Document And Entity Information - USD ($)	9 Months Ended
Document And Entity Information - USD ($)	Sep. 30, 2018	Jun. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	BOK FINANCIAL CORP ET AL
Entity Central Index Key	0000875357
Current Fiscal Year End Date	--12-31
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float		$ 2,441,480,672
Entity Common Stock, Shares Outstanding	65,434,258
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018

Consolidated Statements of Earnings (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest revenue [Abstract]
Loans	$ 218,732	$ 184,200	$ 617,517	$ 514,047
Residential mortgage loans held for sale	2,151	2,095	6,328	6,317
Trading securities	17,295	3,975	38,021	12,497
Investment securities	3,598	3,951	11,118	12,127
Available for sale securities	48,917	44,925	142,303	131,660
Fair value option securities	3,881	5,066	12,627	10,985
Restricted equity securities	5,232	4,826	15,757	13,534
Interest-bearing cash and cash equivalents	3,441	6,375	19,163	15,817
Total interest revenue	303,247	255,413	862,834	716,984
Interest expense [Abstract]
Deposits	24,535	14,530	63,717	38,506
Borrowed funds	35,804	20,361	93,860	47,542
Subordinated debentures	2,025	2,070	6,076	6,098
Total interest expense	62,364	36,961	163,653	92,146
Net interest revenue	240,883	218,452	699,181	624,838
Provision for credit losses	4,000	0	(1,000)	0
Net interest revenue after provision for credit losses	236,883	218,452	700,181	624,838
Total fees and commissions	167,510	173,451	484,349	515,287
Other gains, net	1,441	(1,283)	4,760	8,452
Gain (loss) on derivatives, net	(2,847)	1,033	(11,589)	3,824
Gain (loss) on fair value option securities, net	(4,385)	661	(25,290)	1,505
Change in fair value of mortgage servicing rights	5,972	(639)	28,901	(5,726)
Gain (loss) on available for sale securities, net	250	2,487	(802)	4,916
Total other operating revenue	167,941	175,710	480,329	528,258
Other operating expense [Abstract]
Personnel	143,531	147,910	422,425	428,079
Business promotion	7,620	7,105	21,316	21,560
Professional fees and services	13,209	11,887	38,387	35,723
Net occupancy and equipment	23,394	21,325	70,201	64,074
Insurance	6,232	6,005	19,070	13,098
Data processing and communications	31,665	37,327	87,221	108,559
Printing, postage and supplies	3,837	3,917	11,937	11,908
Net losses and operating expenses of repossessed assets	4,044	6,071	14,471	9,347
Amortization of intangible assets	1,603	1,744	4,289	5,349
Mortgage banking costs	11,741	13,450	34,780	38,525
Other expense	5,741	9,193	19,426	25,308
Total other operating expense	252,617	265,934	743,523	761,530
Net income before taxes	152,207	128,228	436,987	391,566
Federal and state income taxes	34,662	42,438	98,940	128,246
Net income	117,545	85,790	338,047	263,320
Net income attributable to non-controlling interests	289	141	857	1,168
Net income attributable to BOK Financial Corporation shareholders	$ 117,256	$ 85,649	$ 337,190	$ 262,152
Earnings per share: [Abstract]
Basic	$ 1.79	$ 1.31	$ 5.15	$ 4.01
Diluted	$ 1.79	$ 1.31	$ 5.15	$ 4.00
Average shares used in computation: [Abstract]
Basic	64,901,095	64,742,822	64,883,319	64,729,391
Diluted	64,934,351	64,805,172	64,919,728	64,793,893
Dividends declared per share	$ 0.50	$ 0.44	$ 1.40	$ 1.32
Brokerage and trading revenue [Member]
Total fees and commissions	$ 23,086	$ 33,169	$ 80,222	$ 98,556
Transaction card revenue [Member]
Total fees and commissions	21,396	32,844	63,361	90,452
Fiduciary and asset management revenue [Member]
Total fees and commissions	57,514	40,687	141,045	121,126
Deposit service charges and fees [Member]
Total fees and commissions	27,765	28,191	82,753	84,390
Mortgage banking revenue [Member]
Total fees and commissions	23,536	24,890	75,907	80,357
Other revenue [Member]
Total fees and commissions	$ 14,213	$ 13,670	$ 41,061	$ 40,406

Consolidated Statements of Comprehensive Income - USD ($)
$ in Thousands

3 Months Ended

9 Months Ended

Sep. 30, 2018

Sep. 30, 2017

Sep. 30, 2018

Sep. 30, 2017

Statement of Comprehensive Income [Abstract]

Net income

$ 117,545

$ 85,790

$ 338,047

$ 263,320

Other comprehensive income (loss) before income taxes:

Net change in unrealized gain (loss)

(35,941)

512

(166,464)

33,881

Reclassification adjustments included in earnings:

Loss (gain) on available for sale securities, net

(250)

(2,487)

802

(4,916)

Other comprehensive income (loss) before income taxes

(36,191)

(1,975)

(165,662)

28,965

Federal and state income taxes

(9,134)

(768)

(42,183)

^[1]

11,241

^[2]

Other comprehensive income (loss), net of income taxes

(27,057)

(1,207)

(123,479)

17,724

Comprehensive income

90,488

84,583

214,568

281,044

Comprehensive income attributable to non-controlling interests

289

141

857

1,168

Comprehensive income attributable to BOK Financial Corp. shareholders

$ 90,199

$ 84,442

$ 213,711

$ 279,876

[1]	Calculated using a 25 percent blended federal and state statutory tax rate.
[2]	Calculated using a 39 percent blended federal and state statutory tax rate.

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Assets [Abstract]
Cash and due from banks	$ 815,458	$ 602,510	$ 547,203
Interest-bearing cash and cash equivalents	430,789	1,714,544	1,926,779
Trading securities	1,613,400	462,676	614,117
Investment securities	374,039	461,793	466,562
Available for sale securities	8,072,014	8,321,578	8,383,199
Fair value option securities	452,150	755,054	819,531
Restricted equity securities	311,189	320,189	347,542
Residential mortgage loans held for sale	175,866	221,378	275,643
Loans	18,349,459	17,153,424	17,206,834
Allowance for loan losses	(210,569)	(230,682)	(247,703)
Loans, net of allowance	18,138,890	16,922,742	16,959,131
Premises and equipment, net	327,129	317,335	320,060
Receivables	277,738	178,800	173,990
Goodwill	447,430	447,430	446,697
Intangible assets, net	33,370	28,658	39,013
Mortgage servicing rights	284,673	252,867	245,858
Real estate and other repossessed assets, net of allowance	24,515	28,437	32,535
Derivative contracts, net	349,481	220,502	352,559
Cash surrender value of bank-owned life insurance	323,628	316,498	314,201
Receivable on unsettled securities sales	421,313	340,077	370,486
Other assets	416,792	359,092	370,409
Total assets	33,289,864	32,272,160	33,005,515
Deposits [Abstract]
Noninterest-bearing demand deposits	9,063,623	9,243,338	9,185,481
Interest-bearing deposits: [Abstract]
Transaction	9,990,219	10,250,393	10,025,084
Savings	502,601	469,158	465,225
Time	2,075,846	2,098,416	2,172,289
Total deposits	21,632,289	22,061,305	21,848,079
Funds purchased and repurchase agreements	790,741	574,964	390,545
Other borrowings	6,025,483	5,134,897	6,241,275
Subordinated debentures	144,707	144,677	144,668
Accrued interest, taxes and expense	231,592	164,895	152,029
Derivative contracts, net	252,387	171,963	336,327
Due on unsettled securities purchases	414,283	338,745	176,498
Other liabilities	172,622	162,380	201,655
Total liabilities	29,664,104	28,753,826	29,491,076
Shareholders' equity: [Abstract]
Common stock	4	4	4
Capital surplus	1,044,430	1,035,895	1,028,489
Retained earnings	3,297,083	3,048,487	2,999,005
Treasury stock	(564,123)	(552,845)	(545,441)
Accumulated other comprehensive gain (loss)	(162,362)	(36,174)	6,757
Total shareholders’ equity	3,615,032	3,495,367	3,488,814
Non-controlling interests	10,728	22,967	25,625
Total equity	3,625,760	3,518,334	3,514,439
Total liabilities and equity	$ 33,289,864	$ 32,272,160	$ 33,005,515

Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Investment securities [Abstract]
Investment Securities, fair value	$ 382,893	$ 480,035	$ 489,895
Allowance for real estate and other repossessed assets	$ 19,794	$ 12,648	$ 11,738
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)	75,308,727	75,147,686	75,129,535
Common stock, shares outstanding (in shares)	75,308,727	75,147,686	75,129,535
Treasury stock, shares at cost (in shares)	9,874,469	9,752,749	9,672,749

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, 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	263,320			262,152			262,152	1,168
Other comprehensive income (loss)	17,724					17,724	17,724
Stock options exercised (in shares)		80
Stock options exercised	4,564		4,564				4,564
Non-vested shares awarded, net (in shares)		57
Vesting of non-vested shares (in shares)					17
Vesting of non-vested shares	(1,389)				$ (1,389)		(1,389)
Share-based compensation	17,390		17,390				17,390
Cash dividends on common stock	(86,481)			(86,481)			(86,481)
Capital calls and distributions, net	(7,046)							(7,046)
Balance, end of period (in shares) at Sep. 30, 2017		75,130			9,673
Balance, end of period at Sep. 30, 2017	3,514,439	$ 4	1,028,489	2,999,005	$ (545,441)	6,757	3,488,814	25,625
Transition adjustment for unrealized gains and losses on equity securities	(2,709)			2,709		(2,709)
Balance, beginning of period, adjusted	3,518,334	$ 4	1,035,895	3,051,196	$ (552,845)	(38,883)	3,495,367	22,967
Balance, beginning of period (in shares) at Dec. 31, 2017		75,148			9,753
Balance, beginning of period at Dec. 31, 2017	3,518,334	$ 4	1,035,895	3,048,487	$ (552,845)	(36,174)	3,495,367	22,967
Net income	338,047			337,190			337,190	857
Other comprehensive income (loss)	(123,479)					(123,479)	(123,479)
Repurchase of common stock (in shares)					90
Repurchase of common stock	(8,408)				$ (8,408)		(8,408)
Stock options exercised (in shares)		49
Stock options exercised	2,560		2,560				2,560
Non-vested shares awarded, net (in shares)		112
Vesting of non-vested shares (in shares)					31
Vesting of non-vested shares	(2,870)				$ (2,870)		(2,870)
Share-based compensation	5,975		5,975				5,975
Cash dividends on common stock	(91,303)			(91,303)			(91,303)
Sale of non-controlling interests	(10,000)							(10,000)
Capital calls and distributions, net	(3,096)							(3,096)
Balance, end of period (in shares) at Sep. 30, 2018		75,309			9,874
Balance, end of period at Sep. 30, 2018	$ 3,625,760	$ 4	$ 1,044,430	$ 3,297,083	$ (564,123)	$ (162,362)	$ 3,615,032	$ 10,728

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash Flows From Operating Activities: [Abstract]
Net income	$ 338,047	$ 263,320
Adjustments to reconcile net income to net cash used in operating activities:
Provision for credit losses	(1,000)	0
Change in fair value of mortgage servicing rights due to market changes	(28,901)	5,726
Change in the fair value of mortgage servicing rights due to principal payments	25,783	24,928
Net unrealized losses (gains) from derivative contracts	3,309	(3,937)
Share-based compensation	5,975	17,390
Depreciation and amortization	41,999	39,154
Net amortization of securities discounts and premiums	19,001	22,149
Net losses (gains) on financial instruments and other losses (gains), net	5,581	(1,930)
Net gain on mortgage loans held for sale	(26,242)	(35,778)
Mortgage loans originated for sale	(2,093,860)	(2,446,793)
Proceeds from sale of mortgage loans held for sale	2,165,989	2,503,759
Capitalized mortgage servicing rights	(28,688)	(29,439)
Change in trading and fair value option securities	(848,409)	(1,019,906)
Change in receivables	(249,347)	459,480
Change in other assets	(15,157)	(18,991)
Change in accrued interest, taxes and expense	66,697	(99)
Change in other liabilities	229,815	43,767
Net cash used in operating activities	(389,408)	(177,200)
Cash Flows From Investing Activities: [Abstract]
Proceeds from maturities or redemptions of investment securities	89,099	94,243
Proceeds from maturities or redemptions of available for sale securities	1,208,373	1,345,575
Purchases of investment securities	(4,218)	(18,802)
Payments to Acquire Debt Securities, Available-for-sale	1,404,291	2,001,160
Proceeds from sales of available for sale securities	232,826	966,044
Change in amount receivable on unsettled available for sale securities transactions	67,775	(223,037)
Loans originated, net of principal collected	(1,187,762)	(156,404)
Net payments on derivative asset contracts	(39,485)	334,709
Acquisitions, net of cash acquired	(13,870)	0
Proceeds from disposition of assets	265,786	162,793
Purchases of assets	(250,447)	(170,937)
Net cash provided by (used in) investing activities	(1,036,214)	333,024
Cash Flows From Financing Activities: [Abstract]
Net change in demand deposits, transaction deposits and savings accounts	(406,446)	(850,505)
Net change in time deposits	(22,570)	(49,511)
Net change in other borrowed funds	1,035,549	957,859
Net proceeds on derivative liability contracts	42,883	(339,566)
Net change in derivative margin accounts	(46,390)	(8,583)
Change in amount due on unsettled available for sale securities transactions	(148,190)	154,273
Issuance of common and treasury stock, net	(310)	3,175
Repurchase of common stock	(8,408)	0
Dividends paid	(91,303)	(86,481)
Net cash provided by (used in) financing activities	354,815	(219,339)
Net decrease in cash and cash equivalents	(1,070,807)	(63,515)
Cash and cash equivalents at beginning of period	2,317,054	2,537,497
Cash and cash equivalents at end of period	1,246,247	2,473,982
Supplemental Cash Flow Information: [Abstract]
Cash paid for interest	163,381	89,901
Cash paid for taxes	77,373	95,967
Net loans and bank premises transferred to repossessed real estate and other assets	9,513	4,649
Residential mortgage loans guaranteed by U.S. government agencies that became eligible for repurchase during the period	70,814	101,299
Conveyance of other real estate owned guaranteed by U.S. government agencies	$ 32,206	$ 32,033

