BOK Financial (BOKF) 10-K27 Feb 202019 FY Annual reportFinancial data

Company Profile

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
Document And Entity Information - USD ($)	Dec. 31, 2019	Jan. 31, 2020	Jun. 30, 2019
Document and Entity Information [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	0-19341
Entity Registrant Name	BOK FINANCIAL CORP ET AL
Entity Incorporation, State or Country Code	OK
Entity Tax Identification Number	73-1373454
Entity Address, Address Line One	Boston Avenue at Second Street
Entity Address, City or Town	Tulsa,
Entity Address, State or Province	OK
Entity Address, Postal Zip Code	74172
City Area Code	918
Local Phone Number	588-6000
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		70,692,686
Entity Central Index Key	0000875357
Current Fiscal Year End Date	--12-31
Entity Public Float			$ 2,427,342,016
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Statements of Earn

Consolidated Statements of Earnings - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest and dividend revenue [Abstract]
Loans	$ 1,123,791	$ 891,587	$ 696,479
Residential mortgage loans held for sale	7,105	8,123	8,706
Trading securities	61,595	57,531	17,002
Investment securities	13,426	14,775	16,121
Available for sale securities	254,031	197,317	177,070
Fair value option securities	32,936	15,205	16,755
Restricted equity securities	26,860	21,555	18,490
Interest-bearing cash and cash equivalents	12,214	22,333	22,128
Total interest revenue	1,531,958	1,228,426	972,751
Interest Expense [Abstract]
Deposits	175,538	95,517	53,803
Borrowed funds	228,428	138,215	69,008
Subordinated debentures	15,113	9,827	8,239
Total interest expense	419,079	243,559	131,050
Net interest and dividend revenue	1,112,879	984,867	841,701
Provision for credit losses	44,000	8,000	(7,000)
Net interest and dividend revenue after provision for credit losses	1,068,879	976,867	848,701
Total fees and commissions	702,201	643,176	681,014
Other gains (losses), net	9,351	(2,265)	11,434
Gain (loss) on derivatives, net	14,951	(422)	779
Gain (loss) on fair value option securities, net	15,787	(25,572)	(2,733)
Change in fair value of mortgage servicing rights	(53,517)	4,668	172
Gain (loss) on available for sale securities, net	5,597	(2,801)	4,428
Total other operating revenue	694,370	616,784	695,094
Other operating expense [Abstract]
Personnel	660,565	583,131	573,408
Business promotion	35,662	30,523	28,877
Charitable contributions to BOKF Foundation	3,000	2,846	2,000
Professional fees and services	54,861	59,099	51,067
Net occupancy and equipment	110,275	97,981	86,477
Insurance	20,906	23,318	19,653
Data processing and communications	124,983	114,796	146,970
Printing, postage and supplies	16,517	17,169	15,689
Net losses and operating expenses of repossessed assets	6,707	17,052	9,687
Amortization of intangible assets	20,618	9,620	6,779
Mortgage banking costs	50,685	46,298	52,856
Other expense	27,602	26,333	32,054
Total other operating expense	1,132,381	1,028,166	1,025,517
Net income before taxes	630,868	565,485	518,278
Federal and state income taxes	130,183	119,061	182,593
Net income	500,685	446,424	335,685
Net income (loss) attributable to Non-controlling interests	(73)	778	1,041
Net income attributable to BOK Financial Corporation shareholders	$ 500,758	$ 445,646	$ 334,644
Earnings per share: [Abstract]
Basic (in dollars per share)	$ 7.03	$ 6.63	$ 5.11
Diluted (in dollars per share)	$ 7.03	$ 6.63	$ 5.11
Average shares used in computation: [Abstract]
Basic (in shares)	70,787,700	66,628,640	64,745,364
Diluted (in shares)	70,802,612	66,662,273	64,806,284
Dividends declared per share (in dollars per share)	$ 2.01	$ 1.90	$ 1.77
Brokerage and trading revenue [Member]
Total fees and commissions	$ 159,826	$ 108,323	$ 131,601
Transaction card revenue [Member]
Total fees and commissions	87,216	84,025	119,988
Fiduciary and asset management revenue [Member]
Total fees and commissions	177,025	184,703	162,889
Deposit service charges and fees [Member]
Total fees and commissions	112,485	112,153	112,079
Mortgage banking revenue [Member]
Total fees and commissions	107,541	97,787	104,719
Other revenue [Member]
Total fees and commissions	$ 58,108	$ 56,185	$ 49,738

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 500,685		$ 446,424		$ 335,685
Other comprehensive income (loss), before income taxes: [Abstract]
Net change in unrealized gain (loss)	241,047		(48,010)		(26,152)
Reclassification adjustments included in earnings: [Abstract]
Loss (gain) on available for sale securities, net	(5,597)		2,801		(4,428)
Other comprehensive gain (loss), before income taxes	235,450		(45,209)		(30,580)
Federal and state income taxes	57,942	[1]	(11,507)	[1]	(11,923)	[2]
Other comprehensive gain (loss), net of income taxes	177,508		(33,702)		(18,657)
Comprehensive income	678,193		412,722		317,028
Comprehensive income (loss) attributable to non-controlling interests	(73)		778		1,041
Comprehensive income attributable to BOK Financial Corp. shareholders	$ 678,266		$ 411,944		$ 315,987

[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

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets [Abstract]
Cash and due from banks	$ 735,836	$ 741,749
Interest-bearing cash and cash equivalents	522,985	401,675
Trading securities	1,623,921	1,956,923
Investment securities	293,418	355,187
Available for sale securities	11,269,643	8,857,120
Fair value option securities	1,098,577	283,235
Restricted equity securities	460,552	344,447
Residential mortgage loans held for sale	182,271	149,221
Loans	21,750,987	21,656,730
Allowance for loan losses	(210,759)	(207,457)
Loans, net of allowance	21,540,228	21,449,273
Premises and equipment, net	535,519	330,033
Receivables	231,811	204,960
Goodwill	1,048,091	1,049,263
Intangible assets, net	125,271	134,849
Mortgage servicing rights	201,886	259,254
Real estate and other repossessed assets, net of allowance	20,359	17,487
Derivative contracts	323,375	320,929
Cash surrender value of bank-owned life insurance	389,879	381,608
Receivable on unsettled securities sales	1,020,404	336,400
Other assets	547,995	446,891
Total assets	42,172,021	38,020,504
Deposits [Abstract]
Noninterest-bearing demand deposits	9,461,291	10,414,592
Interest-bearing Deposit Liabilities [Abstract]
Transaction	15,391,752	12,206,576
Savings	550,276	529,215
Time	2,217,849	2,113,380
Total deposits	27,621,168	25,263,763
Funds purchased and repurchase agreements	3,818,350	1,018,411
Other borrowings	4,527,055	6,124,390
Subordinated debentures	275,923	275,913
Accrued interest, taxes and expense	259,701	192,826
Derivative contracts	251,128	362,306
Due on unsettled securities purchases	182,547	156,370
Other liabilities	372,230	183,480
Total liabilities	37,308,102	33,577,459
Shareholders' equity: [Abstract]
Common stock	5	5
Capital surplus	1,350,995	1,334,030
Retained earnings	3,729,778	3,369,654
Treasury stock	(329,906)	(198,995)
Accumulated other comprehensive income (loss)	104,923	(72,585)
Total shareholders’ equity	4,855,795	4,432,109
Non-controlling interests	8,124	10,936
Total equity	4,863,919	4,443,045
Total liabilities and equity	$ 42,172,021	$ 38,020,504

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Investment securities [Abstract]
Investment securities, fair value	$ 314,402	$ 367,298
Real estate and other repossessed assets, allowance	$ 11,013	$ 13,665
Shareholders' equity: [Abstract]
Common stock, par value (in dollars per share)	$ 0.00006	$ 0.00006
Common stock, shares authorized (in shares)	2,500,000,000	2,500,000,000
Common stock, shares issued (in shares)	75,758,597	75,711,492
Common stock, shares outstanding (in shares)	75,758,597	75,711,492
Treasury stock, shares at cost (in shares)	5,178,999	3,588,560

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity - 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	335,685			334,644			334,644	1,041
Other comprehensive income (loss), net	(18,657)					(18,657)	(18,657)
Repurchase of common stock (in shares)					80
Repurchase of common stock	(7,403)				$ (7,403)		(7,403)
Stock options exercised (in shares)		100
Stock options exercised	5,758		5,758				5,758
Non-vested shares awarded, net (in shares)		55
Vesting of non-vested shares (in shares)					17
Vesting of non-vested shares	(1,390)				$ (1,390)		(1,390)
Share-based compensation	23,602		23,602				23,602
Cash dividends on common stock	(116,041)			(116,041)			(116,041)
Capital calls and distributions, net	(9,577)							(9,577)
Reclassification of stranded accumulated other comprehensive loss to retained earnings related to tax reform	(6,550)			6,550		(6,550)
Balance, end of period (in shares) at Dec. 31, 2017		75,148			9,753
Balance, end 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
Transition adjustment of new accounting principle	(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
Net income	446,424			445,646			445,646	778
Other comprehensive income (loss), net	(33,702)					(33,702)	(33,702)
Repurchase of common stock (in shares)					616
Repurchase of common stock	(53,465)				$ (53,465)		(53,465)
Stock options exercised (in shares)		54
Stock options exercised	2,781		2,781				2,781
Non-vested shares awarded, net (in shares)		109
Vesting of non-vested shares (in shares)					31
Vesting of non-vested shares	(2,870)				$ (2,870)		(2,870)
Share-based compensation	4,229		4,229				4,229
Cash dividends on common stock	(127,188)			(127,188)			(127,188)
Capital calls and distributions, net	(12,809)							(12,809)
Issuance of shares for CoBiz acquisition (in shares)		400			(6,811)
Issuance of shares fro CoBiz acquisition	701,311	$ 1	291,125		$ 410,185		701,311
Balance, end of period (in shares) at Dec. 31, 2018		75,711			3,589
Balance, end of period at Dec. 31, 2018	4,443,045	$ 5	1,334,030	3,369,654	$ (198,995)	(72,585)	4,432,109	10,936
Transition adjustment of new accounting principle	2,862			2,862			2,862
Balance, beginning of period, Adjusted	4,445,907	$ 5	1,334,030	3,372,516	$ (198,995)	(72,585)	4,434,971	10,936
Net income	500,685			500,758			500,758	(73)
Other comprehensive income (loss), net	177,508					177,508	177,508
Repurchase of common stock (in shares)					1,572
Repurchase of common stock	(129,483)				$ (129,483)		(129,483)
Stock options exercised (in shares)		27
Stock options exercised	1,421		1,421				1,421
Non-vested shares awarded, net (in shares)		21
Vesting of non-vested shares (in shares)					18
Vesting of non-vested shares	(1,428)				$ (1,428)		(1,428)
Share-based compensation	15,544		15,544				15,544
Cash dividends on common stock	(143,496)			(143,496)			(143,496)
Capital calls and distributions, net	(2,739)							(2,739)
Balance, end of period (in shares) at Dec. 31, 2019		75,759			5,179
Balance, end of period at Dec. 31, 2019	$ 4,863,919	$ 5	$ 1,350,995	$ 3,729,778	$ (329,906)	$ 104,923	$ 4,855,795	$ 8,124

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flows From Operating Activities: [Abstract]
Net income	$ 500,685	$ 446,424	$ 335,685
Adjustments to reconcile net income to net cash provided by (used in) operating activities: [Abstract]
Provision for credit losses	44,000	8,000	(7,000)
Change in fair value of mortgage servicing rights due to market changes	53,517	(4,668)	(172)
Change in fair value of mortgage servicing rights due to principal payments	38,979	33,528	33,527
Net unrealized losses (gains) from derivative contracts	(25,936)	4,686	3,704
Share-based compensation	15,544	4,229	23,602
Depreciation and amortization	95,416	60,843	54,466
Net amortization of discounts and premiums	(16,984)	30,945	28,693
Net losses (gains) on financial instruments and other losses (gains), net	(583)	9,585	(2,828)
Net gain on mortgage loans held for sale	(40,402)	(35,705)	(47,159)
Mortgage loans originated for sale	(3,025,930)	(2,587,297)	(3,286,873)
Proceeds from sale of mortgage loans held for sale	3,035,600	2,691,144	3,405,890
Capitalized mortgage servicing rights	(35,128)	(35,247)	(39,149)
Change in trading and fair value option securities	(483,007)	(1,023,097)	(804,204)
Change in receivables	(740,868)	(38,346)	321,880
Change in other assets	18,955	27,507	(5,506)
Change in accrued interest, taxes and expense	34,894	(5,191)	18,191
Change in other liabilities	57,569	(139,346)	182,184
Net cash provided by (used in) operating activities	(473,679)	(552,006)	214,931
Cash Flows From Investing Activities: [Abstract]
Proceeds from maturities or redemptions of investment securities	60,128	124,864	112,022
Proceeds from maturities or redemptions of available for sale securities	1,841,069	1,122,680	1,841,217
Purchases of investment securities	0	(4,468)	(32,972)
Purchases of available for sale securities	(5,245,256)	(1,955,172)	(2,845,557)
Proceeds from sales of available for sale securities	1,211,718	745,643	1,309,215
Change in amount receivable on unsettled available for sale securities transactions	25,410	38,347	(68,792)
Loans originated, net of principal collected	(44,414)	(1,553,033)	(78,232)
Net payments on derivative asset contracts	33,566	(114,417)	479,409
Acquisitions, net of cash acquired	0	(175,755)	0
Proceeds from disposition of assets	178,681	308,762	274,029
Purchases of assets	(384,639)	(345,082)	(250,783)
Net cash provided by (used in) investing activities	(2,323,737)	(1,807,631)	739,556
Cash Flows From Financing Activities: [Abstract]
Net change in demand deposits, transaction deposits and savings accounts	2,252,936	(13,870)	(563,406)
Net change in time deposits	104,288	(73,089)	(123,384)
Net change in other borrowed funds	1,110,970	1,295,484	(10,909)
Change in amount due on unsettled security purchases	(41,651)	(41,319)	144,690
Issuance of common and treasury stock, net	(7)	(88)	4,368
Net change in derivative margin accounts	(207,122)	85,466	(17,726)
Net payments or proceeds on derivative liability contracts	(33,622)	114,076	(485,119)
Repurchase of common stock	(129,483)	(53,465)	(7,403)
Dividends paid	(143,496)	(127,188)	(116,041)
Net cash provided by (used in) financing activities	2,912,813	1,186,007	(1,174,930)
Net increase (decrease) in cash and cash equivalents	115,397	(1,173,630)	(220,443)
Cash and cash equivalents at beginning of period	1,143,424	2,317,054	2,537,497
Cash and cash equivalents at end of period	1,258,821	1,143,424	2,317,054
Supplemental Cash Flow Information: [Abstract]
Cash paid for interest	417,070	243,121	127,513
Cash paid for taxes	87,361	92,291	121,697
Net loans and bank premises transferred to repossessed real estate and other assets	10,665	9,880	7,367
Increase in U.S. government guaranteed loans eligible for repurchase	91,634	100,238	148,107
Increase in receivables from conveyance of GNMA OREO	28,669	38,216	40,528
Right-of-use assets obtained in exchange for operating lease liabilities	$ 62,755	$ 0	$ 0

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
Significant Accounting Policies	Dec. 31, 2019
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Significant Accounting Policies Basis of Presentation The Consolidated Financial Statements of BOK Financial Corporation (“BOK Financial” or “the Company”) have been prepared in conformity with accounting principles generally accepted in the United States ("U.S. GAAP"), including interpretations of U.S. GAAP issued by federal banking regulators and general practices of the banking industry. The Consolidated Financial Statements include the accounts of BOK Financial and its subsidiaries, principally BOKF, NA, BOK Financial Securities, Inc., BOK Financial Private Wealth, Inc., BOK Financial Insurance, Inc. and Cavanal Hill Distributors, Inc. All significant intercompany transactions are eliminated in consolidation. The Consolidated Financial Statements include the assets, liabilities, non-controlling interests and results of operations of variable interest entities (“VIEs”) when BOK Financial is determined to be the primary beneficiary. Variable interest entities are generally defined as entities that either do not have sufficient equity to finance their activities without support from other parties or whose equity investors lack a controlling financial interest. Determination that the Company is the primary beneficiary considers the power to direct the activities that most significantly impact the variable interest's economic performance and the obligation to absorb losses of the variable interest or the right to receive benefits of the variable interest that could be significant to the variable interest. Certain prior year amounts have been reclassified to conform to current year presentation. Nature of Operations BOK Financial, through its subsidiaries, provides a wide range of financial services to commercial and industrial customers, other financial institutions, municipalities, and consumers. These services include depository and cash management; lending and lease financing; mortgage banking; securities brokerage, trading and underwriting; and personal and corporate trust. BOKF, NA operates as Bank of Oklahoma primarily in the Tulsa and Oklahoma City metropolitan areas of the state of Oklahoma and Bank of Texas primarily in the Dallas, Fort Worth and Houston metropolitan areas of the state of Texas. In addition, BOKF, NA does business as BOK Financial in the metropolitan areas of Phoenix, Arizona; Northwest Arkansas; Denver, Colorado; Kansas City, Missouri/Kansas; and as Bank of Albuquerque in Albuquerque, New Mexico. BOKF, NA also operates the TransFund electronic funds network, Cavanal Hill Investment Management, and BOK Financial Asset Management, Inc. Use of Estimates Preparation of BOK Financial's Consolidated Financial Statements requires management to make estimates of future economic activities, including loan collectability, loss contingencies, prepayments and cash flows from customer accounts. These estimates are based upon current conditions and information available to management. Actual results may differ significantly from these estimates. Acquisitions Assets and liabilities acquired, including identifiable intangible assets, are recorded at fair value on the acquisition date. The purchase price includes consideration paid at closing and the estimated fair value of contingent consideration that will be paid in the future, subject to achieving defined performance criteria. Premiums and discounts assigned to interest-earning assets and interest-bearing liabilities are amortized over the lives of the acquired assets and liabilities on either an individual instrument or pool basis. Provision for credit losses is recognized for changes in credit quality after the acquisition date. Goodwill is recognized as the excess of the purchase price over the net fair value of assets acquired and liabilities assumed. The Consolidated Statements of Earnings include the results of operations from the acquisition date. Goodwill and Intangible Assets Goodwill and intangible assets generally result from business combinations and are evaluated for each of BOK Financial's reporting units for impairment annually or more frequently if conditions indicate impairment. The evaluation of possible impairment of goodwill and intangible assets involves significant judgment based upon short-term and long-term projections of future performance. Reporting units are defined by the Company as significant lines of business within each operating segment. This definition is consistent with the manner in which the chief operating decision maker assesses the performance of the Company and makes decisions concerning the allocation of resources. The Company qualitatively assesses whether it is more likely than not that the fair value of the reporting units are less than their carrying value, including goodwill. Reporting unit carrying value includes sufficient capital to exceed regulatory requirements. This assessment includes consideration of relevant events and circumstances including but not limited to macroeconomic conditions, industry and market conditions, the financial and stock performance of the Company and other relevant factors. If the Company concludes based on the qualitative assessment that goodwill may be impaired, a quantitative one-step impairment test will be applied to goodwill at all reporting units. The quantitative analysis compares the fair value of the reporting unit with its carrying value, including goodwill. The fair value of each reporting unit is estimated by the discounted future earnings method. Goodwill is considered impaired if the fair value of the reporting unit is less than the carrying value of the reporting unit, including goodwill. Intangible assets are generally composed of customer relationships, naming rights, non-compete agreements and core deposit premiums. They are amortized using accelerated or straight-line methods, as appropriate, over the estimated benefit periods. These periods range from 3 years to 20 years . The net book values of identifiable intangible assets are evaluated for impairment when economic conditions indicate impairment may exist. Cash Equivalents Due from banks, funds sold (generally federal funds sold for one day ), resell agreements (which generally mature within one day to 30 days ) and investments in money market funds are considered cash equivalents. Securities Securities are identified as trading, investment (held to maturity) or available for sale at the time of purchase based upon the intent of management, liquidity and capital requirements, regulatory limitations and other relevant factors. Trading securities, which are acquired for profit through resale, are carried at fair value with unrealized gains and losses included in current period earnings. Investment securities are carried at amortized cost. Amortization is computed by methods that approximate level yield and is adjusted for changes in prepayment estimates. Securities identified as available for sale are carried at fair value. Unrealized gains and losses are recorded, net of deferred income taxes, as accumulated other comprehensive income in shareholders' equity. Available for sale securities are separately identified as pledged to creditors if the creditor has the right to sell or re-pledge the collateral. The purchase or sale of securities is recognized on a trade date basis. Realized gains and losses on sales of securities are based upon specific identification of the security sold. A receivable or payable is recognized for subsequent transaction settlement. On a quarterly basis, the Company performs separate evaluations of impaired debt investment and available for sale securities to determine if the decline in fair value below the amortized cost is other-than-temporary. Management determines whether it intends to sell or if it is more likely than not that it will be required to sell impaired securities. This determination considers current and forecasted liquidity requirements and securities portfolio management. If the Company intends to sell or it is more likely than not that it will be required to sell the impaired debt security, a charge is recognized against earnings for the entire unrealized loss. For all impaired debt securities for which there is no intent or expected requirement to sell, the evaluation considers all available evidence to assess whether it is more likely than not that all amounts due would not be collected according to the security's contractual terms. Impairment of debt securities rated investment grade by nationally-recognized rating agencies is considered temporary unless specific contrary information is identified. Impairment of debt securities rated below investment grade by at least one of the nationally recognized rating agencies is evaluated based on projections of estimated cash flows. Any expected credit loss due to the inability to collect all amounts due according to the security's contractual terms is recognized as a charge against earnings. Any remaining unrealized loss related to other factors would be recognized in other comprehensive income, net of taxes. BOK Financial may elect to carry certain securities that are not held for trading purposes at fair value with changes in fair value recognized in current period income. These securities are held with the intent that gains or losses will offset changes in the fair value of mortgage servicing rights or other financial instruments. Restricted equity securities represent equity interests the Company is required to hold in the Federal Reserve Banks and Federal Home Loan Banks. Restricted equity securities are carried at cost as these securities do not have a readily determined fair value because ownership of these shares is restricted and they lack a market. The fair value of our securities portfolio is generally based on a single price for each financial instrument provided to us by a third-party pricing service determined by one or more of the following: • Quoted prices for similar, but not identical, assets or liabilities in active markets; • Quoted prices for identical or similar assets or liabilities in inactive markets; • Inputs other than quoted prices that are observable, such as interest rate and yield curves, volatilities, prepayment speeds, loss severities, credit risks and default rates; and • Other inputs derived from or corroborated by observable market inputs. The underlying methods used by the third-party pricing services are considered in determining the primary inputs used to determine fair values. We evaluate the methodologies employed by the third-party pricing services by comparing the price provided by the pricing service with other sources, including brokers' quotes, sales or purchases of similar instruments and discounted cash flows to establish a basis for reliance on the pricing service values. Significant differences between the pricing service provided value and other sources are discussed with the pricing service to understand the basis for their values. Based on all observable inputs, management may adjust prices obtained from third-party pricing services to more appropriately reflect the prices that would be received to sell assets or paid to transfer liabilities in orderly transactions in the current market. Derivative Instruments Derivative instruments may be used by the Company as part of its internal risk management programs or may be offered to customers. All derivative instruments are carried at fair value and changes in fair value are generally reported in income as they occur. The determination of fair value of derivative instruments considers changes in interest rates, commodity prices and foreign exchange rates. Fair values for exchange-traded contracts are based on quoted prices in an active market for identical instruments. Fair values for over-the-counter contracts are generated internally using third-party valuation models. Inputs used in third-party valuation models to determine fair values are considered significant other observable inputs. Credit risk is also considered in determining fair value. Deterioration in the credit rating of customers or other counterparties reduces the fair value of asset contracts. Deterioration of our credit rating could decrease the fair value of our derivative liabilities. When bilateral netting agreements or similar agreements exist between the Company and its counterparties that create a single legal claim or obligation to pay or receive the net amount in settlement of the individual derivative contracts, the Company reports derivative assets and liabilities on a net by derivative contract by counterparty basis. Derivative contracts may also require the Company to provide or receive cash margin as collateral for derivative assets and liabilities. Derivative assets and liabilities are reported net of cash margin when certain conditions are met. In addition, derivative contracts executed with customers under Customer Risk Management Programs may be secured by non-cash collateral in conjunction with a credit agreement with that customer. Access to collateral in the event of default is reasonably assured. BOK Financial may use derivative instruments in managing its interest rate sensitivity, as part of its economic hedge of the changes in the fair value of mortgage servicing rights 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 its economic hedge of changes in the fair value of mortgage servicing rights are included in Other Operating Revenue - Gain (loss) on derivatives, net in the Consolidated Statements of Earnings. Changes in the fair value of derivative instruments used to mitigate the market risk of holding trading securities are included in Operating Revenue - Brokerage and trading revenue. BOK Financial also enters into mortgage loan commitments that are considered derivative contracts. Forward sales contracts that have not been designated as hedging instruments are used to economically hedge these mortgage loan commitments as well as mortgage loans held for sale. Mortgage loan commitments, forward sales contracts, and residential mortgage loans held for sale are carried at fair value. Changes in the fair value are reported in Other Operating Revenue - Mortgage banking revenue. BOK Financial offers programs that permit its customers to manage various risks, including fluctuations in energy, cattle and other agricultural products, interest rates and foreign exchange rates with derivative contracts. Customers may also manage interest rate risk through interest rate swaps used by the borrower to modify interest rate terms of their loans or to-be-announced securities used by our 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 market risk from changes in commodity prices, interest rates or foreign exchange rates. The counterparty contracts are identical to customer contracts, except for a fixed pricing spread or fee paid to BOK Financial as profit and compensation for administrative costs and credit risk which is recognized over the life of the contracts and included in other Operating Revenue - Brokerage and trading revenue in the Consolidated Statements of Earnings. Loans Loans are either secured or unsecured based on the type of loan and the financial condition of the borrower. Repayment is generally expected from cash flow or proceeds from the sale of selected assets of the borrower. BOK Financial is exposed to risk of loss on loans due to the borrower's financial difficulties, which may arise from any number of factors, including problems within the respective industry or local economic conditions. Access to collateral, in the event of borrower default, is reasonably assured through adherence to applicable lending laws and through sound lending standards and credit review procedures. Accounting policies for all loans, excluding residential mortgage loans guaranteed by U.S. government agencies, are as follows. Interest is accrued at the applicable interest rate on the outstanding principal amount. Loans are placed on nonaccruing status when, in the opinion of management, full collection of principal or interest is uncertain. Internally risk graded loans are individually evaluated for nonaccruing status quarterly. Non-risk graded loans are generally placed on nonaccruing status when 90 days or more past due or within 60 days of being notified of the borrower's bankruptcy filing. Interest previously accrued but not collected is charged against interest income when the loan is placed on nonaccruing status. Payments received on nonaccruing loans are applied to principal or recognized as interest income, according to management's judgment as to the collectability of principal. Loans may be returned to accruing status when, in the opinion of management, full collection of principal and interest, including principal previously charged off, is probable based on improvements in the borrower's financial condition or a sustained period of performance. For loans acquired with no evidence of credit deterioration, discounts are accreted on either an individual basis for loans with unique characteristics or on a pool basis for groups of homogeneous loans. Accretion is discontinued when a loan with an individually attributed discount is placed on nonaccruing status. Loans to borrowers experiencing financial difficulties may be modified in troubled debt restructurings ("TDRs"). All TDRs are generally classified as nonaccruing, excluding loans guaranteed by U.S. government agencies. Modifications generally consist of extension of payment terms or interest rate concessions and may result either voluntarily through negotiations with the borrower or involuntarily through court order. Generally, principal and accrued but unpaid interest is not voluntarily forgiven. Performing loans may be renewed under the then current collateral, debt service ratio and other underwriting standards. Nonaccruing loans may also be renewed and will remain classified as nonaccruing. Occasionally, loans, other than residential mortgage loans, may be held for sale in order to manage credit concentration. These loans are carried at the lower of cost or fair value with gains or losses recognized in gain (loss) on assets. All loans are charged-off when the loan balance or a portion of the loan balance is no longer supported by the paying capacity of the borrower or when the required cash flow is reduced in a TDR. The charge-off amount is determined through an evaluation of available cash resources and collateral value. Internally risk graded loans are evaluated quarterly and charge-offs are taken in the quarter in which the loss is identified. Non-risk graded loans that are past due between 60 days and 180 days , based on the loan product type, are charged off. Loans to borrowers whose personal obligation has been discharged through Chapter 7 bankruptcy proceedings are charged off within 60 days of notice of the bankruptcy filing, regardless of payment status. Loan origination and commitment fees and direct loan acquisition and origination costs are deferred and amortized as an adjustment to yield over the life of the loan or over the commitment period, as applicable. Amortization does not anticipate loan prepayments. Net unamortized fees are recognized in full at time of payoff. Qualifying residential mortgage loans guaranteed by U.S. government agencies have been sold into GNMA pools. Under certain performance conditions specified in government programs, the Company has the right, but not the obligation to repurchase loans from GNMA pools. These loans no longer qualify for sale accounting and are recognized in the Consolidated Balance Sheets. Guaranteed loans are considered to be impaired because we do not expect to receive all principal and interest based on the loan's contractual terms. A portion of the principal balance continues to be guaranteed; however, interest accrues at a curtailed rate as specified in the programs. The carrying value of these loans is reduced based on an estimate of expected cash flows discounted at the original note rate plus a liquidity spread. Guaranteed loans may be modified in TDRs in accordance with U.S. government agency guidelines. Interest continues to accrue at the modified rate. Guaranteed loans may either be resold into GNMA pools after a performance period specified by the programs or foreclosed and conveyed to the guarantors. Loans are disaggregated into portfolio segments and further disaggregated into classes. The portfolio segment is the level at which the Company develops and documents a systematic method for determining its Allowance for Credit Losses. Classes are based on the risk characteristics of the loans and the Company's method for monitoring and assessing credit risk. Allowance for Loan Losses and Accrual for Off-Balance Sheet Credit Risk The appropriateness of the allowance for loan losses and accrual for off-balance sheet credit risk (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 to provide financing. A consistent well-documented methodology has been developed and is applied by an independent Credit Administration department to assure consistency across the Company. The allowance for loan losses consists of specific allowances attributed to impaired loans that have not yet been charged down to amounts we expect to recover, general allowances based on estimated loss rates by loan class and nonspecific allowances based on factors that affect more than one portfolio segment. There were no changes to the methodology for estimating general allowances during 2019 or 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 personal loans are risk graded based on a quarterly evaluation of the borrowers' ability to repay. Certain commercial loans and most residential mortgage and personal 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, modified in a troubled debt restructuring 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 loan's initial effective interest rate or the fair value of collateral for certain collateral dependent loans. The fair value of real property held as collateral 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 generally are not adjusted by the Company. Updated appraisals are obtained at least annually or more frequently if market conditions indicate collateral values may have declined. Collateral value of mineral rights is generally determined by our internal staff of engineers based on projected cash flows from proven oil and gas reserves under existing economic and operating conditions. The value of other collateral is generally determined by our special assets staff based on projected liquidation 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 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 an estimated loss rate by loan class. The appropriate historical gross loss rate for each loan class is determined by the greater of the current loss rate based on the most recent twelve months or average loss rate over the long-term credit cycle. Recoveries are not directly considered in the estimation of historical 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, historical 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 weighted average risk grade. This comparison determines whether credit risk in each loan class is increasing or decreasing. Historical 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 a specific loan class which have not yet been represented in the historical 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 portfolio segment or loan class. These factors include trends in the economy in our primary lending areas, concentration in large-balance loans and other relevant factors. An accrual for off-balance sheet credit risk is included in Other liabilities in the Consolidated Balance Sheets. The appropriateness of the accrual is determined in the same manner as the allowance for loan losses. A provision for credit losses is charged against or credited to earnings in amounts necessary to maintain an appropriate Allowance for Credit Losses. Recoveries of loans previously charged off are added to the allowance when received. Real Estate and Other Repossessed Assets Real estate and other repossessed assets are acquired in partial or total forgiveness of loans. These assets are initially recognized at cost, which is determined by fair value at date of foreclosure less estimated disposal costs. They are subsequently carried at the lower of cost or current fair value less estimated disposal costs. Decreases in fair value below cost are recognized as asset-specific valuation allowances which may be reversed when supported by future increases in fair value. Subsequent increases in fair value may be used to reduce the allowance but not below zero. Fair values of real estate are based on “as is” appraisals which are updated at least annually or more frequently for certain asset types or assets located in certain distressed markets. Fair values based on appraisals are generally considered to be based on significant other observable inputs. The Company also considers decreases in listing price and other relevant information in quarterly evaluations and reduces the carrying value of real estate and other repossessed assets when necessary. Fair values based on list prices and other relevant information are generally considered to be based on significant unobservable inputs. Additional costs incurred to complete real estate and other repossessed assets may increase the carrying value, up to current fair value based on “as completed” appraisals. The fair value of mineral rights included in repossessed assets are generally determined by our internal staff of engineers based on projected cash flows from proven oil and gas reserves under existing economic and operating conditions. The value of other repossessed assets is generally determined by our special assets staff based on projected liquidation cash flows under current market conditions. Income generated by these assets is recognized as received. Operating expenses are recognized as incurred. Gains or losses on sales of real estate and other repossessed assets are based on the cash proceeds received less the cost basis of the asset, net of any valuation allowances. The estimated disposal costs of real estate and other repossessed assets are evaluated by the Company on an annual basis based on actual results. Transfers of Financial Assets BOK Financial regularly transfers financial assets as part of its mortgage banking activities and periodically may transfer other financial assets. Transfers are recorded as sales when the criteria for surrender of control are met. The Company has elected to carry certain residential mortgage loans held for sale at fair value under the fair value option. Changes in fair value are recognized in net income as they occur. These loans are reported separately in the Consolidated Balance Sheets and changes in fair value are recorded in Other Operating Revenue - Mortgage banking revenue in the Consolidated Statements of Earnings. Fair value of conforming residential mortgage loans that will be sold to U.S. government agencies is based on sales commitments or market quotes considered Level 2 inputs. Fair value of mortgage loans that are unable to be sold to U.S. government agencies is based on Level 3 inputs using quoted prices of loans that are sold in securitization transactions with a liquidity discount applied. The fair value is corroborated with an independent third party on at least an annual basis. BOK Financial retains a repurchase obligation under underwriting representations and warranties related to residential mortgage loans transferred and generally retains the right to service the loans. These are not credit obligations. The Company may incur a recourse obligation in limited circumstances. Separate accruals are recognized in Other liabilities in the Consolidated Balance Sheets for repurchase and recourse obligations. These reserves reflect the estimated amount of probable loss the Company will incur as a result of repurchasing a loan, indemnifications, and other settlement resolutions. Repurchases of loans with an origination defect that are also credit impaired are considered collateral dependent and are initially recognized at net realizable value (appraised value less the cost to sell). The difference between unpaid principal balance and net realizable value is not accreted. Repurchases of loans with an origination defect that are not credit impaired are carried at fair value as of the repurchase date. Interest income continues to accrue on these loans and the discount is accreted over the estimated life of the loan. The Company may also choose to purchase GNMA loans once certain mandated delinquency criteria are met. The loans that are eligible and are chosen to be repurchased are initially recognized at fair value based on expected cash flow discounted using the average agency guaranteed debenture rates, average actual principal loss rates and liquidity premium. Mortgage Servicing Rights Mortgage servicing rights may be purchased or may be recognized when mortgage loans are originated and sold with servicing rights retained. All mortgage servicing rights are carried at fair value. Changes in the fair value are recognized in earnings as they occur. Mortgage servicing rights are not traded in active markets. A cash flow model is used to determine fair value. Key assumptions and estimates, including projected prepayment speeds and assumed servicing costs, earnings on escrow deposits, ancillary income and discount rates, used by this model are based on current market sources. Assumptions used to value mortgage servicing rights are considered significant unobservable inputs. A separate third-party model is used to estimate prepayment speeds based on interest rates, housing turnover rates, estimated loan curtailment, anticipated defaults and other relevant factors. The prepayment model is updated daily for changes in market conditions and adjusted to better correlate with actual performance of BOK Financial's servici

