income taxes	43,484	33,639	84,176	57,230
Net income	68,299	52,836	132,215	89,890
Net income (loss) attributable to non-controlling interests	0	0	0	0
Net income attributable to BOK Financial Corp. shareholders	68,299	52,836	132,215	89,890
Average assets	17,596,273	16,973,663	17,517,960	16,971,339
Operating Segments [Member] \| Consumer [Member]
Segment Reporting Information [Line Items]
NIR (expense) from external sources	23,503	22,349	44,632	43,799
NIR (expense) from internal sources	11,837	8,876	22,789	18,229
Net interest revenue	35,340	31,225	67,421	62,028
Provision for credit losses	926	1,318	2,198	3,020
Net interest revenue after provision for credit losses	34,414	29,907	65,223	59,008
Other operating revenue	52,102	57,440	99,408	111,469
Other operating expense	55,709	62,806	109,242	118,524
Net direct contribution	30,807	24,541	55,389	51,953
Gain (loss) on financial instruments, net	5,224	15,045	3,557	31,626
Change in fair value of mortgage servicing rights	(6,943)	(16,283)	(5,087)	(44,271)
Gain (loss) on repossessed assets, net	98	252	(39)	406
Corporate expense allocations	17,039	16,630	33,908	32,608
Net income before taxes	12,147	6,925	19,912	7,106
Federal and state income taxes	4,725	2,694	7,746	2,764
Net income	7,422	4,231	12,166	4,342
Net income (loss) attributable to non-controlling interests	0	0	0	0
Net income attributable to BOK Financial Corp. shareholders	7,422	4,231	12,166	4,342
Average assets	8,845,398	8,774,881	8,747,524	8,731,085
Operating Segments [Member] \| Wealth Management [Member]
Segment Reporting Information [Line Items]
NIR (expense) from external sources	10,474	6,271	21,960	12,349
NIR (expense) from internal sources	10,325	7,193	19,181	14,857
Net interest revenue	20,799	13,464	41,141	27,206
Provision for credit losses	(93)	(239)	(53)	(390)
Net interest revenue after provision for credit losses	20,892	13,703	41,194	27,596
Other operating revenue	75,569	75,772	149,727	144,518
Other operating expense	60,615	61,414	121,025	122,098
Net direct contribution	35,846	28,061	69,896	50,016
Gain (loss) on financial instruments, net	0	0	0	0
Change in fair value of mortgage servicing rights	0	0	0	0
Gain (loss) on repossessed assets, net	0	0	0	0
Corporate expense allocations	9,947	10,417	20,619	20,952
Net income before taxes	25,899	17,644	49,277	29,064
Federal and state income taxes	10,075	6,864	19,169	11,306
Net income	15,824	10,780	30,108	17,758
Net income (loss) attributable to non-controlling interests	0	0	0	0
Net income attributable to BOK Financial Corp. shareholders	15,824	10,780	30,108	17,758
Average assets	6,763,093	5,765,390	6,960,872	5,665,218
Funds Management and Other [Member]
Segment Reporting Information [Line Items]
NIR (expense) from external sources	27,063	35,512	60,926	73,920
NIR (expense) from internal sources	(1,815)	(1,494)	(4,830)	(3,878)
Net interest revenue	25,248	34,018	56,096	70,042
Provision for credit losses	(2,061)	12,069	(1,911)	23,947
Net interest revenue after provision for credit losses	27,309	21,949	58,007	46,095
Other operating revenue	(1,197)	833	1,365	(9,636)
Other operating expense	75,433	74,571	153,764	144,670
Net direct contribution	(49,321)	(51,789)	(94,392)	(108,211)
Gain (loss) on financial instruments, net	(5,227)	(15,045)	(3,598)	(31,626)
Change in fair value of mortgage servicing rights	6,943	16,283	5,087	44,271
Gain (loss) on repossessed assets, net	(1,501)	346	(1,359)	274
Corporate expense allocations	(35,848)	(35,930)	(72,020)	(71,187)
Net income before taxes	(13,258)	(14,275)	(22,242)	(24,105)
Federal and state income taxes	(10,579)	(12,700)	(25,283)	(19,375)
Net income	(2,679)	(1,575)	3,041	(4,730)
Net income (loss) attributable to non-controlling interests	719	471	1,027	(1,105)
Net income attributable to BOK Financial Corp. shareholders	(3,398)	(2,046)	2,014	(3,625)
Average assets	$ (836,193)	$ 472,108	$ (566,196)	$ 379,615