Significant Accounting Policies	9 Months Ended
Significant Accounting Policies	Sep. 30, 2018
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 2017 Form 10-K filed with the Securities and Exchange Commission, which contains audited financial statements. Amounts presented as of December 31, 2017 have been derived from the audited financial statements included in BOK Financial’s 2017 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 nine-month period ended September 30, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018. 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. Revenue from financial assets and liabilities is explicitly excluded from the scope of ASU 2014-09. Management adopted the standard in the first quarter of 2018 using the modified retrospective transition method. There were no significant cumulative effect adjustments as a result of implementation as of January 1, 2018 as our current revenue recognition policies generally conform with the principals in ASU 2014-09. 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. Management adopted the standard in the first quarter of 2018. Interchange fees paid to issuing banks for card transactions processed related to its merchant processing services previously included in data processing and communication expense are now netted against the amounts charged to the merchant in transaction card processing revenue. 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. Management adopted the standard in the first quarter of 2018. Upon adoption, net unrealized gains of $2.7 million from equity securities were reclassified from other comprehensive income to retained earnings. 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. As originally issued, ASU 2016-02 required implementation through the modified transition method applied as of the earliest period presented in the financial statements. In 2018 an additional and optional transition method that allows entities to apply the standard as of the adoption date was approved. BOKF intends to elect this optional transition method. BOKF also plans to elect all practical expedients other than the lessee’s practical expedient to combine lease and non-lease components which would further gross up the lease liability and related right of use asset. The Company currently estimates that implementation of ASU 2016-02 will increase reported right of use assets and liabilities by approximately $100 million to $150 million. 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 has established a CECL implementation team in order to evaluate the impact the adoption of ASU 2016-13 will have on the Company's financial statements. The CECL implementation team, overseen by the Chief Credit Officer, Chief Financial Officer, and Chief Risk Officer, has developed a project plan that incorporates input from various departments within the bank including Credit, Financial Reporting, Risk, and Information Technology among others. Key implementation activities for 2018 include portfolio segmentation, credit risk driver identification, model development, as well as process and information systems enhancements. The Company will adopt the standard on January 1, 2020. 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. Management adopted the standard in first quarter of 2018. Adoption of ASU 2016-15 did not have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities ("ASU 2017-12") On August 28, 2017, the FASB issued ASU 2017-12, which amends the hedge accounting recognition and presentation requirements in ASC 815 in order to improve transparency and understandability of information and reduce the complexity. The update expands the types of transactions eligible for hedge accounting, eliminates the requirement to separately measure and present hedge ineffectiveness, simplifies hedge effectiveness assessments and updates documentation and presentation requirements. The update allows the reclassification of certain debt securities from held to maturity to available for sale if the debt security is eligible to be hedged under the last-of-layer method. ASU 2017-12 is effective for the Company for fiscal years beginning after December 15, 2018, and interim periods therein; however, early adoption is permitted. Adoption of ASU 2017-12 is not expected to have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2018-05, Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 (SAB 118). On March 13, 2018, the FASB issued ASU 2018-05, which adds SEC guidance related to SAB 118 - Income Tax Accounting Implications of the Tax Cuts and Jobs Act. ASU 2018-05 was effective upon issuance. The adoption of ASU 2018-05 has not had a significant impact in 2018. FASB Accounting Standards Update No. 2018-15, Intangibles - Goodwill and Other Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract ("ASU 2018-15") On August 29, 2018, the FASB issued ASU 2018-15, which requires a customer in a cloud hosting arrangement that is a service contract to follow the internal use software requirements in ASC 350-40 to determine which implementation costs to capitalize or expense as incurred. Internal use software guidance requires the capitalization of costs incurred during the development phase. Capitalized costs will be amortized over the term of the hosting arrangement beginning when the arrangement is ready for its intended use. ASU 2018-15 is effective for the Company for fiscal years beginning after December 15, 2019; however, early adoption is permitted. The Company elected to early adopt the update prospectively in third quarter of 2018. The adoption of ASU 2018-15 did not have a significant impact in the third quarter.

Securities

9 Months Ended

Sep. 30, 2018

Marketable Securities [Abstract]

Securities [Text Block]

Securities

Trading Securities

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



	September 30, 2018					December 31, 2017					September 30, 2017
	Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)
U.S. government agency debentures	$	80,692	$	21		$	21,196	$	8		$	30,162	$	(101	)
U.S. government agency residential mortgage-backed securities	1,378,450		(3,498		)	392,673		(517		)	516,760		723
Municipal and other tax-exempt securities	41,345		(161		)	13,559		83			56,148		153
Asset-backed securities	72,309		(100		)	23,885		(26		)	—		—
Other trading securities	40,604		5			11,363		4			11,047		23
Total trading securities	$	1,613,400	$	(3,733	)	$	462,676	$	(448	)	$	614,117	$	798

Investment Securities

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



	September 30, 2018
	Amortized		Fair		Gross Unrealized
	Cost		Value		Gain		Loss
Municipal and other tax-exempt	$	157,723	$	158,230	$	1,403	$	(896	)
U.S. government agency residential mortgage-backed securities	13,234		13,201		205		(238		)
Other debt securities	203,082		211,462		10,721		(2,341		)
Total investment securities	$	374,039	$	382,893	$	12,329	$	(3,475	)



	December 31, 2017
	Amortized		Fair		Gross Unrealized
	Cost		Value		Gain		Loss
Municipal and other tax-exempt	$	228,186	$	230,349	$	2,967	$	(804	)
U.S. government agency residential mortgage-backed securities	15,891		16,242		446		(95		)
Other debt securities	217,716		233,444		17,095		(1,367		)
Total investment securities	$	461,793	$	480,035	$	20,508	$	(2,266	)



	September 30, 2017
	Amortized		Fair		Gross Unrealized
	Cost		Value		Gain		Loss
Municipal and other tax-exempt	$	246,000	$	249,250	$	3,415	$	(165	)
U.S. government agency residential mortgage-backed securities	16,926		17,458		594		(62		)
Other debt securities	203,636		223,187		20,141		(590		)
Total investment securities	$	466,562	$	489,895	$	24,150	$	(817	)

The amortized cost and fair values of investment securities at September 30, 2018, 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	$	65,789		$	41,827		$	35,652		$	14,455		$	157,723		4.13
Fair value	65,633			41,432			36,677			14,488			158,230
Nominal yield¹	2.06		%	2.82		%	6.00		%	4.33		%	3.36		%
Other debt securities:
Amortized cost	14,847			60,825			115,587			11,823			203,082			7.23
Fair value	14,941			62,604			123,236			10,681			211,462
Nominal yield	4.17		%	4.70		%	5.76		%	4.34		%	5.25		%
Total fixed maturity securities:
Amortized cost	$	80,636		$	102,652		$	151,239		$	26,278		$	360,805		5.88
Fair value	80,574			104,036			159,913			25,169			369,692
Nominal yield	2.44		%	3.94		%	5.82		%	4.33		%	4.42		%
Residential mortgage-backed securities:
Amortized cost													$	13,234		³
Fair value													13,201
Nominal yield⁴													2.77		%
Total investment securities:
Amortized cost													$	374,039
Fair value													382,893
Nominal yield													4.36		%


¹	Calculated on a taxable equivalent basis using a 25 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 5.2 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):



	September 30, 2018
	Amortized		Fair		Gross Unrealized
	Cost		Value		Gain		Loss			OTTI
U.S. Treasury	$	495	$	490	$	—	$	(5	)	$	—
Municipal and other tax-exempt	4,269		4,349		81		(1		)	—
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	3,057,570		2,959,457		1,653		(99,766		)	—
FHLMC	1,562,569		1,512,928		501		(50,142		)	—
GNMA	677,496		659,967		450		(17,979		)	—
Total U.S. government agencies	5,297,635		5,132,352		2,604		(167,887		)	—
Private issue	54,932		74,685		19,753		—			—
Total residential mortgage-backed securities	5,352,567		5,207,037		22,357		(167,887		)	—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,905,974		2,834,691		1,363		(72,646		)	—
Other debt securities	25,502		25,447		11		(66		)	—
Total available for sale securities	$	8,288,807	$	8,072,014	$	23,812	$	(240,605	)	$	—



	December 31, 2017
	Amortized		Fair		Gross Unrealized
	Cost		Value		Gain		Loss			OTTI
U.S. Treasury	$	1,000	$	1,000	$	—	$	—		$	—
Municipal and other tax-exempt	27,182		27,080		181		(283		)	—
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	3,021,551		2,997,563		11,549		(35,537		)	—
FHLMC	1,545,971		1,531,009		3,148		(18,110		)	—
GNMA	787,626		780,580		1,607		(8,653		)	—
Total U.S. government agencies	5,355,148		5,309,152		16,304		(62,300		)	—
Private issue	74,311		93,221		19,301		—			(391		)
Total residential mortgage-backed securities	5,429,459		5,402,373		35,605		(62,300		)	(391		)
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,858,885		2,834,961		1,963		(25,887		)	—
Other debt securities	25,500		25,481		50		(69		)	—
Perpetual preferred stock	12,562		15,767		3,205		—			—
Equity securities and mutual funds	14,487		14,916		515		(86		)	—
Total available for sale securities	$	8,369,075	$	8,321,578	$	41,519	$	(88,625	)	$	(391	)



	September 30, 2017
	Amortized		Fair		Gross Unrealized
	Cost		Value		Gain		Loss			OTTI
U.S. Treasury	$	1,000	$	999	$	—	$	(1	)	$	—
Municipal and other tax-exempt	28,411		28,368		240		(283		)	—
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	3,103,869		3,108,822		25,510		(20,557		)	—
FHLMC	1,331,212		1,330,159		6,630		(7,683		)	—
GNMA	864,256		862,394		3,254		(5,116		)	—
Other	25,000		25,009		51		(42		)	—
Total U.S. government agencies	5,324,337		5,326,384		35,445		(33,398		)	—
Private issue	80,797		99,994		19,197		—			—
Total residential mortgage-backed securities	5,405,134		5,426,378		54,642		(33,398		)	—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,899,828		2,889,346		5,577		(16,059		)	—
Other debt securities	4,400		4,153		—		(247		)	—
Perpetual preferred stock	12,562		16,245		3,683		—			—
Equity securities and mutual funds	17,803		17,710		655		(748		)	—
Total available for sale securities	$	8,369,138	$	8,383,199	$	64,797	$	(50,736	)	$	—

The amortized cost and fair values of available for sale securities at September 30, 2018, 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 Maturity⁴
U.S. Treasuries:
Amortized cost	$	—		$	495		$	—		$	—			$	495		1.34
Fair value	—			490			—			—				490
Nominal yield	—		%	1.99		%	—		%	—		%		1.99		%
Municipal and other tax-exempt:
Amortized cost	$	—		$	—		$	—		$	4,269			$	4,269		18.72
Fair value	—			—			—			4,349				4,349
Nominal yield¹	—		%	—		%	—		%	5.60		%	⁵	5.60		%
Commercial mortgage-backed securities:
Amortized cost	$	74,694		$	1,070,820		$	1,449,084		$	311,376			$	2,905,974		7.11
Fair value	73,929			1,043,429			1,413,692			303,641				2,834,691
Nominal yield	1.70		%	2.02		%	2.24		%	2.45		%		2.17		%
Other debt securities:
Amortized cost	$	—		$	—		$	—		$	25,502			$	25,502		13.93
Fair value	—			—			—			25,447				25,447
Nominal yield	—		%	—		%	—		%	1.59		%	⁵	1.59		%
Total fixed maturity securities:
Amortized cost	$	74,694		$	1,071,315		$	1,449,084		$	341,147			$	2,936,240		7.18
Fair value	73,929			1,043,919			1,413,692			333,437				2,864,977
Nominal yield	1.70		%	2.02		%	2.24		%	2.42		%		2.17		%
Residential mortgage-backed securities:
Amortized cost														$	5,352,567		²
Fair value														5,207,037
Nominal yield³														2.24		%
Total available-for-sale securities:
Amortized cost														$	8,288,807
Fair value														8,072,014
Nominal yield														2.21		%


¹	Calculated on a taxable equivalent basis using a 25 percent effective tax rate.


²	The average expected lives of mortgage-backed securities were 4.4 years based upon current prepayment assumptions.


³	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.


⁴	Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty.


⁵	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 September 30,					Nine Months Ended September 30,
	2018		2017			2018			2017
Proceeds	$	45,293	$	265,632		$	232,826		$	966,044
Gross realized gains	250		2,768			700			7,623
Gross realized losses	—		(281		)	(1,502		)	(2,707		)
Related federal and state income tax expense (benefit)	64		967			(204		)	1,912

The fair value of debt securities pledged as collateral for repurchase agreements, public trust funds on deposit and for other purposes, as required by law was $8.0 billion at September 30, 2018, $7.3 billion at December 31, 2017 and $7.0 billion at September 30, 2017.

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

Temporarily Impaired Securities as of September 30, 2018

(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	85	$	46,618	$	277	$	54,149	$	619	$	100,767	$	896
U.S. government agency residential mortgage-backed securities	3	6,682		96		2,625		142		9,307		238
Other debt securities	93	38,441		2,035		4,714		306		43,155		2,341
Total investment securities	181	$	91,741	$	2,408	$	61,488	$	1,067	$	153,229	$	3,475



	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	$	490	$	5	$	—	$	—	$	490	$	5
Municipal and other tax-exempt	2	1,046		1		—		—		1,046		1
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	188	1,584,010		32,919		1,277,814		66,847		2,861,824		99,766
FHLMC	99	702,707		15,450		781,589		34,692		1,484,296		50,142
GNMA	38	285,731		5,326		253,506		12,653		539,237		17,979
Total U.S. government agencies	325	2,572,448		53,695		2,312,909		114,192		4,885,357		167,887
Private issue¹	—	—		—		—		—		—		—
Total residential mortgage-backed securities	325	2,572,448		53,695		2,312,909		114,192		4,885,357		167,887
Commercial mortgage-backed securities guaranteed by U.S. government agencies	220	1,174,544		24,982		1,238,848		47,664		2,413,392		72,646
Other debt securities	2	—		—		20,435		66		20,435		66
Total available for sale securities	550	$	3,748,528	$	78,683	$	3,572,192	$	161,922	$	7,320,720	$	240,605


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 December 31, 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	100	$	145,960	$	643	$	5,833	$	161	$	151,793	$	804
U.S. government agency residential mortgage-backed securities	1	—		—		3,356		95		3,356		95
Other debt securities	49	20,091		1,238		3,076		129		23,167		1,367
Total investment securities	150	$	166,051	$	1,881	$	12,265	$	385	$	178,316	$	2,266



	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-exempt	19	12,765		18		4,802		265		17,567		283
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	113	1,203,041		9,618		824,029		25,919		2,027,070		35,537
FHLMC	69	863,778		7,297		385,816		10,813		1,249,594		18,110
GNMA	27	201,887		1,452		248,742		7,201		450,629		8,653
Total U.S. government agencies	209	2,268,706		18,367		1,458,587		43,933		3,727,293		62,300
Private issue¹	8	5,898		391		—		—		5,898		391
Total residential mortgage-backed securities	217	2,274,604		18,758		1,458,587		43,933		3,733,191		62,691
Commercial mortgage-backed securities guaranteed by U.S. government agencies	185	1,465,703		11,824		652,296		14,063		2,117,999		25,887
Other debt securities	2	19,959		41		472		28		20,431		69
Perpetual preferred stocks	—	—		—		—		—		—		—
Equity securities and mutual funds	111	911		7		2,203		79		3,114		86
Total available for sale securities	534	$	3,773,942	$	30,648	$	2,118,360	$	58,368	$	5,892,302	$	89,016


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 September 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	63	$	80,235	$	70	$	9,795	$	95	$	90,030	$	165
U.S. government agency residential mortgage-backed securities	1	3,578		62		—		—		3,578		62
Other debt securities	28	10,022		566		427		24		10,449		590
Total investment securities	92	$	93,835	$	698	$	10,222	$	119	$	104,057	$	817



	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	11	576		1		4,785		282		5,361		283
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	81	1,054,171		10,288		480,994		10,269		1,535,165		20,557
FHLMC	42	477,823		3,546		198,478		4,137		676,301		7,683
GNMA	17	166,565		1,718		124,037		3,398		290,602		5,116
Other	1	19,958		42		—		—		19,958		42
Total U.S. government agencies	141	1,718,517		15,594		803,509		17,804		2,522,026		33,398
Private issue¹	—	—		—		—		—		—		—
Total residential mortgage-backed securities	141	1,718,517		15,594		803,509		17,804		2,522,026		33,398
Commercial mortgage-backed securities guaranteed by U.S. government agencies	137	1,154,911		7,194		559,984		8,865		1,714,895		16,059
Other debt securities	2	—		—		4,153		247		4,153		247
Perpetual preferred stocks	—	—		—		—		—		—		—
Equity securities and mutual funds	91	3,672		696		1,428		52		5,100		748
Total available for sale securities	383	$	2,878,675	$	23,486	$	1,373,859	$	27,250	$	4,252,534	$	50,736


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

Based on evaluations of impaired securities as of September 30, 2018, the Company does not intend to sell any impaired available for sale debt 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 securities 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):



	September 30, 2018					December 31, 2017					September 30, 2017
	Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)
U.S. government agency residential mortgage-backed securities	$	452,150	$	(7,923	)	$	755,054	$	(1,877	)	$	819,531	$	1,671

Derivatives

9 Months Ended

Sep. 30, 2018

Derivative Instrument Detail [Abstract]

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. Deterioration in the credit rating of customer or other counterparties reduced the fair value of asset contracts. Deterioration of our credit rating could decrease the fair value of our derivative liabilities.