Securities

Securities	12 Months Ended
Securities	Dec. 31, 2019
Marketable Securities [Abstract]
Securities [Text Block]	Securities Trading Securities The fair value and net unrealized gain (loss) included in trading securities is as follows (in thousands): December 31, 2019 December 31, 2018 Fair Value Net Unrealized Gain (Loss) Fair Value Net Unrealized Gain (Loss) U.S. government agency debentures $ 44,264 $ 6 $ 63,765 $ 254 Residential agency mortgage-backed securities 1,504,651 2,293 1,791,584 9,966 Municipal and other tax-exempt securities 26,196 60 34,507 (1 ) Asset-backed securities 14,084 (21 ) 42,656 685 Other debt securities 34,726 21 24,411 65 Total trading securities $ 1,623,921 $ 2,359 $ 1,956,923 $ 10,969 Investment Securities The amortized cost and fair values of investment securities are as follows (in thousands): December 31, 2019 Amortized Fair Gross Unrealized Cost Value Gain Loss Municipal and other tax-exempt securities $ 93,653 $ 96,897 $ 3,250 $ (6 ) Residential agency mortgage-backed securities 10,676 11,164 488 — Other debt securities 189,089 206,341 17,547 (295 ) Total investment securities $ 293,418 $ 314,402 $ 21,285 $ (301 ) December 31, 2018 Amortized Fair Gross Unrealized Cost Value Gain Loss Municipal and other tax-exempt securities $ 137,296 $ 138,562 $ 1,858 $ (592 ) Residential agency mortgage-backed securities 12,612 12,770 293 (135 ) Other debt securities 205,279 215,966 12,257 (1,570 ) Total investment securities $ 355,187 $ 367,298 $ 14,408 $ (2,297 ) The amortized cost and fair values of investment securities at December 31, 2019 , 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 Maturity 1 Fixed maturity debt securities: Amortized cost $ 41,670 $ 84,027 $ 144,705 $ 12,340 $ 282,742 5.10 Fair value 41,840 87,883 161,178 12,337 303,238 Residential mortgage-backed securities: Amortized cost $ 10,676 2 Fair value 11,164 Total investment securities: Amortized cost $ 293,418 Fair value 314,402 1 Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty. 2 The average expected lives of residential mortgage-backed securities were 5.0 years based upon current prepayment assumptions. Temporarily Impaired Investment Securities (in thousands): December 31, 2019 Number of Securities Less Than 12 Months 12 Months or Longer Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Investment: Municipal and other tax-exempt 4 $ 1,001 $ 1 $ 1,706 $ 5 $ 2,707 $ 6 Residential agency mortgage-backed securities — — — — — — — Other debt securities 13 275 1 8,041 294 8,316 295 Total investment securities 17 $ 1,276 $ 2 $ 9,747 $ 299 $ 11,023 $ 301 December 31, 2018 Number of Securities Less Than 12 Months 12 Months or Longer Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Investment: Municipal and other tax- exempt 72 $ 18,255 $ 69 $ 66,141 $ 523 $ 84,396 $ 592 Residential agency mortgage-backed securities 2 — — 5,633 135 5,633 135 Other debt securities 72 13,372 64 23,028 1,506 36,400 1,570 Total investment securities 146 $ 31,627 $ 133 $ 94,802 $ 2,164 $ 126,429 $ 2,297 Available for Sale Securities The amortized cost and fair value of available for sale securities are as follows (in thousands): December 31, 2019 Amortized Fair Gross Unrealized Cost Value Gain Loss U.S. Treasury $ 1,598 $ 1,600 $ 2 $ — Municipal and other tax-exempt 1,789 1,861 72 — Mortgage-backed securities: Residential agency 7,956,297 8,046,096 104,912 (15,113 ) Residential non-agency 25,968 41,609 15,641 — Commercial agency 3,145,342 3,178,005 37,808 (5,145 ) Other debt securities 500 472 — (28 ) Total available for sale securities $ 11,131,494 $ 11,269,643 $ 158,435 $ (20,286 ) December 31, 2018 Amortized Fair Gross Unrealized Cost Value Gain Loss U.S. Treasury $ 496 $ 493 $ — $ (3 ) Municipal and other tax-exempt 2,782 2,864 82 — Mortgage-backed securities: Residential agency 5,886,323 5,804,708 16,149 (97,764 ) Residential non-agency 40,948 59,736 18,788 — Commercial agency 2,986,297 2,953,889 7,955 (40,363 ) Other debt securities 35,545 35,430 12 (127 ) Total available for sale securities $ 8,952,391 $ 8,857,120 $ 42,986 $ (138,257 ) The amortized cost and fair values of available for sale securities at December 31, 2019 , 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 Maturity 1 Fixed maturity debt securities: Amortized cost $ 5,105 $ 1,113,463 $ 1,455,340 $ 575,321 $ 3,149,229 8.15 Fair value 5,114 1,122,392 1,474,002 580,430 3,181,938 Residential mortgage-backed securities: Amortized cost $ 7,982,265 2 Fair value 8,087,705 Total available-for-sale securities: Amortized cost $ 11,131,494 Fair value 11,269,643 1 Expected maturities may differ from contractual maturities, because borrowers may have the right to call or prepay obligations with or without penalty. 2 The average expected lives of mortgage-backed securities were 4.0 years based upon current prepayment assumptions. Sales of available for sale securities resulted in gains and losses as follows (in thousands): Year Ended December 31, 2019 2018 2017 Proceeds $ 1,211,718 $ 745,643 $ 1,309,215 Gross realized gains 14,996 7,117 10,223 Gross realized losses (9,399 ) (9,918 ) (5,795 ) Related federal and state income tax expense (benefit) 1,425 (713 ) 1,722 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 $10.1 billion at December 31, 2019 and $9.1 billion at December 31, 2018 . The secured parties do not have the right to sell or re-pledge these securities. Temporarily Impaired Available for Sale Securities (In thousands) December 31, 2019 Number of Securities Less Than 12 Months 12 Months or Longer Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Available for sale: Mortgage-backed securities: Residential agency 133 $ 1,352,597 $ 6,690 $ 686,002 $ 8,423 $ 2,038,599 $ 15,113 Commercial agency 69 830,047 4,238 210,877 907 1,040,924 5,145 Other debt securities 1 — — 472 28 472 28 Total available for sale securities 203 $ 2,182,644 $ 10,928 $ 897,351 $ 9,358 $ 3,079,995 $ 20,286 December 31, 2018 Number of Securities Less Than 12 Months 12 Months or Longer Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Available for sale: U.S. Treasury 1 $ — $ — $ 493 $ 3 $ 493 $ 3 Mortgage-backed securities: Residential agency 289 510,824 1,158 3,641,370 96,606 4,152,194 97,764 Commercial agency 197 179,258 394 1,969,504 39,969 2,148,762 40,363 Other debt securities 3 9,982 63 20,436 64 30,418 127 Total available for sale securities 490 $ 700,064 $ 1,615 $ 5,631,803 $ 136,642 $ 6,331,867 $ 138,257 Based on evaluations of impaired securities as of December 31, 2019 , the Company does not intend to sell any impaired available for sale securities before fair value recovers to the current amortized cost and it is more-likely-than-not that the Company will not be required to sell impaired securities before fair value recovers, which may be maturity. No other-than-temporary impairment losses were recorded in earnings during 2019 and none were recorded in 2018 . Cumulative other-than-temporary impairment on available for sale securities was $36 million at December 31, 2019 and $45 million at December 31, 2018 . The decrease compared to the prior year was due to sales during 2019. Fair Value Option Securities Fair value option securities represent securities which the Company has elected to carry at fair value and are separately identified on the Consolidated Balance Sheets with changes in the fair value recognized in earnings as they occur. Certain residential mortgage-backed securities issued by U.S. government agencies and derivative contracts are held as an economic hedge of the mortgage servicing rights. The fair value and net unrealized gain (loss) included in fair value option securities is as follows (in thousands): December 31, 2019 December 31, 2018 Fair Value Net Unrealized Gain (Loss) Fair Value Net Unrealized Gain (Loss) U.S. Treasury $ 9,917 $ (48 ) $ — $ — Residential agency mortgage-backed securities 1,088,660 14,109 283,235 2,766 Total $ 1,098,577 $ 14,061 $ 283,235 $ 2,766

Derivatives

Derivatives	12 Months Ended
Derivatives	Dec. 31, 2019
Derivative Instrument Detail [Abstract]
Derivatives [Text Block]	Derivatives The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at December 31, 2019 (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 $ — $ — $ — $ — $ — $ — Interest rate swaps 2,464,478 49,100 (1,839 ) 47,261 — 47,261 Energy contracts 2,151,096 144,906 (107,591 ) 37,315 (38 ) 37,277 Agricultural contracts 16,118 1,522 (22 ) 1,500 — 1,500 Foreign exchange contracts 214,119 213,007 — 213,007 — 213,007 Equity option contracts 81,455 3,233 — 3,233 (660 ) 2,573 Total customer risk management programs 4,927,266 411,768 (109,452 ) 302,316 (698 ) 301,618 Trading 69,721,932 131,561 (115,949 ) 15,612 — 15,612 Interest rate risk management programs 1,268,180 6,226 (81 ) 6,145 — 6,145 Total derivative contracts $ 75,917,378 $ 549,555 $ (225,482 ) $ 324,073 $ (698 ) $ 323,375 Liabilities Notional¹ Gross Fair Value Netting Adjustments Net Fair Value Before Cash Collateral Cash Collateral Fair Value Net of Cash Collateral Customer risk management programs: Interest rate contracts To-be-announced residential mortgage-backed securities $ — $ — $ — $ — $ — $ — Interest rate swaps 2,464,478 49,194 (1,839 ) 47,355 (43,932 ) 3,423 Energy contracts 2,105,391 139,311 (107,591 ) 31,720 (6,031 ) 25,689 Agricultural contracts 16,139 1,507 (22 ) 1,485 (1,485 ) — Foreign exchange contracts 207,919 207,020 — 207,020 — 207,020 Equity option contracts 81,455 3,233 — 3,233 — 3,233 Total customer risk management programs 4,875,382 400,265 (109,452 ) 290,813 (51,448 ) 239,365 Trading 65,144,388 125,535 (115,949 ) 9,586 — 9,586 Interest rate risk management programs 380,401 3,121 (81 ) 3,040 (863 ) 2,177 Total derivative contracts $ 70,400,171 $ 528,921 $ (225,482 ) $ 303,439 $ (52,311 ) $ 251,128 1 Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract. The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at December 31, 2018 (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 $ 10,671,151 $ 92,231 $ (26,787 ) $ 65,444 $ — $ 65,444 Interest rate swaps 1,924,131 36,112 (6,688 ) 29,424 (7,934 ) 21,490 Energy contracts 1,472,209 206,418 (60,983 ) 145,435 (106,752 ) 38,683 Agricultural contracts 21,210 842 (201 ) 641 — 641 Foreign exchange contracts 184,990 183,759 — 183,759 — 183,759 Equity option contracts 89,085 2,021 — 2,021 (648 ) 1,373 Total customer risk management programs 14,362,776 521,383 (94,659 ) 426,724 (115,334 ) 311,390 Trading 15,356,909 45,346 (39,521 ) 5,825 — 5,825 Internal risk management programs 553,079 5,064 (1,350 ) 3,714 — 3,714 Total derivative contracts $ 30,272,764 $ 571,793 $ (135,530 ) $ 436,263 $ (115,334 ) $ 320,929 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 $ 10,558,151 $ 90,388 $ (26,787 ) $ 63,601 $ (63,596 ) $ 5 Interest rate swaps 1,924,131 36,288 (6,688 ) 29,600 (4,110 ) 25,490 Energy contracts 1,434,247 202,494 (60,983 ) 141,511 (1,490 ) 140,021 Agricultural contracts 21,214 812 (201 ) 611 — 611 Foreign exchange contracts 177,423 175,922 — 175,922 — 175,922 Equity option contracts 89,085 2,021 — 2,021 — 2,021 Total customer risk management programs 14,204,251 507,925 (94,659 ) 413,266 (69,196 ) 344,070 Trading 19,374,294 56,983 (39,521 ) 17,462 — 17,462 Internal risk management programs 260,348 9,439 (1,350 ) 8,089 (7,315 ) 774 Total derivative contracts $ 33,838,893 $ 574,347 $ (135,530 ) $ 438,817 $ (76,511 ) $ 362,306 1 Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract. The following summarizes the pre-tax net gains (losses) on derivative instruments and where they are recorded in the Consolidated Statements of Earnings (in thousands): Year Ended December 31, 2019 2018 2017 Brokerage and Trading Revenue Gain (Loss) on Derivatives, Net Brokerage and Trading Revenue Gain (Loss) on Derivatives, Net Brokerage and Trading Revenue Gain (Loss) on Derivatives, Net Customer risk management programs: Interest rate contracts To-be-announced residential mortgage-backed securities $ 9,579 $ — $ 27,190 $ — $ 34,532 $ — Interest rate swaps 3,647 — 2,614 — 2,647 — Energy contracts 5,064 — 8,443 — 5,536 — Agricultural contracts 28 — 53 — 79 — Foreign exchange contracts 623 — 535 — 1,352 — Equity option contracts — — — — — — Total customer risk management programs 18,941 — 38,835 — 44,146 — Trading 13,999 — (13,643 ) — 4,615 — Internal risk management programs — 14,951 — (422 ) — 779 Total derivative contracts $ 32,940 $ 14,951 $ 25,192 $ (422 ) $ 48,761 $ 779 As discussed in Note 7 , certain derivative contracts not designated as hedging instruments related to mortgage loan commitments and forward sales contracts are included in Residential mortgage loans held for sale on the Consolidated Balance Sheets. See Note 7 for additional discussion of notional, fair value and impact on earnings of these contracts. No derivative contracts have been designated as hedging instruments for financial reporting purposes.