Fair Value Measurements, Fair Value Of Financial Instruments as Measured On a Recurring Basis (Details) - USD ($)
$ in Thousands

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2016

Jun. 30, 2016

Mar. 31, 2016

Dec. 31, 2015

$ 441,414

$ 337,628

$ 211,622

8,341,041

8,676,829

8,830,689

445,169

77,046

263,265

Derviative contracts, net of cash collateral, Assets, Fair value

245,239

$ 249,403

247,073

190,747

$ 196,055

$ 218,605

280,289

689,872

883,673

Derivative contracts, net of cash collateral, Liabilities, Fair Value

285,819

664,531

719,159

U.S. government agency debentures

U.S. government agency residential mortgage-backed securities

20,954

6,234

18,909

365,171

310,067

122,306

5,382,377

5,460,386

5,700,268

Municipal and other tax-exempt securities

445,169

77,046

237,959

45,444

14,427

52,721

32,765

40,993

50,262

Other trading securities

9,845

6,900

17,686

U.S. Treasury

998

999

1,004

Privately issued residential mortgage-backed securities

0

25,306

Commercial mortgage-backed securities guaranteed by U.S. government agencies

103,383

115,535

126,313

2,782,070

3,017,933

2,911,946

Other debt securities

Perpetual preferred stock

4,152

4,151

Equity securities and mutual funds

16,568

18,474

17,931

Fair Value, Measurements, Recurring [Member]

18,728

18,357

18,814

441,414

337,628

211,622

8,341,041

8,676,829

8,830,689

263,265

287,259

301,897

430,728

Derviative contracts, net of cash collateral, Assets, Fair value

245,239

^[1]

247,073

^[2]

190,747

^[3]

280,289

^[4]

689,872

^[5]

883,673

^[6]

Derivative contracts, net of cash collateral, Liabilities, Fair Value

285,819

^[4]

664,531

^[5]

719,159

^[6]

Fair Value, Measurements, Recurring [Member] | U.S. government agency debentures

Fair Value, Measurements, Recurring [Member] | U.S. government agency residential mortgage-backed securities

20,954

6,234

18,909

365,171

310,067

122,306

5,382,377

5,460,386

5,700,268

Fair Value, Measurements, Recurring [Member] | Municipal and other tax-exempt securities

445,169

77,046

237,959

45,444

14,427

52,721

Fair Value, Measurements, Recurring [Member] | Other trading securities

32,765

40,993

50,262

Fair Value, Measurements, Recurring [Member] | U.S. Treasury

9,845

6,900

17,686

998

999

1,004

Fair Value, Measurements, Recurring [Member] | Privately issued residential mortgage-backed securities

25,306

Fair Value, Measurements, Recurring [Member] | Commercial mortgage-backed securities guaranteed by U.S. government agencies

103,383

115,535

126,313

Fair Value, Measurements, Recurring [Member] | Other debt securities

2,782,070

3,017,933

2,911,946

Fair Value, Measurements, Recurring [Member] | Perpetual preferred stock

4,152

4,151

Fair Value, Measurements, Recurring [Member] | Equity securities and mutual funds

16,568

18,474

17,931

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]

18,728

18,357

18,814

0

4,514

4,494

4,789

25,306

0

Derviative contracts, net of cash collateral, Assets, Fair value

0

^[1]