When bilateral netting agreements or similar 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 to mitigate the market risk of holding trading securities. Changes in the fair value of derivative instruments used in managing interest rate sensitivity and as part of the economic hedge of changes in the fair value of mortgage servicing rights are included in Other operating revenue – Gain (loss) on derivatives, net in the Consolidated Statements of Earnings. Changes in the fair value of derivative instruments used to mitigate the market risk of holding trading securities are included in Other operating revenue – Brokerage and trading revenue.

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 September 30, 2018 (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	$	12,423,155	$	45,983	$	(18,338	)	$	27,645	$	—		$	27,645
Interest rate swaps	1,702,731		46,160		(1,300		)	44,860		(13,307		)	31,553
Energy contracts	1,509,976		202,086		(67,611		)	134,475		(3,020		)	131,455
Agricultural contracts	26,318		1,024		(196		)	828		—			828
Foreign exchange contracts	148,824		146,719		—			146,719		—			146,719
Equity option contracts	89,606		4,144		—			4,144		(660		)	3,484
Total customer risk management programs	15,900,610		446,116		(87,445		)	358,671		(16,987		)	341,684
Internal risk management programs	1,064,113		23,887		(16,090		)	7,797		—			7,797
Total derivative contracts	$	16,964,723	$	470,003	$	(103,535	)	$	366,468	$	(16,987	)	$	349,481

	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	$	12,160,590	$	43,074	$	(18,338	)	$	24,736	$	—		$	24,736
Interest rate swaps	1,702,731		46,162		(1,300		)	44,862		(3,844		)	41,018
Energy contracts	1,485,036		200,290		(67,611		)	132,679		(115,191		)	17,488
Agricultural contracts	26,316		998		(196		)	802		—			802
Foreign exchange contracts	145,943		143,817		—			143,817		(48		)	143,769
Equity option contracts	89,606		4,144		—			4,144		—			4,144
Total customer risk management programs	15,610,222		438,485		(87,445		)	351,040		(119,083		)	231,957
Internal risk management programs	4,079,094		36,520		(16,090		)	20,430		—			20,430
Total derivative contracts	$	19,689,316	$	475,005	$	(103,535	)	$	371,470	$	(119,083	)	$	252,387


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, 2017 (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	$	12,347,542	$	23,606	$	(18,096	)	$	5,510	$	—		$	5,510
Interest rate swaps	1,478,944		28,278		—			28,278		(4,964		)	23,314
Energy contracts	1,190,067		103,044		(47,873		)	55,171		(196		)	54,975
Agricultural contracts	53,238		1,576		(960		)	616		—			616
Foreign exchange contracts	132,397		129,551		—			129,551		(448		)	129,103
Equity option contracts	99,633		5,503		—			5,503		(920		)	4,583
Total customer risk management programs	15,301,821		291,558		(66,929		)	224,629		(6,528		)	218,101
Internal risk management programs	4,736,701		9,494		(7,093		)	2,401		—			2,401
Total derivative contracts	$	20,038,522	$	301,052	$	(74,022	)	$	227,030	$	(6,528	)	$	220,502

	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	$	11,537,742	$	20,367	$	(18,096	)	$	2,271	$	(704	)	$	1,567
Interest rate swaps	1,478,944		28,298		—			28,298		(12,896		)	15,402
Energy contracts	1,166,924		101,603		(47,873		)	53,730		(42,767		)	10,963
Agricultural contracts	48,552		1,551		(960		)	591		—			591
Foreign exchange contracts	126,251		123,321		—			123,321		(53		)	123,268
Equity option contracts	99,633		5,503		—			5,503		—			5,503
Total customer risk management programs	14,458,046		280,643		(66,929		)	213,714		(56,420		)	157,294
Internal risk management programs	5,728,421		21,762		(7,093		)	14,669		—			14,669
Total derivative contracts	$	20,186,467	$	302,405	$	(74,022	)	$	228,383	$	(56,420	)	$	171,963


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 September 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	$	14,244,442	$	38,875	$	(9,547	)	$	29,328	$	—		$	29,328
Interest rate swaps	1,368,210		27,016		—			27,016		(2,820		)	24,196
Energy contracts	983,794		45,368		(35,166		)	10,202		(238		)	9,964
Agricultural contracts	60,745		1,870		(1,172		)	698		—			698
Foreign exchange contracts	252,525		249,788		—			249,788		—			249,788
Equity option contracts	101,841		4,871		—			4,871		(920		)	3,951
Total customer risk management programs	17,011,557		367,788		(45,885		)	321,903		(3,978		)	317,925
Internal risk management programs	11,941,260		34,634		—			34,634		—			34,634
Total derivative contracts	$	28,952,817	$	402,422	$	(45,885	)	$	356,537	$	(3,978	)	$	352,559

	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	$	14,244,442	$	34,948	$	(9,547	)	$	25,401	$	(374	)	$	25,027
Interest rate swaps	1,368,230		27,056		—			27,056		(16,599		)	10,457
Energy contracts	939,350		42,744		(35,166		)	7,578		—			7,578
Agricultural contracts	60,746		1,846		(1,172		)	674		—			674
Foreign exchange contracts	249,269		245,925		—			245,925		(1,395		)	244,530
Equity option contracts	101,841		4,871		—			4,871		—			4,871
Total customer risk management programs	16,963,878		357,390		(45,885		)	311,505		(18,368		)	293,137
Internal risk management programs	9,180,531		43,190		—			43,190		—			43,190
Total derivative contracts	$	26,144,409	$	400,580	$	(45,885	)	$	354,695	$	(18,368	)	$	336,327


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
	September 30, 2018					September 30, 2017
	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	$	7,272	$	—		$	9,181		$	—
Interest rate swaps	618		—			767			—
Energy contracts	541		—			378			—
Agricultural contracts	6		—			38			—
Foreign exchange contracts	78		—			164			—
Equity option contracts	—		—			—			—
Total customer risk management programs	8,515		—			10,528			—
Internal risk management programs	6,124		(2,847		)	(711		)	1,033
Total derivative contracts	$	14,639	$	(2,847	)	$	9,817		$	1,033




	Nine Months Ended
	September 30, 2018					September 30, 2017
	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	$	21,677	$	—		$	26,413	$	—
Interest rate swaps	2,057		—			1,891		—
Energy contracts	5,097		—			4,917		—
Agricultural contracts	36		—			58		—
Foreign exchange contracts	350		—			524		—
Equity option contracts	—		—			—		—
Total customer risk management programs	29,217		—			33,803		—
Internal risk management programs	3,260		(11,589		)	5,307		3,824
Total derivative contracts	$	32,477	$	(11,589	)	$	39,110	$	3,824

Loans and Allowances for Credit Losses

9 Months Ended

Sep. 30, 2018

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.

Occasionally, loans, other than residential mortgage loans, may be held for sale in order to manage credit concentration. These loans are carried at the lower of cost or fair value with gains or losses recognized in other gains (losses), net in the Statements of Earnings.

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. Amortization does not anticipate loan prepayments. Net unamortized fees are recognized in full at time of payoff.

Qualifying residential mortgage loans guaranteed by U.S. government agencies have been sold into GNMA pools. Under certain performance conditions specified in government programs, the Company 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 original principal guarantee remains; 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):



	September 30, 2018								December 31, 2017
	Fixed Rate		Variable Rate		Non-accrual		Total		Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	2,150,138	$	9,316,473	$	109,490	$	11,576,101	$	2,217,432	$	8,379,240	$	137,303	$	10,733,975
Commercial real estate	603,515		3,199,844		1,316		3,804,675		548,692		2,928,440		2,855		3,479,987
Residential mortgage	1,592,249		337,576		41,917		1,971,742		1,608,655		317,584		47,447		1,973,686
Personal	163,067		833,605		269		996,941		154,517		810,990		269		965,776
Total	$	4,508,969	$	13,687,498	$	152,992	$	18,349,459	$	4,529,296	$	12,436,254	$	187,874	$	17,153,424
Accruing loans past due (90 days)¹							$	518							$	633



	September 30, 2017
	Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	2,225,470	$	8,393,564	$	176,900	$	10,795,934
Commercial real estate	564,681		2,950,486		2,975		3,518,142
Residential mortgage	1,589,013		311,231		45,506		1,945,750
Personal	153,750		793,003		255		947,008
Total	$	4,532,914	$	12,448,284	$	225,636	$	17,206,834
Accruing loans past due (90 days)¹							$	253


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

At September 30, 2018, loans to businesses and collateral primarily located in Texas totaled $6.1 billion or 33 percent of the total loan portfolio. Loans to businesses and individuals with collateral primarily located in Oklahoma totaled $3.6 billion or 20 percent of our total loan portfolio. Loans for which the collateral location is not relevant, such as unsecured loans and reserve-based energy loans, are distributed by the borrower's primary operating location. These geographic concentrations subject the loan portfolio to the general economic conditions within these areas.

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 September 30, 2018, commercial loans with collateral primarily located in Texas market totaled $3.8 billion or 33 percent of the commercial loan portfolio segment and commercial loans with collateral primarily located in Oklahoma totaled $2.3 billion or 20 percent of the commercial loan portfolio segment.

The commercial loan portfolio segment is further divided into loan classes. The energy loan class totaled $3.3 billion or 18 percent of total loans at September 30, 2018, including $2.7 billion of outstanding loans to energy producers. Approximately 57 percent of committed production loans are secured by properties primarily producing oil and 43 percent are secured by properties producing natural gas. The services loan class totaled $3.0 billion or 16 percent of total loans at September 30, 2018. 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, educational services, consumer services, financial services and loans to entities providing services for real estate and construction. The healthcare loan class totaled $2.4 billion or 13 percent of total loans at September 30, 2018. 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 September 30, 2018, 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 3 years to ten years, then adjust annually thereafter.

At September 30, 2018, residential mortgage loans included $181 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 $696 million at September 30, 2018. Approximately 61 percent of the home equity loan portfolio is comprised of first lien loans and 39 percent of the home equity portfolio is comprised of junior lien loans. Junior lien loans are distributed 44 percent to amortizing term loans and 56 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 revolving period of 5 years followed by 15 years 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 revolving term of 5 years, 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 September 30, 2018, outstanding commitments totaled $10.7 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 September 30, 2018, outstanding standby letters of credit totaled $672 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 nine months ended September 30, 2018.

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 September 30, 2018 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate		Residential Mortgage			Personal			Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	113,722		$	58,758	$	18,544		$	8,646		$	15,472	$	215,142
Provision for loan losses	(1,285		)	1,391		1			883			3,418		4,408
Loans charged off	(9,602		)	—		(91		)	(1,380		)	—		(11,073		)
Recoveries	1,263			40		229			560			—		2,092
Ending balance	$	104,098		$	60,189	$	18,683		$	8,709		$	18,890	$	210,569
Allowance for off-balance sheet credit losses:
Beginning balance	$	2,361		$	17	$	53		$	2		$	—	$	2,433
Provision for off-balance sheet credit losses	(424		)	19		(3		)	—			—		(408		)
Ending balance	$	1,937		$	36	$	50		$	2		$	—	$	2,025

Total provision for credit losses	$	(1,709	)	$	1,410	$	(2	)	$	883		$	3,418	$	4,000

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 nine months ended September 30, 2018 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance			Total
Allowance for loan losses:
Beginning balance	$	124,269		$	56,621		$	18,451		$	9,124		$	22,217		$	230,682
Provision for loan losses	2,720			248			(418		)	1,486			(3,327		)	709
Loans charged off	(24,940		)	—			(326		)	(3,802		)	—			(29,068		)
Recoveries	2,049			3,320			976			1,901			—			8,246
Ending balance	$	104,098		$	60,189		$	18,683		$	8,709		$	18,890		$	210,569
Allowance for off-balance sheet credit losses:
Beginning balance	$	3,644		$	45		$	43		$	2		$	—		$	3,734
Provision for off-balance sheet credit losses	(1,707		)	(9		)	7			—			—			(1,709		)
Ending balance	$	1,937		$	36		$	50		$	2		$	—		$	2,025

Total provision for credit losses	$	1,013		$	239		$	(411	)	$	1,486		$	(3,327	)	$	(1,000	)

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 three months ended September 30, 2017 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	137,742		$	58,580		$	18,259		$	8,106		$	27,374	$	250,061
Provision for loan losses	2,474			(2,914		)	168			598			704		1,030
Loans charged off	(4,429		)	—			(168		)	(1,228		)	—		(5,825		)
Recoveries	1,014			739			134			550			—		2,437
Ending balance	$	136,801		$	56,405		$	18,393		$	8,026		$	28,078	$	247,703
Allowance for off-balance sheet credit losses:
Beginning balance	$	6,301		$	84		$	38		$	8		$	—	$	6,431
Provision for off-balance sheet credit losses	(976		)	(49		)	1			(6		)	—		(1,030		)
Ending balance	$	5,325		$	35		$	39		$	2		$	—	$	5,401