Loans and Allowances for Credit

Loans and Allowances for Credit Losses	12 Months Ended
Loans and Allowances for Credit Losses	Dec. 31, 2019
Loans and Leases Receivable, Net Amount [Abstract]
Loans and Allowances for Credit Losses [Text Block]	Loans and Allowances for Credit Losses The portfolio segments of the loan portfolio are as follows (in thousands): December 31, 2019 December 31, 2018 Fixed Rate Variable Rate Non-accrual Total Fixed Rate Variable Rate Non-accrual Total Commercial $ 3,231,485 $ 10,684,749 $ 115,416 $ 14,031,650 $ 2,251,188 $ 11,285,049 $ 99,841 $ 13,636,078 Commercial real estate 1,056,321 3,349,836 27,626 4,433,783 1,477,274 3,265,918 21,621 4,764,813 Residential mortgage 1,652,653 393,897 37,622 2,084,172 1,830,224 358,254 41,555 2,230,033 Personal 193,903 1,007,192 287 1,201,382 190,687 834,889 230 1,025,806 Total $ 6,134,362 $ 15,435,674 $ 180,951 $ 21,750,987 $ 5,749,373 $ 15,744,110 $ 163,247 $ 21,656,730 Accruing loans past due (90 days) 1 $ 7,680 $ 1,338 Foregone interest on nonaccrual loans $ 17,409 $ 15,502 1 Excludes residential mortgage loans guaranteed by agencies of the U.S. government. At December 31, 2019 , loans to businesses and individuals with collateral primarily located in Texas totaled $6.8 billion or 31% of the total loan portfolio. Loans to businesses and individuals with collateral primarily located in Oklahoma totaled $3.5 billion or 16% of our total loan portfolio. Loans to businesses and individuals with collateral primarily located in Colorado totaled $2.8 billion or 13% of our total loan portfolio. Loans for which the collateral location is not relevant, such as unsecured loans and reserve-based energy loans, are distributed by the borrower’s primary operating location. These geographic concentrations subject the loan portfolio to the general economic conditions within these areas. At December 31, 2018 , loans to businesses and individuals with collateral primarily located in Texas totaled $6.4 billion or 30% of the loan portfolio and loans to businesses and individuals with collateral primarily located in Oklahoma totaled $3.5 billion or 16% of the loan portfolio. Commercial Commercial loans represent loans for working capital, facilities acquisition or expansion, purchases of equipment and other needs of commercial customers primarily located within our geographical footprint. Commercial loans are underwritten individually and represent on-going relationships based on a thorough knowledge of the customer, the customer’s industry and market. While commercial loans are generally secured by the customer’s assets including real property, inventory, accounts receivable, operating equipment, interest in mineral rights and other property and may also include personal guarantees of the owners and related parties, the primary source of repayment of the loans is the on-going cash flow from operations of the customer’s business. Inherent lending risk is centrally monitored on a continuous basis from underwriting throughout the life of the loan for compliance with commercial lending policies. At December 31, 2019 , commercial loans with collateral primarily located in Texas totaled $4.7 billion or 33% of the commercial loan portfolio segment. Commercial loans with collateral primarily located in Oklahoma totaled $2.0 billion or 14% of the commercial loan portfolio segment. Commercial loans with collateral primarily located in Colorado totaled $2.0 billion or 14% of the commercial loan portfolio segment. The commercial loan portfolio segment is further divided into loan classes. The services loan class totaled $3.1 billion or 14% of total loans. Approximately $1.5 billion of loans in the services class consisted of loans with individual balances of less than $10 million . Businesses included in the services class include commercial services, Native American tribal governments, financial services, entertainment and recreation and education. The energy loan class totaled $4.0 billion or 18% of total loans, including $3.1 billion of outstanding loans to energy producers. Approximately 58% of committed production loans were secured by properties primarily producing oil and 42% are secured by properties producing natural gas. The healthcare loan class totaled $3.0 billion or 14% of total loans. The healthcare loan class consists primarily of loans for the development and operation of senior housing and care facilities, including independent living, assisted living and skilled nursing. Healthcare also includes loans to hospitals and other medical service providers. At December 31, 2018 , commercial loans with collateral primarily located in Texas totaled $4.1 billion or 30% of the commercial loan portfolio segment and commercial loans with collateral primarily located in Oklahoma totaled $2.2 billion or 16% of the commercial loan portfolio segment. The energy loan class totaled $3.6 billion or 17% of total loans, including $2.9 billion of outstanding loans to energy producers. At December 31, 2018 , approximately 57% of committed production loans were secured by properties primarily producing oil and 43% were secured by properties producing natural gas. The services loan class totaled $3.3 billion or 15% of total loans. Approximately $2.3 billion of loans in the services category consisted of loans with individual balances of less than $10 million . The healthcare loan class totaled $2.8 billion or 13% of total loans. Commercial Real Estate Commercial real estate loans are for the construction of buildings or other improvements to real estate and property held by borrowers for investment purposes primarily within our geographical footprint. We require collateral values in excess of the loan amounts, demonstrated cash flows in excess of expected debt service requirements, equity investment in the project and a portion of the project already sold, leased or permanent financing already secured. The expected cash flows from all significant new or renewed income producing property commitments are stress tested to reflect the risks in varying interest rates, vacancy rates and rental rates. As with commercial loans, inherent lending risks are centrally monitored on a continuous basis from underwriting throughout the life of the loan for compliance with applicable lending policies. At December 31, 2019 , 24% of commercial real estate loans are secured by properties primarily located in the Dallas and Houston areas of Texas. An additional 11% of commercial real estate loans are secured by properties located primarily in the Denver, Colorado metropolitan area. At December 31, 2018 , 26% of commercial real estate loans were secured by properties in Texas, 9% of commercial real estate loans were secured by properties in 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 other unsecured loans. Residential mortgage and personal loans are made in accordance with underwriting policies. 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% . Loan-to-value (“LTV”) ratios are tiered from 60% to 100% , 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 10 years , then adjust annually thereafter. At December 31, 2019 and 2018 , residential mortgage loans included $198 million and $191 million , respectively, 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 $829 million at December 31, 2019 and $917 million at December 31, 2018 . At December 31, 2019 , 63% of the home equity loan portfolio was comprised of first lien loans and 37% of the home equity portfolio was comprised of junior lien loans. Junior lien loans were distributed 35% to amortizing term loans and 65% to revolving lines of credit. At December 31, 2018 , 65% of the home equity portfolio was comprised of first lien loans and 35% of the home equity loan portfolio was comprised of junior lien loans. Junior lien loans were distributed 36% to amortizing term loans and 64% to revolving lines of credit. Home equity loans generally require a minimum FICO score of 700 and a maximum DTI of 40%. The maximum loan amount available for our home equity loan products is generally $400 thousand . Revolving loans have a 5 year revolving period followed by 15 year term of amortizing repayments. Interest-only home equity loans may not be extended for any additional revolving time. All other home equity loans may be extended at management's discretion for an additional 5 year revolving term subject to an update of certain credit information. At December 31, 2019 , 28% of residential mortgage loans are secured by properties located in Oklahoma, 28% of residential mortgage loans are secured by properties located in Texas and 15% of residential mortgage are secured by properties located in Colorado. At December 31, 2018 , 28% of residential mortgage were secured by properties in Texas, 26% of residential mortgage loans were secured by properties in Oklahoma and 19% of residential mortgage loans are secured by properties in Colorado. Credit Commitments Commitments to extend credit are agreements to lend to a customer as long as there is no violation of conditions established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. At December 31, 2019 , outstanding commitments totaled $11.1 billion . Because some commitments are expected to expire before being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. BOK Financial uses the same credit policies in making commitments as it does loans. The amount of collateral obtained, if deemed necessary, is based upon management’s credit evaluation of the borrower. Standby letters of credit are conditional commitments issued to guarantee the performance of a customer to a third party. Because the credit risk involved in issuing standby letters of credit is essentially the same as that involved in extending loan commitments, BOK Financial uses the same credit policies in evaluating the creditworthiness of the customer. Additionally, BOK Financial uses the same evaluation process in obtaining collateral on standby letters of credit as it does for loan commitments. The term of these standby letters of credit is defined in each commitment and typically corresponds with the underlying loan commitment. At December 31, 2019 , outstanding standby letters of credit totaled $646 million . Commercial letters of credit are used to facilitate customer trade transactions with the drafts being drawn when the underlying transaction is consummated. At December 31, 2019 , outstanding commercial letters of credit totaled $1.2 million . Allowances for Credit Losses BOK Financial maintains an allowance for loan losses and an accrual for off-balance sheet credit risk. The accrual for off-balance sheet credit risk is maintained at a level that is appropriate to cover estimated losses associated with credit instruments that are not currently recognized as assets such as loan commitments, standby letters of credit or guarantees. As discussed in greater detail in Note 7 , the Company also has separate accruals related to 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 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, concentration in loans with large balances and other relevant factors. The activity in the allowance for loan losses and the accrual for off-balance sheet credit risk related to loan commitments and standby letters of credit for the year ended December 31, 2019 is summarized as follows (in thousands): Commercial Commercial Real Estate Residential Mortgage Personal Nonspecific Allowance Total Allowance for loan losses: Beginning balance $ 102,226 $ 60,026 $ 17,964 $ 9,473 $ 17,768 $ 207,457 Provision for loan losses 57,125 (12,046 ) (3,838 ) 3,537 (573 ) 44,205 Loans charged off (43,185 ) (1,161 ) (288 ) (6,343 ) — (50,977 ) Recoveries 2,021 4,986 562 2,505 — 10,074 Ending balance $ 118,187 $ 51,805 $ 14,400 $ 9,172 $ 17,195 $ 210,759 Accrual for off-balance sheet credit risk: Beginning balance $ 1,655 $ 52 $ 52 $ 31 $ — $ 1,790 Provision for off-balance sheet credit risk (221 ) 55 (8 ) (31 ) — (205 ) Ending balance $ 1,434 $ 107 $ 44 $ — $ — $ 1,585 Total provision for credit losses $ 56,904 $ (11,991 ) $ (3,846 ) $ 3,506 $ (573 ) $ 44,000 The activity in the allowance for loan losses and the accrual for off-balance sheet credit risk related to loan commitments and standby letters of credit for the year ended December 31, 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 12,521 (147 ) (1,156 ) 3,175 (4,449 ) 9,944 Loans charged off (37,880 ) — (378 ) (5,325 ) — (43,583 ) Recoveries 3,316 3,552 1,047 2,499 — 10,414 Ending balance $ 102,226 $ 60,026 $ 17,964 $ 9,473 $ 17,768 $ 207,457 Accrual for off-balance sheet credit risk: Beginning balance $ 3,644 $ 45 $ 43 $ 2 $ — $ 3,734 Provision for off-balance sheet credit risk (1,989 ) 7 9 29 — (1,944 ) Ending balance $ 1,655 $ 52 $ 52 $ 31 $ — $ 1,790 Total provision for credit losses $ 10,532 $ (140 ) $ (1,147 ) $ 3,204 $ (4,449 ) $ 8,000 The activity in the allowance for loan losses and the accrual for off-balance sheet credit risk related to loan commitments and standby letters of credit for the year ended December 31, 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 (595 ) 4,008 116 2,964 (5,983 ) 510 Loans charged off (19,810 ) (76 ) (649 ) (5,064 ) — (25,599 ) Recoveries 4,461 1,940 760 2,451 — 9,612 Ending balance $ 124,269 $ 56,621 $ 18,451 $ 9,124 $ 22,217 $ 230,682 Accrual for off-balance sheet credit risk: Beginning balance $ 11,063 $ 123 $ 50 $ 8 $ — $ 11,244 Provision for off-balance sheet credit risk (7,419 ) (78 ) (7 ) (6 ) — (7,510 ) Ending balance $ 3,644 $ 45 $ 43 $ 2 $ — $ 3,734 Total provision for credit losses $ (8,014 ) $ 3,930 $ 109 $ 2,958 $ (5,983 ) $ (7,000 ) The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2019 is as follows (in thousands): Collectively Measured for Impairment Individually Measured for Impairment Total Recorded Investment Related Allowance Recorded Investment Related Allowance Recorded Investment Related Allowance Commercial $ 13,916,234 $ 100,773 $ 115,416 $ 17,414 $ 14,031,650 $ 118,187 Commercial real estate 4,406,157 51,805 27,626 — 4,433,783 51,805 Residential mortgage 2,046,550 14,400 37,622 — 2,084,172 14,400 Personal 1,201,095 9,172 287 — 1,201,382 9,172 Total 21,570,036 176,150 180,951 17,414 21,750,987 193,564 Nonspecific allowance — — — — — 17,195 Total $ 21,570,036 $ 176,150 $ 180,951 $ 17,414 $ 21,750,987 $ 210,759 The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 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 $ 13,536,237 $ 93,494 $ 99,841 $ 8,732 $ 13,636,078 $ 102,226 Commercial real estate 4,743,192 60,026 21,621 — 4,764,813 60,026 Residential mortgage 2,188,478 17,964 41,555 — 2,230,033 17,964 Personal 1,025,576 9,473 230 — 1,025,806 9,473 Total 21,493,483 180,957 163,247 8,732 21,656,730 189,689 Nonspecific allowance — — — — — 17,768 Total $ 21,493,483 $ 180,957 $ 163,247 $ 8,732 $ 21,656,730 $ 207,457 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 personal 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 personal 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 December 31, 2019 is as follows (in thousands): Internally Risk Graded Non-Graded Total Recorded Investment Related Allowance Recorded Investment Related Allowance Recorded Investment Related Allowance Commercial $ 13,997,538 $ 117,236 $ 34,112 $ 951 $ 14,031,650 $ 118,187 Commercial real estate 4,433,783 51,805 — — 4,433,783 51,805 Residential mortgage 279,113 3,085 1,805,059 11,315 2,084,172 14,400 Personal 1,116,297 7,003 85,085 2,169 1,201,382 9,172 Total 19,826,731 179,129 1,924,256 14,435 21,750,987 193,564 Nonspecific allowance — — — — — 17,195 Total $ 19,826,731 $ 179,129 $ 1,924,256 $ 14,435 $ 21,750,987 $ 210,759 The 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, 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 $ 13,586,654 $ 101,303 $ 49,424 $ 923 $ 13,636,078 $ 102,226 Commercial real estate 4,764,813 60,026 — — 4,764,813 60,026 Residential mortgage 505,046 3,310 1,724,987 14,654 2,230,033 17,964 Personal 948,890 6,633 76,916 2,840 1,025,806 9,473 Total 19,805,403 171,272 1,851,327 18,417 21,656,730 189,689 Nonspecific allowance — — — — — 17,768 Total $ 19,805,403 $ 171,272 $ 1,851,327 $ 18,417 $ 21,656,730 $ 207,457 Loans are considered to be performing if they are in compliance with the original terms of the agreement which is consistent with the regulatory guideline of “pass.” Performing also includes loans considered to be “other loans especially mentioned” by regulatory guidelines and all residential mortgage loans guaranteed by agencies of the U.S. government that continue to accrue interest based on criteria of the guarantor's 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 in accordance with the original terms of the loan agreements 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 December 31, 2019 by the risk grade categories (in thousands): Internally Risk Graded Non-Graded Performing Pass Other Loans Especially Mentioned Accruing Substandard Nonaccrual Performing Nonaccrual Total Commercial: Energy $ 3,700,406 $ 117,298 $ 63,951 $ 91,722 $ — $ — $ 3,973,377 Services 3,050,946 29,943 33,791 7,483 — — 3,122,163 Wholesale/retail 1,749,023 5,281 5,399 1,163 — — 1,760,866 Manufacturing 623,219 18,214 13,883 10,133 — — 665,449 Healthcare 2,995,514 13,117 20,805 4,480 — — 3,033,916 Public finance 709,868 — — — — — 709,868 Other commercial and industrial 709,729 4,028 17,744 398 34,075 37 766,011 Total commercial 13,538,705 187,881 155,573 115,379 34,075 37 14,031,650 Commercial real estate: Residential construction and land development 150,529 — — 350 — — 150,879 Retail 743,343 12,067 1,243 18,868 — — 775,521 Office 923,202 5,177 — — — — 928,379 Multifamily 1,257,005 1,604 95 6,858 — — 1,265,562 Industrial 852,539 1,658 1,011 909 — — 856,117 Other commercial real estate 455,045 1,639 — 641 — — 457,325 Total commercial real estate 4,381,663 22,145 2,349 27,626 — — 4,433,783 Residential mortgage: Permanent mortgage 276,138 78 2,404 493 758,260 19,948 1,057,321 Permanent mortgages guaranteed by U.S. government agencies — — — — 191,694 6,100 197,794 Home equity — — — — 817,976 11,081 829,057 Total residential mortgage 276,138 78 2,404 493 1,767,930 37,129 2,084,172 Personal 1,116,196 45 — 56 84,853 232 1,201,382 Total $ 19,312,702 $ 210,149 $ 160,326 $ 143,554 $ 1,886,858 $ 37,398 $ 21,750,987 The following table summarizes the Company’s loan portfolio at December 31, 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 $ 3,414,039 $ 42,176 $ 86,624 47,494 $ — $ — $ 3,590,333 Services 3,167,203 49,761 32,661 8,567 — — 3,258,192 Wholesale/retail 1,593,902 18,809 7,131 1,316 — — 1,621,158 Manufacturing 668,438 30,934 22,230 8,919 — — 730,521 Healthcare 2,730,121 14,920 37,698 16,538 — — 2,799,277 Public finance 804,550 — — — — — 804,550 Other commercial and industrial 756,815 1,266 7,588 16,954 49,371 53 832,047 Total commercial 13,135,068 157,866 193,932 99,788 49,371 53 13,636,078 Commercial real estate: Residential construction and land development 148,234 — — 350 — — 148,584 Retail 885,588 11,926 1,289 20,279 — — 919,082 Office 1,059,334 10,532 3,054 — — — 1,072,920 Multifamily 1,287,471 281 12 301 — — 1,288,065 Industrial 776,898 — 1,208 — — — 778,106 Other commercial real estate 555,301 1,188 876 691 — — 558,056 Total commercial real estate 4,712,826 23,927 6,439 21,621 — — 4,764,813 Residential mortgage: Permanent mortgage 269,678 52 9,730 1,991 819,199 21,960 1,122,610 Permanent mortgages guaranteed by U.S. government agencies — — — — 183,734 7,132 190,866 Home equity 223,298 — 296 — 682,491 10,472 916,557 Total residential mortgage 492,976 52 10,026 1,991 1,685,424 39,564 2,230,033 Personal 944,256 115 4,443 76 76,762 154 1,025,806 Total $ 19,285,126 $ 181,960 $ 214,840 123,476 $ 1,811,557 $ 39,771 $ 21,656,730 Impaired Loans Loans are considered to be impaired when it is probable that the Company will not be able to collect all amounts due according to the contractual terms of the loan agreement. This includes all nonaccruing loans, all loans modified in a troubled debt restructuring and all loans repurchased from GNMA pools. A summary of impaired loans follows (in thousands): As of December 31, 2019 Year Ended Recorded Investment December 31, 2019 Unpaid Principal Balance Total With No With Allowance Related Allowance Average Recorded Interest Income Recognized Commercial: Energy $ 149,441 $ 91,722 $ 44,244 $ 47,478 $ 16,854 $ 69,119 $ — Services 10,923 7,483 6,301 1,182 240 5,854 — Wholesale/retail 1,980 1,163 902 261 101 916 — Manufacturing 10,848 10,133 9,914 219 219 9,144 — Healthcare 13,774 4,480 4,480 — — 7,798 — Public finance — — — — — — — Other commercial and industrial 8,227 435 435 — — 8,568 — Total commercial 195,193 115,416 66,276 49,140 17,414 101,399 — Commercial real estate: Residential construction and land development 1,306 350 350 — — 350 — Retail 20,265 18,868 18,868 — — 19,573 — Office — — — — — — — Multifamily 6,858 6,858 6,858 — — 3,580 — Industrial 909 909 909 — — 454 — Other commercial real estate 801 641 641 — — 666 — Total commercial real estate 30,139 27,626 27,626 — — 24,623 — Residential mortgage: Permanent mortgage 24,868 20,441 20,441 — — 22,196 1,198 Permanent mortgage guaranteed by U.S. government agencies 1 204,187 197,794 197,794 — — 195,009 7,733 Home equity 12,967 11,081 11,081 — — 10,776 — Total residential mortgage 242,022 229,316 229,316 — — 227,981 8,931 Personal 360 287 287 — — 259 — Total $ 467,714 $ 372,645 $ 323,505 $ 49,140 $ 17,414 $ 354,262 $ 8,931 1 All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2019 , $6.1 million of these loans are nonaccruing and $192 million are accruing based on the guarantee by U.S. government agencies. Generally, no interest income is recognized on impaired loans until all principal balances, including amounts charged-off, have been recovered. As of December 31, 2018 Year Ended Recorded Investment December 31, 2018 Unpaid Principal Balance Total With No Allowance With Allowance Related Allowance Average Recorded Investment Interest Income Recognized Commercial: Energy $ 79,675 $ 47,494 $ 18,639 $ 28,855 $ 5,362 $ 69,645 $ — Services 13,437 8,567 8,489 78 74 4,509 — Wholesale/retail 1,722 1,316 1,015 301 101 1,784 — Manufacturing 10,055 8,919 8,673 246 246 7,249 — Healthcare 24,319 16,538 10,563 5,975 2,949 14,297 — Public finance — — — — — — — Other commercial and industrial 26,955 17,007 17,007 — — 17,976 — Total commercial 156,163 99,841 64,386 35,455 8,732 115,460 — Commercial real estate: Residential construction and land development 1,306 350 350 — — 1,091 — Retail 27,680 20,279 20,279 — — 10,278 — Office — — — — — 137 — Multifamily 301 301 301 — — 151 — Industrial — — — — — — — Other commercial real estate 851 691 691 — — 581 — Total commercial real estate 30,138 21,621 21,621 — — 12,238 — Residential mortgage: Permanent mortgage 28,716 23,951 23,951 — — 24,572 1,233 Permanent mortgage guaranteed by U.S. government agencies 1 196,296 190,866 190,866 — — 180,813 7,172 Home equity 12,196 10,472 10,472 — — 11,774 — Total residential mortgage 237,208 225,289 225,289 — — 217,159 8,405 Personal 278 230 230 — — 250 — Total $ 423,787 $ 346,981 $ 311,526 $ 35,455 $ 8,732 $ 345,107 $ 8,405 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, 2018 , $7.1 million of these loans are nonaccruing and $184 million are accruing based on the guarantee by U.S. government agencies. Troubled Debt Restructurings At December 31, 2019 the Company has $132 million in troubled debt restructurings (TDRs), of which $92 million are accruing residential mortgage loans guaranteed by U.S. government agencies. Approximately $57 million of TDRs are performing in accordance with the modified terms. The loans designated as TDRs had $18.6 million in charge offs during the year ended December 31, 2019 . At December 31, 2018 , TDRs totaled $166 million , of which $86 million were accruing residential mortgage loans guaranteed by U.S. government agencies. Approximately $71 million of TDRs were performing. The loans designated as TDRs had $16.1 million in charge offs during the year ended December 31, 2018 . TDRs generally consist of interest rate concessions, payment stream concessions or a combination of concessions to distressed borrowers. During the year ended December 31, 2019 , $37 million of loans were restructured. During the year ended December 31, 2018 , $75 million of loans were restructured. 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 December 31, 2019 is as follows (in thousands): Past Due Current 30 to 59 Days 60 to 89 Days 90 Days or More Nonaccrual Total Commercial: Energy $ 3,881,244 $ 401 10 $ — $ 91,722 $ 3,973,377 Services 3,105,621 1,737 523 6,799 7,483 3,122,163 Wholesale/retail 1,758,878 712 113 — 1,163 1,760,866 Manufacturing 654,329 410 190 387 10,133 665,449 Healthcare 3,027,329 2,039 — 68 4,480 3,033,916 Public finance 707,638 2,230 — — — 709,868 Other commercial and industrial 764,390 414 772 — 435 766,011 Total commercial 13,899,429 7,943 1,608 7,254 115,416 14,031,650 Commercial real estate: Residential construction and land development 147,379 3,093 — 57 350 150,879 Retail 756,653 — — — 18,868 775,521 Office 928,379 — — — — 928,379 Multifamily 1,258,704 — — — 6,858 1,265,562 Industrial 855,208 — — — 909 856,117 Other commercial real estate 454,253 1,827 250 354 641 457,325 Total commercial real estate 4,400,576 4,920 250 411 27,626 4,433,783 Residential mortgage: Permanent mortgage 1,034,716 2,011 153 — 20,441 1,057,321 Permanent mortgages guaranteed by U.S. government agencies 46,898 24,203 18,187 102,406 6,100 197,794 Home equity 814,325 3,343 308 — 11,081 829,057 Total residential mortgage 1,895,939 29,557 18,648 102,406 37,622 2,084,172 Personal 1,196,362 4,664 54 15 287 1,201,382 Total $ 21,392,306 $ 47,084 20,560 $ 110,086 $ 180,951 $ 21,750,987 A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of December 31, 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 $ 3,542,839 $ — — $ — $ 47,494 $ 3,590,333 Services 3,237,578 6,009 6,038 — 8,567 3,258,192 Wholesale/retail 1,619,290 515 37 — 1,316 1,621,158 Manufacturing 721,204 392 6 — 8,919 730,521 Healthcare 2,781,944 241 — 554 16,538 2,799,277 Public finance 804,550 — — — — 804,550 Other commercial and industrial 814,489 518 25 8 17,007 832,047 Total commercial 13,521,894 7,675 6,106 562 99,841 13,636,078 Commercial real estate: Residential construction and land development 147,705 249 280 — 350 148,584 Retail 884,424 14,379 — — 20,279 919,082 Office 1,072,920 — — — — 1,072,920 Multifamily 1,287,483 281 — — 301 1,288,065 Industrial 776,898 1,208 — — — 778,106 Other commercial real estate 556,239 412 — 714 691 558,056 Total commercial real estate 4,725,669 16,529 280 714 21,621 4,764,813 Residential mortgage: Permanent mortgage 1,095,097 3,196 366 — 23,951 1,122,610 Permanent mortgages guaranteed by U.S. government agencies 37,459 24,369 16,345 105,561 7,132 190,866 Home equity 904,572 1,102 352 59 10,472 916,557 Total residential mortgage 2,037,128 28,667 17,063 105,620 41,555 2,230,033 Personal 1,024,298 479 796 3 230 1,025,806 Total $ 21,308,989 $ 53,350 24,245 $ 106,899 $ 163,247 $ 21,656,730

Premises and Equipment and Leas

Premises and Equipment and Leases	12 Months Ended
Premises and Equipment and Leases	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Premises and Equipment Disclosure [Text Block]	Premises and Equipment and Leases Premises and equipment at December 31 are summarized as follows (in thousands): December 31, 2019 2018 Land $ 69,960 $ 70,575 Buildings and improvements 421,952 266,733 Software and related integration 98,487 150,207 Furniture and equipment 135,153 129,988 Construction in progress 53,498 27,514 Premises and equipment 779,050 645,017 Less accumulated depreciation 243,531 314,984 Premises and equipment, net of accumulated depreciation $ 535,519 $ 330,033 Depreciation expense of premises and equipment was $51.6 million , $51.2 million and $47.7 million for the years ended December 31, 2019 , 2018 and 2017 , respectively. Effective January 1, 2019, premises and equipment included right-of-use assets for leased office space and facilities. Leases are at market rates at inception and may contain escalations based on consumer price index or similar benchmarks and options to renew at then market rates. At December 31, 2019 , right-of-use assets of $180 million are included in buildings and improvements and related right-of-use liabilities are included in other liabilities. The weighted-average remaining lease term was 11.1 years and the weighted average discount rate on operating leases was 3.2 percent . Operating lease costs recognized as occupancy and equipment expense were $24.2 million for the year ended December 31, 2019 . Operating cash flows from operating leases were $23.3 million for the year ended December 31, 2019 . Total rent expense for BOK Financial was $43.0 million in 2019 , $28.5 million in 2018 and $27.5 million in 2017 . At December 31, 2019 , un-discounted operating lease liabilities are scheduled to mature as follows: $27.5 million in 2020 , $25.7 million in 2021 , $20.1 million in 2022 , $18.9 million in 2023 , $18.2 million in 2024 and $127 million thereafter. Operating expense and short term lease costs total $12.6 million for the year ended December 31, 2019 . BOKF, NA is obligated under a long-term lease for its bank premises in downtown Tulsa. The original lease dated November 1, 1976 was renegotiated on July 1, 2019. The new lease will terminate on December 31, 2034. The Company has the option to renew for an additional 10 years. Premises leases may include options to renew at then current market rates and may include escalation provisions based upon changes in consumer price index or similar benchmarks.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
Goodwill and Intangible Assets	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets [Text Block]	Goodwill and Intangible Assets On October 1, 2018 , the Company acquired CoBiz Financial, Inc. ("CoBiz") , parent company of CoBiz Bank. The Company paid total consideration of $944 million , which included $243 million in cash along with the issuance of 7.2 million shares of BOK Financial common stock valued at $701 million in exchange for all the outstanding shares of CoBiz. Goodwill acquired was attributed to synergies expected to be gained through consolidation of administrative functions resulting in cost savings. The purchase price allocation was completed in 2019 with no significant change from the preliminary purchase price allocation. 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 the acquisition was $14 million and included $6.7 million of intangible assets. The following table presents the original cost and accumulated amortization of intangible assets (in thousands): Dec. 31, 2019 2018 Core deposit premiums $ 103,200 $ 103,200 Less accumulated amortization 19,364 5,032 Net core deposit premiums 83,836 98,168 Other identifiable intangible assets 74,372 63,497 Less accumulated amortization 32,937 26,816 Net other identifiable intangible assets 41,435 36,681 Total intangible assets, net $ 125,271 $ 134,849 Expected amortization expense for intangible assets that will continue to be amortized (in thousands): Core Deposit Premiums Other Identifiable Intangible Assets Total 2020 $ 12,892 $ 7,405 $ 20,297 2021 11,893 6,706 18,599 2022 10,981 5,339 16,320 2023 10,145 4,298 14,443 2024 9,379 3,284 12,663 Thereafter 28,546 14,403 42,949 $ 83,836 $ 41,435 $ 125,271 The changes in the carrying value of goodwill by operating segment are as follows (in thousands): Commercial Banking Consumer Banking Wealth Management Funds Management and Other Total Balance, December 31, 2017 313,270 43,458 90,702 — 447,430 Goodwill recognized during 2018 1 — — — 601,833 601,833 Balance, December 31, 2018 313,270 43,458 90,702 601,833 1,049,263 Adjustment 1 600,661 — — (601,833 ) (1,172 ) Balance, December 31, 2019 $ 913,931 $ 43,458 $ 90,702 $ — $ 1,048,091 1 Goodwill related to the CoBiz acquisition was not yet allocated to the operating segments as of December 31, 2018 and was included in Funds Management and Other in 2018 then allocated during 2019. The annual goodwill evaluations for 2019 and 2018 did not indicate impairment for any reporting unit. Economic conditions did not indicate that impairment existed for any identifiable intangible assets and therefore no impairment evaluation was performed.

Mortgage Banking Activities Mor

Mortgage Banking Activities Mortgage Banking Activities (Notes)	12 Months Ended
	Dec. 31, 2019
Mortgage Banking [Abstract]
Mortgage Banking Activities [Text Block]	Mortgage Banking Activities Residential Mortgage Loan Production The Company originates, markets and services conventional and government-sponsored residential mortgage loans. Generally, conforming fixed rate residential mortgage loans are held for sale in the secondary market and non-conforming and adjustable-rate residential mortgage loans are held for investment. The volume of mortgage loans originated for sale and secondary market prices are the primary drivers of originating and marketing revenue. Residential mortgage loan commitments are generally outstanding for 60 to 90 days, which represents the typical period from commitment to originate a residential mortgage loan to when the closed loan is sold to an investor. Residential mortgage loan commitments are subject to both credit and interest rate risk. Credit risk is managed through underwriting policies and procedures, including collateral requirements, which are generally accepted by the secondary loan markets. Exposure to interest rate fluctuations is partially managed through forward sales of residential mortgage-backed securities and forward sales contracts. These latter contracts set the price for loans that will be delivered in the next 60 to 90 days. The unpaid principal balance of residential mortgage loans held for sale, notional amounts of derivative contracts related to residential mortgage loan commitments and forward contract sales and their related fair values included in Mortgage loans held for sale on the Consolidated Balance Sheets were (in thousands): December 31, 2019 December 31, 2018 Unpaid Principal Balance/ Notional Fair Value Unpaid Principal Balance/ Notional Fair Value Residential mortgage loans held for sale $ 175,117 $ 177,703 $ 145,057 $ 146,971 Residential mortgage loan commitments 158,460 5,233 160,848 5,378 Forward sales contracts 315,203 (665 ) 274,000 (3,128 ) $ 182,271 $ 149,221 No residential mortgage loans held for sale were 90 days or more past due or considered impaired as of December 31, 2019 or December 31, 2018 . No credit losses were recognized on residential mortgage loans held for sale for the years ended December 31, 2019 , 2018 and 2017 . Mortgage banking revenue was as follows (in thousands): Year Ended 2019 2018 2017 Production revenue: Net realized gains on sales of mortgage loans $ 39,730 $ 36,379 $ 45,128 Net change in unrealized gain on mortgage loans held for sale 672 (674 ) 2,031 Net change in the fair value of mortgage loan commitments (145 ) (1,145 ) (3,210 ) Net change in the fair value of forward sales contracts 2,463 (2,870 ) (5,451 ) Total mortgage production revenue 42,720 31,690 38,498 Servicing revenue 64,821 66,097 66,221 Total mortgage banking revenue $ 107,541 $ 97,787 $ 104,719 Mortgage production revenue includes gain (loss) on residential mortgage loans held for sale and changes in the fair value of derivative contracts not designated as hedging instruments related to residential mortgage loan commitments and forward sales contracts. Servicing revenue includes servicing fee income and late charges on loans serviced for others. Residential Mortgage Servicing The Company generally retains the right to service residential mortgage loans sold and may purchase mortgage servicing rights. The unpaid principal balance of loans serviced for others is the primary driver of servicing revenue. The following represents a summary of mortgage servicing rights (Dollars in thousands): December 31, 2019 2018 2017 Number of residential mortgage loans serviced for others 126,828 132,463 136,528 Outstanding principal balance of residential mortgage loans serviced for others $ 20,727,106 $ 21,658,335 $ 22,046,632 Weighted average interest rate 3.98 % 3.99 % 3.94 % Remaining contractual term (in months) 289 293 297 Activity in capitalized mortgage servicing rights during the three years ended December 31, 2019 is as follows (in thousands): Balance, December 31, 2016 $ 247,073 Additions, net 39,149 Change in fair value due to loan runoff (33,527 ) Change in fair value due to market changes 172 Balance, December 31, 2017 252,867 Additions, net 35,247 Change in fair value due to loan runoff (33,528 ) Change in fair value due to market changes 4,668 Balance, December 31, 2018 259,254 Additions, net 35,128 Change in fair value due to loan runoff (38,979 ) Change in fair value due to market changes (53,517 ) Balance, December 31, 2019 $ 201,886 Changes in the fair value of mortgage servicing rights due to market changes are included in Other operating revenue in the Consolidated Statements of Earnings. Changes in fair value due to loan runoff are included in Mortgage banking costs. Mortgage servicing rights are not traded in active markets. Fair value is determined by discounting the projected net cash flows. Significant assumptions used to determine fair value considered to be significant unobservable inputs were as follows: December 31, 2019 2018 Discount rate – risk-free rate plus a market premium 9.81% 9.90% Prepayment rate - based upon loan interest rate, original term and loan type 8.28% - 16.05% 8.05% - 15.74% Loan servicing costs – annually per loan based upon loan type: Performing loans $68 - $94 $67 - $93 Delinquent loans $150 - $500 $150 - $500 Loans in foreclosure $1,000 - $4,000 $1,000 - $4,000 Primary/secondary mortgage rate spread 104 bps 105 bps Escrow earnings rate – indexed to rates paid on deposit accounts with comparable average life 1.73% 2.57% Delinquency rate 2.73% 2.74% 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.

Deposits

Deposits	12 Months Ended
Deposits	Dec. 31, 2019
Deposits [Abstract]
Deposits [Text Block]	Interest expense on deposits is summarized as follows (in thousands): Year Ended December 31, 2019 2018 2017 Transaction deposits $ 132,854 $ 65,859 $ 28,627 Savings 677 439 359 Time: Certificates of deposits under $100,000 8,299 5,751 7,702 Certificates of deposits $100,000 and over 29,288 19,739 12,393 Other time deposits 4,420 3,729 4,722 Total time 42,007 29,219 24,817 Total $ 175,538 $ 95,517 $ 53,803 The aggregate amounts of time deposits in denominations of $250,000 or more at December 31, 2019 and 2018 were $845 million and $756 million , respectively. Time deposit maturities are as follows: 2020 – $1.5 billion , 2021 – $230 million , 2022 – $104 million , 2023 – $103 million , 2024 – $55 million and $228 million thereafter. The aggregate amount of overdrawn customer transaction deposits that have been reclassified as loan balances was $8.7 million at December 31, 2019 and $27 million at December 31, 2018 .