0

^[2]

0

^[3]

20,213

^[4]

7,541

^[5]

7,246

^[6]

Derivative contracts, net of cash collateral, Liabilities, Fair Value

5,919

^[4]

6,972

^[5]

4,808

^[6]

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. government agency debentures

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. government agency residential mortgage-backed securities

0

0

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Municipal and other tax-exempt securities

0

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other trading securities

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Treasury

0

998

999

1,004

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Privately issued residential mortgage-backed securities

25,306

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial mortgage-backed securities guaranteed by U.S. government agencies

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other debt securities

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Perpetual preferred stock

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Equity securities and mutual funds

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]

3,516

3,495

3,785

441,414

337,628

211,622

8,327,720

8,662,394

8,812,149

237,959

274,524

290,280

420,979

Derviative contracts, net of cash collateral, Assets, Fair value

0

^[1]

0

^[2]

0

^[3]

260,076

^[4]

682,331

^[5]

876,427

^[6]

Derivative contracts, net of cash collateral, Liabilities, Fair Value

279,900

^[4]

657,559

^[5]

714,351

^[6]

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. government agency debentures

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. government agency residential mortgage-backed securities

20,954

6,234

18,909

365,171

310,067

122,306

5,382,377

5,460,386

5,700,268

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Municipal and other tax-exempt securities

445,169

77,046

237,959

45,444

14,427

52,721

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other trading securities

28,110

35,204

40,662

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Treasury

9,845

6,900

17,686

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Privately issued residential mortgage-backed securities

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial mortgage-backed securities guaranteed by U.S. government agencies

103,383

115,535

126,313

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other debt securities

2,782,070

3,017,933

2,911,946

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Perpetual preferred stock

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Equity securities and mutual funds

16,568

18,474

17,931

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]

15,212

14,862

15,029

0

8,807

9,941

13,751

0

12,735

11,617

9,749

Derviative contracts, net of cash collateral, Assets, Fair value

245,239

^[1]

247,073

^[2]

190,747

^[3]

0

^[4]

0

^[5]

0

^[6]

Derivative contracts, net of cash collateral, Liabilities, Fair Value

0

^[4]

0

^[5]

0

^[6]

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. government agency debentures

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. government agency residential mortgage-backed securities

0

0

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Municipal and other tax-exempt securities

0

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other trading securities

4,655

5,789

9,600

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Treasury

0

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Privately issued residential mortgage-backed securities

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial mortgage-backed securities guaranteed by U.S. government agencies

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other debt securities

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Perpetual preferred stock

4,152

4,151

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Equity securities and mutual funds

0

Available-for-sale securities [Member] | Municipal and other tax-exempt securities

$ 0

[1]	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 6, Mortgage Banking Activities.
[2]	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 6, Mortgage Banking Activities.
[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 6, Mortgage Banking Activities.
[4]	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 energy and interest rate derivative contacts. Derivative contacts in liability positions that were valued using quoted prices in active markets for identical instruments are exchange-traded interest rate and agricultural derivative contracts, net of cash margin.
[5]	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 contacts, 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, energy and agricultural derivative contracts, net of 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 energy and agricultural derivative contacts, 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 energy derivative contracts, net cash margin.

Fair Value Measurements, Measured On Recurring Basis Significant Unobservable Inputs (Details) - Fair Value, Measurements, Recurring [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($)
$ in Thousands

3 Months Ended

6 Months Ended

Jun. 30, 2017

Jun. 30, 2016

Jun. 30, 2017

Jun. 30, 2016

Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]

Balance, beginning of period

$ 5,722

$ 9,614

$ 5,789

$ 9,610

Transfer to Level 3 from Level 2

0

^[1]

0

^[2]

0

^[1]

0

^[2]

Purchases

0

Proceeds from sales

0

Redemptions and distributions

(1,100)

0

(1,100)

0

Other comprehensive income (loss)

33

(14)