Total provision for credit losses	$	1,498		$	(2,963	)	$	169		$	592		$	704	$	—

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 nine months ended September 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	665			4,050			82			1,168			(122		)	5,843
Loans charged off	(6,556		)	(76		)	(444		)	(3,774		)	—			(10,850		)
Recoveries	2,479			1,682			531			1,859			—			6,551
Ending balance	$	136,801		$	56,405		$	18,393		$	8,026		$	28,078		$	247,703
Allowance for off-balance sheet credit losses:
Beginning balance	$	11,063		$	123		$	50		$	8		$	—		$	11,244
Provision for off-balance sheet credit losses	(5,738		)	(88		)	(11		)	(6		)	—			(5,843		)
Ending balance	$	5,325		$	35		$	39		$	2		$	—		$	5,401

Total provision for credit losses	$	(5,073	)	$	3,962		$	71		$	1,162		$	(122	)	$	—

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at September 30, 2018 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	$	11,466,611	$	90,301	$	109,490	$	13,797	$	11,576,101	$	104,098
Commercial real estate	3,803,359		60,189		1,316		—		3,804,675		60,189
Residential mortgage	1,929,825		18,683		41,917		—		1,971,742		18,683
Personal	996,672		8,709		269		—		996,941		8,709
Total	18,196,467		177,882		152,992		13,797		18,349,459		191,679

Nonspecific allowance	—		—		—		—		—		18,890

Total	$	18,196,467	$	177,882	$	152,992	$	13,797	$	18,349,459	$	210,569

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 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	$	10,596,672	$	115,438	$	137,303	$	8,831	$	10,733,975	$	124,269
Commercial real estate	3,477,132		56,621		2,855		—		3,479,987		56,621
Residential mortgage	1,926,239		18,451		47,447		—		1,973,686		18,451
Personal	965,507		9,124		269		—		965,776		9,124
Total	16,965,550		199,634		187,874		8,831		17,153,424		208,465

Nonspecific allowance	—		—		—		—		—		22,217

Total	$	16,965,550	$	199,634	$	187,874	$	8,831	$	17,153,424	$	230,682

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at September 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	$	10,619,034	$	123,517	$	176,900	$	13,284	$	10,795,934	$	136,801
Commercial real estate	3,515,167		56,405		2,975		—		3,518,142		56,405
Residential mortgage	1,900,244		18,393		45,506		—		1,945,750		18,393
Personal	946,753		8,026		255		—		947,008		8,026
Total	16,981,198		206,341		225,636		13,284		17,206,834		219,625

Nonspecific allowance	—		—		—		—		—		28,078

Total	$	16,981,198	$	206,341	$	225,636	$	13,284	$	17,206,834	$	247,703

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 September 30, 2018 is as follows (in thousands):



	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	11,549,529	$	103,185	$	26,572	$	913	$	11,576,101	$	104,098
Commercial real estate	3,804,675		60,189		—		—		3,804,675		60,189
Residential mortgage	262,612		3,099		1,709,130		15,584		1,971,742		18,683
Personal	916,587		6,509		80,354		2,200		996,941		8,709
Total	16,533,403		172,982		1,816,056		18,697		18,349,459		191,679

Nonspecific allowance	—		—		—		—		—		18,890

Total	$	16,533,403	$	172,982	$	1,816,056	$	18,697	$	18,349,459	$	210,569

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, 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	$	10,706,035	$	123,383	$	27,940	$	886	$	10,733,975	$	124,269
Commercial real estate	3,479,987		56,621		—		—		3,479,987		56,621
Residential mortgage	234,477		2,947		1,739,209		15,504		1,973,686		18,451
Personal	877,390		6,461		88,386		2,663		965,776		9,124
Total	15,297,889		189,412		1,855,535		19,053		17,153,424		208,465

Nonspecific allowance	—		—		—		—		—		22,217

Total	$	15,297,889	$	189,412	$	1,855,535	$	19,053	$	17,153,424	$	230,682

The allowance for loan losses and recorded investment of the related loans by portfolio segment for risk graded and non-risk graded loans at September 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	$	10,750,657	$	135,846	$	45,277	$	955	$	10,795,934	$	136,801
Commercial real estate	3,518,142		56,405		—		—		3,518,142		56,405
Residential mortgage	226,306		3,068		1,719,444		15,325		1,945,750		18,393
Personal	856,030		6,043		90,978		1,983		947,008		8,026
Total	15,351,135		201,362		1,855,699		18,263		17,206,834		219,625

Nonspecific allowance	—		—		—		—		—		28,078

Total	$	15,351,135	$	201,362	$	1,855,699	$	18,263	$	17,206,834	$	247,703

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 September 30, 2018 by the risk grade categories (in thousands):



	Internally Risk Graded								Non-Graded
	Performing
	Pass		Other Loans Especially Mentioned		Accruing Substandard		Nonaccrual		Performing		Nonaccrual		Total
Commercial:
Energy	$	3,127,227	$	7,233	$	106,374	$	54,033	$	—	$	—	$	3,294,867
Services	2,974,082		27,337		11,795		4,097		—		—		3,017,311
Wholesale/retail	1,636,405		1,508		3,567		9,249		—		—		1,650,729
Manufacturing	631,198		7,265		12,917		9,202		—		—		660,582
Healthcare	2,402,801		2,614		16,204		15,704		—		—		2,437,323
Other commercial and industrial	471,188		385		—		17,144		26,511		61		515,289
Total commercial	11,242,901		46,342		150,857		109,429		26,511		61		11,576,101

Commercial real estate:
Residential construction and land development	99,694		1,828		—		350		—		—		101,872
Retail	737,313		—		21,333		777		—		—		759,423
Office	817,854		6,975		—		—		—		—		824,829
Multifamily	1,120,145		—		21		—		—		—		1,120,166
Industrial	695,554		—		1,220		—		—		—		696,774
Other commercial real estate	300,887		535		—		189		—		—		301,611
Total commercial real estate	3,771,447		9,338		22,574		1,316		—		—		3,804,675

Residential mortgage:
Permanent mortgage	259,106		—		2,520		986		810,445		21,869		1,094,926
Permanent mortgages guaranteed by U.S. government agencies	—		—		—		—		172,928		7,790		180,718
Home equity	—		—		—		—		684,826		11,272		696,098
Total residential mortgage	259,106		—		2,520		986		1,668,199		40,931		1,971,742

Personal	916,430		47		34		76		80,161		193		996,941

Total	$	16,189,884	$	55,727	$	175,985	$	111,807	$	1,774,871	$	41,185	$	18,349,459

The following table summarizes the Company’s loan portfolio at December 31, 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	$	2,632,986	$	60,288	$	144,598	$	92,284	$	—	$	—	$	2,930,156
Services	2,943,869		13,927		26,533		2,620		—		—		2,986,949
Wholesale/retail	1,443,917		19,263		5,502		2,574		—		—		1,471,256
Manufacturing	472,869		6,653		11,290		5,962		—		—		496,774
Healthcare	2,253,497		3,186		43,305		14,765		—		—		2,314,753
Other commercial and industrial	478,951		7		8,161		19,028		27,870		70		534,087
Total commercial	10,226,089		103,324		239,389		137,233		27,870		70		10,733,975

Commercial real estate:
Residential construction and land development	113,190		1,828		395		1,832		—		—		117,245
Retail	686,915		4,243		98		276		—		—		691,532
Office	824,408		7,087		—		275		—		—		831,770
Multifamily	979,969		—		48		—		—		—		980,017
Industrial	573,014		—		—		—		—		—		573,014
Other commercial real estate	285,506		145		286		472		—		—		286,409
Total commercial real estate	3,463,002		13,303		827		2,855		—		—		3,479,987

Residential mortgage:
Permanent mortgage	232,492		—		822		1,163		784,928		24,030		1,043,435
Permanent mortgages guaranteed by U.S. government agencies	—		—		—		—		188,327		9,179		197,506
Home equity	—		—		—		—		719,670		13,075		732,745
Total residential mortgage	232,492		—		822		1,163		1,692,925		46,284		1,973,686

Personal	875,696		1,548		63		83		88,200		186		965,776

Total	$	14,797,279	$	118,175	$	241,101	$	141,334	$	1,808,995	$	46,540	$	17,153,424

The following table summarizes the Company’s loan portfolio at September 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	$	2,436,465	$	114,065	$	206,768	$	110,683	$	—	$	—	$	2,867,981
Services	2,932,577		26,372		7,390		1,174		—		—		2,967,513
Wholesale/retail	1,637,698		9,021		9,486		1,893		—		—		1,658,098
Manufacturing	486,383		7,181		16,823		9,059		—		—		519,446
Healthcare	2,150,099		31,855		33,051		24,446		—		—		2,239,451
Other commercial and industrial	458,796		52		9,820		29,500		45,132		145		543,445
Total commercial	10,102,018		188,546		283,338		176,755		45,132		145		10,795,934

Commercial real estate:
Residential construction and land development	110,178		—		—		1,924		—		—		112,102
Retail	724,887		689		—		289		—		—		725,865
Office	788,539		8,275		—		275		—		—		797,089
Multifamily	998,125		—		884		—		—		—		999,009
Industrial	591,080		—		—		—		—		—		591,080
Other commercial real estate	292,509		—		1		487		—		—		292,997
Total commercial real estate	3,505,318		8,964		885		2,975		—		—		3,518,142

Residential mortgage:
Permanent mortgage	224,235		393		462		1,216		764,252		23,407		1,013,965
Permanent mortgages guaranteed by U.S. government agencies	—		—		—		—		178,479		8,891		187,370
Home equity	—		—		—		—		732,423		11,992		744,415
Total residential mortgage	224,235		393		462		1,216		1,675,154		44,290		1,945,750

Personal	855,857		49		38		86		90,809		169		947,008

Total	$	14,687,428	$	197,952	$	284,723	$	181,032	$	1,811,095	$	44,604	$	17,206,834

Impaired Loans

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

A summary of impaired loans follows (in thousands):



	As of										For the				For the
	September 30, 2018										Three Months Ended				Nine Months Ended
			Recorded Investment								September 30, 2018				September 30, 2018
	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	$	73,600	$	54,033	$	28,180	$	25,853	$	5,305	$	59,815	$	—	$	73,159	$	—
Services	6,959		4,097		4,021		76		76		4,237		—		3,358		—
Wholesale/retail	14,281		9,249		2,227		7,022		4,102		11,672		—		5,911		—
Manufacturing²	9,212		9,202		6,217		2,985		2,985		6,096		—		7,582		—
Healthcare	25,923		15,704		13,162		2,542		1,329		15,915		—		15,235		—
Other commercial and industrial	26,645		17,205		17,205		—		—		17,499		—		18,151		—
Total commercial	156,620		109,490		71,012		38,478		13,797		115,234		—		123,396		—

Commercial real estate:
Residential construction and land development	1,306		350		350		—		—		350		—		1,091		—
Retail	7,951		777		777		—		—		923		—		527		—
Office	—		—		—		—		—		137		—		137		—
Multifamily	—		—		—		—		—		—		—		—		—
Industrial	—		—		—		—		—		—		—		—		—
Other commercial real estate	354		189		189		—		—		246		—		330		—
Total commercial real estate	9,611		1,316		1,316		—		—		1,656		—		2,085		—

Residential mortgage:
Permanent mortgage	27,603		22,855		22,855		—		—		22,980		318		24,024		947
Permanent mortgage guaranteed by U.S. government agencies¹	185,788		180,718		180,718		—		—		174,653		1,557		178,643		4,979
Home equity	13,048		11,272		11,272		—		—		11,472		—		12,174		—
Total residential mortgage	226,439		214,845		214,845		—		—		209,105		1,875		214,841		5,926

Personal	320		269		269		—		—		305		—		269		—

Total	$	392,990	$	325,920	$	287,442	$	38,478	$	13,797	$	326,300	$	1,875	$	340,591	$	5,926


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 September 30, 2018, $7.8 million of these loans were nonaccruing and $173 million were accruing based on the guarantee by U.S. government agencies.


²	Impaired manufacturing sector loans included $6.2 million of loans from an affiliated entity, with no allowance as the fair value of the collateral exceeded the outstanding principal balance at September 30, 2018.

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, 2017 follows (in thousands):



			Recorded Investment
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance
Commercial:
Energy	$	111,011	$	92,284	$	40,968	$	51,316	$	8,814
Services	5,324		2,620		2,620		—		—
Wholesale/retail	9,099		2,574		2,574		—		—
Manufacturing	6,073		5,962		5,962		—		—
Healthcare	25,140		14,765		14,765		—		—
Other commercial and industrial	27,957		19,098		19,080		18		17
Total commercial	184,604		137,303		85,969		51,334		8,831

Commercial real estate:
Residential construction and land development	3,285		1,832		1,832		—		—
Retail	509		276		276		—		—
Office	287		275		275		—		—
Multifamily	—		—		—		—		—
Industrial	—		—		—		—		—
Other commercial real estate	670		472		472		—		—
Total commercial real estate	4,751		2,855		2,855		—		—

Residential mortgage:
Permanent mortgage	30,435		25,193		25,193		—		—
Permanent mortgage guaranteed by U.S. government agencies¹	203,814		197,506		197,506		—		—
Home equity	14,548		13,075		13,075		—		—
Total residential mortgage	248,797		235,774		235,774		—		—

Personal	307		269		269		—		—

Total	$	438,459	$	376,201	$	324,867	$	51,334	$	8,831


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, 2017, $9.2 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 September 30, 2017 follows (in thousands):



											For the				For the
	As of September 30, 2017										Three Months Ended				Nine Months Ended
			Recorded Investment								September 30, 2017				September 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	$	133,643	$	110,683	$	45,169	$	65,514	$	4,944	$	117,338	$	—	$	121,591	$	—
Services	3,838		1,174		1,174		—		—		4,464		—		4,674		—
Wholesale/retail	8,418		1,893		1,893		—		—		6,256		—		6,650		—
Manufacturing	9,674		9,059		9,059		—		—		9,357		—		6,995		—
Healthcare	24,591		24,446		474		23,972		8,323		24,476		—		12,635		—
Other commercial and industrial	38,222		29,645		29,626		19		17		25,138		—		25,382		—
Total commercial	218,386		176,900		87,395		89,505		13,284		187,029		—		177,927		—

Commercial real estate:
Residential construction and land development	3,532		1,924		1,924		—		—		1,988		—		2,679		—
Retail	513		289		289		—		—		295		—		308		—
Office	287		275		275		—		—		335		—		351		—
Multifamily	—		—		—		—		—		5		—		19		—
Industrial	—		—		—		—		—		—		—		38		—
Other commercial real estate	671		487		487		—		—		752		—		855		—
Total commercial real estate	5,003		2,975		2,975		—		—		3,375		—		4,250		—

Residential mortgage:
Permanent mortgage	29,861		24,623		24,623		—		—		24,019		315		23,739		912
Permanent mortgage guaranteed by U.S. government agencies¹	193,594		187,370		187,370		—		—		188,461		1,884		199,532		5,809
Home equity	13,332		11,992		11,992		—		—		11,880		—		11,755		—
Total residential mortgage	236,787		223,985		223,985		—		—		224,360		2,199		235,026		6,721

Personal	290		255		255		—		—		263		—		273		—

Total	$	460,466	$	404,115	$	314,610	$	89,505	$	13,284	$	415,027	$	2,199	$	417,476	$	6,721


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 September 30, 2017, $8.9 million of these loans were nonaccruing and $178 million were accruing based on the guarantee by U.S. government agencies.