Other Borrowed Funds

Other Borrowed Funds	12 Months Ended
Other Borrowed Funds	Dec. 31, 2019
Debt Disclosure [Abstract]
Other Borrowed Funds [Text Block]	Other Borrowed Funds Information relating to other borrowings is summarized as follows (dollars in thousands): As of Year Ended December 31, 2019 December 31, 2019 Balance Rate Average Balance Rate Maximum Funds purchased 3,390,528 1.53 % 2,438,376 2.08 % 3,390,528 Repurchase agreements 427,822 0.50 % 399,785 0.57 % 427,822 Other borrowings: Federal Home Loan Bank advances 4,500,000 1.79 % 7,122,466 2.44 % 8,000,000 GNMA repurchase liability 15,417 4.32 % 13,746 4.47 % 19,581 Other 11,638 5.09 % 11,144 5.30 % 34,676 Total other borrowings 4,527,055 7,147,356 2.45 % Subordinated debentures 1 275,923 5.15 % 276,075 5.47 % 275,923 Total other borrowed funds $ 8,621,328 $ 10,261,592 2.37 % As of Year Ended December 31, 2018 December 31, 2018 Balance Rate Average Balance Rate Maximum Funds purchased 402,450 2.34 % 419,322 1.89 % 949,531 Repurchase agreements 615,961 0.36 % 464,582 0.28 % 615,961 Other borrowings: Federal Home Loan Bank advances 6,100,000 2.65 % 6,207,142 2.06 % 6,500,000 GNMA repurchase liability 15,552 4.43 % 14,783 4.47 % 16,529 Other 8,838 2.90 % 14,516 2.67 % 20,422 Total other borrowings 6,124,390 6,236,441 2.07 % Subordinated debentures 1 275,913 5.34 % 177,884 5.52 % 275,913 Total other borrowed funds $ 7,418,714 $ 7,298,229 2.03 % As of Year Ended December 31, 2017 December 31, 2017 Balance Rate Average Balance Rate Maximum Funds purchased 58,628 1.00 % 58,064 0.73 % 80,967 Repurchase agreements 516,335 0.17 % 433,791 0.10 % 536,094 Other borrowings: Federal Home Loan Bank advances 5,100,000 1.47 % 5,882,466 1.13 % 6,200,000 GNMA repurchase liability 19,947 4.22 % 20,509 4.59 % 24,139 Other 14,950 2.61 % 16,317 3.35 % 18,610 Total other borrowings 5,134,897 5,919,292 1.15 % Subordinated debentures 1 144,677 5.60 % 147,954 5.57 % 151,875 Total other borrowed funds $ 5,854,537 $ 6,559,101 1.18 % 1 Parent Company only. Aggregate annual principal repayments at December 31, 2019 are as follows (in thousands): 2020 $ 8,335,742 2021 1,244 2022 575 2023 1,454 2024 3,599 Thereafter 278,714 Total $ 8,621,328 Funds purchased are unsecured and generally mature within one day to ninety days from the transaction date. Securities repurchase agreements are recorded as secured borrowings that generally mature within ninety days and are secured by certain available for sale securities. Additional information relating to securities sold under agreements to repurchase and related liabilities at December 31, 2019 and 2018 is as follows (dollars in thousands): December 31, 2019 Amortized Fair Repurchase Security Sold/Maturity Cost Value Liability 1 Rate U.S. government agency mortgage-backed securities: Overnight 1 $ 431,939 $ 435,898 $ 427,822 0.50 % Long-term — — — — % Total Agency Securities $ 431,939 $ 435,898 $ 427,822 0.50 % December 31, 2018 Amortized Fair Repurchase Security Sold/Maturity Cost Value Liability 1 Rate U.S. government agency mortgage-backed securities: Overnight 1 $ 636,864 $ 628,229 $ 615,961 0.36 % Long-term — — — — % Total Agency Securities $ 636,864 $ 628,229 $ 615,961 0.36 % 1 BOK Financial maintains control over the securities underlying overnight repurchase agreements and generally transfers control over securities underlying longer-term dealer repurchase agreements to the respective counterparty. Borrowings from the Federal Home Loan Banks are used for funding purposes. In accordance with policies of the Federal Home Loan Banks, BOK Financial has granted a blanket pledge of eligible assets (generally unencumbered U.S. Treasury and residential mortgage-backed securities, 1-4 family loans and multifamily loans) as collateral for these advances. The Federal Home Loan Banks have issued letters of credit totaling $661 million to secure BOK Financial’s obligations to depositors of public funds. The unused credit available to BOK Financial at December 31, 2019 pursuant to the Federal Home Loan Bank’s collateral policies is $4.9 billion . In 2016, BOK Financial issued $150 million of subordinated debt that will mature on June 30, 2056 . Interest on this debt bears an interest rate of 5.375% , payable quarterly. On June 30, 2021 , BOK Financial will have the option to redeem the debt at the principal amount plus accrued interest, subject to regulatory approval. As a result of the acquisition of CoBiz Financial, we obtained $60 million of subordinated debt issued in June 2015 that will mature on June 25, 2030 . This debt bears interest at the rate of 5.625% through June 2025 and thereafter, the notes will bear interest at an annual floating rate equal to three-month LIBOR plus 3.17% . The debt contains a call option that allows for repayment prior to contractual maturity. The call option is available on June 25, 2025 and quarterly thereafter at 100% of the principal amount. Also through CoBiz Financial, we acquired junior subordinated debentures split across three issuance tranches. Junior subordinated debentures of $21 million will mature September 17, 2033 and bear an interest rate of three-month LIBOR plus 2.95% that resets quarterly. Junior subordinated debentures of $31 million will mature on July 23, 2034 and bear an interest rate of three-month LIBOR plus 2.60% that resets quarterly. Junior subordinated debentures of $20 million will mature on September 30, 2035 and bear an interest rate of three-month LIBOR plus 1.45% that resets quarterly. The junior subordinated debentures are subject to early redemption prior to maturity. BOK Financial Securities, Inc. may borrow funds from Pershing, LLC ("Pershing"), a clearing broker/dealer and a wholly owned subsidiary of Bank of New York Mellon, for the purposes of financing securities purchases or to facilitate funding of investment banking activities, on terms to be negotiated at the time of the borrowing. BOK Financial Securities, Inc. had no borrowings outstanding at December 31, 2019 and none at December 31, 2018 . The Company has a liability related to the repurchase of certain delinquent residential mortgage loans previously sold into GNMA mortgage pools. Interest is payable at rates contractually due to investors.

Federal and State Income Taxes

Federal and State Income Taxes	12 Months Ended
Federal and State Income Taxes	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Federal and State Income Taxes [Text Block]	Federal and State Income Taxes Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of deferred tax assets and liabilities are as follows (in thousands): December 31, 2019 2018 Deferred tax assets: Credit loss reserves $ 50,611 $ 49,804 Lease liability 46,084 — Deferred compensation 25,976 25,608 Purchased loan discount 18,042 27,283 Unearned fees 9,080 9,814 Share-based compensation 7,392 4,434 Valuation adjustments 1,545 9,619 Available for sale securities mark to market — 24,441 Other 26,384 31,489 Total deferred tax assets 185,114 182,492 Deferred tax liabilities: Mortgage servicing rights 48,435 61,844 Right-of-use asset 42,180 — Available for sale securities mark to market 33,140 — Acquired identifiable intangible 23,181 28,620 Depreciation 18,909 15,966 Lease financing 10,720 10,040 Other 34,826 30,566 Total deferred tax liabilities 211,391 147,036 Net deferred tax assets (liabilities) $ (26,277 ) $ 35,456 No valuation allowance was necessary on deferred tax assets as of December 31, 2019 and 2018 . The significant components of the provision for income taxes attributable to continuing operations for BOK Financial are shown below (in thousands): Year Ended December 31, 2019 2018 2017 Current income tax expense: Federal $ 110,887 $ 103,748 $ 141,607 State 15,088 15,253 14,592 Total current income tax expense 125,975 119,001 156,199 Deferred income tax expense: Federal 3,416 (190 ) 25,525 State 792 250 869 Total deferred income tax expense 4,208 60 26,394 Total income tax expense $ 130,183 $ 119,061 $ 182,593 The reconciliations of income attributable to continuing operations at the U.S. federal statutory tax rate to income tax expense are as follows (in thousands): Year Ended December 31, 2019 2018 2017 Amount: Federal statutory tax $ 132,482 $ 118,752 $ 181,397 Tax exempt revenue (12,227 ) (8,311 ) (12,402 ) Effect of state income taxes, net of federal benefit 12,715 12,430 10,701 Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments (5,127 ) (4,559 ) (6,811 ) Other, net 2,340 749 9,708 Total income tax expense $ 130,183 $ 119,061 $ 182,593 Year Ended December 31, 2019 2018 2017 Percent of pretax income: Federal statutory tax 21.0 % 21.0 % 35.0 % Tax exempt revenue (1.9 ) (1.5 ) (2.4 ) Effect of state income taxes, net of federal benefit 2.0 2.2 2.0 Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments (0.8 ) (0.8 ) (1.3 ) Other, net 0.3 0.2 1.9 Total 20.6 % 21.1 % 35.2 % A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands): 2019 2018 2017 Balance as of January 1 $ 18,869 $ 18,110 $ 15,841 Additions for tax for current year positions 5,649 2,649 4,645 Settlements during the period — — — Lapses of applicable statute of limitations (4,053 ) (1,890 ) (2,376 ) Balance as of December 31 $ 20,465 $ 18,869 $ 18,110 Of the above unrecognized tax benefits, $14.7 million , if recognized, would have affected the effective tax rate. BOK Financial recognizes interest and penalties accrued related to unrecognized tax benefits in income tax expense. The Company recognized $2.2 million for 2019 , $1.7 million for 2018 and $1.2 million for 2017 in interest and penalties. The Company had approximately $5.6 million and $5.0 million accrued for the payment of interest and penalties at December 31, 2019 and 2018 , respectively. Federal statutes remain open for federal tax returns filed in the previous three reporting periods. Various state income tax statutes remain open for the previous three to six

Employee Benefits

Employee Benefits	12 Months Ended
Employee Benefits	Dec. 31, 2019
Retirement Benefits [Abstract]
Employee Benefits [Text Block]	Employee Benefits BOK Financial sponsors a defined benefit cash balance Pension Plan for all employees who satisfy certain age and service requirements. Pension Plan benefits were curtailed as of April 1, 2006. No participants may be added to the plan and no additional service benefits will be accrued. Interest continues to accrue on employees' account balances at a variable rate tied to the five-year trailing average of five-year U.S. Treasury securities plus 1.5% . The rate has a floor of 3.0% and a ceiling of 5.0% . The 2019 quarterly variable rates ranged from 3.32% to 3.40% . The projected benefit obligation and fair value of plan assets, respectively, were $24.5 million and $36.4 million at December 31, 2019 and $24.5 million and $33.6 million at December 31, 2018 . The net periodic benefit credit was $815 thousand for December 31, 2019 , $583 thousand for December 31, 2018 and $704 thousand for December 31, 2017 . Total expected future benefit payments related to the Pension Plan were $27.8 million at December 31, 2019 . The following table presents the weighted-average assumptions used in the measurement of the Company's net periodic benefit cost as of December 31: 2019 2018 Discount rate 4.10 % 3.30 % Expected return on plan assets 5.50 % 5.50 % Assets of the Pension Plan consist primarily of shares in the Cavanal Hill Active Core Fund. The stated objective of this fund is to provide an attractive total return with a well-balanced mix of equities and bonds. The typical portfolio mix is approximately 60% equities and 40% bonds. The net asset value of shares in the Cavanal Hill Funds is reported daily based on market quotations for the Fund’s securities. Management considers the Fund's recent and long-term performance as indicators when setting the expected return on plan assets. No minimum contribution was required for 2019 , 2018 or 2017 . Employee contributions to the Thrift Plan are eligible for Company matching equal to 6% of base compensation, as defined in the plan. The Company-provided matching contribution rates range from 50% for employees with less than 4 years of service to 200% for employees with 15 or more years of service. Additionally, a maximum Company-provided, non-elective annual contribution of up to $750 per participant is provided for employees whose annual base compensation is less than $40,000 . Participants may direct investments in their accounts to a variety of options, including a BOK Financial common stock fund and Cavanal Hill funds. Employer contributions, which are invested in accordance with the participant’s investment options, vest over five years . Thrift Plan expenses were $27.6 million for 2019 , $25.1 million for 2018 and $22.8 million for 2017 .

Share-Based Compensation Plans

Share-Based Compensation Plans	12 Months Ended
Share-Based Compensation Plans	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Share-Based Compensation Plans [Text Block]	Share-Based Compensation Plans The shareholders and Board of Directors of BOK Financial have approved various share-based compensation plans. An independent compensation committee of the Board of Directors determines the number of awards granted to the Chief Executive Officer and other senior executives. Share-based compensation is granted to other officers and employees as determined by the Chief Executive Officer. The following table presents stock options outstanding under these plans (in thousands, except for per share data): Number Weighted- Average Exercise Price Aggregate Intrinsic Value Options outstanding at: December 31, 2017 117,551 $ 53.26 $ 4,592 December 31, 2018 63,058 54.89 1,163 December 31, 2019 36,100 56.75 1,106 Options vested at: December 31, 2017 51,286 $ 48.62 $ 2,241 December 31, 2018 33,573 53.09 679 December 31, 2019 27,193 57.08 824 No options have been awarded since 2013. At December 31, 2019 , the weighted average remaining contractual life of options outstanding was 1.76 years and the weighted average remaining contractual life of vested options was 1.35 years . The aggregate intrinsic value of options exercised was $761 thousand for 2019 , $2.3 million for 2018 and $3.5 million for 2017 . The Company also awards restricted stock to certain officers and employees and restricted stock units ("RSUs) to certain executives, (collectively "non-vested shares"). Vesting of all non-vested shares is subject to service requirements. Additionally, vesting of certain non-vested shares is subject to performance criteria based on changes in the Company's earnings per share relative to defined peers. The following represents a summary of the non-vested shares for the three years ended December 31, 2019 (in thousands): Restricted Stock Restricted Stock Units Shares Weighted Average Grant Date Fair Value Units Weighted Average Grant Date Fair Value Non-vested at January 1, 2017 786,706 — Granted 177,807 $ 86.95 — — — Vested (194,419 ) 63.07 — — Forfeited (102,991 ) 78.70 — — Non-vested at December 31, 2017 667,103 — Granted 150,419 $ 85.58 — — Vested (242,215 ) 74.85 — — Forfeited (47,700 ) 75.68 — — Non-vested at December 31, 2018 527,607 — Granted 145,724 $ 76.74 46,689 $ 87.40 Vested (114,201 ) 61.28 — — Forfeited (131,952 ) 83.69 — — Non-vested at December 31, 2019 427,178 46,689 Compensation expense recognized on non-vested shares totaled $15.1 million for 2019 , $3.6 million for 2018 and $23.2 million for 2017 . Unrecognized compensation cost of non-vested shares totaled $14.9 million at December 31, 2019 . We expect to recognize compensation expense of $9.4 million in 2020 , $5.3 million in 2021 , and $144 thousand in 2022 . Compensation cost for restricted stock units is variable based on the current fair value of BOK Financial common shares. Vesting of 222,164

Related Parties

Related Parties	12 Months Ended
Related Parties	Dec. 31, 2019
Related Party Transactions [Abstract]
Related Parties [Text Block]	Related Parties In compliance with applicable banking regulations, the Company may extend credit to certain executive officers, directors, principal shareholders and their affiliates (collectively referred to as “related parties”) in the ordinary course of business. The Company’s loans to related parties do not involve more than the normal credit risk. Activity in loans to related parties is summarized as follows (in thousands): Year Ended December 31, 2019 2018 Beginning balance $ 75,265 $ 110,246 Advances 886,610 1,479,735 Payments (896,643 ) (1,514,841 ) Adjustments 1 9,957 125 Ending balance $ 75,189 $ 75,265 1 Adjustments generally consist of changes in status as a related party. As defined by banking regulations, loan commitments and equity investments from the subsidiary banks to a single affiliate may not exceed 10% of unimpaired capital and surplus while loan commitments and equity investments to all affiliates may not exceed 20% of unimpaired capital and surplus. All loans to affiliates must be fully secured by eligible collateral. At December 31, 2019 , loan commitments and equity investments were limited to $370 million to a single affiliate and $739 million to all affiliates. The largest loan commitment and equity investment to a single affiliate was $257 million and the aggregate loan commitments and equity investments to all affiliates were $392 million . The largest outstanding amount to a single affiliate at December 31, 2019 was $4.3 million and the total outstanding amounts to all affiliates were $5.0 million . At December 31, 2018 , total loan commitments and equity investments to all affiliates were $313 million and the total outstanding amounts to all affiliates were $883 thousand . Certain related parties are customers of the Company for services other than loans, including consumer banking, corporate banking, risk management, wealth management, brokerage and trading, or fiduciary/trust services. The Company engages in transactions with related parties in the ordinary course of business in compliance with applicable regulations. QuikTrip Corporation has entered into a fee sharing agreement with TransFund, BOKF’s electronic funds transfer network (“TransFund”), respecting transactions completed at TransFund automated teller machines placed in QuikTrip locations. In 2019 , BOKF paid QuikTrip approximately $10.0 million pursuant to this agreement. A BOK Financial director is Chief Executive Officer, Chairman, and a significant shareholder of QuikTrip Corporation. Cavanal Hill Investment Management, Inc., a wholly-owned subsidiary of BOKF, NA, is the administrator to and investment advisor for the Cavanal Hill Funds (the "Funds"), a diversified, open-ended investment company established as a business trust under the Investment Company Act of 1940 (the "1940 Act"). BOKF, NA is custodian and Cavanal Hill Distributors, Inc. is distributor for the Funds. The Funds’ products are offered to customers, employee benefit plans, trusts and the general public in the ordinary course of business. Approximately 84% of the Funds’ assets of $ 3.7 billion are held for the Company's clients. A Company executive officer serves on the Funds' board of trustees and officers of BOKF, NA serve as president and secretary of the Funds. A majority of the members of the Funds’ board of trustees are, however, independent of the Company and the Funds are managed by its board of trustees.

Commitments and Contingent Liab

Commitments and Contingent Liabilities	12 Months Ended
Commitments and Contingent Liabilities	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities [Text Block]	Commitments and Contingent Liabilities Litigation Contingencies As a member of Visa, BOK Financial is obligated for a proportionate share of certain covered litigation losses incurred by Visa under a retrospective responsibility plan. A contingent liability was recognized for the Company’s share of Visa’s covered litigation liabilities. Visa funded an escrow account to cover litigation claims, including covered litigation losses under the retrospective responsibility plan, with proceeds from its initial public offering in 2008 and from available cash. BOK Financial currently owns 252,233 Visa Class B shares which are convertible into 409,324 shares of Visa Class A shares after the final settlement of all covered litigation. Class B shares may be diluted in the future if the escrow fund is not adequate to cover future covered litigation costs. No value has been currently assigned to the Class B shares. On June 24, 2015, BOKF, NA received a complaint alleging that an employee had colluded with a bond issuer and an individual in misusing revenues pledged to municipal bonds for which BOKF, NA served as trustee under the bond indenture. The Company conducted an investigation and concluded that employees in one of its Corporate Trust offices had, with respect to a single group of affiliated bond issuances, violated Company policies and procedures by waiving financial covenants, granting forbearances and accepting, without disclosure to the bondholders, debt service payments from sources other than pledged revenues. The relationship manager was terminated. The Company reported the circumstances to, and cooperated with an investigation by, the Securities and Exchange Commission ("SEC"). On December 28, 2015, in an action brought by the SEC, the United States District Court for the District of New Jersey entered a judgment against the principals involved in issuing the bonds, precluding the principals from denying the alleged violations of the federal securities laws and requiring the principals to pay all outstanding principal, accrued interest, and other amounts required under the bond documents, less the value of the facilities securing repayment of the bonds, subject to oversight by a court appointed monitor (“Payment Plan”). On September 7, 2016, BOKF, NA agreed, and the SEC entered, a consent order finding that BOKF, NA had violated Section 17(a) of the Securities Act of 1933 and Section 10(b) of the Securities Exchange Act and requiring BOKF, NA to disgorge $1,067,721 of fees and pay a civil penalty of $600,000 . BOKF, NA disgorged the fees and paid the penalty. On August 26, 2016, BOKF, NA was sued in the United States District Court for New Jersey by two bondholders in a putative class action on behalf of all holders of the bonds alleging BOKF, NA participated in the fraudulent sale of securities by the principals. The New Jersey Federal District Action has been stayed until March 20, 2020. On September 14, 2016, BOKF, NA was sued in the District Court of Tulsa County, Oklahoma by 19 bondholders alleging BOKF, NA participated in the fraudulent sale of securities by the principals. The Tulsa County District Court Action is pending on BOKF, NA’s motion to dismiss. Four separate small groups of bondholders filed arbitration complaints with the Financial Institutions Regulatory Association respecting the bonds and other bonds for which BOKF, NA served as indenture trustee. BOKF, NA challenged the FINRA proceedings in the United States District Court of Nevada. On appeal, the United States Court of Appeals for the Ninth Circuit held BOKF, NA was not subject to FINRA jurisdiction. The four FINRA complaints were then dismissed. On July 9, 2019, the New Jersey Federal District Court terminated the Payment Plan except with respect to facilities then under contract to be sold as to which the Payment Plan continued until January 17, 2020. On January 8, 2020, the New Jersey District Court entered judgment against the principal individual and his wife for $36,805,051 in principal amount and $10,937,831 in pre-judgment interest. Management is no longer able to conclude that the individual principal and his wife will be successful in paying the obligations they have to pay the bonds in full. Under all circumstances, the obligation of the principals to repay the bonds continues as an obligation not dischargeable in bankruptcy. If the individual principal and his wife do not have the financial ability to pay the bonds in full, a bondholder loss could become probable. Management has been advised by counsel that BOKF, NA has valid defenses to claims of bondholders and that no loss to the company is probable. No provision for losses has been made at this time. BOKF, NA estimates that, upon sale of all facilities securing payment of the bonds, including those currently under contract and those not currently under contract, approximately $20 million will remain outstanding. A reasonable estimate cannot be made of the amount of any bondholder loss, though the amount of bondholder loss could be material to the company in the event a loss to the company becomes probable. On March 5, 2018, BOKF, NA was sued in the Fulton, Georgia County District Court by 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. BOKF, NA is advised by counsel that BOKF, NA has valid defenses to the plaintiffs’ claims and no loss is probable. On March 14, 2017, BOKF, NA was sued in the United States District Court for the Northern District of Oklahoma by bondholders in a second putative class action representing a different set of municipal securities. The bondholders in this second action 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 BOKF, NA also served as indenture trustee. The bondholders allege BOKF, NA failed to disclose that the seller of the purchased facilities had engaged in the conduct complained of in the New Jersey action. BOKF, NA 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 BOKF, NA 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 BOKF, NA is interest and exceeds permitted rates. On September 18, 2018, the District Court dismissed the Texas action and the plaintiff appealed the dismissal to the United States Court of Appeals for the Fifth Circuit which heard argument on October 8, 2019. On August 22, 2018, a plaintiff filed a second putative class action in the United States District Court for New Mexico making the same allegations as the Texas action. The District Court dismissed the plaintiff’s action. The plaintiffs filed a motion for reconsideration and the action is pending on that motion. Management is advised by counsel that a loss is not probable in either the now dismissed Texas action or the New Mexico action and that the loss, if any, cannot be reasonably estimated. On 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 a private equity fund and invests in several tax credit entities and other funds as permitted by banking regulations. Consolidation of these investments is based on the variable interest model. At December 31, 2019 , the Company has $259 million in interests in various alternative investments generally consisting of unconsolidated limited partnership interests in entities for which investment return is in the form of low income housing tax credits or other investments in merchant banking activities. The investment balance also included of $82 million in unfunded commitments included in Other liabilities on the Consolidated Balance Sheets. At December 31, 2018 , the Company had $237 million in interests in various alternative investments and included $74 million in unfunded commitments included in Other liabilities. Other Commitments and Contingencies Cavanal Hill Funds’ assets include U.S. Treasury and government securities money market funds. Assets of these funds consist of highly-rated, short-term obligations of the U.S. Treasury and Agencies. The net asset value of units in these funds was $1.00 at December 31, 2019 . An investment in these funds is not insured by the Federal Deposit Insurance Corporation or guaranteed by BOK Financial or any of its subsidiaries. BOK Financial may, but is not obligated to purchase assets from these funds to maintain the net asset value at $1.00 . No assets were purchased from the funds in 2019 or 2018 . The Federal Reserve Bank requires member banks to maintain certain minimum average cash balances. Member banks may satisfy reserve balance requirements through holdings of vault cash and balances maintained directly with a Federal Reserve Bank. The combined average balance of vault cash and balances held at the Federal Reserve Bank was $618 million for the year ended December 31, 2019 and $1.2 billion for the year ended December 31, 2018 .

Earnings Per Share

Earnings Per Share	12 Months Ended
Earnings Per Share	Dec. 31, 2019
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	Earnings Per Share The following table presents the computation of basic and diluted earnings per share (dollars in thousands, except per share data): Year Ended 2019 2018 2017 Numerator: Net income attributable to BOK Financial Corp. shareholders $ 500,758 $ 445,646 $ 334,644 Less: Earnings allocated to participating securities 3,227 3,737 3,561 Numerator for basic earnings per share – income available to common shareholders 497,531 441,909 331,083 Effect of reallocating undistributed earnings of participating securities — 1 2 Numerator for diluted earnings per share – income available to common shareholders $ 497,531 $ 441,910 $ 331,085 Denominator: Weighted average shares outstanding 71,250,081 67,190,257 65,440,832 Less: Participating securities included in weighted average shares outstanding 462,381 561,617 695,468 Denominator for basic earnings per common share 70,787,700 66,628,640 64,745,364 Dilutive effect of employee stock compensation plans 14,912 33,633 60,920 Denominator for diluted earnings per common share 70,802,612 66,662,273 64,806,284 Basic earnings per share $ 7.03 $ 6.63 $ 5.11 Diluted earnings per share $ 7.03 $ 6.63 $ 5.11

Shareholders' Equity

Shareholders' Equity	12 Months Ended
Shareholders' Equity	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Shareholders' Equity [Text Block]	Shareholders Equity Preferred Stock One billion shares of preferred stock with a par value of $0.00005 per share are authorized. The Series A Preferred Stock has no voting rights except as otherwise provided by Oklahoma corporate law and may be converted into one share of Common Stock for each 36 shares of Series A Preferred Stock at the option of the holder . Dividends are cumulative at an annual rate of ten percent of the $0.06 per share liquidation preference value when declared and are payable in cash. Aggregate liquidation preference is $15 million . No Series A Preferred Stock was outstanding in 2019 , 2018 or 2017 . Common Stock Common stock consists of 2.5 billion authorized shares with a $0.00006 par value. Holders of common shares are entitled to one vote per share at the election of the Board of Directors and on any question arising at any shareholders’ meeting and to receive dividends when and as declared. Additionally, regulations restrict the ability of national banks and bank holding companies to pay dividends. Subsidiary Banks The amounts of dividends that BOK Financial’s subsidiary bank can declare and the amounts of loans the subsidiary bank can extend to affiliates are limited by various federal banking regulations and state corporate law. Generally, dividends declared during a calendar year are limited to net profits, as defined, for the year plus retained profits for the preceding two years. Dividends are further restricted by minimum capital requirements. Regulatory Capital BOK Financial and the subsidiary bank is subject to various capital requirements administered by the federal banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory and additional discretionary actions by regulators that could have a material effect on BOK Financial's operations. These capital requirements include quantitative measures of assets, liabilities and certain off-balance sheet items. The capital standards are also subject to qualitative judgments by the regulators. New capital rules were effective for BOK Financial on January 1, 2015. Components of these rules phased in through January 1, 2019. A bank falling below the minimum capital requirements, including the capital conservation buffer, would be subject to regulatory restrictions on capital distributions (including but not limited to dividends and share repurchases) and executive bonus payments. For a banking institution to qualify as well capitalized, Common Equity Tier 1, Tier I, Total and Leverage capital ratios must be at least 6.5% , 8% , 10% and 5% , respectively. Tier I capital consists primarily of common stockholders' equity, excluding unrealized gains or losses on available for sale securities, less goodwill, core deposit premiums and certain other intangible assets. Total capital consists primarily of Tier I capital plus preferred stock, subordinated debt and allowances for credit losses, subject to certain limitations. The subsidiary banks exceeded the regulatory definition of well capitalized as of December 31, 2019 and December 31, 2018 . A summary of regulatory capital minimum requirements and levels follows (dollars in thousands): Minimum Capital Requirement Capital Conservation Buffer 1 Minimum Capital Requirement Including Capital Conservation Buffer Well Capitalized Bank Requirement December 31, 2019 December 31, 2018 Common Equity Tier 1 Capital (to Risk Weighted Assets): Consolidated 4.50% 2.50% 7.00% N/A $ 3,608,821 11.39 % $ 3,356,524 10.92 % BOKF, NA 4.50% N/A 4.50% 6.50% 3,414,446 10.90 % 2,894,119 10.50 % CoBiz Bank 2 4.50% N/A 4.50% 6.50% — — % 317,944 10.65 % Tier I Capital (to Risk Weighted Assets): Consolidated 6.00% 2.50% 8.50% N/A $ 3,608,821 11.39 % $ 3,356,524 10.92 % BOKF, NA 6.00% N/A 6.00% 8.00% 3,414,446 10.90 % 2,894,119 10.50 % CoBiz Bank 2 6.00% N/A 6.00% 8.00% — — % 317,944 10.65 % Total Capital (to Risk Weighted Assets): Consolidated 8.00% 2.50% 10.50% N/A $ 4,097,087 12.94 % $ 3,841,684 12.50 % BOKF, NA 8.00% N/A 8.00% 10.00% 3,692,010 11.79 % 3,103,366 11.26 % CoBiz Bank 2 8.00% N/A 8.00% 10.00% — — % 382,944 12.83 % Leverage (Tier I Capital to Average Assets): Consolidated 4.00% N/A 4.00% N/A $ 3,608,820 8.40 % $ 3,356,524 8.96 % BOKF, NA 4.00% N/A 4.00% 5.00% 3,414,446 7.98 % 2,894,119 8.56 % CoBiz Bank 2 4.00% N/A 4.00% 5.00% — — % 317,944 8.25 % 1 Capital conservation buffer was effective January 1, 2016 and phased in through 2019. The phased in capital conservation buffer was 2.50% at December 31, 2019 and 1.875% at December 31, 2018 . The fully phased in requirement of 2.50% is included in the table above. 2 CoBiz Bank was acquired by BOK Financial effective October 1, 2018 and merged into BOKF, NA during the first quarter of 2019. 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) (28,170 ) 2,018 (26,152 ) Reclassification adjustments included in earnings: Gain on available for sale securities, net (4,428 ) — (4,428 ) Other comprehensive income (loss), before income taxes (32,598 ) 2,018 (30,580 ) Federal and state income tax 1 (12,708 ) 785 (11,923 ) Other comprehensive income (loss), net of income taxes (19,890 ) 1,233 (18,657 ) Reclassification of stranded accumulated other comprehensive loss related to tax reform (6,408 ) (142 ) (6,550 ) Balance, December 31, 2017 (35,385 ) (789 ) (36,174 ) Transition adjustment for net unrealized gains on equity securities (2,709 ) — (2,709 ) Net change in unrealized gain (loss) (46,941 ) (1,069 ) (48,010 ) Reclassification adjustments included in earnings: Loss on available for sale securities, net 2,801 — 2,801 Other comprehensive income (loss), before income taxes (44,140 ) (1,069 ) (45,209 ) Federal and state income tax 2 (11,235 ) (272 ) (11,507 ) Other comprehensive income (loss), net of income taxes (32,905 ) (797 ) (33,702 ) Balance, December 31, 2018 (70,999 ) (1,586 ) (72,585 ) Net change in unrealized gain (loss) 239,017 2,030 241,047 Reclassification adjustments included in earnings: Gain on available for sale securities, net (5,597 ) — (5,597 ) Other comprehensive income (loss), before income taxes 233,420 2,030 235,450 Federal and state income tax 2 57,425 517 57,942 Other comprehensive income (loss), net of income taxes 175,995 1,513 177,508 Balance, December 31, 2019 $ 104,996 $ (73 ) $ 104,923 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.