(34)

(10)

Balance, end of period

4,655

9,600

4,655

9,600

Available-for-sale securities [Member] | Municipal and other tax-exempt securities | Mortgage banking revenue [Member]

Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]

Gain (loss) recognized in earnings

0

Available-for-sale securities [Member] | Other debt securities

Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]

Balance, beginning of period

4,153

4,151

4,152

4,151

Transfer to Level 3 from Level 2

0

^[1]

0

^[2]

0

^[1]

0

^[2]

Purchases

0

Proceeds from sales

0

Redemptions and distributions

0

Other comprehensive income (loss)

(1)

0

Balance, end of period

4,152

4,151

4,152

4,151

Available-for-sale securities [Member] | Other debt securities | Mortgage banking revenue [Member]

Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]

Gain (loss) recognized in earnings

0

Residential mortgage loans held for sale [Member]

Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]

Balance, beginning of period

12,679

8,099

11,617

7,874

Transfer to Level 3 from Level 2

853

^[1]

3,080

^[2]

2,740

^[1]

3,540

^[2]

Purchases

0

Proceeds from sales

(1,030)

(1,249)

(1,702)

(1,362)

Redemptions and distributions

0

Other comprehensive income (loss)

0

Balance, end of period

12,735

9,749

12,735

9,749

Residential mortgage loans held for sale [Member] | Mortgage banking revenue [Member]

Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]

Gain (loss) recognized in earnings

$ 233

$ (181)

$ 80

$ (303)

[1]	1 Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.
[2]	1 Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.

Fair Value Measurements Fair Value Measurements, Financial Instruments Measured On a Recurring Basis, Quantitative Information (Details) - Fair Value, Measurements, Recurring [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($)
$ in Thousands

6 Months Ended

12 Months Ended

Jun. 30, 2017

Jun. 30, 2016

Dec. 31, 2016

Available-for-sale securities [Member] | Municipal and other tax-exempt securities

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Fair Value Inputs, Asset, Par Value

$ 5,095

$ 10,370

$ 6,195

Fair Value Inputs, Asset, Amortized Cost/Unpaid Principal Balance

5,067

10,312

6,163

Fair Value Inputs, Asset, Fair Value

$ 4,655

$ 9,600

$ 5,789

Fair Value Measurements, Significant Unobservable Input

Discounted cash flows

^[1]

Discounted cash flows

^[2]

Discounted cash flows

^[3]

Interest rate spread

Fair Value Inputs, Assets, Discount Rate, Minimum

5.98%

^[4]

5.34%

^[5]

5.91%

^[6]

Fair Value Inputs, Assets, Discount Rate, Maximum

5.98%

^[4]

5.64%

^[5]

6.21%

^[6]

Fair Value Inputs, Assets, Discount Rate, Weighted Average

5.98%

^[4]

5.60%

^[5]

6.16%

^[6]

Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Minimum

90.00%

^[7]

90.00%

^[8]

90.00%

^[9]

Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Maximum

94.90%

^[7]

93.28%

^[8]

93.40%

^[9]

Fair Value Inputs, Fair Value As Percentage of Par Value, Weighted Average

92.93%

^[7]

92.58%

^[8]

92.20%

^[9]

Investment Grade Tax Exempt Securities Yield Spread Over Comparable Securities Minimum

360

474

467

Investment Grade Tax Exempt Securities Yield Spread Over Comparable Securities Maximum

446

513

525

Available-for-sale securities [Member] | Other debt securities

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Fair Value Inputs, Asset, Par Value

$ 4,400

Fair Value Inputs, Asset, Amortized Cost/Unpaid Principal Balance

4,400

Fair Value Inputs, Asset, Fair Value

$ 4,152

$ 4,151

$ 4,152

Fair Value Measurements, Significant Unobservable Input

Discounted cash flows

^[1]

Discounted cash flows

^[2]

Discounted cash flows

^[3]