Troubled Debt Restructurings

At September 30, 2018 the Company had $171 million in troubled debt restructurings (TDRs), of which $83 million were accruing residential mortgage loans guaranteed by U.S. government agencies. Approximately $83 million of TDRs were performing in accordance with the modified terms.

At December 31, 2017, the Company had $126 million in TDRs, of which $74 million were accruing residential mortgage loans guaranteed by U.S. government agencies. Approximately $48 million of TDRs were performing in accordance with the modified terms.

At September 30, 2017, TDRs totaled $129 million, of which $69 million were accruing residential mortgage loans guaranteed by U.S. government agencies. Approximately $60 million of TDRs were performing in accordance with the modified terms.

TDRs generally consist of interest rate concessions, payment stream concessions or a combination of concessions to distressed borrowers. During the three and nine months ended September 30, 2018, $31 million and $76 million of loans were restructured and $4.5 million and $10.2 million of loans designated as TDRs were charged off. During the three and nine months ended September 30, 2017, $11 million and $53 million of loans were restructured and $4.4 million and $4.4 million of loans designated as TDRs were charged off.

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 September 30, 2018 is as follows (in thousands):



			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	3,240,684	$	150	$	—	$	—	$	54,033	$	3,294,867
Services	3,006,581		4,908		1,725		—		4,097		3,017,311
Wholesale/retail	1,641,447		33		—		—		9,249		1,650,729
Manufacturing	648,242		3,138		—		—		9,202		660,582
Healthcare	2,421,166		453		—		—		15,704		2,437,323
Other commercial and industrial	498,066		18		—		—		17,205		515,289
Total commercial	11,456,186		8,700		1,725		—		109,490		11,576,101

Commercial real estate:
Residential construction and land development	101,185		337		—		—		350		101,872
Retail	758,646		—		—		—		777		759,423
Office	824,829		—		—		—		—		824,829
Multifamily	1,120,166		—		—		—		—		1,120,166
Industrial	696,774		—		—		—		—		696,774
Other commercial real estate	300,450		530		45		397		189		301,611
Total commercial real estate	3,802,050		867		45		397		1,316		3,804,675

Residential mortgage:
Permanent mortgage	1,064,618		5,721		1,732		—		22,855		1,094,926
Permanent mortgages guaranteed by U.S. government agencies	39,523		23,370		13,753		96,282		7,790		180,718
Home equity	682,940		1,609		156		121		11,272		696,098
Total residential mortgage	1,787,081		30,700		15,641		96,403		41,917		1,971,742

Personal	995,714		900		58		—		269		996,941

Total	$	18,041,031	$	41,167	$	17,469	$	96,800	$	152,992	$	18,349,459

A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of December 31, 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	$	2,833,668	$	—	$	4,204	$	—	$	92,284	$	2,930,156
Services	2,983,222		514		486		107		2,620		2,986,949
Wholesale/retail	1,468,284		398		—		—		2,574		1,471,256
Manufacturing	490,739		—		73		—		5,962		496,774
Healthcare	2,284,770		15,218		—		—		14,765		2,314,753
Other commercial and industrial	514,701		85		78		125		19,098		534,087
Total commercial	10,575,384		16,215		4,841		232		137,303		10,733,975

Commercial real estate:
Residential construction and land development	115,213		200		—		—		1,832		117,245
Retail	691,256		—		—		—		276		691,532
Office	831,118		254		—		123		275		831,770
Multifamily	979,625		22		370		—		—		980,017
Industrial	573,014		—		—		—		—		573,014
Other commercial real estate	285,937		—		—		—		472		286,409
Total commercial real estate	3,476,163		476		370		123		2,855		3,479,987

Residential mortgage:
Permanent mortgage	1,014,588		3,435		219		—		25,193		1,043,435
Permanent mortgages guaranteed by U.S. government agencies	22,692		18,978		13,468		133,189		9,179		197,506
Home equity	717,007		2,206		440		17		13,075		732,745
Total residential mortgage	1,754,287		24,619		14,127		133,206		47,447		1,973,686

Personal	964,374		681		191		261		269		965,776

Total	$	16,770,208	$	41,991	$	19,529	$	133,822	$	187,874	$	17,153,424

A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of September 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	$	2,752,259	$	—	$	5,039	$	—	$	110,683	$	2,867,981
Services	2,963,746		2,343		250		—		1,174		2,967,513
Wholesale/retail	1,654,018		1,748		409		30		1,893		1,658,098
Manufacturing	508,231		—		2,156		—		9,059		519,446
Healthcare	2,214,849		156		—		—		24,446		2,239,451
Other commercial and industrial	513,748		52		—		—		29,645		543,445
Total commercial	10,606,851		4,299		7,854		30		176,900		10,795,934

Commercial real estate:
Residential construction and land development	109,994		184		—		—		1,924		112,102
Retail	724,850		726		—		—		289		725,865
Office	796,687		127		—		—		275		797,089
Multifamily	999,009		—		—		—		—		999,009
Industrial	591,080		—		—		—		—		591,080
Other commercial real estate	292,322		1		—		187		487		292,997
Total commercial real estate	3,513,942		1,038		—		187		2,975		3,518,142

Residential mortgage:
Permanent mortgage	985,183		3,705		454		—		24,623		1,013,965
Permanent mortgages guaranteed by U.S. government agencies	25,169		17,346		13,343		122,621		8,891		187,370
Home equity	728,884		3,066		445		28		11,992		744,415
Total residential mortgage	1,739,236		24,117		14,242		122,649		45,506		1,945,750

Personal	943,368		3,296		81		8		255		947,008

Total	$	16,803,397	$	32,750	$	22,177	$	122,874	$	225,636	$	17,206,834

- Definition

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.

+ References + Details

Acquisition Acquisition	9 Months Ended
Acquisition Acquisition	Sep. 30, 2018
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	On October 1, 2018, the Company acquired CoBiz Financial, Inc. (CoBiz). CoBiz is headquartered in Denver with a presence in Colorado and Arizona. The Company paid total consideration of $944 million, which included $242 million in cash along with the issuance of 7.2 million shares of BOK Financial stock valued at $702 million in exchange for all outstanding shares of CoBiz stock. As of September 30, 2018, CoBiz had $3.1 billion in loans, $3.9 billion in total assets, $3.3 billion in deposits and $339 million in equity. The assets and liabilities of CoBiz and the results of its operations will be consolidated for periods after the acquisition date. On May 1, 2018, the Company acquired a majority voting interest in Switchgrass Holdings, LLC, a restaurant franchise owner and operator, pursuant to merchant banking regulations and restrictions. The purchase price for this acquisition was $14 million. As of September 30, 2018, the preliminary purchase price allocation included $6.7 million of intangible assets.

Mortgage Banking Activities

9 Months Ended

Sep. 30, 2018

Mortgage Banking [Abstract]

Mortgage Banking Activities [Text Block]

Mortgage Banking Activities

Residential Mortgage Loan Production

The Company originates, markets and services conventional and government-sponsored residential mortgage loans. Generally, conforming fixed rate residential mortgage loans are held for sale in the secondary market and non-conforming and adjustable-rate residential mortgage loans are 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 sales 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):



	September 30, 2018				December 31, 2017					September 30, 2017
	Unpaid Principal Balance/ Notional		Fair Value		Unpaid Principal Balance/ Notional		Fair Value			Unpaid Principal Balance/ Notional		Fair Value
Residential mortgage loans held for sale	$	169,095	$	169,226	$	212,525	$	215,113		$	261,868	$	265,783
Residential mortgage loan commitments	197,752		5,027		222,919		6,523			334,337		9,066
Forward sales contracts	330,876		1,613		380,159		(258		)	524,878		794
			$	175,866			$	221,378				$	275,643

No residential mortgage loans held for sale were 90 days or more past due or considered impaired as of September 30, 2018, December 31, 2017 or September 30, 2017. No credit losses were recognized on residential mortgage loans held for sale for the nine month period ended September 30, 2018 and 2017.

Mortgage banking revenue was as follows (in thousands):



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Production revenue:
Net realized gains on sale of mortgage loans	$	9,063		$	12,041		$	28,699		$	32,443
Net change in unrealized gain on mortgage loans held for sale	(2,135		)	(1,492		)	(2,457		)	3,335
Net change in the fair value of mortgage loan commitments	(2,446		)	(1,927		)	(1,496		)	(667		)
Net change in the fair value of forward sales contracts	2,768			(293		)	1,871			(4,399		)
Total production revenue	7,250			8,329			26,617			30,712
Servicing revenue	16,286			16,561			49,290			49,645
Total mortgage banking revenue	$	23,536		$	24,890		$	75,907		$	80,357

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):



	September 30, 2018			December 31, 2017			September 30, 2017
Number of residential mortgage loans serviced for others	133,538			136,528			137,359
Outstanding principal balance of residential mortgage loans serviced for others	$	21,826,773		$	22,046,632		$	22,063,121
Weighted average interest rate	3.97		%	3.94		%	3.95		%
Remaining term (in months)	295			297			298

The following represents activity in capitalized mortgage servicing rights (in thousands):



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Beginning Balance	$	278,719		$	245,239		$	252,867		$	247,073
Additions, net	8,968			9,925			28,688			29,439
Change in fair value due to principal payments	(8,986		)	(8,667		)	(25,783		)	(24,928		)
Change in fair value due to market assumption changes	5,972			(639		)	28,901			(5,726		)
Ending Balance	$	284,673		$	245,858		$	284,673		$	245,858

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

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



	September 30, 2018	December 31, 2017	September 30, 2017
Discount rate – risk-free rate plus a market premium	9.95%	9.84%	9.84%
Prepayment rate - based upon loan interest rate, original term and loan type	7.85%-15.04%	8.72%-15.16%	8.71%-15.43%
Loan servicing costs – annually per loan based upon loan type:
Performing loans	$66-$92	$65-$88	$65-$120
Delinquent loans	$150-$500	$150-$500	$150-$500
Loans in foreclosure	$1,000-$4,000	$1,000-$4,000	$1,000-$4,250
Escrow earnings rate – indexed to rates paid on deposit accounts with comparable average life	3.07%	2.24%	2.00%
Primary/secondary mortgage rate spread	105 bps	105 bps	105 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 September 30, 2018 follows (in thousands):



			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Total
FHLMC	$	7,804,568	$	84,339	$	14,825	$	22,326	$	7,926,058
FNMA	6,495,003		91,699		14,698		17,281		6,618,681
GNMA	6,569,093		245,827		54,429		16,867		6,886,216
Other	388,107		5,290		529		1,892		395,818
Total	$	21,256,771	$	427,155	$	84,481	$	58,366	$	21,826,773

Commitments and Contingent Liabilities

9 Months Ended

Sep. 30, 2018

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 411,089 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 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 (now estimated to be approximately $40 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. Two separate small groups of bondholders have filed arbitration complaints with the Financial Institutions Regulatory Association respecting the bonds and other bonds for which the Bank served as indenture trustee. Management has been advised by counsel that the Bank has valid defenses to the claims.

On September 15, 2017, the principal of the bond issuances filed for protection under Chapter 11 of the United States Bankruptcy Code in the United States Bankruptcy Court for the Northern District of Georgia. The principal subsequently sought and obtained an order dismissing the Chapter 11 proceeding. The obligation of the principal to pay all principal and interest on the bonds is non-dischargeable in bankruptcy.

A hearing on a motion by the principal to extend the time within which to perform the Court ordered payment plan until December 31, 2019 and a motion by Court Monitor compelling the principal to perform his obligation to maintain the minimum segregated account balance before the Federal Judge in New Jersey is scheduled for October 26, 2018. We expect that the extension will be granted, but there is no assurance that it will be. The Bank continues to expect 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 5, 2018, the Bank was sued in the Fulton, Georgia County District Court by the administratrix of a deceased resident who had sued for and obtained a judgment for wrongful death against one of the operators of a nursing home financed by one of the bonds which are the subject of the litigation discussed above. The judgment is alleged to total approximately $8 million in principal and interest at this time. Plaintiff alleges that BOKF, in its capacity as indenture trustee for the bonds, colluded with the borrower and others to defraud creditors of the nursing home by misleading the public about the solvency of the nursing home. Plaintiff alleges that this conduct has prevented her from collecting on her judgment. The Bank is advised by counsel that the Bank has valid defenses to the plaintiffs’ claims and no loss is probable.

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 representing a different set of municipal securities. 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. Management is advised by counsel that a loss is not probable and that the loss, if any, cannot be reasonably estimated.

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 the Bank is interest and exceeds permitted rates. This action makes the same allegations as a putative class action that was dismissed by the United States District Court for the Northern District of Oklahoma on October 19, 2015. On August 22, 2018, a plaintiff filed a second putative class action in the United States District Court for New Mexico making the same allegations as the Texas action. On September 18,2018, the District Court dismissed the Texas action. Management is advised by counsel that a loss is not probable in the New Mexico action or the Texas action and that the loss, if any, cannot be reasonably estimated.

On July 6, 2018, a plaintiff served a petition in a putative class action in the Oklahoma District Court for Tulsa County Oklahoma alleging BOKF NA breached its Demand Deposit Agreements by charging overdraft and not sufficient funds fees to deposit accounts on the day of the transaction triggering the fee and by the bank's debit hold process causing overdraft fees. 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 $3.4 million at September 30, 2018. 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 September 30, 2018, December 31, 2017 and September 30, 2017 is as follows (in thousands):



	September 30, 2018
	Loans		Other assets		Other liabilities		Other borrowings		Non-controlling interests
Consolidated:
Private equity funds	$	—	$	11,535	$	—	$	—	$	8,693
Tax credit entities	—		—		—		—		—
Other	—		17,145		1,358		—		2,035
Total consolidated	$	—	$	28,680	$	1,358	$	—	$	10,728

Unconsolidated:
Tax credit entities	$	62,188	$	158,429	$	54,460	$	—	$	—
Other	—		47,906		16,200		—		—
Total unconsolidated	$	62,188	$	206,335	$	70,660	$	—	$	—



	December 31, 2017
	Loans		Other assets		Other liabilities		Other borrowings		Non-controlling interests
Consolidated:
Private equity funds	$	—	$	14,783	$	—	$	—	$	11,927
Tax credit entities	10,000		10,964		—		10,964		10,000
Other	—		1,040		—		—		1,040
Total consolidated	$	10,000	$	26,787	$	—	$	10,964	$	22,967

Unconsolidated:
Tax credit entities	$	52,852	$	153,506	$	47,859	$	—	$	—
Other	—		38,397		22,968		—		—
Total unconsolidated	$	52,852	$	191,903	$	70,827	$	—	$	—



	September 30, 2017
	Loans		Other assets		Other liabilities		Other borrowings		Non-controlling interests
Consolidated:
Private equity funds	$	—	$	15,621	$	—	$	—	$	12,806
Tax credit entities	10,000		11,119		—		10,963		10,000
Other	—		15,618		1,588		3,104		2,819
Total consolidated	$	10,000	$	42,358	$	1,588	$	14,067	$	25,625

Unconsolidated:
Tax credit entities	$	65,247	$	145,479	$	61,364	$	—	$	—
Other	—		32,462		13,657		—		—
Total unconsolidated	$	65,247	$	177,941	$	75,021	$	—	$	—

Shareholders' Equity

9 Months Ended

Sep. 30, 2018

Stockholders' Equity Note [Abstract]

Shareholders' Equity [Text Block]

Shareholders' Equity

On October 30, 2018, the Company declared a quarterly cash dividend of $0.50 per common share payable on or about November 26, 2018 to shareholders of record as of November 12, 2018.