Reportable Segments

Reportable Segments	12 Months Ended
Reportable Segments	Dec. 31, 2019
Segment Reporting [Abstract]
Reportable Segments [Text Block]	Reportable Segments BOK Financial operates three principal lines of business: Commercial Banking, Consumer Banking and Wealth Management. Commercial Banking includes lending, treasury and cash management services and customer risk management products to small businesses, middle market and larger commercial customers. Commercial Banking also includes the TransFund EFT network. Consumer Banking includes retail lending and deposit services, lending and deposit services to small business customers served through the consumer branch network and all mortgage banking activities. Wealth Management provides fiduciary services, private bank services, insurance and investment advisory services in all markets. Wealth Management also underwrites state and municipal securities and engages in brokerage and trading activities. In addition to its lines of business, BOK Financial has a Funds Management unit. The primary purpose of this unit is to manage overall liquidity needs and interest rate risk. Each line of business borrows funds from and provides funds to the Funds Management unit as needed to support their operations. Operating results for Funds Management and Other include the effect of interest rate risk positions and risk management activities, securities gains and losses including impairment charges, the provision for credit losses in excess of net loans charged off, tax planning strategies and certain executive compensation costs that are not attributed to the lines of business. BOK Financial allocates resources and evaluates performance of its lines of business after allocation of funds, actual net credit losses and capital costs. In addition, we measure the performance of our business lines after allocation of certain indirect expenses and taxes on statutory rates. The allocation for the prior comparable periods have been revised on a comparable basis. The cost of funds borrowed from the Funds Management unit by the operating lines of business is transfer priced at rates that approximate market rates for funds with similar duration. Market rates are generally based on the applicable LIBOR or interest rate swap rates, adjusted for prepayment risk. This method of transfer-pricing funds that support assets of the operating lines of business tends to insulate them from interest rate risk. The value of funds provided by the operating lines of business to the Funds Management unit is based on rates which approximate the wholesale market rates for funds with similar duration and re-pricing characteristics. Market rates are generally based on LIBOR or interest rate swap rates. The funds credit formula applied to deposit products with indeterminate maturities is established based on their re-pricing characteristics reflected in a combination of the short-term LIBOR rates and a moving average of an intermediate term swap rate, with an appropriate spread applied to both. Shorter duration products are weighted towards the short-term LIBOR rate and longer duration products are weighted towards intermediate swap rates. The expected duration ranges from 30 days for certain rate-sensitive deposits to five years. Substantially all revenue is from domestic customers. No single external customer accounts for more than 10% of total revenue. Net loans charged off and provision for credit losses represents net loans charged off as attributed to the lines of business and the provision for credit losses in excess of net charge-offs attributed to Funds Management and Other. The operations of CoBiz, acquired on October 1, 2018 were allocated to the operating segments in the second quarter of 2019. Prior to April 1, 2019, CoBiz operations were included in Funds Management and other. Reportable segments reconciliation to the Consolidated Financial Statements for the year ended December 31, 2019 is as follows (in thousands): Commercial Consumer Wealth Management Funds Management and Other BOK Financial Consolidated Net interest and dividend revenue from external sources $ 919,148 $ 99,679 $ 61,277 $ 32,775 $ 1,112,879 Net interest revenue (expense) from internal sources (242,907 ) 95,775 38,815 108,317 — Net interest and dividend revenue 676,241 195,454 100,092 141,092 1,112,879 Provision for credit losses 39,011 6,271 (308 ) (974 ) 44,000 Net interest and dividend revenue after provision for credit losses 637,230 189,183 100,400 142,066 1,068,879 Other operating revenue 170,412 187,500 341,389 (4,931 ) 694,370 Other operating expense 252,459 230,916 277,267 371,739 1,132,381 Net direct contribution 555,183 145,767 164,522 (234,604 ) 630,868 Gain (loss) on financial instruments, net 106 30,375 2 (30,483 ) — Change in fair value of mortgage servicing rights — (53,517 ) — 53,517 — Gain (loss) on repossessed assets, net 331 496 — (827 ) — Corporate expense allocations 43,055 47,169 36,239 (126,463 ) — Net income before taxes 512,565 75,952 128,285 (85,934 ) 630,868 Federal and state income taxes 137,759 19,346 32,954 (59,876 ) 130,183 Net income 374,806 56,606 95,331 (26,058 ) 500,685 Net income attributable to non-controlling interests — — — (73 ) (73 ) Net income attributable to BOK Financial Corp. shareholders $ 374,806 $ 56,606 $ 95,331 $ (25,985 ) $ 500,758 Average assets $ 22,807,589 $ 9,301,341 $ 10,204,426 $ (219,009 ) $ 42,094,347 Reportable segments reconciliation to the Consolidated Financial Statements for the year ended December 31, 2018 is as follows (in thousands): Commercial Consumer Wealth Management Funds Management and Other BOK Financial Consolidated Net interest and dividend revenue from external sources $ 726,855 $ 83,231 $ 81,528 $ 93,253 $ 984,867 Net interest revenue (expense) from internal sources (159,954 ) 73,448 31,480 55,026 — Net interest and dividend revenue 566,901 156,679 113,008 148,279 984,867 Provision for credit losses 30,358 5,143 (288 ) (27,213 ) 8,000 Net interest and dividend revenue after provision for credit losses 536,543 151,536 113,296 175,492 976,867 Other operating revenue 162,701 178,123 296,369 (20,409 ) 616,784 Other operating expense 202,095 231,075 257,650 337,346 1,028,166 Net direct contribution 497,149 98,584 152,015 (182,263 ) 565,485 Gain (loss) on financial instruments, net 26 (25,021 ) 7 24,988 — Change in fair value of mortgage servicing rights — 4,668 — (4,668 ) — Gain (loss) on repossessed assets, net (6,532 ) 247 — 6,285 — Corporate expense allocations 36,670 44,398 35,920 (116,988 ) — Net income before taxes 453,973 34,080 116,102 (38,670 ) 565,485 Federal and state income taxes 120,458 8,681 30,075 (40,153 ) 119,061 Net income 333,515 25,399 86,027 1,483 446,424 Net income attributable to non-controlling interests — — — 778 778 Net income attributable to BOK Financial Corp. shareholders $ 333,515 $ 25,399 $ 86,027 $ 705 $ 445,646 Average assets $ 18,432,035 $ 8,303,263 $ 8,447,784 $ (245,552 ) $ 34,937,530 Reportable segments reconciliation to the Consolidated Financial Statements for the year ended December 31, 2017 is as follows (in thousands): Commercial Consumer Wealth Management Funds Management and Other BOK Financial Consolidated Net interest and dividend revenue from external sources $ 618,325 $ 84,286 $ 45,024 $ 94,066 $ 841,701 Net interest revenue (expense) from internal sources (92,055 ) 53,916 38,344 (205 ) — Net interest and dividend revenue 526,270 138,202 83,368 93,861 841,701 Provision for credit losses 13,877 4,786 (696 ) (24,967 ) (7,000 ) Net interest and dividend revenue after provision for credit losses 512,393 133,416 84,064 118,828 848,701 Other operating revenue 208,404 184,878 301,434 378 695,094 Other operating expense 235,793 241,805 254,495 293,424 1,025,517 Net direct contribution 485,004 76,489 131,003 (174,218 ) 518,278 Gain (loss) on financial instruments, net 52 (2,052 ) — 2,000 — Change in fair value of mortgage servicing rights — 172 — (172 ) — Gain on repossessed assets, net (2,681 ) 223 387 2,071 — Corporate expense allocations 28,060 49,344 32,693 (110,097 ) — Net income before taxes 454,315 25,488 98,697 (60,222 ) 518,278 Federal and state income taxes 186,518 9,915 38,848 (52,688 ) 182,593 Net income 267,797 15,573 59,849 (7,534 ) 335,685 Net loss attributable to non-controlling interests — — — 1,041 1,041 Net income attributable to BOK Financial Corp. shareholders $ 267,797 $ 15,573 $ 59,849 $ (8,575 ) $ 334,644 Average assets $ 17,766,027 $ 8,544,117 $ 7,072,622 $ (435,272 ) $ 32,947,494

Fees and Commission Revenue (No

Fees and Commission Revenue (Notes)	12 Months Ended
Fees and Commission Revenue (Notes)	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Fees and Commissions Revenue [Text Block]	Fees and Commissions Revenue Fees and commissions revenue by reportable segment and primary service line is as follows for the year ended December 31, 2019 . Commercial Consumer Wealth Management Funds Management and Other Consolidated Out of Scope 1 In Scope 2 Trading revenue $ — $ — $ 88,558 $ — $ 88,558 $ 88,558 $ — Customer hedging revenue 8,422 — 9,667 852 18,941 18,941 — Retail brokerage revenue — — 16,251 (115 ) 16,136 — 16,136 Insurance brokerage revenue — — 10,131 3,730 13,861 — 13,861 Investment banking revenue 10,136 — 12,194 — 22,330 8,678 13,652 Brokerage and trading revenue 18,558 — 136,801 4,467 159,826 116,177 43,649 TransFund EFT network revenue 73,479 3,924 (82 ) 3 77,324 — 77,324 Merchant services revenue 8,607 56 — 123 8,786 — 8,786 Corporate card revenue 1,072 — 32 2 1,106 — 1,106 Transaction card revenue 83,158 3,980 (50 ) 128 87,216 — 87,216 Personal trust revenue — — 81,763 — 81,763 — 81,763 Corporate trust revenue — — 24,635 — 24,635 — 24,635 Institutional trust & retirement plan services revenue — — 44,352 — 44,352 — 44,352 Investment management services and other — — 24,725 1,550 26,275 — 26,275 Fiduciary and asset management revenue — — 175,475 1,550 177,025 — 177,025 Commercial account service charge revenue 42,251 1,713 2,137 1,804 47,905 — 47,905 Overdraft fee revenue 313 35,134 138 (229 ) 35,356 — 35,356 Check card revenue — 21,865 — 165 22,030 — 22,030 Automated service charge and other deposit fee revenue 823 6,155 168 48 7,194 — 7,194 Deposit service charges and fees 43,387 64,867 2,443 1,788 112,485 — 112,485 Mortgage production revenue — 42,724 — (4 ) 42,720 42,720 — Mortgage servicing revenue — 66,692 — (1,871 ) 64,821 64,821 — Mortgage banking revenue — 109,416 — (1,875 ) 107,541 107,541 — Other revenue 23,564 9,733 26,664 (1,853 ) 58,108 39,428 18,680 Total fees and commissions revenue $ 168,667 $ 187,996 $ 341,333 $ 4,205 $ 702,201 $ 263,146 $ 439,055 1 Out of scope revenue generally relates to financial instruments or contractual rights and obligations within the scope of other applicable accounting guidance. 2 In scope revenue represents revenue subject to FASB ASC Topic 606, Revenue from Contracts with Customers. Fees and commissions revenue by reportable segment and primary service line is as follows for the year ended December 31, 2018 . Commercial Consumer Wealth Management Funds Management and Other Consolidated Out of Scope 1 In Scope 2 Trading revenue $ — $ — $ 28,077 $ — $ 28,077 $ 28,077 $ — Customer hedging revenue 7,748 — 27,512 3,574 38,834 38,834 — Retail brokerage revenue — — 19,030 (1,078 ) 17,952 — 17,952 Insurance brokerage revenue — — — 4,198 4,198 — 4,198 Investment banking revenue 7,628 — 11,634 — 19,262 6,380 12,882 Brokerage and trading revenue 15,376 — 86,253 6,694 108,323 73,291 35,032 TransFund EFT network revenue 72,280 4,017 (82 ) 6 76,221 — 76,221 Merchant services revenue 7,666 59 — 79 7,804 — 7,804 Corporate card revenue — — — — — — — Transaction card revenue 79,946 4,076 (82 ) 85 84,025 — 84,025 Personal trust revenue — — 96,839 — 96,839 — 96,839 Corporate trust revenue — — 22,292 — 22,292 — 22,292 Institutional trust & retirement plan services revenue — — 44,400 76 44,476 — 44,476 Investment management services and other — — 19,729 1,367 21,096 — 21,096 Fiduciary and asset management revenue — — 183,260 1,443 184,703 — 184,703 Commercial account service charge revenue 41,931 1,445 2,331 1,565 47,272 — 47,272 Overdraft fee revenue 370 36,177 134 (145 ) 36,536 — 36,536 Check card revenue — 20,967 — 339 21,306 — 21,306 Automated service charge and other deposit fee revenue 282 6,621 62 74 7,039 — 7,039 Deposit service charges and fees 42,583 65,210 2,527 1,833 112,153 — 112,153 Mortgage production revenue — 31,690 — — 31,690 31,690 — Mortgage servicing revenue — 67,980 — (1,883 ) 66,097 66,097 — Mortgage banking revenue — 99,670 — (1,883 ) 97,787 97,787 — Other revenue 24,044 9,218 24,507 (1,584 ) 56,185 38,306 17,879 Total fees and commissions revenue $ 161,949 $ 178,174 $ 296,465 $ 6,588 $ 643,176 $ 209,384 $ 433,792 1 Out of scope revenue generally relates to financial instruments or contractual rights and obligations within the scope of other applicable accounting guidance. 2 In scope revenue represents revenue subject to FASB ASC Topic 606, Revenue from Contracts with Customers.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
Fair Value Measurements	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements [Text Block]	Fair Value Measurements Fair value is defined by applicable accounting guidance as the price to sell an asset or transfer a liability in an orderly transaction between market participants in the principal market for the given asset or liability at the measurement date based on market conditions at that date. An orderly transaction assumes exposure to the market for a customary period for marketing activities prior to the measurement date and not a forced liquidation or distressed sale. Certain assets and liabilities are recorded in the Company’s financial statements at fair value. Some are recorded on a recurring basis and some on a non-recurring basis. For some assets and liabilities, observable market transactions and market information might be available. For other assets and liabilities, observable market transactions and market information might not be available. A hierarchy for fair value has been established which categorizes into three levels the inputs to valuation techniques used to measure fair value. The three levels are as follows: Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) - fair value is based on unadjusted quoted prices in active markets for identical assets or liabilities. Significant Other Observable Inputs (Level 2) - fair value is based on significant other observable inputs which are generally determined based on a single price for each financial instrument provided to us by an applicable third-party pricing service and is based on one or more of the following: • Quoted prices for similar, but not identical, assets or liabilities in active markets; • Quoted prices for identical or similar assets or liabilities in inactive markets; • Inputs other than quoted prices that are observable, such as interest rate and yield curves, volatilities, prepayment speeds, loss severities, credit risks and default rates; • Other inputs derived from or corroborated by observable market inputs. Significant Unobservable Inputs (Level 3) - fair value is based upon model-based valuation techniques for which at least one significant assumption is not observable in the market. Transfers between levels are recognized as of the end of the reporting period. There were no transfers in or out of quoted prices in active markets for identical instruments to significant other observable inputs or significant unobservable inputs during the year ended December 31, 2019 and 2018 , respectively. Transfers between significant other observable inputs and significant unobservable inputs during the year ended December 31, 2019 and 2018 are included in the summary of changes in recurring fair values measured using unobservable inputs. Additionally, $208 million of held-to-maturity other debt securities were transferred from significant other observable inputs to significant unobservable inputs at December 31, 2018 due to a lack of currently available observable inputs. The underlying methods used by the third-party pricing services are considered in determining the primary inputs used to determine fair values. Management has evaluated the methodologies employed by the third-party pricing services by comparing the price provided by the pricing service with other sources, including brokers' quotes, sales or purchases of similar instruments and discounted cash flows to establish a basis for reliance on the pricing service values. Significant differences between the pricing service provided value and other sources are discussed with the pricing service to understand the basis for their values. Based on all observable inputs, management may adjust prices obtained from third-party pricing services to more appropriately reflect the prices that would be received to sell assets or paid to transfer liabilities in orderly transactions in the current market. No significant adjustments were made to prices provided by third-party pricing services at December 31, 2019 and 2018 . Assets and Liabilities Measured at Fair Value on a Recurring Basis The fair value of financial assets and liabilities that are measured on a recurring basis is as follows as of December 31, 2019 (in thousands): Total Quoted Prices in Active Markets for Identical Instruments Significant Other Observable Inputs Significant Unobservable Inputs Assets: Trading securities: U.S. government agency debentures $ 44,264 $ — $ 44,264 $ — Residential agency mortgage-backed securities 1,504,651 — 1,504,651 — Municipal and other tax-exempt securities 26,196 — 26,196 — Asset-backed securities 14,084 — 14,084 — Other trading securities 34,726 — 34,726 — Total trading securities 1,623,921 — 1,623,921 — Available for sale securities: U.S. Treasury 1,600 1,600 — — Municipal and other tax-exempt securities 1,861 — 1,861 — Residential agency mortgage-backed securities 8,046,096 — 8,046,096 — Residential non-agency mortgage-backed securities 41,609 — 41,609 — Commercial agency mortgage-backed securities guaranteed 3,178,005 — 3,178,005 — Other debt securities 472 — — 472 Total available for sale securities 11,269,643 1,600 11,267,571 472 Fair value option securities: U.S. Treasury 9,917 9,917 — — Residential agency mortgage-backed securities 1,088,660 — 1,088,660 — Total fair value option securities 1,098,577 9,917 1,088,660 — Residential mortgage loans held for sale 182,271 — 173,958 8,313 Mortgage servicing rights, net 1 201,886 — — 201,886 Derivative contracts, net of cash margin 2 323,375 8,944 314,431 — Liabilities: Derivative contracts, net of cash margin 2 251,128 — 251,128 — 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 7 , Mortgage Banking Activities . 2 See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts in a net asset position that were valued based on quoted prices in active markets or identical instruments (Level 1) are exchange-traded interest rate and energy derivative contracts, net of cash margin. Derivative contracts in a net liability position that were valued using quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate and agricultural derivative contracts, fully offset by cash margin. The fair value of financial assets and liabilities that are measured on a recurring basis is as follows as of December 31, 2018 (in thousands): Total Quoted Prices in Active Markets for Identical Instruments Significant Other Observable Inputs Significant Unobservable Inputs Assets: Trading securities: U.S. government agency debentures $ 63,765 $ — $ 63,765 $ — Residential agency mortgage-backed securities 1,791,584 — 1,791,584 — Municipal and other tax-exempt securities 34,507 — 34,507 — Asset-backed securities 42,656 — 42,656 — Other trading securities 24,411 — 24,411 — Total trading securities 1,956,923 — 1,956,923 — Available for sale securities: U.S. Treasury 493 493 — — Municipal and other tax-exempt securities 2,864 — 2,864 — Residential agency mortgage-backed securities 5,804,708 — 5,804,708 — Residential non-agency mortgage-backed securities 59,736 — 59,736 — Commercial agency mortgage-backed securities guaranteed 2,953,889 — 2,953,889 — Other debt securities 35,430 — 34,958 472 Total available for sale securities 8,857,120 493 8,856,155 472 Fair value option securities – Residential agency mortgage-backed securities 283,235 — 283,235 — Residential mortgage loans held for sale 149,221 — 134,014 15,207 Mortgage servicing rights, net 1 259,254 — — 259,254 Derivative contracts, net of cash margin 2 320,929 44,074 276,855 — Liabilities: Derivative contracts, net of cash margin 2 362,306 — 362,306 — 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 7 , Mortgage Banking Activities. 2 See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts in a net asset position that were valued based on quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate, energy and agricultural derivative contracts, net of cash margin. Derivative contracts in a net liability position that were valued using quoted prices in active markets for identical instruments based on quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate derivative contracts, fully offset by cash margin. Following is a description of the Company's valuation methodologies used for assets and liabilities measured on a recurring basis: Securities The fair values of trading, available for sale and fair value option securities are based on quoted prices for identical instruments in active markets, when available. If quoted prices for identical instruments are not available, fair values are based on significant other observable inputs such as quoted prices of comparable instruments or interest rates and credit spreads, yield curves, volatilities, prepayment speeds and loss severities. The fair value of certain available for sale and held-to-maturity municipal and other debt securities may be based on significant unobservable inputs. These significant unobservable inputs include limited observed trades, projected cash flows, current credit rating of the issuers and, when applicable, the insurers of the debt and observed trades of similar debt. Discount rates are primarily based on reference to interest rate spreads on comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies adjusted for a lack of trading volume. Significant unobservable inputs are developed by investment securities professionals involved in the active trading of similar securities. A summary of significant inputs used to value these securities follows. A management committee composed of senior members from the Company's Capital Markets, Risk Management and Finance departments assess the appropriateness of these inputs quarterly. Derivatives All derivative instruments are carried on the balance sheet at fair value. Fair values for exchange-traded contracts are based on quoted prices. Fair values for over-the-counter interest rate, commodity and foreign exchange contracts are based on valuations provided either by third-party dealers in the contracts, quotes provided by independent pricing services, or a third-party provided pricing model that uses significant other observable market inputs. Credit risk is considered in determining the fair value of derivative instruments. Management determines fair value adjustments based on various risk factors including but not limited to counterparty credit rating or equivalent loan grading, derivative contract notional size, price volatility of the underlying commodity, duration of the derivative contracts and expected loss severity. Expected loss severity is based on historical losses for similarly risk graded commercial loan customers. Decreases in counterparty credit rating or grading and increases in price volatility and expected loss severity all tend to increase the credit quality adjustment which reduces the fair value of asset contracts. We also consider our own credit risk in determining the fair value of derivative contracts. Changes in our credit rating would affect the fair value of our derivative liabilities. In the event of a credit downgrade, the fair value of our derivative liabilities would increase. Residential Mortgage Loans Held for Sale Residential mortgage loans held for sale are carried on the balance sheet at fair value. The fair values of conforming residential mortgage loans held for sale are based upon quoted market prices of such loans sold in securitization transactions, including related unfunded loan commitments. The fair value of mortgage loans that are unable to be sold to U.S. government agencies is determined using quoted prices of loans that are sold in securitization transactions with a liquidity discount applied. The following represents the changes related to assets measured at fair value on a recurring basis using significant unobservable inputs (in thousands): Available for Sale Securities Residential mortgage loans held for sale Municipal and other tax-exempt securities Other debt securities Balance, December 31, 2017 $ 4,802 $ 472 $ 12,299 Transfer to Level 3 from Level 2 1 — — 6,183 Purchases and capital calls — — — Redemptions and distributions (5,095 ) — — Proceeds from sales — — (2,706 ) Gain (loss) recognized in earnings: Mortgage banking revenue — — (569 ) Other comprehensive income (loss): Net change in unrealized gain (loss) 293 — — Balance, December 31, 2018 — 472 15,207 Transfer to Level 3 from Level 2 1 — — 2,449 Purchases and capital calls — — — Redemptions and distributions — — — Proceeds from sales — — (9,972 ) Gain (loss) recognized in earnings: Mortgage banking revenue — — 629 Other comprehensive income (loss): Net change in unrealized gain (loss) — — — Balance, December 31, 2019 $ — $ 472 $ 8,313 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 December 31, 2019 follows (in thousands): Quantitative Information about Level 3 Recurring Fair Value Measurements Fair Value Valuation Technique(s) Significant Unobservable Input Range (Weighted Average) Available for sale securities: Other debt securities 472 Discounted cash flows 1 Interest rate spread 7.08%-7.08% (7.08%) 3 94.4%-94.4% (94.4%) 2 Residential mortgage loans held for sale 8,313 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 95.23% 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 approximately 3% . A summary of quantitative information about Recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of December 31, 2018 follows (in thousands): Quantitative Information about Level 3 Recurring Fair Value Measurements Fair Value Valuation Technique(s) Significant Unobservable Input Range (Weighted Average) Available for sale securities: Other debt securities 472 Discounted cash flows 1 Interest rate spread 7.88%-7.88% (7.88%) 3 94.44%-94.44% (94.44%) 2 Residential mortgage loans held for sale 15,207 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 92.38% 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% . Fair Value of Assets and Liabilities Measured on a Non-Recurring Basis Assets measured at fair value on a non-recurring basis include pension plan assets, which are based on quoted prices in active markets for identical instruments, collateral for certain impaired loans and real property and other assets acquired to satisfy loans, which are based primarily on comparisons to completed sales of similar assets. The following represents the carrying value of assets measured at fair value on a non-recurring basis and related losses recorded during the year. The carrying value represents only those assets with the balance sheet date for which the fair value was adjusted during the year: Carrying Value at December 31, 2019 Fair Value Adjustments for the Quoted Prices in Active Markets for Identical Instruments Significant Other Observable Inputs Significant Unobservable Inputs Gross charge-offs against allowance for loan losses Net losses (gains) and expenses of repossessed assets, net Impaired loans $ — $ 41 $ 55,665 $ 31,305 $ — Real estate and other repossessed assets — 5,986 1,551 — (461 ) Carrying Value at December 31, 2018 Fair Value Adjustments for the Quoted Prices in Active Markets for Identical Instruments Significant Other Observable Inputs Significant Unobservable Inputs Gross charge-offs against allowance for loan losses Net losses (gains) and expenses of repossessed assets, net Impaired loans $ — $ 1,074 $ 17,401 $ 17,434 $ — Real estate and other repossessed assets — 4,795 6,366 — 7,269 The fair value of collateral-dependent impaired loans and real estate and other repossessed assets and the related fair value adjustments are generally based on unadjusted third-party appraisals. Our appraisal review policies require appraised values to be supported by observed inputs derived principally from or corroborated by observable market data. Appraisals that are not based on observable inputs or that require significant adjustments or fair value measurements that are not based on third-party appraisals are considered to be based on significant unobservable inputs. Non-recurring fair value measurements of collateral-dependent 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 comparable assets, uncorroborated expert opinions or management's knowledge of the collateral or industry. Non-recurring fair value measurements of collateral dependent loans secured by mineral rights are generally determined by our internal staff of engineers on projected cash flows under current market conditions and are based on significant unobservable inputs. Projected cash flows are discounted according to risk characteristics of the underlying oil and gas properties. Assets are evaluated to demonstrate with reasonable certainty that crude oil, natural gas and natural gas liquids can be recovered from known oil and gas reservoirs under existing economic and operating conditions at current prices with existing conventional equipment, operating methods and costs. Significant unobservable inputs are developed by asset management and workout professionals and approved by senior Credit Administration executives. A summary of quantitative information about Non-recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of December 31, 2019 follows (in thousands): Quantitative Information about Level 3 Non-recurring Fair Value Measurements Fair Value Valuation Technique(s) Significant Unobservable Input Range (Weighted Average) Impaired loans $ 55,665 Discounted cash flows Management knowledge of industry and non-real estate collateral including but not limited to recoverable oil & gas reserves, forward looking commodity prices, and estimated operating costs 4% - 94% (55%) 1 Real estate and other repossessed assets 1,551 Discounted cash flows Marketability adjustments off appraised value 2 74% - 86% (84%) 1 Represents fair value as a percentage of the unpaid principal balance. 2 Marketability adjustments include consideration of estimated costs to sell which is approximately 10% of the fair value. A summary of quantitative information about Non-recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of December 31, 2018 follows (in thousands): Quantitative Information about Level 3 Non-recurring Fair Value Measurements Fair Value Valuation Technique(s) Significant Unobservable Input Range (Weighted Average) Impaired loans $ 17,401 Discounted cash flows Management knowledge of industry and non-real estate collateral including but not limited to recoverable oil & gas reserves, forward looking commodity prices, and estimated operating costs 35% - 80% (50%) 1 Real estate and other repossessed assets 6,366 Discounted cash flows Recoverable oil and gas reserves, forward-looking commodity prices and estimated operating costs N/A 1 Represents fair value as a percentage of the unpaid principal balance. The table above excludes the initial measurement of assets and liabilities that were acquired as part of the CoBiz acquisition in October 1, 2018. These assets and liabilities were recorded at their fair value upon acquisition in accordance with U.S. GAAP and were not re-measured during the periods presented unless specifically required by U.S. GAAP. Acquisition date fair values represent either Level 2 fair value measurements (investment securities, deposits, property, equipment, and debt) or Level 3 fair value measurements (loans and core deposit intangible assets). The fair value of pension plan assets was approximately $36 million at December 31, 2019 and $34 million at December 31, 2018 , determined by significant other observable inputs. Fair value adjustments of pension plan assets along with changes in the projected benefit obligation are recognized in other comprehensive income. Fair Value of Financial Instruments The following table presents the carrying values and estimated fair values of all financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring basis or non-recurring (dollars in thousands): December 31, 2019 Carrying Value Estimated Fair Value Quoted Prices in Active Markets for Identical Instruments (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Cash and due from banks $ 735,836 $ 735,836 $ 735,836 $ — $ — Interest-bearing cash and cash equivalents 522,985 522,985 522,985 — — Trading securities: U.S. government agency debentures 44,264 44,264 — 44,264 — Residential agency mortgage-backed securities 1,504,651 1,504,651 — 1,504,651 — Municipal and other tax-exempt securities 26,196 26,196 — 26,196 — Asset-backed securities 14,084 14,084 — 14,084 — Other trading securities 34,726 34,726 — 34,726 — Total trading securities 1,623,921 1,623,921 — 1,623,921 — Investment securities: Municipal and other tax-exempt securities 93,653 96,897 — 96,897 — Residential agency mortgage-backed securities 10,676 11,164 — 11,164 — Other debt securities 189,089 206,341 — 8,206 198,135 Total investment securities 293,418 314,402 — 116,267 198,135 Available for sale securities: U.S. Treasury 1,600 1,600 1,600 — — Municipal and other tax-exempt securities 1,861 1,861 — 1,861 — Residential agency mortgage-backed securities 8,046,096 8,046,096 — 8,046,096 — Residential non-agency mortgage-backed securities 41,609 41,609 — 41,609 — Commercial agency mortgage-backed securities 3,178,005 3,178,005 — 3,178,005 — Other debt securities 472 472 — — 472 Total available for sale securities 11,269,643 11,269,643 1,600 11,267,571 472 Fair value option securities: U.S. Treasury 9,917 9,917 9,917 — — Residential agency mortgage-backed securities 1,088,660 1,088,660 — 1,088,660 — Total fair value option securities 1,098,577 1,098,577 9,917 1,088,660 — Residential mortgage loans held for sale 182,271 182,271 — 173,958 8,313 Loans: Commercial 14,031,650 13,966,221 — — 13,966,221 Commercial real estate 4,433,783 4,422,717 — — 4,422,717 Residential mortgage 2,084,172 2,098,093 — — 2,098,093 Personal 1,201,382 1,202,298 — — 1,202,298 Total loans 21,750,987 21,689,329 — — 21,689,329 Allowance for loan losses (210,759 ) — — — — Loans, net of allowance 21,540,228 21,689,329 — — 21,689,329 Mortgage servicing rights 201,886 201,886 — — 201,886 Derivative instruments with positive fair value, net of cash margin 323,375 323,375 8,944 314,431 — Deposits with no stated maturity 25,403,319 25,403,319 — — 25,403,319 Time deposits 2,217,849 2,212,467 — — 2,212,467 Other borrowed funds 8,345,405 8,315,860 — — 8,315,860 Subordinated debentures 275,923 284,627 — 284,627 — Derivative instruments with negative fair value, net of cash margin 251,128 251,128 — 251,128 — December 31, 2018 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 $ 741,749 $ 741,749 $ 741,749 $ — $ — Interest-bearing cash and cash equivalents 401,675 401,675 401,675 — — Trading securities: U.S. government agency debentures 63,765 63,765 — 63,765 — Residential agency mortgage-backed securities 1,791,584 1,791,584 — 1,791,584 — Municipal and other tax-exempt securities 34,507 34,507 — 34,507 — Asset-backed securities 42,656 42,656 — 42,656 — Other trading securities 24,411 24,411 — 24,411 — Total trading securities 1,956,923 1,956,923 — 1,956,923 — Investment securities: Municipal and other tax-exempt securities 137,296 138,562 — 138,562 — Residential agency mortgage-backed securities 12,612 12,770 — 12,770 — Other debt securities 205,279 215,966 — 7,905 208,061 Total investment securities 355,187 367,298 — 159,237 208,061 Available for sale securities: U.S. Treasury securities 493 493 493 — — Municipal and other tax-exempt securities 2,864 2,864 — 2,864 — Residential agency mortgage-backed securities 5,804,708 5,804,708 — 5,804,708 — Residential non-agency mortgage-backed securities 59,736 59,736 — 59,736 — Commercial agency mortgage-backed securities 2,953,889 2,953,889 — 2,953,889 — Other debt securities 35,430 35,430 — 34,958 472 Total available for sale securities 8,857,120 8,857,120 493 8,856,155 472 Fair value option securities – Residential agency mortgage-backed securities 283,235 283,235 — 283,235 — Residential mortgage loans held for sale 149,221 149,221 — 134,014 15,207 Loans: Commercial 13,636,078 13,526,162 — — 13,526,162 Commercial real estate 4,764,813 4,713,747 — — 4,713,747 Residential mortgage 2,230,033 2,213,951 — — 2,213,951 Personal 1,025,806 1,024,368 — — 1,024,368 Total loans 21,656,730 21,478,228 — — 21,478,228 Allowance for loan losses (207,457 ) — — — — Loans, net of allowance 21,449,273 21,478,228 — — 21,478,228 Mortgage servicing rights 259,254 259,254 — — 259,254 Derivative instruments with positive fair value, net of cash margin 320,929 320,929 44,074 276,855 — Deposits with no stated maturity 23,150,383 23,150,383 — — 23,150,383 Time deposits 2,113,380 2,073,538 — — 2,073,538 Other borrowed funds 7,142,801 7,071,953 — — 7,071,953 Subordinated debentures 275,913 261,977 — 261,977 — Derivative instruments with negative fair value, net of cash margin 362,306 362,306 — 362,306 — Because no market exists for certain of these financial instruments and management does not intend to sell these financial instruments, the fair values shown in the tables above may not represent values at which the respective financial instruments could be sold individually or in the aggregate at the given reporting date. Fair Value Election As more fully disclosed in Note 2 and Note 7 to the Consolidated Financial Statements, the Company has elected to carry all U.S. government agency residential mortgage-backed securities held as economic hedges against changes in the fair value of mortgage servicing rights and all residential mortgage loans originated for sale at fair value. Changes in the fair value of these financial instruments are recognized in earnings.