Interest rate spread

Fair Value Inputs, Assets, Discount Rate, Minimum

5.41%

^[10]

5.51%

^[11]

6.01%

^[12]

Fair Value Inputs, Assets, Discount Rate, Maximum

6.72%

^[10]

5.96%

^[11]

6.26%

^[12]

Fair Value Inputs, Assets, Discount Rate, Weighted Average

6.57%

^[10]

5.91%

^[11]

6.23%

^[12]

Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Minimum

94.31%

^[7]

94.32%

^[8]

94.34%

^[9]

Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Maximum

94.38%

^[7]

94.34%

^[8]

94.36%

^[9]

Fair Value Inputs, Fair Value As Percentage of Par Value, Weighted Average

94.37%

^[7]

94.34%

^[8]

94.36%

^[9]

Average Yields On Comparable Short-term Taxable Securities, Maximum

3.00%

1.00%

Residential mortgage loans held for sale [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Fair Value Inputs, Asset, Amortized Cost/Unpaid Principal Balance

$ 13,274

$ 10,518

$ 12,431

Fair Value Inputs, Asset, Fair Value

$ 12,563

$ 9,749

$ 11,617

Fair Value Measurements, Significant Unobservable Input

Quoted prices of loans sold in securitization transactions, with a liquidity discount applied

Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.

Liquidity Discount on Mortgage Loans Qualifying for Sale to US Govt Agencies

94.64%

92.69%

93.45%

[1]	Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume
[2]	Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume
[3]	Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume
[4]	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 360 to 446 basis points over average yields for comparable tax-exempt securities.
[5]	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 474 to 513 basis points over average yields for comparable tax-exempt securities.
[6]	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 467 to 525 basis points over average yields for comparable tax-exempt securities.
[7]	Represents fair value as a percentage of par value.
[8]	Represents fair value as a percentage of par value.
[9]	Represents fair value as a percentage of par value.
[10]	Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 3 percent.
[11]	Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 1 percent.
[12]	Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 1 percent.

Fair Value Measurements, Fair Value Measured On a Nonrecurring Basis (Details) - Fair Value, Measurements, Nonrecurring [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross charge-offs against allowance for loan losses	$ 232	$ 7,041	$ 676	$ 29,186
Net losses and expenses of repossessed assets, net	0	0	0	0
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	0	0
Net losses and expenses of repossessed assets, net	772	751	906	1,068
Fair Value, Inputs, Level 1 [Member] \| Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	0	0	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]
Carrying Value	0	0	0	0
Fair Value, Inputs, Level 2 [Member] \| Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	464	634	464	634
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]
Carrying Value	3,488	5,709	3,488	5,709
Fair Value, Inputs, Level 3 [Member] \| Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	3,570	42,342	3,570	42,342
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]
Carrying Value	$ 530	$ 1,693	$ 530	$ 1,693

Fair Value Measurements Fair Value Measurement, Measured On Non-Recurring Basis, Signfiicant Unobservable Inputs, Quantitative Information (Details) - Fair Value, Measurements, Nonrecurring [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($)
$ in Thousands

3 Months Ended

Jun. 30, 2017

Jun. 30, 2016

Impaired Loans [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Carrying Value

$ 3,570

$ 42,342

Fair Value Measurements, Significant Unobservable Input

Discounted cash flows

Recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs

Fair Value of Impaired Loans as a Percentage of Unpaid Principal Balance [Abstract]

Fair Value Measurements, Fair Value of Impaired Loans as a Percentage of Unpaid Principal Balance, Minimum

^[1]

75.00%

25.00%

Fair Value Measurements, Fair Value of Impaired Loans as a Percentage of Unpaid Principal Balance, Maximum

^[1]

90.00%

71.00%

Fair Value of Impaired Loans as a Percentage of Unpaid Principal Balance, Weighted Average

^[1]

83.00%

58.00%

Real estate and other repossessed assets [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Carrying Value

$ 530

$ 1,693