Dividends declared were $0.50 and $1.40 per share during the three and nine months ended September 30, 2018 and $0.44 and $1.32 per share during the three and nine months ended September 30, 2017.

Accumulated Other Comprehensive Income (Loss)

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

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



	Unrealized Gain (Loss) on
	Available for Sale Securities			Employee Benefit Plans			Total
Balance, December 31, 2016	$	(9,087	)	$	(1,880	)	$	(10,967	)
Net change in unrealized gain (loss)	33,876			5			33,881
Reclassification adjustments included in earnings:
Gain on available for sale securities, net	(4,916		)	—			(4,916		)
Other comprehensive income (loss), before income taxes	28,960			5			28,965
Federal and state income taxes¹	11,239			2			11,241
Other comprehensive income (loss), net of income taxes	17,721			3			17,724
Balance, September 30, 2017	$	8,634		$	(1,877	)	$	6,757

Balance, December 31, 2017	$	(35,385	)	$	(789	)	$	(36,174	)
Transition adjustment for net unrealized gains on equity securities	(2,709		)	—			(2,709		)
Net change in unrealized gain (loss)	(166,464		)	—			(166,464		)
Reclassification adjustments included in earnings:
Loss on available for sale securities, net	802			—			802
Other comprehensive income (loss), before income taxes	(165,662		)	—			(165,662		)
Federal and state income taxes²	(42,183		)	—			(42,183		)
Other comprehensive income (loss), net of income taxes	(123,479		)	—			(123,479		)
Balance, September 30, 2018	$	(161,573	)	$	(789	)	$	(162,362	)


¹	Calculated using a 39 percent blended federal and state statutory tax rate.

²

Calculated using a 25 percent blended federal and state statutory tax rate.

Earnings Per Share

9 Months Ended

Sep. 30, 2018

Earnings Per Share [Abstract]

Earnings Per Share [Text Block]

Earnings Per Share



(In thousands, except share and per share amounts)	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Numerator:
Net income attributable to BOK Financial Corp. shareholders	$	117,256	$	85,649	$	337,190	$	262,152
Less: Earnings allocated to participating securities	963		888		2,940		2,817
Numerator for basic earnings per share – income available to common shareholders	116,293		84,761		334,250		259,335
Effect of reallocating undistributed earnings of participating securities	1		1		1		2
Numerator for diluted earnings per share – income available to common shareholders	$	116,294	$	84,762	$	334,251	$	259,337

Denominator:
Weighted average shares outstanding	$	65,438,849	$	65,423,258	$	65,455,306	$	65,432,313
Less: Participating securities included in weighted average shares outstanding	537,754		680,436		571,987		702,922
Denominator for basic earnings per common share	64,901,095		64,742,822		64,883,319		64,729,391
Dilutive effect of employee stock compensation plans¹	33,256		62,350		36,409		64,502
Denominator for diluted earnings per common share	$	64,934,351	$	64,805,172	$	64,919,728	$	64,793,893

Basic earnings per share	$	1.79	$	1.31	$	5.15	$	4.01
Diluted earnings per share	$	1.79	$	1.31	$	5.15	$	4.00
¹ Excludes employee stock options with exercise prices greater than current market price.	—		—		—		—

Reportable Segments

9 Months Ended

Sep. 30, 2018

Segment Reporting [Abstract]

Reportable Segments [Text Block]

Reportable Segments

Reportable segments reconciliation to the Consolidated Financial Statements for the three months ended September 30, 2018 is as follows (in thousands):



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	187,417		$	21,075		$	23,131		$	9,260		$	240,883
Net interest revenue (expense) from internal sources	(42,270		)	19,039			6,267			16,964			—
Net interest revenue	145,147			40,114			29,398			26,224			240,883
Provision for credit losses	8,047			1,451			(84		)	(5,414		)	4,000
Net interest revenue after provision for credit losses	137,100			38,663			29,482			31,638			236,883
Other operating revenue	40,522			44,023			83,357			39			167,941
Other operating expense	49,136			53,187			62,255			88,039			252,617
Net direct contribution	128,486			29,499			50,584			(56,362		)	152,207
Gain (loss) on financial instruments, net	(3		)	(7,228		)	7			7,224			—
Change in fair value of mortgage servicing rights	—			5,972			—			(5,972		)	—
Gain (loss) on repossessed assets, net	(1,869		)	(87		)	—			1,956			—
Corporate expense allocations	11,027			15,863			11,126			(38,016		)	—
Net income before taxes	115,587			12,293			39,465			(15,138		)	152,207
Federal and state income taxes	30,623			3,131			10,134			(9,226		)	34,662
Net income	84,964			9,162			29,331			(5,912		)	117,545
Net income attributable to non-controlling interests	—			—			—			289			289
Net income attributable to BOK Financial Corp. shareholders	$	84,964		$	9,162		$	29,331		$	(6,201	)	$	117,256

Average assets	$	18,499,979		$	8,323,542		$	8,498,363		$	(1,626,067	)	$	33,695,817

Reportable segments reconciliation to the Consolidated Financial Statements for the nine months ended September 30, 2018 is as follows (in thousands):



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	529,958		$	64,574		$	57,612		$	47,037		$	699,181
Net interest revenue (expense) from internal sources	(107,715		)	51,811			26,431			29,473			—
Net interest revenue	422,243			116,385			84,043			76,510			699,181
Provision for credit losses	18,781			3,890			(236		)	(23,435		)	(1,000		)
Net interest revenue after provision for credit losses	403,462			112,495			84,279			99,945			700,181
Other operating revenue	123,244			135,292			228,766			(6,973		)	480,329
Other operating expense	143,085			158,947			186,549			254,942			743,523
Net direct contribution	383,621			88,840			126,496			(161,970		)	436,987
Gain on financial instruments, net	13			(36,901		)	7			36,881			—
Change in fair value of mortgage servicing rights	—			28,901			—			(28,901		)	—
Gain (loss) on repossessed assets, net	(6,102		)	(21		)	—			6,123			—
Corporate expense allocations	34,802			47,760			33,223			(115,785		)	—
Net income before taxes	342,730			33,059			93,280			(32,082		)	436,987
Federal and state income taxes	90,943			8,421			23,982			(24,406		)	98,940
Net income	251,787			24,638			69,298			(7,676		)	338,047
Net income attributable to non-controlling interests	—			—			—			857			857
Net income attributable to BOK Financial Corp. shareholders	$	251,787		$	24,638		$	69,298		$	(8,533	)	$	337,190

Average assets	$	18,124,571		$	8,381,204		$	8,364,712		$	(1,094,992	)	$	33,775,495

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



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	160,572		$	21,965		$	11,170		$	24,745		$	218,452
Net interest revenue (expense) from internal sources	(25,460		)	13,981			9,604			1,875			—
Net interest revenue	135,112			35,946			20,774			26,620			218,452
Provision for credit losses	3,217			1,316			(623		)	(3,910		)	—
Net interest revenue after provision for credit losses	131,895			34,630			21,397			30,530			218,452
Other operating revenue	54,670			44,968			75,707			365			175,710
Other operating expense	57,345			56,147			61,792			90,650			265,934
Net direct contribution	129,220			23,451			35,312			(59,755		)	128,228
Gain (loss) on financial instruments, net	4			1,686			—			(1,690		)	—
Change in fair value of mortgage servicing rights	—			(639		)	—			639			—
Gain (loss) on repossessed assets, net	(4,126		)	292			—			3,834			—
Corporate expense allocations	8,733			16,920			9,819			(35,472		)	—
Net income before taxes	116,365			7,870			25,493			(21,500		)	128,228
Federal and state income taxes	47,755			3,061			10,021			(18,399		)	42,438
Net income	68,610			4,809			15,472			(3,101		)	85,790
Net income attributable to non-controlling interests	—			—			—			141			141
Net income (loss) attributable to BOK Financial Corp. shareholders	$	68,610		$	4,809		$	15,472		$	(3,242	)	$	85,649

Average assets	$	17,780,494		$	8,683,998		$	6,992,021		$	(448,343	)	$	33,008,170

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



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	462,325		$	61,313		$	33,130		$	68,070		$	624,838
Net interest revenue (expense) from internal sources	(65,291		)	39,845			28,784			(3,338		)	—
Net interest revenue	397,034			101,158			61,914			64,732			624,838
Provision for credit losses	2,982			3,515			(676		)	(5,821		)	—
Net interest revenue after provision for credit losses	394,052			97,643			62,590			70,553			624,838
Other operating revenue	157,868			140,847			225,434			4,109			528,258
Other operating expense	169,761			164,138			182,816			244,815			761,530
Net direct contribution	382,159			74,352			105,208			(170,153		)	391,566
Gain (loss) on financial instruments, net	46			5,242			—			(5,288		)	—
Change in fair value of mortgage servicing rights	—			(5,726		)	—			5,726			—
Gain (loss) on repossessed assets, net	(2,728		)	253			—			2,475			—
Corporate expense allocations	26,407			50,577			30,438			(107,422		)	—
Net income before taxes	353,070			23,544			74,770			(59,818		)	391,566
Federal and state income taxes	144,704			9,159			29,450			(55,067		)	128,246
Net income	208,366			14,385			45,320			(4,751		)	263,320
Net income attributable to non-controlling interests	—			—			—			1,168			1,168
Net income attributable to BOK Financial Corp. shareholders	$	208,366		$	14,385		$	45,320		$	(5,919	)	$	262,152

Average assets	$	17,738,224		$	8,469,201		$	6,971,369		$	(401,356	)	$	32,777,438

Fees and Commissions Revenue Fees and Commissions Revenue

9 Months Ended

Sep. 30, 2018

Revenue from Contract with Customer [Abstract]

Fees and Commissions Revenue [Text Block]

Fees and Commissions Revenue

Fees and commissions revenue is generated through the sales of products, consisting primarily of financial instruments, and the performance of services for customers under contractual obligations. Revenue from providing services for customers is recognized at the time services are provided in an amount that reflects the consideration we expect to be entitled to for those services. Revenue is recognized based on the application of five steps:


•	Identify the contract with a customer


•	Identify the performance obligations in the contract


•	Determine the transaction price


•	Allocate the transaction price to the performance obligations in the contract


•	Recognize revenue when (or as) the Company satisfies a performance obligation

For contracts with multiple performance obligations, individual performance obligations are accounted for separately if the customer can benefit from the good or service on its own or with other resources readily available to the customer and the promise to transfer goods and services to the customer is separately identifiable in the contract. The transaction price is allocated to the performance obligations based on relative standalone selling prices.

Revenue is recognized on a gross basis whenever we have primary responsibility and risk in providing the services or products to our customers and have discretion in establishing the price for the services or products. Revenue is recognized on a net basis whenever we act as an agent for products or services of others.

Brokerage and trading revenue includes revenues from trading, customer hedging, retail brokerage and investment banking. Trading revenue includes net realized and unrealized gains primarily related to sales of securities to institutional customers and related derivative contracts. Customer hedging revenue includes realized and unrealized changes in the fair value of derivative contracts held for customer risk management programs including credit valuation adjustments, as necessary. We offer commodity, interest rate, foreign exchange and equity derivatives to our customers. These customer contracts are offset with contracts with selected counterparties and exchanges to minimize changes in market risk from changes in commodity prices, interest rates or foreign exchange rates. Retail brokerage revenue represents fees and commissions earned on sales of fixed income securities, annuities, mutual funds and other financial instruments to retail customers. Investment banking revenue includes fees earned upon completion of underwriting and financial advisory services. Investment banking revenue also includes fees earned in conjunction with loan syndications.

Transaction card revenue includes merchant discount fees and electronic funds transfer network fees, net of interchange fees paid to card issuers and assessments paid to card networks. Merchant discount fees represent fees paid by customers for account management and electronic processing of card transactions. Merchant discount fees are recognized at the time the customer’s transactions are processed or other services are performed. The Company also maintains the TransFund electronic funds transfer network for the benefit of its members, which includes the Bank. Electronic funds transfer fees are recognized as electronic transactions processed on behalf of its members.

Fiduciary and asset management revenue includes fees from asset management, custody, recordkeeping, investment advisory and administration services. Revenue is recognized on an accrual basis at the time the services are performed and may be based on either the fair value of the account or the service provided.

Deposit service charges and fees include commercial account service charges, overdraft fees, check card fee revenue and automated service charge and other deposit service fees. Fees are recognized at least quarterly in accordance with published deposit account agreements and disclosure statements for retail accounts or contractual agreements for commercial accounts. Item charges for overdraft or non-sufficient funds items are recognized as items are presented for payment. Account balance charges and activity fees are accrued monthly and collected in arrears. Commercial account activity fees may be offset by an earnings credit based on account balances. Check card fees represent interchange fees paid by a merchant bank for transactions processed from cards issued by the Company. Check card fees are recognized when transactions are processed.

Mortgage banking revenue includes revenues recognized in conjunction with the origination, marketing and servicing of conventional and government-sponsored residential mortgage loans. Mortgage production revenue includes net realized gains (losses) on sales of residential mortgage loans in the secondary market and the net change in unrealized gains (losses) on residential mortgage loans held for sale. Mortgage production revenue also includes changes in the fair value of derivative contracts not designated as hedging instruments related to residential mortgage loan commitments and forward sales contracts. Mortgage servicing revenue includes servicing fee income and late charges on loans serviced for others.

Fees and commissions revenue by reportable segment and primary service line is as follows for the three months ended September 30, 2018.