Parent Company Only Financial S

Parent Company Only Financial Statements Parent Company Only Financial Statements	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Condensed Financial Information of Parent Company Only Disclosure [Text Block]	Parent Company Only Financial Statements Summarized financial information for BOK Financial – Parent Company Only follows: Balance Sheets (In thousands) December 31, 2019 2018 Assets Cash and cash equivalents $ 214,779 $ 167,093 Loan to bank subsidiary 65,220 65,228 Investment in bank subsidiaries 4,602,977 4,236,654 Investment in non-bank subsidiaries 216,542 218,007 Other assets 38,082 32,999 Total assets $ 5,137,600 $ 4,719,981 Liabilities and Shareholders’ Equity Liabilities: Other liabilities $ 5,882 $ 11,959 Subordinated debentures 275,923 275,913 Total liabilities 281,805 287,872 Shareholders’ equity: Common stock 5 5 Capital surplus 1,350,995 1,334,030 Retained earnings 3,729,778 3,369,654 Treasury stock (329,906 ) (198,995 ) Accumulated other comprehensive income (loss) 104,923 (72,585 ) Total shareholders’ equity 4,855,795 4,432,109 Total liabilities and shareholders’ equity $ 5,137,600 $ 4,719,981 Statements of Earnings (In thousands) Year Ended December 31, 2019 2018 2017 Dividends, interest and fees received from bank subsidiaries $ 344,007 $ 426,071 $ 150,149 Dividends, interest and fees received from non-bank subsidiaries 9,325 12,800 17,500 Other revenue 1,036 954 936 Total revenue 354,368 439,825 168,585 Interest expense 15,113 9,827 8,239 Other operating expense 2,352 12,110 2,014 Total expense 17,465 21,937 10,253 Net income before taxes, other losses, net, and equity in undistributed income of subsidiaries 336,903 417,888 158,332 Other gains (losses), net 3,310 (3,921 ) — Net income before taxes and equity in undistributed income of subsidiaries 340,213 413,967 158,332 Federal and state income taxes (4,516 ) (7,078 ) (4,305 ) Net income before equity in undistributed income of subsidiaries 344,729 421,045 162,637 Equity in undistributed income of bank subsidiaries 166,797 37,515 181,552 Equity in undistributed income of non-bank subsidiaries (10,768 ) (12,914 ) (9,545 ) Net income attributable to BOK Financial Corp. shareholders $ 500,758 $ 445,646 $ 334,644 Statements of Cash Flows (In thousands) Year Ended December 31, 2019 2018 2017 Cash Flows From Operating Activities: Net income $ 500,758 $ 445,646 $ 334,644 Adjustments to reconcile net income to net cash provided by operating activities: Equity in undistributed income of bank subsidiaries (166,797 ) (37,515 ) (181,552 ) Equity in undistributed income of non-bank subsidiaries 10,768 12,914 9,545 Change in other assets (5,075 ) (1,072 ) 12 Change in other liabilities 855 (13,434 ) 7,457 Net cash provided by operating activities 340,509 406,539 170,106 Cash Flows From Investing Activities: Proceeds from sales of available for sale securities — — 3,000 Investment in subsidiaries (19,837 ) (31,901 ) (4,355 ) Acquisitions, net of cash acquired — (232,680 ) — Net cash used in investing activities (19,837 ) (264,581 ) (1,355 ) Cash Flows From Financing Activities: Net change in other borrowed funds — — (7,217 ) Issuance of common and treasury stock, net (7 ) (88 ) 4,368 Dividends paid (143,496 ) (127,188 ) (116,041 ) Repurchase of common stock (129,483 ) (53,465 ) (7,403 ) Net cash used in financing activities (272,986 ) (180,741 ) (126,293 ) Net increase (decrease) in cash and cash equivalents 47,686 (38,783 ) 42,458 Cash and cash equivalents at beginning of period 167,093 205,876 163,418 Cash and cash equivalents at end of period $ 214,779 $ 167,093 $ 205,876 Cash paid for interest $ 15,099 $ 11,457 $ 6,211

Subsequent Events

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events The Company evaluated events from the date of the Consolidated Financial Statements on December 31, 2019 through the issuance of those consolidated financial statements included in this Annual Report on Form 10-K. No events were identified requiring recognition in and/or disclosure in the Consolidated Financial Statements.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation [Policy Text Block]	The Consolidated Financial Statements of BOK Financial Corporation (“BOK Financial” or “the Company”) have been prepared in conformity with accounting principles generally accepted in the United States ("U.S. GAAP"), including interpretations of U.S. GAAP issued by federal banking regulators and general practices of the banking industry.
Consolidation [Policy Text Block]	The Consolidated Financial Statements include the accounts of BOK Financial and its subsidiaries, principally BOKF, NA, BOK Financial Securities, Inc., BOK Financial Private Wealth, Inc., BOK Financial Insurance, Inc. and Cavanal Hill Distributors, Inc. All significant intercompany transactions are eliminated in consolidation. The Consolidated Financial Statements include the assets, liabilities, non-controlling interests and results of operations of variable interest entities (“VIEs”) when BOK Financial is determined to be the primary beneficiary. Variable interest entities are generally defined as entities that either do not have sufficient equity to finance their activities without support from other parties or whose equity investors lack a controlling financial interest. Determination that the Company is the primary beneficiary considers the power to direct the activities that most significantly impact the variable interest's economic performance and the obligation to absorb losses of the variable interest or the right to receive benefits of the variable interest that could be significant to the variable interest.
Reclassifications [Text Block]	Certain prior year amounts have been reclassified to conform to current year presentation.
Nature of Operations [Text Block]	Nature of Operations BOK Financial, through its subsidiaries, provides a wide range of financial services to commercial and industrial customers, other financial institutions, municipalities, and consumers. These services include depository and cash management; lending and lease financing; mortgage banking; securities brokerage, trading and underwriting; and personal and corporate trust. BOKF, NA operates as Bank of Oklahoma primarily in the Tulsa and Oklahoma City metropolitan areas of the state of Oklahoma and Bank of Texas primarily in the Dallas, Fort Worth and Houston metropolitan areas of the state of Texas. In addition, BOKF, NA does business as BOK Financial in the metropolitan areas of Phoenix, Arizona; Northwest Arkansas; Denver, Colorado; Kansas City, Missouri/Kansas; and as Bank of Albuquerque in Albuquerque, New Mexico. BOKF, NA also operates the TransFund electronic funds network, Cavanal Hill Investment Management, and BOK Financial Asset Management, Inc.
Use of Estimates [Policy Text Block]	Use of Estimates Preparation of BOK Financial's Consolidated Financial Statements requires management to make estimates of future economic activities, including loan collectability, loss contingencies, prepayments and cash flows from customer accounts. These estimates are based upon current conditions and information available to management. Actual results may differ significantly from these estimates.
Acquisitions [Policy Text Block]	Acquisitions Assets and liabilities acquired, including identifiable intangible assets, are recorded at fair value on the acquisition date. The purchase price includes consideration paid at closing and the estimated fair value of contingent consideration that will be paid in the future, subject to achieving defined performance criteria. Premiums and discounts assigned to interest-earning assets and interest-bearing liabilities are amortized over the lives of the acquired assets and liabilities on either an individual instrument or pool basis. Provision for credit losses is recognized for changes in credit quality after the acquisition date. Goodwill is recognized as the excess of the purchase price over the net fair value of assets acquired and liabilities assumed. The Consolidated Statements of Earnings include the results of operations from the acquisition date.
Goodwill and Intangible Assets [Policy Text Block]	Goodwill and Intangible Assets Goodwill and intangible assets generally result from business combinations and are evaluated for each of BOK Financial's reporting units for impairment annually or more frequently if conditions indicate impairment. The evaluation of possible impairment of goodwill and intangible assets involves significant judgment based upon short-term and long-term projections of future performance. Reporting units are defined by the Company as significant lines of business within each operating segment. This definition is consistent with the manner in which the chief operating decision maker assesses the performance of the Company and makes decisions concerning the allocation of resources. The Company qualitatively assesses whether it is more likely than not that the fair value of the reporting units are less than their carrying value, including goodwill. Reporting unit carrying value includes sufficient capital to exceed regulatory requirements. This assessment includes consideration of relevant events and circumstances including but not limited to macroeconomic conditions, industry and market conditions, the financial and stock performance of the Company and other relevant factors. If the Company concludes based on the qualitative assessment that goodwill may be impaired, a quantitative one-step impairment test will be applied to goodwill at all reporting units. The quantitative analysis compares the fair value of the reporting unit with its carrying value, including goodwill. The fair value of each reporting unit is estimated by the discounted future earnings method. Goodwill is considered impaired if the fair value of the reporting unit is less than the carrying value of the reporting unit, including goodwill. Intangible assets are generally composed of customer relationships, naming rights, non-compete agreements and core deposit premiums. They are amortized using accelerated or straight-line methods, as appropriate, over the estimated benefit periods. These periods range from 3 years to 20 years . The net book values of identifiable intangible assets are evaluated for impairment when economic conditions indicate impairment may exist.
Cash Equivalents [Policy Text Block]	Cash Equivalents Due from banks, funds sold (generally federal funds sold for one day ), resell agreements (which generally mature within one day to 30 days ) and investments in money market funds are considered cash equivalents.
Securities [Policy Text Block]	Securities Securities are identified as trading, investment (held to maturity) or available for sale at the time of purchase based upon the intent of management, liquidity and capital requirements, regulatory limitations and other relevant factors. Trading securities, which are acquired for profit through resale, are carried at fair value with unrealized gains and losses included in current period earnings. Investment securities are carried at amortized cost. Amortization is computed by methods that approximate level yield and is adjusted for changes in prepayment estimates. Securities identified as available for sale are carried at fair value. Unrealized gains and losses are recorded, net of deferred income taxes, as accumulated other comprehensive income in shareholders' equity. Available for sale securities are separately identified as pledged to creditors if the creditor has the right to sell or re-pledge the collateral. The purchase or sale of securities is recognized on a trade date basis. Realized gains and losses on sales of securities are based upon specific identification of the security sold. A receivable or payable is recognized for subsequent transaction settlement. On a quarterly basis, the Company performs separate evaluations of impaired debt investment and available for sale securities to determine if the decline in fair value below the amortized cost is other-than-temporary. Management determines whether it intends to sell or if it is more likely than not that it will be required to sell impaired securities. This determination considers current and forecasted liquidity requirements and securities portfolio management. If the Company intends to sell or it is more likely than not that it will be required to sell the impaired debt security, a charge is recognized against earnings for the entire unrealized loss. For all impaired debt securities for which there is no intent or expected requirement to sell, the evaluation considers all available evidence to assess whether it is more likely than not that all amounts due would not be collected according to the security's contractual terms. Impairment of debt securities rated investment grade by nationally-recognized rating agencies is considered temporary unless specific contrary information is identified. Impairment of debt securities rated below investment grade by at least one of the nationally recognized rating agencies is evaluated based on projections of estimated cash flows. Any expected credit loss due to the inability to collect all amounts due according to the security's contractual terms is recognized as a charge against earnings. Any remaining unrealized loss related to other factors would be recognized in other comprehensive income, net of taxes. BOK Financial may elect to carry certain securities that are not held for trading purposes at fair value with changes in fair value recognized in current period income. These securities are held with the intent that gains or losses will offset changes in the fair value of mortgage servicing rights or other financial instruments. Restricted equity securities represent equity interests the Company is required to hold in the Federal Reserve Banks and Federal Home Loan Banks. Restricted equity securities are carried at cost as these securities do not have a readily determined fair value because ownership of these shares is restricted and they lack a market. The fair value of our securities portfolio is generally based on a single price for each financial instrument provided to us by a third-party pricing service determined by one or more of the following: • Quoted prices for similar, but not identical, assets or liabilities in active markets; • Quoted prices for identical or similar assets or liabilities in inactive markets; • Inputs other than quoted prices that are observable, such as interest rate and yield curves, volatilities, prepayment speeds, loss severities, credit risks and default rates; and • Other inputs derived from or corroborated by observable market inputs. The underlying methods used by the third-party pricing services are considered in determining the primary inputs used to determine fair values. We evaluate the methodologies employed by the third-party pricing services by comparing the price provided by the pricing service with other sources, including brokers' quotes, sales or purchases of similar instruments and discounted cash flows to establish a basis for reliance on the pricing service values. Significant differences between the pricing service provided value and other sources are discussed with the pricing service to understand the basis for their values. Based on all observable inputs, management may adjust prices obtained from third-party pricing services to more appropriately reflect the prices that would be received to sell assets or paid to transfer liabilities in orderly transactions in the current market.
Derivatives Instruments [Policy Text Block]	Derivative Instruments Derivative instruments may be used by the Company as part of its internal risk management programs or may be offered to customers. All derivative instruments are carried at fair value and changes in fair value are generally reported in income as they occur. The determination of fair value of derivative instruments considers changes in interest rates, commodity prices and foreign exchange rates. Fair values for exchange-traded contracts are based on quoted prices in an active market for identical instruments. Fair values for over-the-counter contracts are generated internally using third-party valuation models. Inputs used in third-party valuation models to determine fair values are considered significant other observable inputs. Credit risk is also considered in determining fair value. Deterioration in the credit rating of customers or other counterparties reduces the fair value of asset contracts. Deterioration of our credit rating could decrease the fair value of our derivative liabilities. When bilateral netting agreements or similar agreements exist between the Company and its counterparties that create a single legal claim or obligation to pay or receive the net amount in settlement of the individual derivative contracts, the Company reports derivative assets and liabilities on a net by derivative contract by counterparty basis. Derivative contracts may also require the Company to provide or receive cash margin as collateral for derivative assets and liabilities. Derivative assets and liabilities are reported net of cash margin when certain conditions are met. In addition, derivative contracts executed with customers under Customer Risk Management Programs may be secured by non-cash collateral in conjunction with a credit agreement with that customer. Access to collateral in the event of default is reasonably assured. BOK Financial may use derivative instruments in managing its interest rate sensitivity, as part of its economic hedge of the changes in the fair value of mortgage servicing rights 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 its economic hedge of changes in the fair value of mortgage servicing rights are included in Other Operating Revenue - Gain (loss) on derivatives, net in the Consolidated Statements of Earnings. Changes in the fair value of derivative instruments used to mitigate the market risk of holding trading securities are included in Operating Revenue - Brokerage and trading revenue. BOK Financial also enters into mortgage loan commitments that are considered derivative contracts. Forward sales contracts that have not been designated as hedging instruments are used to economically hedge these mortgage loan commitments as well as mortgage loans held for sale. Mortgage loan commitments, forward sales contracts, and residential mortgage loans held for sale are carried at fair value. Changes in the fair value are reported in Other Operating Revenue - Mortgage banking revenue. BOK Financial offers programs that permit its customers to manage various risks, including fluctuations in energy, cattle and other agricultural products, interest rates and foreign exchange rates with derivative contracts. Customers may also manage interest rate risk through interest rate swaps used by the borrower to modify interest rate terms of their loans or to-be-announced securities used by our 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 market risk from changes in commodity prices, interest rates or foreign exchange rates. The counterparty contracts are identical to customer contracts, except for a fixed pricing spread or fee paid to BOK Financial as profit and compensation for administrative costs and credit risk which is recognized over the life of the contracts and included in other Operating Revenue - Brokerage and trading revenue in the Consolidated Statements of Earnings.
Loans [Policy Text Block]	Loans Loans are either secured or unsecured based on the type of loan and the financial condition of the borrower. Repayment is generally expected from cash flow or proceeds from the sale of selected assets of the borrower. BOK Financial is exposed to risk of loss on loans due to the borrower's financial difficulties, which may arise from any number of factors, including problems within the respective industry or local economic conditions. Access to collateral, in the event of borrower default, is reasonably assured through adherence to applicable lending laws and through sound lending standards and credit review procedures. Accounting policies for all loans, excluding residential mortgage loans guaranteed by U.S. government agencies, are as follows. Interest is accrued at the applicable interest rate on the outstanding principal amount. Loans are placed on nonaccruing status when, in the opinion of management, full collection of principal or interest is uncertain. Internally risk graded loans are individually evaluated for nonaccruing status quarterly. Non-risk graded loans are generally placed on nonaccruing status when 90 days or more past due or within 60 days of being notified of the borrower's bankruptcy filing. Interest previously accrued but not collected is charged against interest income when the loan is placed on nonaccruing status. Payments received on nonaccruing loans are applied to principal or recognized as interest income, according to management's judgment as to the collectability of principal. Loans may be returned to accruing status when, in the opinion of management, full collection of principal and interest, including principal previously charged off, is probable based on improvements in the borrower's financial condition or a sustained period of performance. For loans acquired with no evidence of credit deterioration, discounts are accreted on either an individual basis for loans with unique characteristics or on a pool basis for groups of homogeneous loans. Accretion is discontinued when a loan with an individually attributed discount is placed on nonaccruing status. Loans to borrowers experiencing financial difficulties may be modified in troubled debt restructurings ("TDRs"). All TDRs are generally classified as nonaccruing, excluding loans guaranteed by U.S. government agencies. Modifications generally consist of extension of payment terms or interest rate concessions and may result either voluntarily through negotiations with the borrower or involuntarily through court order. Generally, principal and accrued but unpaid interest is not voluntarily forgiven. Performing loans may be renewed under the then current collateral, debt service ratio and other underwriting standards. Nonaccruing loans may also be renewed and will remain classified as nonaccruing. Occasionally, loans, other than residential mortgage loans, may be held for sale in order to manage credit concentration. These loans are carried at the lower of cost or fair value with gains or losses recognized in gain (loss) on assets. All loans are charged-off when the loan balance or a portion of the loan balance is no longer supported by the paying capacity of the borrower or when the required cash flow is reduced in a TDR. The charge-off amount is determined through an evaluation of available cash resources and collateral value. Internally risk graded loans are evaluated quarterly and charge-offs are taken in the quarter in which the loss is identified. Non-risk graded loans that are past due between 60 days and 180 days , based on the loan product type, are charged off. Loans to borrowers whose personal obligation has been discharged through Chapter 7 bankruptcy proceedings are charged off within 60 days of notice of the bankruptcy filing, regardless of payment status. Loan origination and commitment fees and direct loan acquisition and origination costs are deferred and amortized as an adjustment to yield over the life of the loan or over the commitment period, as applicable. Amortization does not anticipate loan prepayments. Net unamortized fees are recognized in full at time of payoff. Qualifying residential mortgage loans guaranteed by U.S. government agencies have been sold into GNMA pools. Under certain performance conditions specified in government programs, the Company has the right, but not the obligation to repurchase loans from GNMA pools. These loans no longer qualify for sale accounting and are recognized in the Consolidated Balance Sheets. Guaranteed loans are considered to be impaired because we do not expect to receive all principal and interest based on the loan's contractual terms. A portion of the principal balance continues to be guaranteed; however, interest accrues at a curtailed rate as specified in the programs. The carrying value of these loans is reduced based on an estimate of expected cash flows discounted at the original note rate plus a liquidity spread. Guaranteed loans may be modified in TDRs in accordance with U.S. government agency guidelines. Interest continues to accrue at the modified rate. Guaranteed loans may either be resold into GNMA pools after a performance period specified by the programs or foreclosed and conveyed to the guarantors. Loans are disaggregated into portfolio segments and further disaggregated into classes. The portfolio segment is the level at which the Company develops and documents a systematic method for determining its Allowance for Credit Losses. Classes are based on the risk characteristics of the loans and the Company's method for monitoring and assessing credit risk.
Allowance for Loan Losses and Accrual for Off-Balance Sheet Credit Losses [Policy Text Block]	Allowance for Loan Losses and Accrual for Off-Balance Sheet Credit Risk The appropriateness of the allowance for loan losses and accrual for off-balance sheet credit risk (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 to provide financing. A consistent well-documented methodology has been developed and is applied by an independent Credit Administration department to assure consistency across the Company. The allowance for loan losses consists of specific allowances attributed to impaired loans that have not yet been charged down to amounts we expect to recover, general allowances based on estimated loss rates by loan class and nonspecific allowances based on factors that affect more than one portfolio segment. There were no changes to the methodology for estimating general allowances during 2019 or 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 personal loans are risk graded based on a quarterly evaluation of the borrowers' ability to repay. Certain commercial loans and most residential mortgage and personal 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, modified in a troubled debt restructuring 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 loan's initial effective interest rate or the fair value of collateral for certain collateral dependent loans. The fair value of real property held as collateral 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 generally are not adjusted by the Company. Updated appraisals are obtained at least annually or more frequently if market conditions indicate collateral values may have declined. Collateral value of mineral rights is generally determined by our internal staff of engineers based on projected cash flows from proven oil and gas reserves under existing economic and operating conditions. The value of other collateral is generally determined by our special assets staff based on projected liquidation 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 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 an estimated loss rate by loan class. The appropriate historical gross loss rate for each loan class is determined by the greater of the current loss rate based on the most recent twelve months or average loss rate over the long-term credit cycle. Recoveries are not directly considered in the estimation of historical 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, historical 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 weighted average risk grade. This comparison determines whether credit risk in each loan class is increasing or decreasing. Historical 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 a specific loan class which have not yet been represented in the historical 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 portfolio segment or loan class. These factors include trends in the economy in our primary lending areas, concentration in large-balance loans and other relevant factors. An accrual for off-balance sheet credit risk is included in Other liabilities in the Consolidated Balance Sheets. The appropriateness of the accrual is determined in the same manner as the allowance for loan losses. A provision for credit losses is charged against or credited to earnings in amounts necessary to maintain an appropriate Allowance for Credit Losses. Recoveries of loans previously charged off are added to the allowance when received.
Real Estate and Other Repossessed Assets [Policy Text Block]	Real Estate and Other Repossessed Assets Real estate and other repossessed assets are acquired in partial or total forgiveness of loans. These assets are initially recognized at cost, which is determined by fair value at date of foreclosure less estimated disposal costs. They are subsequently carried at the lower of cost or current fair value less estimated disposal costs. Decreases in fair value below cost are recognized as asset-specific valuation allowances which may be reversed when supported by future increases in fair value. Subsequent increases in fair value may be used to reduce the allowance but not below zero. Fair values of real estate are based on “as is” appraisals which are updated at least annually or more frequently for certain asset types or assets located in certain distressed markets. Fair values based on appraisals are generally considered to be based on significant other observable inputs. The Company also considers decreases in listing price and other relevant information in quarterly evaluations and reduces the carrying value of real estate and other repossessed assets when necessary. Fair values based on list prices and other relevant information are generally considered to be based on significant unobservable inputs. Additional costs incurred to complete real estate and other repossessed assets may increase the carrying value, up to current fair value based on “as completed” appraisals. The fair value of mineral rights included in repossessed assets are generally determined by our internal staff of engineers based on projected cash flows from proven oil and gas reserves under existing economic and operating conditions. The value of other repossessed assets is generally determined by our special assets staff based on projected liquidation cash flows under current market conditions. Income generated by these assets is recognized as received. Operating expenses are recognized as incurred. Gains or losses on sales of real estate and other repossessed assets are based on the cash proceeds received less the cost basis of the asset, net of any valuation allowances. The estimated disposal costs of real estate and other repossessed assets are evaluated by the Company on an annual basis based on actual results.
Transfers of Financial Assets [Policy Text Block]	Transfers of Financial Assets BOK Financial regularly transfers financial assets as part of its mortgage banking activities and periodically may transfer other financial assets. Transfers are recorded as sales when the criteria for surrender of control are met. The Company has elected to carry certain residential mortgage loans held for sale at fair value under the fair value option. Changes in fair value are recognized in net income as they occur. These loans are reported separately in the Consolidated Balance Sheets and changes in fair value are recorded in Other Operating Revenue - Mortgage banking revenue in the Consolidated Statements of Earnings. Fair value of conforming residential mortgage loans that will be sold to U.S. government agencies is based on sales commitments or market quotes considered Level 2 inputs. Fair value of mortgage loans that are unable to be sold to U.S. government agencies is based on Level 3 inputs using quoted prices of loans that are sold in securitization transactions with a liquidity discount applied. The fair value is corroborated with an independent third party on at least an annual basis. BOK Financial retains a repurchase obligation under underwriting representations and warranties related to residential mortgage loans transferred and generally retains the right to service the loans. These are not credit obligations. The Company may incur a recourse obligation in limited circumstances. Separate accruals are recognized in Other liabilities in the Consolidated Balance Sheets for repurchase and recourse obligations. These reserves reflect the estimated amount of probable loss the Company will incur as a result of repurchasing a loan, indemnifications, and other settlement resolutions. Repurchases of loans with an origination defect that are also credit impaired are considered collateral dependent and are initially recognized at net realizable value (appraised value less the cost to sell). The difference between unpaid principal balance and net realizable value is not accreted. Repurchases of loans with an origination defect that are not credit impaired are carried at fair value as of the repurchase date. Interest income continues to accrue on these loans and the discount is accreted over the estimated life of the loan. The Company may also choose to purchase GNMA loans once certain mandated delinquency criteria are met. The loans that are eligible and are chosen to be repurchased are initially recognized at fair value based on expected cash flow discounted using the average agency guaranteed debenture rates, average actual principal loss rates and liquidity premium.
Mortgage Servicing Rights [Policy Text Block]	Mortgage Servicing Rights Mortgage servicing rights may be purchased or may be recognized when mortgage loans are originated and sold with servicing rights retained. All mortgage servicing rights are carried at fair value. Changes in the fair value are recognized in earnings as they occur. Mortgage servicing rights are not traded in active markets. A cash flow model is used to determine fair value. Key assumptions and estimates, including projected prepayment speeds and assumed servicing costs, earnings on escrow deposits, ancillary income and discount rates, used by this model are based on current market sources. Assumptions used to value mortgage servicing rights are considered significant unobservable inputs. A separate third-party model is used to estimate prepayment speeds based on interest rates, housing turnover rates, estimated loan curtailment, anticipated defaults and other relevant factors. The prepayment model is updated daily for changes in market conditions and adjusted to better correlate with actual performance of BOK Financial's servicing portfolio. Fair value estimates from outside sources are received at least annually to corroborate the results of the valuation model.
Premises and Equipment [Policy Text Block]	Premises and Equipment Premises and equipment are carried at cost, including capitalized interest when appropriate, less accumulated depreciation and amortization. Depreciation and amortization are computed on a straight-line basis over the estimated useful lives of the assets or, for leasehold improvements, over the shorter of the estimated useful lives or remaining lease terms. Useful lives range from 5 years to 40 years for buildings and improvements, 3 years to 10 years for software and related implementation costs, and 3 years to 10 years for furniture and equipment. Construction in progress represents facilities construction and data processing systems projects underway that have not yet been placed into service. Depreciation and amortization begin once the assets are placed into service. Repair and maintenance costs, including software maintenance and enhancement costs, are charged to expense as incurred. Software licensing costs are generally charged to expense as incurred. Software licensing costs are capitalized if the contractual right to take possession of the software exists and it is feasible to take possession without significant penalty. Capitalized costs are amortized over the shorter of the estimated useful life of the software or remaining contractual life of the license. Premises no longer used by the Company are transferred to real estate and other repossessed assets. The transferred amount is the lower of cost less accumulated depreciation or fair value less estimated disposal costs as of the transfer date. Premises and equipment includes rights to use leased facilities and equipment. Right of use assets are initially measured by the present value of future rent payments over lease terms, adjusted for rent concessions. Rent payments exclude both payments made for non-lease components such as services and variable lease payments other than payments dependent on an index at lease commencement. Lease term includes options reasonably certain to be exercised. The right of use assets and lease liabilities are amortized to achieve straight-line expense over the lease term. Upon lease modification, the right of use asset and liability are reassessed and remeasured. Right of use assets are evaluated for impairment when facts and circumstances change that indicate an impairment may be necessary. Leases less than twelve months are excluded from capitalization. Ongoing technology projects of significant size or length are reviewed at least annually for impairment. Accumulated costs are reviewed for projects or components of projects that do not support the value of the asset being developed. Findings of obsolescence, duplicate effort or other conditions that do not support the recorded value are impaired, with the cost of the impaired components being charged to current-year earnings.
Federal and State Income Taxes [Policy Text Block]	Federal and State Income Taxes BOK Financial and its subsidiaries file consolidated tax returns. The subsidiaries provide for income taxes on a separate return basis and remit to BOK Financial amounts determined to be currently payable. BOK Financial is an agent for its subsidiaries under the Company's tax sharing agreements and has no ownership rights to any refunds received for the benefit of its subsidiaries. Current income tax expense or benefit is based on an evaluation that considers estimated taxable income, tax credits, and statutory federal and state income tax rates. The amount of current income tax expense or benefit recognized in any period may differ from amounts reported to taxing authorities. Annually, tax returns are filed with each jurisdiction where the Company conducts business and recognized current income tax expense or benefit is adjusted to the filed tax returns. Deferred tax assets and liabilities are based upon the temporary differences between the values of assets and liabilities as recognized in the financial statements and their related tax basis using enacted tax rates in effect for the year in which the differences are expected to be recovered or settled. The effect of changes in statutory tax rates on the measurement of deferred tax assets and liabilities is recognized through income tax expense in the period the change is enacted. A valuation allowance is provided when it is more likely than not that some portion of the entire deferred tax asset may not be realized. BOK Financial has unrecognized tax benefits, which are included in accrued current income taxes payable, for the uncertain portion of recorded tax benefits and related interest. These uncertainties result from the application of complex tax laws, rules, regulations and interpretations, primarily in state taxing jurisdictions. Unrecognized tax benefits are assessed quarterly and may be adjusted through current income tax expense in future periods based on changing facts and circumstances, completion of examinations by taxing authorities or expiration of a statute of limitations. Estimated penalties and interest on uncertain tax positions are recognized in income tax expense.
Employee Benefit Plans [Policy Text Block]	Employee Benefit Plans BOK Financial sponsors a defined contribution plan (“Thrift Plan”) and a defined benefit cash balance pension plan (“Pension Plan”). Employer contributions to the Thrift Plan, which matches employee contributions subject to percentage and years of service limits, are expensed when incurred. Pension Plan costs, which are based upon actuarial computations of current costs, are expensed annually. Pension Plan benefits were curtailed as of April 1, 2006. No participants may be added to the Pension Plan and no additional service benefits will be accrued. BOK Financial recognizes the funded status of its employee benefit plans. Adjustments required to recognize the Pension Plan's net funded status are made through accumulated other comprehensive income, net of deferred income taxes.
Shared-Based Compensation Plans [Policy Text Block]	Share-Based Compensation Plans BOK Financial awards stock options and non-vested common shares as compensation to certain officers. The grant date fair value of stock options is based on the Black-Scholes option pricing model. Stock options generally have graded vesting over 7 years . Each tranche is considered a separate award for valuation and compensation cost recognition. Grant date fair value of non-vested shares is based on the then-current market value of BOK Financial common stock. Non-vested shares generally cliff vest in 3 years and are subject to a holding period after vesting of 2 years . Compensation cost is initially based on the grant date fair value of the award and recognized as expense over the service period, which is generally the vesting period. Expense is reduced for estimated forfeitures over the vesting period and adjusted for actual forfeitures as they occur. Share-based compensation awarded to certain officers has performance conditions that affect the number of awards granted. Compensation cost is adjusted based on the probable outcome of the performance conditions. Restricted stock units ("RSUs") may also be awarded for certain executives who have elected to defer income recognition upon vesting of their awards. RSUs are subject to the same vesting criteria as non-vested shares. The value of the awards will vary in amounts equal to changes in the fair value of an equal number of BOKF Financial common shares. Tax effects of share-based payments are recognized through tax expense. Dividends on non-vested shares are charged to retained earnings. Dividend equivalents on RSU's are charged to expense.
Other Operating Revenue [Policy Text Block]	Other Operating Revenue Fees and commissions revenue is generated through the sales of products, consisting primarily of financial instruments, and the performance of services for customers under contractual obligations. Revenue from providing services for customers is recognized at the time services are provided in an amount that reflects the consideration we expect to be entitled to for those services. Revenue is recognized based on the application of five steps: • Identify the contract with a customer • Identify the performance obligations in the contract • Determine the transaction price • Allocate the transaction price to the performance obligations in the contract • Recognize revenue when (or as) the Company satisfies a performance obligation For contracts with multiple performance obligations, individual performance obligations are accounted for separately if the customer can benefit from the good or service on its own or with other resources readily available to the customer and the promise to transfer goods and services to the customer is separately identifiable in the contract. The transaction price is allocated to the performance obligations based on relative standalone selling prices. Revenue is recognized on a gross basis whenever we have primary responsibility and risk in providing the services or products to our customers and have discretion in establishing the price for the services or products. Revenue is recognized on a net basis whenever we act as an agent for products or services of others. Brokerage and trading revenue includes revenues from trading, customer hedging, retail brokerage, investment banking and insurance brokerage. Trading revenue includes net realized and unrealized gains primarily related to sales of securities to institutional customers and related derivative contracts. Customer hedging revenue includes realized and unrealized changes in the fair value of derivative contracts held for customer risk management programs including credit valuation adjustments, as necessary. We offer commodity, interest rate, foreign exchange and equity derivatives to our customers. These customer contracts are offset with contracts with selected counterparties and exchanges to minimize changes in market risk from changes in commodity prices, interest rates or foreign exchange rates. Retail brokerage revenue represents fees and commissions earned on sales of fixed income securities, annuities, mutual funds and other financial instruments to retail customers. Investment banking revenue includes fees earned upon completion of underwriting and financial advisory services. Investment banking revenue also includes fees earned in conjunction with loan syndications. Insurance brokerage revenues represent fees and commissions earned on placement of insurance products with carriers for property and casualty and health coverage. Transaction card revenue includes merchant discount fees and electronic funds transfer network fees, net of interchange fees paid to card issuers and assessments paid to card networks. Merchant discount fees represent fees paid by customers for account management and electronic processing of card transactions. Merchant discount fees are recognized at the time the customer’s transactions are processed or other services are performed. The Company also maintains the TransFund electronic funds transfer network for the benefit of its members, which includes BOKF, NA. Electronic funds transfer fees are recognized as electronic transactions are processed on behalf of its members. Fiduciary and asset management revenue includes fees from asset management, custody, recordkeeping, investment advisory and administration services. Revenue is recognized on an accrual basis at the time the services are performed and may be based on either the fair value of the account or the service provided. Deposit service charges and fees include commercial account service charges, overdraft fees, check card fee revenue and automated service charge and other deposit service fees. Fees are recognized at least quarterly in accordance with published deposit account agreements and disclosure statements for retail accounts or contractual agreements for commercial accounts. Item charges for overdraft or non-sufficient funds items are recognized as items are presented for payment. Account balance charges and activity fees are accrued monthly and collected in arrears. Commercial account activity fees may be offset by an earnings credit based on account balances. Check card fees represent interchange fees paid by a merchant bank for transactions processed from cards issued by the Company. Check card fees are recognized when transactions are processed. Mortgage banking revenue includes revenues recognized in conjunction with the origination, marketing and servicing of conventional and government-sponsored residential mortgage loans. Mortgage production revenue includes net realized gains (losses) on sales of residential mortgage loans in the secondary market and the net change in unrealized gains (losses) on residential mortgage loans held for sale. Mortgage production revenue also includes changes in the fair value of derivative contracts not designated as hedging instruments related to residential mortgage loan commitments and forward sales contracts. Mortgage servicing revenue includes servicing fee income and late charges on loans serviced for others.
Newly Adopted and Pending Accounting Pronouncements [Policy Text Block]	Newly Adopted and Pending Accounting Pronouncements The following is a summary of newly adopted and pending accounting pronouncements that may have a more than insignificant effect on the Company's financial statements. Financial Accounting Standards Board ("FASB") FASB Accounting Standards Update No. 2016-02, Leases (Topic 842) ("ASU 2016-02") On February 25, 2016, the FASB issued ASU 2016-02 to increase transparency and comparability by recognizing lease assets and liabilities on the balance sheet and disclosing key information about leasing arrangements. Lessees are required to recognize an obligation for future lease payments measured on a discounted basis and a right-of-use asset. The Company adopted the new standard January 1, 2019 through a cumulative effect adjustment to retained earnings. Prior periods were not restated. BOKF elected to apply all practical expedients other than the lessee's practical expedient to combine lease and non-lease components which would further gross up lease liability and the related right-of-use asset. The implementation of ASU 2016-02 increased the reported right-of-use asset and lease liability by $137 million . The effect on retained earnings was immaterial. FASB Accounting Standards Update No. 2019-01, Leases (Topic 842): Codification Improvements ("ASU 2019-01") On March 5, 2019, the FASB issued ASU 2019-01 which amends certain aspects of leasing standard ASU 2016-02. ASU 2019-01 provides guidance for determining fair value of the underlying asset by lessors that are not manufacturers or dealers. The ASU also requires depository and lending lessors within the scope of ASC 942 to classify principal payments received from sales-type and direct financing leases within "investing activities" on the statement of cash flows. For the two issues above, the ASU is effective for the Company for fiscal years beginning after December 15, 2019, and interim periods therein; however, early adoption is permitted. Additionally, ASU 2019-01 also clarifies interim disclosure requirements during transition and is effective with the original transition requirements in Topic 842. Adoption of ASU 2019-01 is not expected to have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Assets Measured at Amortized Cost ("ASU 2016-13") On June 16, 2016, the FASB issued ASU 2016-13 to provide more timely recording of credit losses on loans and other financial assets measured at amortized cost, effective for the Company's annual reporting periods beginning after December 15, 2019, including interim periods within those fiscal years. The Company has established a CECL implementation team to evaluate the impact to 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. The Audit and Credit Committees of the Board of Directors are periodically updated on project progress. The implementation team has completed the design of internal controls over the expected credit losses estimate and is formalizing control procedures, governance, and approval processes. This includes finalizing model validation, refinement of model assumptions and qualitative framework, and drafting policies, reporting, and disclosures. The Company adopted the standard on January 1, 2020 through a cumulative-effect adjustment to retained earnings. FASB Accounting Standards Update No. 2019-04, Codification Improvements to Topic 326, Financial Instruments-Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments ("ASU 2019-04") On April 25, 2019, the FASB issued ASU 2019-04 which clarifies certain aspects of the accounting for credit losses, hedging activities, and financial instruments addressed by ASUs 2016-13, 2017-12, and 2016-01, respectively. Significant amendments made to the provisions of ASU 2016-13 by ASU 2019-04 include providing certain alternatives for the measurement of the allowance for credit losses on accrued interest receivable and clarifying steps entities should take when recording the transfer of loans or debt securities between measurement classification or categories. ASU 2019-04 further clarifies the expectation that entities include recoveries of financial assets in the calculation of the current expected credit losses allowance for both pools of financial assets and individual financial assets. Significant amendments made to the provisions of ASU 2017-12 by ASU 2019-04 include clarification on partial-term fair value hedges of interest rate risk, amortization of fair value hedge basis adjustments and disclosure of fair value hedge basis adjustments. Significant amendments made to provisions of ASU 2016-01 include clarification of the measurement alternative practice for equity securities and remeasurement of equity securities at historical exchange rates. ASU 2019-04 includes other amendments which clarify various provisions within the codification. ASU 2019-04 is effective for the Company for fiscal years beginning after December 15, 2019 and interim periods therein. Adoption of ASU 2019-04 is not expected to have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2019-05, Financial Instruments-Credit Losses (Topic 326): Targeted Transition Relief ("ASU 2019-05") On May 15, 2019, the FASB issued ASU 2019-05 which provides transition relief for entities adopting the Board's credit losses standard, ASU 2016-13. ASU 2019-05 amends ASU 2016-13 to allow companies to irrevocably elect, upon adoption of ASU 2016-13, the fair value option for financial instruments that meet specific requirements and is effective for the Company for annual reporting periods beginning after December 15, 2019. Adoption of ASU 2019-05 is not expected to have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2019-11, Codification Improvements to Topic 326: Financial Instruments-Credit Losses ("ASU 2019-11") On November 27, 2019, the FASB issued ASU 2019-11 which revises certain aspects of new guidance on credit losses. Topics addressed include purchased credit-deteriorated assets, transition relief for troubled debt restructurings, disclosure relief for accrued interest receivable, and financial assets secured by collateral maintenance provisions. ASU 2019-11 is effective for the Company for annual reporting periods beginning after December 15, 2019. Adoption of ASU 2019-11 is not expected to have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ("ASU 2019-12")