	Commercial		Consumer		Wealth Management			Funds Management & Other			Consolidated		Out of Scope¹		In Scope²
Trading revenue	$	—	$	—	$	4,830		$	—		$	4,830	$	4,830	$	—
Customer hedging revenue	1,350		—		6,935			229			8,514		8,514		—
Retail brokerage revenue	—		—		4,568			(73		)	4,495		—		4,495
Investment banking revenue	1,765		—		3,482			—			5,247		1,411		3,836
Brokerage and trading revenue	3,115		—		19,815			156			23,086		14,755		8,331
TransFund EFT network revenue	18,397		1,009		(21		)	2			19,387		—		19,387
Merchant services revenue	1,995		14		—			—			2,009		—		2,009
Transaction card revenue	20,392		1,023		(21		)	2			21,396		—		21,396
Personal trust revenue	—		—		35,528			—			35,528		—		35,528
Corporate trust revenue	—		—		5,741			—			5,741		—		5,741
Institutional trust & retirement plan services revenue	—		—		11,056			—			11,056		—		11,056
Investment management services and other	—		—		5,236			(47		)	5,189		—		5,189
Fiduciary and asset management revenue	—		—		57,561			(47		)	57,514		—		57,514
Commercial account service charge revenue	10,294		366		587			(3		)	11,244		—		11,244
Overdraft fee revenue	95		9,413		30			3			9,541		—		9,541
Check card revenue	—		5,254		—			—			5,254		—		5,254
Automated service charge and other deposit fee revenue	35		1,661		22			8			1,726		—		1,726
Deposit service charges and fees	10,424		16,694		639			8			27,765		—		27,765
Mortgage production revenue	—		7,250		—			—			7,250		7,250		—
Mortgage servicing revenue	—		16,748		—			(462		)	16,286		16,286		—
Mortgage banking revenue	—		23,998		—			(462		)	23,536		23,536		—
Other revenue	5,460		2,323		5,568			862			14,213		10,051		4,162
Total fees and commissions revenue	$	39,391	$	44,038	$	83,562		$	519		$	167,510	$	48,342	$	119,168


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


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

Fees and commissions revenue by reportable segment and primary service line is as follows for the nine months ended September 30, 2018.



	Commercial		Consumer		Wealth Management			Funds Management & Other			Consolidated		Out of Scope¹		In Scope²
Trading revenue	$	—	$	—	$	21,562		$	—		$	21,562	$	21,562	$	—
Customer hedging revenue	6,264		—		21,511			1,441			29,216		29,216		—
Retail brokerage revenue	—		—		14,306			(246		)	14,060		—		14,060
Investment banking revenue	5,729		—		9,655			—			15,384		4,772		10,612
Brokerage and trading revenue	11,993		—		67,034			1,195			80,222		55,550		24,672
TransFund EFT network revenue	54,647		3,005		(61		)	5			57,596		—		57,596
Merchant services revenue	5,720		45		—			—			5,765		—		5,765
Transaction card revenue	60,367		3,050		(61		)	5			63,361		—		63,361
Personal trust revenue	—		—		75,568			—			75,568		—		75,568
Corporate trust revenue	—		—		16,317			—			16,317		—		16,317
Institutional trust & retirement plan services revenue	—		—		33,545			—			33,545		—		33,545
Investment management services and other	—		—		15,760			(145		)	15,615		—		15,615
Fiduciary and asset management revenue	—		—		141,190			(145		)	141,045		—		141,045
Commercial account service charge revenue	32,150		1,087		1,802			(3		)	35,036		—		35,036
Overdraft fee revenue	283		26,665		96			13			27,057		—		27,057
Check card revenue	—		15,515		—			—			15,515		—		15,515
Automated service charge and other deposit fee revenue	110		4,953		72			10			5,145		—		5,145
Deposit service charges and fees	32,543		48,220		1,970			20			82,753		—		82,753
Mortgage production revenue	—		26,617		—			—			26,617		26,617		—
Mortgage servicing revenue	—		50,677		—			(1,387		)	49,290		49,290		—
Mortgage banking revenue	—		77,294		—			(1,387		)	75,907		75,907		—
Other revenue	17,379		6,770		18,725			(1,813		)	41,061		27,778		13,283
Total fees and commissions revenue	$	122,282	$	135,334	$	228,858		$	(2,125	)	$	484,349	$	159,235	$	325,114


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

²

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

Fair Value Measurements

9 Months Ended

Sep. 30, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements [Text Block]

Fair Value Measurements

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

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

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

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


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


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


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


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

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

Transfers between levels are recognized as of the end of the reporting period. There were no transfers in or out of quoted prices in active markets for identical instruments to significant other observable inputs or significant unobservable inputs during the nine months ended September 30, 2018 and 2017, respectively. Transfers between significant other observable inputs and significant unobservable inputs during the nine months ended September 30, 2018 and 2017 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 September 30, 2018, December 31, 2017 or September 30, 2017.

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 September 30, 2018 (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	$	80,692	$	—	$	80,692	$	—
U.S. government agency residential mortgage-backed securities	1,378,450		—		1,378,450		—
Municipal and other tax-exempt securities	41,345		—		41,345		—
Asset-backed securities	72,309		—		72,309		—
Other trading securities	40,604		—		40,604		—
Total trading securities	1,613,400		—		1,613,400		—
Available for sale securities:
U.S. Treasury	490		490		—		—
Municipal and other tax-exempt securities	4,349		—		4,349
U.S. government agency residential mortgage-backed securities	5,132,352		—		5,132,352		—
Privately issued residential mortgage-backed securities	74,685		—		74,685		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,834,691		—		2,834,691		—
Other debt securities	25,447		—		24,975		472
Total available for sale securities	8,072,014		490		8,071,052		472
Fair value option securities – U.S. government agency residential mortgage-backed securities	452,150		—		452,150		—
Residential mortgage loans held for sale	175,866		—		159,028		16,838
Mortgage servicing rights¹	284,673		—		—		284,673
Derivative contracts, net of cash collateral²	349,481		26,196		323,285		—
Liabilities:
Derivative contracts, net of cash collateral²	252,387		17,872		234,515		—


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 interest rate and agricultural derivative contacts, net of cash margin. Derivative contacts in liability positions that were valued using quoted prices in active markets for identical instruments are exchange-traded energy and interest rate 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, 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	$	21,196	$	—	$	21,196	$	—
U.S. government agency residential mortgage-backed securities	392,673		—		392,673		—
Municipal and other tax-exempt securities	13,559		—		13,559		—
Asset-backed securities	23,885		—		23,885		—
Other trading securities	11,363		—		11,363		—
Total trading securities	462,676		—		462,676		—
Available for sale securities:
U.S. Treasury	1,000		1,000		—		—
Municipal and other tax-exempt securities	27,080		—		22,278		4,802
U.S. government agency residential mortgage-backed securities	5,309,152		—		5,309,152		—
Privately issued residential mortgage-backed securities	93,221		—		93,221		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,834,961		—		2,834,961		—
Other debt securities	25,481		—		25,009		472
Perpetual preferred stock	15,767		—		15,767		—
Equity securities and mutual funds	14,916		—		14,916		—
Total available for sale securities	8,321,578		1,000		8,315,304		5,274
Fair value option securities – U.S. government agency residential mortgage-backed securities	755,054		—		755,054		—
Residential mortgage loans held for sale	221,378		—		209,079		12,299
Mortgage servicing rights¹	252,867		—		—		252,867
Derivative contracts, net of cash collateral²	220,502		8,179		212,323		—
Liabilities:
Derivative contracts, net of cash collateral²	171,963		—		171,963		—


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, energy and agricultural derivative contacts. 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, fully offset by cash margin.

The fair value of financial assets and liabilities measured on a recurring basis was as follows as of September 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	$	30,162	$	—	$	30,162	$	—
U.S. government agency residential mortgage-backed securities	516,760		—		516,760		—
Municipal and other tax-exempt securities	56,148		—		56,148		—
Other trading securities	11,047		—		11,047		—
Total trading securities	614,117		—		614,117		—
Available for sale securities:
U.S. Treasury	999		999		—		—
Municipal and other tax-exempt securities	28,368		—		23,583		4,785
U.S. government agency residential mortgage-backed securities	5,326,384		—		5,326,384		—
Privately issued residential mortgage-backed securities	99,994		—		99,994		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,889,346		—		2,889,346		—
Other debt securities	4,153		—		—		4,153
Perpetual preferred stock	16,245		—		16,245		—
Equity securities and mutual funds	17,710		2,578		15,132		—
Total available for sale securities	8,383,199		3,577		8,370,684		8,938
Fair value option securities – U.S. government agency residential mortgage-backed securities	819,531		—		819,531		—
Residential mortgage loans held for sale	275,643		—		263,543		12,100
Mortgage servicing rights¹	245,858		—		—		245,858
Derivative contracts, net of cash collateral²	352,559		8,498		344,061		—
Liabilities:
Derivative contracts, net of cash collateral²	336,327		6,903		329,424		—


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, energy and agricultural derivative contacts. Derivative contracts in liability positions that were valued using quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate 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 current fair value, probability of default and loss given default.

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

Residential Mortgage Loans Held for Sale

Residential mortgage loans held for sale are carried on the balance sheet at fair value. The fair values of 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.

The following represents the changes for the three and nine months ended September 30, 2018 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, June 30, 2018	$	2,030		$	471	$	14,243
Transfer to Level 3 from Level 2¹	—			—		2,862
Purchases	—			—		—
Proceeds from sales	—			—		(143		)
Redemptions and distributions	(2,050		)	—		—
Gain (loss) recognized in earnings:
Mortgage banking revenue	—			—		(124		)
Other comprehensive income (loss):
Net change in unrealized gain (loss)	20			1		—
Balance, September 30, 2018	$	—		$	472	$	16,838


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, December 31, 2017	$	4,802		$	472	$	12,299
Transfer to Level 3 from Level 2¹	—			—		5,603
Purchases	—			—		—
Proceeds from sales	—			—		(853		)
Redemptions and distributions	(5,095		)	—		—
Gain (loss) recognized in earnings:
Mortgage banking revenue	—			—		(211		)
Other comprehensive income (loss):
Net change in unrealized gain (loss)	293					—
Balance, September 30, 2018	$	—		$	472	$	16,838


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 nine months ended September 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, June 30, 2017	$	4,655	$	4,152	$	12,735
Transfer to Level 3 from Level 2¹	—		—		176
Purchases	—		—		—
Proceeds from sales	—		—		(847		)
Redemptions and distributions			—		—
Gain (loss) recognized in earnings:
Mortgage banking revenue	—		—		36
Other comprehensive income (loss):
Net change in unrealized gain (loss)	130		1		—
Balance, September 30, 2017	$	4,785	$	4,153	$	12,100


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, December 31, 2016	$	5,789		$	4,152	$	11,617
Transfer to Level 3 from Level 2¹	—			—		2,916
Purchases	—			—		—
Proceeds from sales	—			—		(2,549		)
Redemptions and distributions	(1,100		)	—		—
Gain (loss) recognized in earnings
Mortgage banking revenue	—			—		116
Other comprehensive income (loss):
Net change in unrealized gain (loss)	96			1		—
Balance, September 30, 2017	$	4,785		$	4,153	$	12,100


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 September 30, 2018 follows (in thousands):



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

Available for sale securities
Other debt securities	472	Discounted cash flows	¹	Interest rate spread	6.37%-6.37% (6.37%)	³
Other debt securities	472	Discounted cash flows	¹	Interest rate spread	94.36%-94.36% (94.36%)	²
Residential mortgage loans held for sale	16,838	Quoted prices of loans sold in securitization transactions, with a liquidity discount applied		Liquidity discount applied to the market value of mortgage loans qualifying for sale to U.S. government agencies.	94.94%


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	Represents fair value as a percentage of par value.


³	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 assets measured at fair value on a recurring basis using Significant Unobservable Inputs (Level 3) as of December 31, 2017 follows (in thousands):



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

Available for sale securities
Municipal and other tax-exempt securities	$	4,802	Discounted cash flows	¹	Interest rate spread	6.60%-6.60% (6.60%)	²
Municipal and other tax-exempt securities	$	4,802	Discounted cash flows	¹	Interest rate spread	92.25%-94.76% (93.75%)	³
Other debt securities	472		Discounted cash flows	¹	Interest rate spread	6.85%-6.85% (6.85%)	⁴
Other debt securities	472		Discounted cash flows	¹	Interest rate spread	94.39%-94.39% (94.39%)	³
Residential mortgage loans held for sale	12,299		Quoted prices of loans sold in securitization transactions, with a liquidity discount applied		Liquidity discount applied to the market value of mortgage loans qualifying for sale to U.S. government agencies.	94.75%


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 372 to 466 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 assets measured at fair value on a recurring basis using Significant Unobservable Inputs (Level 3) as of September 30, 2017 follows (in thousands):



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

Available for sale securities
Municipal and other tax-exempt securities	$	4,785	Discounted cash flows	¹	Interest rate spread	6.05%-6.05% (6.05%)	²
Municipal and other tax-exempt securities	$	4,785	Discounted cash flows	¹	Interest rate spread	92.25%-95.02% (93.91%)	³
Other debt securities	4,153		Discounted cash flows	¹	Interest rate spread	6.65%-6.73% (6.72%)	⁴
Other debt securities	4,153		Discounted cash flows	¹	Interest rate spread	94.38%-94.38% (94.38%)	³

Residential mortgage loans held for sale	12,100		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.	95.94%


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 352 to 467 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.