Reclassifications (Policies)

Reclassifications (Policies)	12 Months Ended
Reclassifications (Policies)	Dec. 31, 2019
Accounting Policies [Abstract]
Reclassifications [Text Block]	Certain prior year amounts have been reclassified to conform to current year presentation.

Securities (Tables)

Securities (Tables)	12 Months Ended
Securities (Tables)	Dec. 31, 2019
Marketable Securities [Abstract]
Trading Securities [Table Text Block]	The fair value and net unrealized gain (loss) included in trading securities is as follows (in thousands): December 31, 2019 December 31, 2018 Fair Value Net Unrealized Gain (Loss) Fair Value Net Unrealized Gain (Loss) U.S. government agency debentures $ 44,264 $ 6 $ 63,765 $ 254 Residential agency mortgage-backed securities 1,504,651 2,293 1,791,584 9,966 Municipal and other tax-exempt securities 26,196 60 34,507 (1 ) Asset-backed securities 14,084 (21 ) 42,656 685 Other debt securities 34,726 21 24,411 65 Total trading securities $ 1,623,921 $ 2,359 $ 1,956,923 $ 10,969
Investment Securities (Held-to-Maturity) [Table Text Block]	The amortized cost and fair values of investment securities are as follows (in thousands): December 31, 2019 Amortized Fair Gross Unrealized Cost Value Gain Loss Municipal and other tax-exempt securities $ 93,653 $ 96,897 $ 3,250 $ (6 ) Residential agency mortgage-backed securities 10,676 11,164 488 — Other debt securities 189,089 206,341 17,547 (295 ) Total investment securities $ 293,418 $ 314,402 $ 21,285 $ (301 ) December 31, 2018 Amortized Fair Gross Unrealized Cost Value Gain Loss Municipal and other tax-exempt securities $ 137,296 $ 138,562 $ 1,858 $ (592 ) Residential agency mortgage-backed securities 12,612 12,770 293 (135 ) Other debt securities 205,279 215,966 12,257 (1,570 ) Total investment securities $ 355,187 $ 367,298 $ 14,408 $ (2,297 ) The amortized cost and fair values of investment securities at December 31, 2019 , 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 Maturity 1 Fixed maturity debt securities: Amortized cost $ 41,670 $ 84,027 $ 144,705 $ 12,340 $ 282,742 5.10 Fair value 41,840 87,883 161,178 12,337 303,238 Residential mortgage-backed securities: Amortized cost $ 10,676 2 Fair value 11,164 Total investment securities: Amortized cost $ 293,418 Fair value 314,402 1 Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty. 2 The average expected lives of residential mortgage-backed securities were 5.0 years based upon current prepayment assumptions. Temporarily Impaired Investment Securities (in thousands): December 31, 2019 Number of Securities Less Than 12 Months 12 Months or Longer Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Investment: Municipal and other tax-exempt 4 $ 1,001 $ 1 $ 1,706 $ 5 $ 2,707 $ 6 Residential agency mortgage-backed securities — — — — — — — Other debt securities 13 275 1 8,041 294 8,316 295 Total investment securities 17 $ 1,276 $ 2 $ 9,747 $ 299 $ 11,023 $ 301 December 31, 2018 Number of Securities Less Than 12 Months 12 Months or Longer Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Investment: Municipal and other tax- exempt 72 $ 18,255 $ 69 $ 66,141 $ 523 $ 84,396 $ 592 Residential agency mortgage-backed securities 2 — — 5,633 135 5,633 135 Other debt securities 72 13,372 64 23,028 1,506 36,400 1,570 Total investment securities 146 $ 31,627 $ 133 $ 94,802 $ 2,164 $ 126,429 $ 2,297
Available for Sale Securities [Table Text Block]	The amortized cost and fair value of available for sale securities are as follows (in thousands): December 31, 2019 Amortized Fair Gross Unrealized Cost Value Gain Loss U.S. Treasury $ 1,598 $ 1,600 $ 2 $ — Municipal and other tax-exempt 1,789 1,861 72 — Mortgage-backed securities: Residential agency 7,956,297 8,046,096 104,912 (15,113 ) Residential non-agency 25,968 41,609 15,641 — Commercial agency 3,145,342 3,178,005 37,808 (5,145 ) Other debt securities 500 472 — (28 ) Total available for sale securities $ 11,131,494 $ 11,269,643 $ 158,435 $ (20,286 ) December 31, 2018 Amortized Fair Gross Unrealized Cost Value Gain Loss U.S. Treasury $ 496 $ 493 $ — $ (3 ) Municipal and other tax-exempt 2,782 2,864 82 — Mortgage-backed securities: Residential agency 5,886,323 5,804,708 16,149 (97,764 ) Residential non-agency 40,948 59,736 18,788 — Commercial agency 2,986,297 2,953,889 7,955 (40,363 ) Other debt securities 35,545 35,430 12 (127 ) Total available for sale securities $ 8,952,391 $ 8,857,120 $ 42,986 $ (138,257 ) The amortized cost and fair values of available for sale securities at December 31, 2019 , 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 Maturity 1 Fixed maturity debt securities: Amortized cost $ 5,105 $ 1,113,463 $ 1,455,340 $ 575,321 $ 3,149,229 8.15 Fair value 5,114 1,122,392 1,474,002 580,430 3,181,938 Residential mortgage-backed securities: Amortized cost $ 7,982,265 2 Fair value 8,087,705 Total available-for-sale securities: Amortized cost $ 11,131,494 Fair value 11,269,643 1 Expected maturities may differ from contractual maturities, because borrowers may have the right to call or prepay obligations with or without penalty. 2 The average expected lives of mortgage-backed securities were 4.0 years based upon current prepayment assumptions. Sales of available for sale securities resulted in gains and losses as follows (in thousands): Year Ended December 31, 2019 2018 2017 Proceeds $ 1,211,718 $ 745,643 $ 1,309,215 Gross realized gains 14,996 7,117 10,223 Gross realized losses (9,399 ) (9,918 ) (5,795 ) Related federal and state income tax expense (benefit) 1,425 (713 ) 1,722
Debt Securities, Available for Sale, Unrealized Loss Position [Table Text Block]	Temporarily Impaired Available for Sale Securities (In thousands) December 31, 2019 Number of Securities Less Than 12 Months 12 Months or Longer Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Available for sale: Mortgage-backed securities: Residential agency 133 $ 1,352,597 $ 6,690 $ 686,002 $ 8,423 $ 2,038,599 $ 15,113 Commercial agency 69 830,047 4,238 210,877 907 1,040,924 5,145 Other debt securities 1 — — 472 28 472 28 Total available for sale securities 203 $ 2,182,644 $ 10,928 $ 897,351 $ 9,358 $ 3,079,995 $ 20,286 December 31, 2018 Number of Securities Less Than 12 Months 12 Months or Longer Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Available for sale: U.S. Treasury 1 $ — $ — $ 493 $ 3 $ 493 $ 3 Mortgage-backed securities: Residential agency 289 510,824 1,158 3,641,370 96,606 4,152,194 97,764 Commercial agency 197 179,258 394 1,969,504 39,969 2,148,762 40,363 Other debt securities 3 9,982 63 20,436 64 30,418 127 Total available for sale securities 490 $ 700,064 $ 1,615 $ 5,631,803 $ 136,642 $ 6,331,867 $ 138,257
Fair Value Option Securities [Table Text Block]	The fair value and net unrealized gain (loss) included in fair value option securities is as follows (in thousands): December 31, 2019 December 31, 2018 Fair Value Net Unrealized Gain (Loss) Fair Value Net Unrealized Gain (Loss) U.S. Treasury $ 9,917 $ (48 ) $ — $ — Residential agency mortgage-backed securities 1,088,660 14,109 283,235 2,766 Total $ 1,098,577 $ 14,061 $ 283,235 $ 2,766

Derivatives (Tables)

Derivatives (Tables)	12 Months Ended
Derivatives (Tables)	Dec. 31, 2019
Derivative Instrument Detail [Abstract]
Derivative Contracts [Table Text Block]	The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at December 31, 2019 (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 $ — $ — $ — $ — $ — $ — Interest rate swaps 2,464,478 49,100 (1,839 ) 47,261 — 47,261 Energy contracts 2,151,096 144,906 (107,591 ) 37,315 (38 ) 37,277 Agricultural contracts 16,118 1,522 (22 ) 1,500 — 1,500 Foreign exchange contracts 214,119 213,007 — 213,007 — 213,007 Equity option contracts 81,455 3,233 — 3,233 (660 ) 2,573 Total customer risk management programs 4,927,266 411,768 (109,452 ) 302,316 (698 ) 301,618 Trading 69,721,932 131,561 (115,949 ) 15,612 — 15,612 Interest rate risk management programs 1,268,180 6,226 (81 ) 6,145 — 6,145 Total derivative contracts $ 75,917,378 $ 549,555 $ (225,482 ) $ 324,073 $ (698 ) $ 323,375 Liabilities Notional¹ Gross Fair Value Netting Adjustments Net Fair Value Before Cash Collateral Cash Collateral Fair Value Net of Cash Collateral Customer risk management programs: Interest rate contracts To-be-announced residential mortgage-backed securities $ — $ — $ — $ — $ — $ — Interest rate swaps 2,464,478 49,194 (1,839 ) 47,355 (43,932 ) 3,423 Energy contracts 2,105,391 139,311 (107,591 ) 31,720 (6,031 ) 25,689 Agricultural contracts 16,139 1,507 (22 ) 1,485 (1,485 ) — Foreign exchange contracts 207,919 207,020 — 207,020 — 207,020 Equity option contracts 81,455 3,233 — 3,233 — 3,233 Total customer risk management programs 4,875,382 400,265 (109,452 ) 290,813 (51,448 ) 239,365 Trading 65,144,388 125,535 (115,949 ) 9,586 — 9,586 Interest rate risk management programs 380,401 3,121 (81 ) 3,040 (863 ) 2,177 Total derivative contracts $ 70,400,171 $ 528,921 $ (225,482 ) $ 303,439 $ (52,311 ) $ 251,128 1 Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract. The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at December 31, 2018 (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 $ 10,671,151 $ 92,231 $ (26,787 ) $ 65,444 $ — $ 65,444 Interest rate swaps 1,924,131 36,112 (6,688 ) 29,424 (7,934 ) 21,490 Energy contracts 1,472,209 206,418 (60,983 ) 145,435 (106,752 ) 38,683 Agricultural contracts 21,210 842 (201 ) 641 — 641 Foreign exchange contracts 184,990 183,759 — 183,759 — 183,759 Equity option contracts 89,085 2,021 — 2,021 (648 ) 1,373 Total customer risk management programs 14,362,776 521,383 (94,659 ) 426,724 (115,334 ) 311,390 Trading 15,356,909 45,346 (39,521 ) 5,825 — 5,825 Internal risk management programs 553,079 5,064 (1,350 ) 3,714 — 3,714 Total derivative contracts $ 30,272,764 $ 571,793 $ (135,530 ) $ 436,263 $ (115,334 ) $ 320,929 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 $ 10,558,151 $ 90,388 $ (26,787 ) $ 63,601 $ (63,596 ) $ 5 Interest rate swaps 1,924,131 36,288 (6,688 ) 29,600 (4,110 ) 25,490 Energy contracts 1,434,247 202,494 (60,983 ) 141,511 (1,490 ) 140,021 Agricultural contracts 21,214 812 (201 ) 611 — 611 Foreign exchange contracts 177,423 175,922 — 175,922 — 175,922 Equity option contracts 89,085 2,021 — 2,021 — 2,021 Total customer risk management programs 14,204,251 507,925 (94,659 ) 413,266 (69,196 ) 344,070 Trading 19,374,294 56,983 (39,521 ) 17,462 — 17,462 Internal risk management programs 260,348 9,439 (1,350 ) 8,089 (7,315 ) 774 Total derivative contracts $ 33,838,893 $ 574,347 $ (135,530 ) $ 438,817 $ (76,511 ) $ 362,306 1 Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.
Derivative Instruments, Gain (Loss) in Statement of Earnings [Table Text Block]	The following summarizes the pre-tax net gains (losses) on derivative instruments and where they are recorded in the Consolidated Statements of Earnings (in thousands): Year Ended December 31, 2019 2018 2017 Brokerage and Trading Revenue Gain (Loss) on Derivatives, Net Brokerage and Trading Revenue Gain (Loss) on Derivatives, Net Brokerage and Trading Revenue Gain (Loss) on Derivatives, Net Customer risk management programs: Interest rate contracts To-be-announced residential mortgage-backed securities $ 9,579 $ — $ 27,190 $ — $ 34,532 $ — Interest rate swaps 3,647 — 2,614 — 2,647 — Energy contracts 5,064 — 8,443 — 5,536 — Agricultural contracts 28 — 53 — 79 — Foreign exchange contracts 623 — 535 — 1,352 — Equity option contracts — — — — — — Total customer risk management programs 18,941 — 38,835 — 44,146 — Trading 13,999 — (13,643 ) — 4,615 — Internal risk management programs — 14,951 — (422 ) — 779 Total derivative contracts $ 32,940 $ 14,951 $ 25,192 $ (422 ) $ 48,761 $ 779