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 September 30, 2018 for which the fair value was adjusted during the nine months ended September 30, 2018:



							Fair Value Adjustments for the
	Carrying Value at September 30, 2018						Three Months Ended September 30, 2018 Recognized in:				Nine Months Ended September 30, 2018 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	$	—	$	1,065	$	24,428	$	9,086	$	—	$	16,279	$	—
Real estate and other repossessed assets	—		4,608		6,545		—		2,161		—		7,388

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 September 30, 2017 for which the fair value was adjusted during the nine months ended September 30, 2017:



							Fair Value Adjustments for the
	Carrying Value at September 30, 2017						Three Months Ended September 30, 2017 Recognized in:				Nine Months Ended September 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	$	—	$	423	$	10,960	$	4,397	$	—	$	5,058	$	—
Real estate and other repossessed assets	—		4,392		6,845		—		4,683		—		4,915

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 September 30, 2018 follows (in thousands):



	Fair Value		Valuation Technique(s)	Unobservable Input	Range (Weighted Average)
Impaired loans	$	24,428	Discounted cash flows	Management knowledge of industry and non-real estate collateral including but not limited to recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs	41% - 84% (55%)¹
Real estate and other repossessed assets	6,545		Discounted cash flows	Recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs	N/A


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

A summary of quantitative information about Non-recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of September 30, 2017 follows (in thousands):



	Fair Value		Valuation Technique(s)	Unobservable Input	Range (Weighted Average)
Impaired loans	$	10,960	Discounted cash flows	Recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs	64% - 88% (68%)¹
Real estate and other repossessed assets	6,845		Discounted cash flows	Recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs	N/A


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

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 September 30, 2018 (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	$	815,458		$	815,458	$	815,458	$	—	$	—
Interest-bearing cash and cash equivalents	430,789			430,789		430,789		—		—
Trading securities:
U.S. government agency debentures	80,692			80,692		—		80,692		—
U.S. government agency residential mortgage-backed securities	1,378,450			1,378,450		—		1,378,450		—
Municipal and other tax-exempt securities	41,345			41,345		—		41,345		—
Asset-backed securities	72,309			72,309		—		72,309		—
Other trading securities	40,604			40,604		—		40,604		—
Total trading securities	1,613,400			1,613,400		—		1,613,400		—
Investment securities:
Municipal and other tax-exempt securities	157,723			158,230		—		158,230		—
U.S. government agency residential mortgage-backed securities	13,234			13,201		—		13,201		—
Other debt securities	203,082			211,462		—		211,462		—
Total investment securities	374,039			382,893		—		382,893		—
Available for sale securities:
U.S. Treasury	490			490		490		—		—
Municipal and other tax-exempt securities	4,349			4,349		—		4,349
U.S. government agency residential mortgage-backed securities	5,132,352			5,132,352		—		5,132,352		—
Privately issued residential mortgage-backed securities	74,685			74,685		—		74,685		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,834,691			2,834,691		—		2,834,691		—
Other debt securities	25,447			25,447		—		24,975		472
Total available for sale securities	8,072,014			8,072,014		490		8,071,052		472
Fair value option securities – U.S. government agency residential mortgage-backed securities	452,150			452,150		—		452,150		—
Residential mortgage loans held for sale	175,866			175,866		—		159,028		16,838
Loans:
Commercial	11,576,101			11,431,818		—		—		11,431,818
Commercial real estate	3,804,675			3,738,494		—		—		3,738,494
Residential mortgage	1,971,742			1,937,171		—		—		1,937,171
Personal	996,941			1,003,857		—		—		1,003,857
Total loans	18,349,459			18,111,340		—		—		18,111,340
Allowance for loan losses	(210,569		)	—		—		—		—
Loans, net of allowance	18,138,890			18,111,340		—		—		18,111,340
Mortgage servicing rights	284,673			284,673		—		—		284,673
Derivative instruments with positive fair value, net of cash collateral	349,481			349,481		26,196		323,285		—
Deposits with no stated maturity	19,556,443			19,556,443		—		—		19,556,443
Time deposits	2,075,846			2,023,244		—		—		2,023,244
Other borrowed funds	6,816,224			6,530,396		—		—		6,530,396
Subordinated debentures	144,707			144,186		—		144,186		—
Derivative instruments with negative fair value, net of cash collateral	252,387			252,387		17,872		234,515		—

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, 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	$	602,510		$	602,510	$	602,510	$	—	$	—
Interest-bearing cash and cash equivalents	1,714,544			1,714,544		1,714,544		—		—
Trading securities:
U.S. government agency debentures	21,196			21,196		—		21,196		—
U.S. government agency residential mortgage-backed securities	392,673			392,673		—		392,673		—
Municipal and other tax-exempt securities	13,559			13,559		—		13,559		—
Asset-backed securities	23,885			23,885		—		23,885		—
Other trading securities	11,363			11,363		—		11,363		—
Total trading securities	462,676			462,676		—		462,676		—
Investment securities:
Municipal and other tax-exempt securities	228,186			230,349		—		230,349		—
U.S. government agency residential mortgage-backed securities	15,891			16,242		—		16,242		—
Other debt securities	217,716			233,444		—		233,444		—
Total investment securities	461,793			480,035		—		480,035		—
Available for sale securities:
U.S. Treasury	1,000			1,000		1,000		—		—
Municipal and other tax-exempt securities	27,080			27,080		—		22,278		4,802
U.S. government agency residential mortgage-backed securities	5,309,152			5,309,152		—		5,309,152		—
Privately issued residential mortgage-backed securities	93,221			93,221		—		93,221		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,834,961			2,834,961		—		2,834,961		—
Other debt securities	25,481			25,481		—		25,009		472
Perpetual preferred stock	15,767			15,767		—		15,767		—
Equity securities and mutual funds	14,916			14,916		—		14,916		—
Total available for sale securities	8,321,578			8,321,578		1,000		8,315,304		5,274
Fair value option securities – U.S. government agency residential mortgage-backed securities	755,054			755,054		—		755,054		—
Residential mortgage loans held for sale	221,378			221,378		—		209,079		12,299
Loans:
Commercial	10,733,975			10,524,627		—		—		10,524,627
Commercial real estate	3,479,987			3,428,733		—		—		3,428,733
Residential mortgage	1,973,686			1,977,721		—		—		1,977,721
Personal	965,776			956,706		—		—		956,706
Total loans	17,153,424			16,887,787		—		—		16,887,787
Allowance for loan losses	(230,682		)	—		—		—		—
Loans, net of allowance	16,922,742			16,887,787		—		—		16,887,787
Mortgage servicing rights	252,867			252,867		—		—		252,867
Derivative instruments with positive fair value, net of cash collateral	220,502			220,502		8,179		212,323		—
Deposits with no stated maturity	19,962,889			19,962,889		—		—		19,962,889
Time deposits	2,098,416			2,064,558		—		—		2,064,558
Other borrowed funds	5,709,861			5,703,121		—		—		5,703,121
Subordinated debentures	144,677			148,207		—		148,207		—
Derivative instruments with negative fair value, net of cash collateral	171,963			171,963		—		171,963		—

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 September 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	$	547,203		$	547,203	$	547,203	$	—	$	—
Interest-bearing cash and cash equivalents	1,926,779			1,926,779		1,926,779		—		—
Trading securities:
U.S. government agency debentures	30,162			30,162		—		30,162		—
U.S. government agency residential mortgage-backed securities	516,760			516,760		—		516,760		—
Municipal and other tax-exempt securities	56,148			56,148		—		56,148		—
Other trading securities	11,047			11,047		—		11,047		—
Total trading securities	614,117			614,117		—		614,117		—
Investment securities:
Municipal and other tax-exempt securities	246,000			249,250		—		249,250		—
U.S. government agency residential mortgage-backed securities	16,926			17,458		—		17,458		—
Other debt securities	203,636			223,187		—		223,187		—
Total investment securities	466,562			489,895		—		489,895		—
Available for sale securities:
U.S. Treasury	999			999		999		—		—
Municipal and other tax-exempt securities	28,368			28,368		—		23,583		4,785
U.S. government agency residential mortgage-backed securities	5,326,384			5,326,384		—		5,326,384		—
Privately issued residential mortgage-backed securities	99,994			99,994		—		99,994		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,889,346			2,889,346		—		2,889,346		—
Other debt securities	4,153			4,153		—		—		4,153
Perpetual preferred stock	16,245			16,245		—		16,245		—
Equity securities and mutual funds	17,710			17,710		2,578		15,132		—
Total available for sale securities	8,383,199			8,383,199		3,577		8,370,684		8,938
Fair value option securities – U.S. government agency residential mortgage-backed securities	819,531			819,531		—		819,531		—
Residential mortgage loans held for sale	275,643			275,643		—		263,543		12,100
Loans:
Commercial	10,795,934			10,574,720		—		—		10,574,720
Commercial real estate	3,518,142			3,467,009		—		—		3,467,009
Residential mortgage	1,945,750			1,958,632		—		—		1,958,632
Personal	947,008			938,819		—		—		938,819
Total loans	17,206,834			16,939,180		—		—		16,939,180
Allowance for loan losses	(247,703		)	—		—		—		—
Loans, net of allowance	16,959,131			16,939,180		—		—		16,939,180
Mortgage servicing rights	245,858			245,858		—		—		245,858
Derivative instruments with positive fair value, net of cash collateral	352,559			352,559		8,498		344,061		—
Deposits with no stated maturity	19,675,790			19,675,790		—		—		19,675,790
Time deposits	2,172,289			2,138,367		—		—		2,138,367
Other borrowed funds	6,631,820			6,609,642		—		—		6,609,642
Subordinated debentures	144,668			146,693		—		146,693		—
Derivative instruments with negative fair value, net of cash collateral	336,327			336,327		6,903		329,424		—

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

Fair Value Election

As more fully disclosed in Note 2 and Note 6 to the Consolidated Financial Statements, the Company has elected to carry all residential mortgage-backed securities guaranteed by U.S. government agencies held as economic hedges against changes in the fair value of mortgage servicing rights and all residential mortgage loans originated for sale at fair value. Changes in the fair value of these financial instruments are recognized in earnings.

- Definition

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

+ References + Details

Federal and State Income Taxes Federal and State Income Taxes

9 Months Ended

Sep. 30, 2018

Income Tax Disclosure [Abstract]

Income Tax Disclosure [Text Block]

Federal and State Income Taxes

The Tax Cuts and Jobs Act (the "Act") enacted on December 22, 2017, reduced the federal corporate income tax rate from 35% to 21% beginning January 1, 2018. Provisions of the Act are broad and complex, and we continue to evaluate its effect on the Company's financial statements. Results of this evaluation did not significantly impact the Company's financial position or results of operations for the three and nine months ended September 30, 2018.

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



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Amount:
Federal statutory tax	$	31,963		$	44,880		$	91,767		$	137,048
Tax exempt revenue	(2,059		)	(3,001		)	(5,524		)	(9,336		)
Effect of state income taxes, net of federal benefit	3,740			2,486			10,685			7,875
Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments	56			(387		)	(2,611		)	(3,363		)
Share-based compensation	(26		)	(169		)	(2,070		)	(2,470		)
Adjustment to provisional amounts related to tax reform	—			—			1,895			—
Other, net	988			(1,371		)	4,798			(1,508		)
Total income tax expense	$	34,662		$	42,438		$	98,940		$	128,246



	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Percent of pretax income:
Federal statutory tax	21.0	%	35.0	%	21.0	%	35.0	%
Tax exempt revenue	(1.4	)	(2.3	)	(1.3	)	(2.4	)
Effect of state income taxes, net of federal benefit	2.5		1.9		2.4		2.0
Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments	—		(0.3	)	(0.6	)	(0.9	)
Share-based compensation	—		(0.1	)	(0.5	)	(0.6	)
Adjustment to provisional amounts related to tax reform	—		—		0.4		—
Other, net	0.7		(1.1	)	1.2		(0.3	)
Total	22.8	%	33.1	%	22.6	%	32.8	%

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2018
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events The Company evaluated events from the date of the consolidated financial statements on September 30, 2018 through the issuance of those consolidated financial statements included in this Quarterly Report on Form 10-Q. Except as discussed in Note 5, no other events were identified requiring recognition in and/or disclosure in the consolidated financial statements.

Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2018

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. Revenue from financial assets and liabilities is explicitly excluded from the scope of ASU 2014-09. Management adopted the standard in the first quarter of 2018 using the modified retrospective transition method. There were no significant cumulative effect adjustments as a result of implementation as of January 1, 2018 as our current revenue recognition policies generally conform with the principals in ASU 2014-09.

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. Management adopted the standard in the first quarter of 2018. Interchange fees paid to issuing banks for card transactions processed related to its merchant processing services previously included in data processing and communication expense are now netted against the amounts charged to the merchant in transaction card processing revenue.

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. Management adopted the standard in the first quarter of 2018. Upon adoption, net unrealized gains of $2.7 million from equity securities were reclassified from other comprehensive income to retained earnings.

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. As originally issued, ASU 2016-02 required implementation through the modified transition method applied as of the earliest period presented in the financial statements. In 2018 an additional and optional transition method that allows entities to apply the standard as of the adoption date was approved. BOKF intends to elect this optional transition method. BOKF also plans to elect all practical expedients other than the lessee’s practical expedient to combine lease and non-lease components which would further gross up the lease liability and related right of use asset. The Company currently estimates that implementation of ASU 2016-02 will increase reported right of use assets and liabilities by approximately $100 million to $150 million.

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 has established a CECL implementation team in order to evaluate the impact the adoption of ASU 2016-13 will have on the Company's financial statements. The CECL implementation team, overseen by the Chief Credit Officer, Chief Financial Officer, and Chief Risk Officer, has developed a project plan that incorporates input from various departments within the bank including Credit, Financial Reporting, Risk, and Information Technology among others. Key implementation activities for 2018 include portfolio segmentation, credit risk driver identification, model development, as well as process and information systems enhancements. The Company will adopt the standard on January 1, 2020.

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. Management adopted the standard in first quarter of 2018. Adoption of ASU 2016-15 did not have a material impact on the Company's financial statements.

FASB Accounting Standards Update No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities ("ASU 2017-12")

On August 28, 2017, the FASB issued ASU 2017-12, which amends the hedge accounting recognition and presentation requirements in ASC 815 in order to improve transparency and understandability of information and reduce the complexity. The update expands the types of transactions eligible for hedge accounting, eliminates the requirement to separately measure and present hedge ineffectiveness, simplifies hedge effectiveness assessments and updates documentation and presentation requirements. The update allows the reclassification of certain debt securities from held to maturity to available for sale if the debt security is eligible to be hedged under the last-of-layer method. ASU 2017-12 is effective for the Company for fiscal years beginning after December 15, 2018, and interim periods therein; however, early adoption is permitted. Adoption of ASU 2017-12 is not expected to have a material impact on the Company's financial statements.

FASB Accounting Standards Update No. 2018-05, Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 (SAB 118).

On March 13, 2018, the FASB issued ASU 2018-05, which adds SEC guidance related to SAB 118 - Income Tax Accounting Implications of the Tax Cuts and Jobs Act. ASU 2018-05 was effective upon issuance. The adoption of ASU 2018-05 has not had a significant impact in 2018.

FASB Accounting Standards Update No. 2018-15, Intangibles - Goodwill and Other Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract ("ASU 2018-15")

On August 29, 2018, the FASB issued ASU 2018-15, which requires a customer in a cloud hosting arrangement that is a service contract to follow the internal use software requirements in ASC 350-40 to determine which implementation costs to capitalize or expense as incurred. Internal use software guidance requires the capitalization of costs incurred during the development phase. Capitalized costs will be amortized over the term of the hosting arrangement beginning when the arrangement is ready for its intended use. ASU 2018-15 is effective for the Company for fiscal years beginning after December 15, 2019; however, early adoption is permitted. The Company elected to early adopt the update prospectively in third quarter of 2018. The adoption of ASU 2018-15 did not have a significant impact in the third quarter.

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. Deterioration in the credit rating of customer or other counterparties reduced the fair value of asset contracts. Deterioration of our credit rating could decrease the fair value of our derivative liabilities.

When bilateral netting agreements or similar 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 to mitigate the market risk of holding trading securities. Changes in the fair value of derivative instruments used in managing interest rate sensitivity and as part of the economic hedge of changes in the fair value of mortgage servicing rights are included in Other operating revenue – Gain (loss) on derivatives, net in the Consolidated Statements of Earnings. Changes in the fair value of derivative instruments used to mitigate the market risk of holding trading securities are included in Other operating revenue – Brokerage and trading revenue.

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]