Loans and Allowances for Cred_2

Loans and Allowances for Credit Losses (Tables)	12 Months Ended
Loans and Allowances for Credit Losses (Tables)	Dec. 31, 2019
Loans and Leases Receivable, Net Amount [Abstract]
Schedule of the Loans by Portfolio Segment [Table Text Block]	The portfolio segments of the loan portfolio are as follows (in thousands): December 31, 2019 December 31, 2018 Fixed Rate Variable Rate Non-accrual Total Fixed Rate Variable Rate Non-accrual Total Commercial $ 3,231,485 $ 10,684,749 $ 115,416 $ 14,031,650 $ 2,251,188 $ 11,285,049 $ 99,841 $ 13,636,078 Commercial real estate 1,056,321 3,349,836 27,626 4,433,783 1,477,274 3,265,918 21,621 4,764,813 Residential mortgage 1,652,653 393,897 37,622 2,084,172 1,830,224 358,254 41,555 2,230,033 Personal 193,903 1,007,192 287 1,201,382 190,687 834,889 230 1,025,806 Total $ 6,134,362 $ 15,435,674 $ 180,951 $ 21,750,987 $ 5,749,373 $ 15,744,110 $ 163,247 $ 21,656,730 Accruing loans past due (90 days) 1 $ 7,680 $ 1,338 Foregone interest on nonaccrual loans $ 17,409 $ 15,502 1
Rollforward of Allowance For Loan Losses And Accrual for Off-Balnace Sheet Credit Losses [Table Text Block]	The activity in the allowance for loan losses and the accrual for off-balance sheet credit risk related to loan commitments and standby letters of credit for the year ended December 31, 2019 is summarized as follows (in thousands): Commercial Commercial Real Estate Residential Mortgage Personal Nonspecific Allowance Total Allowance for loan losses: Beginning balance $ 102,226 $ 60,026 $ 17,964 $ 9,473 $ 17,768 $ 207,457 Provision for loan losses 57,125 (12,046 ) (3,838 ) 3,537 (573 ) 44,205 Loans charged off (43,185 ) (1,161 ) (288 ) (6,343 ) — (50,977 ) Recoveries 2,021 4,986 562 2,505 — 10,074 Ending balance $ 118,187 $ 51,805 $ 14,400 $ 9,172 $ 17,195 $ 210,759 Accrual for off-balance sheet credit risk: Beginning balance $ 1,655 $ 52 $ 52 $ 31 $ — $ 1,790 Provision for off-balance sheet credit risk (221 ) 55 (8 ) (31 ) — (205 ) Ending balance $ 1,434 $ 107 $ 44 $ — $ — $ 1,585 Total provision for credit losses $ 56,904 $ (11,991 ) $ (3,846 ) $ 3,506 $ (573 ) $ 44,000 The activity in the allowance for loan losses and the accrual for off-balance sheet credit risk related to loan commitments and standby letters of credit for the year ended December 31, 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 12,521 (147 ) (1,156 ) 3,175 (4,449 ) 9,944 Loans charged off (37,880 ) — (378 ) (5,325 ) — (43,583 ) Recoveries 3,316 3,552 1,047 2,499 — 10,414 Ending balance $ 102,226 $ 60,026 $ 17,964 $ 9,473 $ 17,768 $ 207,457 Accrual for off-balance sheet credit risk: Beginning balance $ 3,644 $ 45 $ 43 $ 2 $ — $ 3,734 Provision for off-balance sheet credit risk (1,989 ) 7 9 29 — (1,944 ) Ending balance $ 1,655 $ 52 $ 52 $ 31 $ — $ 1,790 Total provision for credit losses $ 10,532 $ (140 ) $ (1,147 ) $ 3,204 $ (4,449 ) $ 8,000 The activity in the allowance for loan losses and the accrual for off-balance sheet credit risk related to loan commitments and standby letters of credit for the year ended December 31, 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 (595 ) 4,008 116 2,964 (5,983 ) 510 Loans charged off (19,810 ) (76 ) (649 ) (5,064 ) — (25,599 ) Recoveries 4,461 1,940 760 2,451 — 9,612 Ending balance $ 124,269 $ 56,621 $ 18,451 $ 9,124 $ 22,217 $ 230,682 Accrual for off-balance sheet credit risk: Beginning balance $ 11,063 $ 123 $ 50 $ 8 $ — $ 11,244 Provision for off-balance sheet credit risk (7,419 ) (78 ) (7 ) (6 ) — (7,510 ) Ending balance $ 3,644 $ 45 $ 43 $ 2 $ — $ 3,734 Total provision for credit losses $ (8,014 ) $ 3,930 $ 109 $ 2,958 $ (5,983 ) $ (7,000 ) The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2019 is as follows (in thousands): Collectively Measured for Impairment Individually Measured for Impairment Total Recorded Investment Related Allowance Recorded Investment Related Allowance Recorded Investment Related Allowance Commercial $ 13,916,234 $ 100,773 $ 115,416 $ 17,414 $ 14,031,650 $ 118,187 Commercial real estate 4,406,157 51,805 27,626 — 4,433,783 51,805 Residential mortgage 2,046,550 14,400 37,622 — 2,084,172 14,400 Personal 1,201,095 9,172 287 — 1,201,382 9,172 Total 21,570,036 176,150 180,951 17,414 21,750,987 193,564 Nonspecific allowance — — — — — 17,195 Total $ 21,570,036 $ 176,150 $ 180,951 $ 17,414 $ 21,750,987 $ 210,759 The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 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 $ 13,536,237 $ 93,494 $ 99,841 $ 8,732 $ 13,636,078 $ 102,226 Commercial real estate 4,743,192 60,026 21,621 — 4,764,813 60,026 Residential mortgage 2,188,478 17,964 41,555 — 2,230,033 17,964 Personal 1,025,576 9,473 230 — 1,025,806 9,473 Total 21,493,483 180,957 163,247 8,732 21,656,730 189,689 Nonspecific allowance — — — — — 17,768 Total $ 21,493,483 $ 180,957 $ 163,247 $ 8,732 $ 21,656,730 $ 207,457
Schedule of Credit Quality Indicators [Table Text Block]	The allowance for loan losses and recorded investment of the related loans by portfolio segment for risk graded and non-risk graded loans at December 31, 2019 is as follows (in thousands): Internally Risk Graded Non-Graded Total Recorded Investment Related Allowance Recorded Investment Related Allowance Recorded Investment Related Allowance Commercial $ 13,997,538 $ 117,236 $ 34,112 $ 951 $ 14,031,650 $ 118,187 Commercial real estate 4,433,783 51,805 — — 4,433,783 51,805 Residential mortgage 279,113 3,085 1,805,059 11,315 2,084,172 14,400 Personal 1,116,297 7,003 85,085 2,169 1,201,382 9,172 Total 19,826,731 179,129 1,924,256 14,435 21,750,987 193,564 Nonspecific allowance — — — — — 17,195 Total $ 19,826,731 $ 179,129 $ 1,924,256 $ 14,435 $ 21,750,987 $ 210,759 The 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, 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 $ 13,586,654 $ 101,303 $ 49,424 $ 923 $ 13,636,078 $ 102,226 Commercial real estate 4,764,813 60,026 — — 4,764,813 60,026 Residential mortgage 505,046 3,310 1,724,987 14,654 2,230,033 17,964 Personal 948,890 6,633 76,916 2,840 1,025,806 9,473 Total 19,805,403 171,272 1,851,327 18,417 21,656,730 189,689 Nonspecific allowance — — — — — 17,768 Total $ 19,805,403 $ 171,272 $ 1,851,327 $ 18,417 $ 21,656,730 $ 207,457 Loans are considered to be performing if they are in compliance with the original terms of the agreement which is consistent with the regulatory guideline of “pass.” Performing also includes loans considered to be “other loans especially mentioned” by regulatory guidelines and all residential mortgage loans guaranteed by agencies of the U.S. government that continue to accrue interest based on criteria of the guarantor's 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 in accordance with the original terms of the loan agreements 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 December 31, 2019 by the risk grade categories (in thousands): Internally Risk Graded Non-Graded Performing Pass Other Loans Especially Mentioned Accruing Substandard Nonaccrual Performing Nonaccrual Total Commercial: Energy $ 3,700,406 $ 117,298 $ 63,951 $ 91,722 $ — $ — $ 3,973,377 Services 3,050,946 29,943 33,791 7,483 — — 3,122,163 Wholesale/retail 1,749,023 5,281 5,399 1,163 — — 1,760,866 Manufacturing 623,219 18,214 13,883 10,133 — — 665,449 Healthcare 2,995,514 13,117 20,805 4,480 — — 3,033,916 Public finance 709,868 — — — — — 709,868 Other commercial and industrial 709,729 4,028 17,744 398 34,075 37 766,011 Total commercial 13,538,705 187,881 155,573 115,379 34,075 37 14,031,650 Commercial real estate: Residential construction and land development 150,529 — — 350 — — 150,879 Retail 743,343 12,067 1,243 18,868 — — 775,521 Office 923,202 5,177 — — — — 928,379 Multifamily 1,257,005 1,604 95 6,858 — — 1,265,562 Industrial 852,539 1,658 1,011 909 — — 856,117 Other commercial real estate 455,045 1,639 — 641 — — 457,325 Total commercial real estate 4,381,663 22,145 2,349 27,626 — — 4,433,783 Residential mortgage: Permanent mortgage 276,138 78 2,404 493 758,260 19,948 1,057,321 Permanent mortgages guaranteed by U.S. government agencies — — — — 191,694 6,100 197,794 Home equity — — — — 817,976 11,081 829,057 Total residential mortgage 276,138 78 2,404 493 1,767,930 37,129 2,084,172 Personal 1,116,196 45 — 56 84,853 232 1,201,382 Total $ 19,312,702 $ 210,149 $ 160,326 $ 143,554 $ 1,886,858 $ 37,398 $ 21,750,987 The following table summarizes the Company’s loan portfolio at December 31, 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 $ 3,414,039 $ 42,176 $ 86,624 47,494 $ — $ — $ 3,590,333 Services 3,167,203 49,761 32,661 8,567 — — 3,258,192 Wholesale/retail 1,593,902 18,809 7,131 1,316 — — 1,621,158 Manufacturing 668,438 30,934 22,230 8,919 — — 730,521 Healthcare 2,730,121 14,920 37,698 16,538 — — 2,799,277 Public finance 804,550 — — — — — 804,550 Other commercial and industrial 756,815 1,266 7,588 16,954 49,371 53 832,047 Total commercial 13,135,068 157,866 193,932 99,788 49,371 53 13,636,078 Commercial real estate: Residential construction and land development 148,234 — — 350 — — 148,584 Retail 885,588 11,926 1,289 20,279 — — 919,082 Office 1,059,334 10,532 3,054 — — — 1,072,920 Multifamily 1,287,471 281 12 301 — — 1,288,065 Industrial 776,898 — 1,208 — — — 778,106 Other commercial real estate 555,301 1,188 876 691 — — 558,056 Total commercial real estate 4,712,826 23,927 6,439 21,621 — — 4,764,813 Residential mortgage: Permanent mortgage 269,678 52 9,730 1,991 819,199 21,960 1,122,610 Permanent mortgages guaranteed by U.S. government agencies — — — — 183,734 7,132 190,866 Home equity 223,298 — 296 — 682,491 10,472 916,557 Total residential mortgage 492,976 52 10,026 1,991 1,685,424 39,564 2,230,033 Personal 944,256 115 4,443 76 76,762 154 1,025,806 Total $ 19,285,126 $ 181,960 $ 214,840 123,476 $ 1,811,557 $ 39,771 $ 21,656,730
Summary of Impaired Loans [Table Text Block]	As of December 31, 2019 Year Ended Recorded Investment December 31, 2019 Unpaid Principal Balance Total With No With Allowance Related Allowance Average Recorded Interest Income Recognized Commercial: Energy $ 149,441 $ 91,722 $ 44,244 $ 47,478 $ 16,854 $ 69,119 $ — Services 10,923 7,483 6,301 1,182 240 5,854 — Wholesale/retail 1,980 1,163 902 261 101 916 — Manufacturing 10,848 10,133 9,914 219 219 9,144 — Healthcare 13,774 4,480 4,480 — — 7,798 — Public finance — — — — — — — Other commercial and industrial 8,227 435 435 — — 8,568 — Total commercial 195,193 115,416 66,276 49,140 17,414 101,399 — Commercial real estate: Residential construction and land development 1,306 350 350 — — 350 — Retail 20,265 18,868 18,868 — — 19,573 — Office — — — — — — — Multifamily 6,858 6,858 6,858 — — 3,580 — Industrial 909 909 909 — — 454 — Other commercial real estate 801 641 641 — — 666 — Total commercial real estate 30,139 27,626 27,626 — — 24,623 — Residential mortgage: Permanent mortgage 24,868 20,441 20,441 — — 22,196 1,198 Permanent mortgage guaranteed by U.S. government agencies 1 204,187 197,794 197,794 — — 195,009 7,733 Home equity 12,967 11,081 11,081 — — 10,776 — Total residential mortgage 242,022 229,316 229,316 — — 227,981 8,931 Personal 360 287 287 — — 259 — Total $ 467,714 $ 372,645 $ 323,505 $ 49,140 $ 17,414 $ 354,262 $ 8,931 1 All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2019 , $6.1 million of these loans are nonaccruing and $192 million are accruing based on the guarantee by U.S. government agencies. Generally, no interest income is recognized on impaired loans until all principal balances, including amounts charged-off, have been recovered. As of December 31, 2018 Year Ended Recorded Investment December 31, 2018 Unpaid Principal Balance Total With No Allowance With Allowance Related Allowance Average Recorded Investment Interest Income Recognized Commercial: Energy $ 79,675 $ 47,494 $ 18,639 $ 28,855 $ 5,362 $ 69,645 $ — Services 13,437 8,567 8,489 78 74 4,509 — Wholesale/retail 1,722 1,316 1,015 301 101 1,784 — Manufacturing 10,055 8,919 8,673 246 246 7,249 — Healthcare 24,319 16,538 10,563 5,975 2,949 14,297 — Public finance — — — — — — — Other commercial and industrial 26,955 17,007 17,007 — — 17,976 — Total commercial 156,163 99,841 64,386 35,455 8,732 115,460 — Commercial real estate: Residential construction and land development 1,306 350 350 — — 1,091 — Retail 27,680 20,279 20,279 — — 10,278 — Office — — — — — 137 — Multifamily 301 301 301 — — 151 — Industrial — — — — — — — Other commercial real estate 851 691 691 — — 581 — Total commercial real estate 30,138 21,621 21,621 — — 12,238 — Residential mortgage: Permanent mortgage 28,716 23,951 23,951 — — 24,572 1,233 Permanent mortgage guaranteed by U.S. government agencies 1 196,296 190,866 190,866 — — 180,813 7,172 Home equity 12,196 10,472 10,472 — — 11,774 — Total residential mortgage 237,208 225,289 225,289 — — 217,159 8,405 Personal 278 230 230 — — 250 — Total $ 423,787 $ 346,981 $ 311,526 $ 35,455 $ 8,732 $ 345,107 $ 8,405 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, 2018 , $7.1 million of these loans are nonaccruing and $184 million are accruing based on the guarantee by U.S. government agencies.
Summary of Loans by Aging Status [Table Text Block]	A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of December 31, 2019 is as follows (in thousands): Past Due Current 30 to 59 Days 60 to 89 Days 90 Days or More Nonaccrual Total Commercial: Energy $ 3,881,244 $ 401 10 $ — $ 91,722 $ 3,973,377 Services 3,105,621 1,737 523 6,799 7,483 3,122,163 Wholesale/retail 1,758,878 712 113 — 1,163 1,760,866 Manufacturing 654,329 410 190 387 10,133 665,449 Healthcare 3,027,329 2,039 — 68 4,480 3,033,916 Public finance 707,638 2,230 — — — 709,868 Other commercial and industrial 764,390 414 772 — 435 766,011 Total commercial 13,899,429 7,943 1,608 7,254 115,416 14,031,650 Commercial real estate: Residential construction and land development 147,379 3,093 — 57 350 150,879 Retail 756,653 — — — 18,868 775,521 Office 928,379 — — — — 928,379 Multifamily 1,258,704 — — — 6,858 1,265,562 Industrial 855,208 — — — 909 856,117 Other commercial real estate 454,253 1,827 250 354 641 457,325 Total commercial real estate 4,400,576 4,920 250 411 27,626 4,433,783 Residential mortgage: Permanent mortgage 1,034,716 2,011 153 — 20,441 1,057,321 Permanent mortgages guaranteed by U.S. government agencies 46,898 24,203 18,187 102,406 6,100 197,794 Home equity 814,325 3,343 308 — 11,081 829,057 Total residential mortgage 1,895,939 29,557 18,648 102,406 37,622 2,084,172 Personal 1,196,362 4,664 54 15 287 1,201,382 Total $ 21,392,306 $ 47,084 20,560 $ 110,086 $ 180,951 $ 21,750,987 A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of December 31, 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 $ 3,542,839 $ — — $ — $ 47,494 $ 3,590,333 Services 3,237,578 6,009 6,038 — 8,567 3,258,192 Wholesale/retail 1,619,290 515 37 — 1,316 1,621,158 Manufacturing 721,204 392 6 — 8,919 730,521 Healthcare 2,781,944 241 — 554 16,538 2,799,277 Public finance 804,550 — — — — 804,550 Other commercial and industrial 814,489 518 25 8 17,007 832,047 Total commercial 13,521,894 7,675 6,106 562 99,841 13,636,078 Commercial real estate: Residential construction and land development 147,705 249 280 — 350 148,584 Retail 884,424 14,379 — — 20,279 919,082 Office 1,072,920 — — — — 1,072,920 Multifamily 1,287,483 281 — — 301 1,288,065 Industrial 776,898 1,208 — — — 778,106 Other commercial real estate 556,239 412 — 714 691 558,056 Total commercial real estate 4,725,669 16,529 280 714 21,621 4,764,813 Residential mortgage: Permanent mortgage 1,095,097 3,196 366 — 23,951 1,122,610 Permanent mortgages guaranteed by U.S. government agencies 37,459 24,369 16,345 105,561 7,132 190,866 Home equity 904,572 1,102 352 59 10,472 916,557 Total residential mortgage 2,037,128 28,667 17,063 105,620 41,555 2,230,033 Personal 1,024,298 479 796 3 230 1,025,806 Total $ 21,308,989 $ 53,350 24,245 $ 106,899 $ 163,247 $ 21,656,730

Premises and Equipment and Le_2

Premises and Equipment and Leases Premises and Equipment and Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Premises and Equipment [Table Text Block]	Premises and equipment at December 31 are summarized as follows (in thousands): December 31, 2019 2018 Land $ 69,960 $ 70,575 Buildings and improvements 421,952 266,733 Software and related integration 98,487 150,207 Furniture and equipment 135,153 129,988 Construction in progress 53,498 27,514 Premises and equipment 779,050 645,017 Less accumulated depreciation 243,531 314,984 Premises and equipment, net of accumulated depreciation $ 535,519 $ 330,033

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
Goodwill and Intangible Assets (Tables)	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets [Table Text Block]	The following table presents the original cost and accumulated amortization of intangible assets (in thousands): Dec. 31, 2019 2018 Core deposit premiums $ 103,200 $ 103,200 Less accumulated amortization 19,364 5,032 Net core deposit premiums 83,836 98,168 Other identifiable intangible assets 74,372 63,497 Less accumulated amortization 32,937 26,816 Net other identifiable intangible assets 41,435 36,681 Total intangible assets, net $ 125,271 $ 134,849
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	Expected amortization expense for intangible assets that will continue to be amortized (in thousands): Core Deposit Premiums Other Identifiable Intangible Assets Total 2020 $ 12,892 $ 7,405 $ 20,297 2021 11,893 6,706 18,599 2022 10,981 5,339 16,320 2023 10,145 4,298 14,443 2024 9,379 3,284 12,663 Thereafter 28,546 14,403 42,949 $ 83,836 $ 41,435 $ 125,271
Schedule of Goodwill [Table Text Block]	The changes in the carrying value of goodwill by operating segment are as follows (in thousands): Commercial Banking Consumer Banking Wealth Management Funds Management and Other Total Balance, December 31, 2017 313,270 43,458 90,702 — 447,430 Goodwill recognized during 2018 1 — — — 601,833 601,833 Balance, December 31, 2018 313,270 43,458 90,702 601,833 1,049,263 Adjustment 1 600,661 — — (601,833 ) (1,172 ) Balance, December 31, 2019 $ 913,931 $ 43,458 $ 90,702 $ — $ 1,048,091 1 Goodwill related to the CoBiz acquisition was not yet allocated to the operating segments as of December 31, 2018 and was included in Funds Management and Other in 2018 then allocated during 2019.

Mortgage Banking Activities (Ta

Mortgage Banking Activities (Tables)	12 Months Ended
Mortgage Banking Activities (Tables)	Dec. 31, 2019
Mortgage Banking [Abstract]
Components of Residential Mortgage Loans Held For Sale [Table Text Block]	The unpaid principal balance of residential mortgage loans held for sale, notional amounts of derivative contracts related to residential mortgage loan commitments and forward contract sales and their related fair values included in Mortgage loans held for sale on the Consolidated Balance Sheets were (in thousands): December 31, 2019 December 31, 2018 Unpaid Principal Balance/ Notional Fair Value Unpaid Principal Balance/ Notional Fair Value Residential mortgage loans held for sale $ 175,117 $ 177,703 $ 145,057 $ 146,971 Residential mortgage loan commitments 158,460 5,233 160,848 5,378 Forward sales contracts 315,203 (665 ) 274,000 (3,128 ) $ 182,271 $ 149,221
Mortgage Banking Revenue [Table Text Block]	Mortgage banking revenue was as follows (in thousands): Year Ended 2019 2018 2017 Production revenue: Net realized gains on sales of mortgage loans $ 39,730 $ 36,379 $ 45,128 Net change in unrealized gain on mortgage loans held for sale 672 (674 ) 2,031 Net change in the fair value of mortgage loan commitments (145 ) (1,145 ) (3,210 ) Net change in the fair value of forward sales contracts 2,463 (2,870 ) (5,451 ) Total mortgage production revenue 42,720 31,690 38,498 Servicing revenue 64,821 66,097 66,221 Total mortgage banking revenue $ 107,541 $ 97,787 $ 104,719
Summary of Mortgage Servicing Rights [Table Text Block]	The following represents a summary of mortgage servicing rights (Dollars in thousands): December 31, 2019 2018 2017 Number of residential mortgage loans serviced for others 126,828 132,463 136,528 Outstanding principal balance of residential mortgage loans serviced for others $ 20,727,106 $ 21,658,335 $ 22,046,632 Weighted average interest rate 3.98 % 3.99 % 3.94 % Remaining contractual term (in months) 289 293 297
Activity in Capitalized Mortgage Servicing Rights [Table Text Block]	Activity in capitalized mortgage servicing rights during the three years ended December 31, 2019 is as follows (in thousands): Balance, December 31, 2016 $ 247,073 Additions, net 39,149 Change in fair value due to loan runoff (33,527 ) Change in fair value due to market changes 172 Balance, December 31, 2017 252,867 Additions, net 35,247 Change in fair value due to loan runoff (33,528 ) Change in fair value due to market changes 4,668 Balance, December 31, 2018 259,254 Additions, net 35,128 Change in fair value due to loan runoff (38,979 ) Change in fair value due to market changes (53,517 ) Balance, December 31, 2019 $ 201,886
Assumptions to Value Mortgage Servicing Rights [Table Text Block]	Significant assumptions used to determine fair value considered to be significant unobservable inputs were as follows: December 31, 2019 2018 Discount rate – risk-free rate plus a market premium 9.81% 9.90% Prepayment rate - based upon loan interest rate, original term and loan type 8.28% - 16.05% 8.05% - 15.74% Loan servicing costs – annually per loan based upon loan type: Performing loans $68 - $94 $67 - $93 Delinquent loans $150 - $500 $150 - $500 Loans in foreclosure $1,000 - $4,000 $1,000 - $4,000 Primary/secondary mortgage rate spread 104 bps 105 bps Escrow earnings rate – indexed to rates paid on deposit accounts with comparable average life 1.73% 2.57% Delinquency rate 2.73% 2.74%

Deposits (Tables)

Deposits (Tables)	12 Months Ended
Deposits (Tables)	Dec. 31, 2019
Deposits [Abstract]
Interest Expense on Deposits Disclosure [Table Text Block]	Interest expense on deposits is summarized as follows (in thousands): Year Ended December 31, 2019 2018 2017 Transaction deposits $ 132,854 $ 65,859 $ 28,627 Savings 677 439 359 Time: Certificates of deposits under $100,000 8,299 5,751 7,702 Certificates of deposits $100,000 and over 29,288 19,739 12,393 Other time deposits 4,420 3,729 4,722 Total time 42,007 29,219 24,817 Total $ 175,538 $ 95,517 $ 53,803

Other Borrowed Funds Other Borr

Other Borrowed Funds Other Borrowed Funds (Tables)	12 Months Ended
Other Borrowed Funds Other Borrowed Funds (Tables)	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of Other Borrowed Funds [Table Text Block]	Information relating to other borrowings is summarized as follows (dollars in thousands): As of Year Ended December 31, 2019 December 31, 2019 Balance Rate Average Balance Rate Maximum Funds purchased 3,390,528 1.53 % 2,438,376 2.08 % 3,390,528 Repurchase agreements 427,822 0.50 % 399,785 0.57 % 427,822 Other borrowings: Federal Home Loan Bank advances 4,500,000 1.79 % 7,122,466 2.44 % 8,000,000 GNMA repurchase liability 15,417 4.32 % 13,746 4.47 % 19,581 Other 11,638 5.09 % 11,144 5.30 % 34,676 Total other borrowings 4,527,055 7,147,356 2.45 % Subordinated debentures 1 275,923 5.15 % 276,075 5.47 % 275,923 Total other borrowed funds $ 8,621,328 $ 10,261,592 2.37 % As of Year Ended December 31, 2018 December 31, 2018 Balance Rate Average Balance Rate Maximum Funds purchased 402,450 2.34 % 419,322 1.89 % 949,531 Repurchase agreements 615,961 0.36 % 464,582 0.28 % 615,961 Other borrowings: Federal Home Loan Bank advances 6,100,000 2.65 % 6,207,142 2.06 % 6,500,000 GNMA repurchase liability 15,552 4.43 % 14,783 4.47 % 16,529 Other 8,838 2.90 % 14,516 2.67 % 20,422 Total other borrowings 6,124,390 6,236,441 2.07 % Subordinated debentures 1 275,913 5.34 % 177,884 5.52 % 275,913 Total other borrowed funds $ 7,418,714 $ 7,298,229 2.03 % As of Year Ended December 31, 2017 December 31, 2017 Balance Rate Average Balance Rate Maximum Funds purchased 58,628 1.00 % 58,064 0.73 % 80,967 Repurchase agreements 516,335 0.17 % 433,791 0.10 % 536,094 Other borrowings: Federal Home Loan Bank advances 5,100,000 1.47 % 5,882,466 1.13 % 6,200,000 GNMA repurchase liability 19,947 4.22 % 20,509 4.59 % 24,139 Other 14,950 2.61 % 16,317 3.35 % 18,610 Total other borrowings 5,134,897 5,919,292 1.15 % Subordinated debentures 1 144,677 5.60 % 147,954 5.57 % 151,875 Total other borrowed funds $ 5,854,537 $ 6,559,101 1.18 %
Schedule of Maturities of Other Borrowed Funds [Table Text Block]	Aggregate annual principal repayments at December 31, 2019 are as follows (in thousands): 2020 $ 8,335,742 2021 1,244 2022 575 2023 1,454 2024 3,599 Thereafter 278,714 Total $ 8,621,328
Schedule of Repurchase Agreements [Table Text Block]	Additional information relating to securities sold under agreements to repurchase and related liabilities at December 31, 2019 and 2018 is as follows (dollars in thousands): December 31, 2019 Amortized Fair Repurchase Security Sold/Maturity Cost Value Liability 1 Rate U.S. government agency mortgage-backed securities: Overnight 1 $ 431,939 $ 435,898 $ 427,822 0.50 % Long-term — — — — % Total Agency Securities $ 431,939 $ 435,898 $ 427,822 0.50 % December 31, 2018 Amortized Fair Repurchase Security Sold/Maturity Cost Value Liability 1 Rate U.S. government agency mortgage-backed securities: Overnight 1 $ 636,864 $ 628,229 $ 615,961 0.36 % Long-term — — — — % Total Agency Securities $ 636,864 $ 628,229 $ 615,961 0.36 % 1 BOK Financial maintains control over the securities underlying overnight repurchase agreements and generally transfers control over securities underlying longer-term dealer repurchase agreements to the respective counterparty.

Federal and State Income Taxes

Federal and State Income Taxes (Tables)	12 Months Ended
Federal and State Income Taxes (Tables)	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of deferred tax assets and liabilities are as follows (in thousands): December 31, 2019 2018 Deferred tax assets: Credit loss reserves $ 50,611 $ 49,804 Lease liability 46,084 — Deferred compensation 25,976 25,608 Purchased loan discount 18,042 27,283 Unearned fees 9,080 9,814 Share-based compensation 7,392 4,434 Valuation adjustments 1,545 9,619 Available for sale securities mark to market — 24,441 Other 26,384 31,489 Total deferred tax assets 185,114 182,492 Deferred tax liabilities: Mortgage servicing rights 48,435 61,844 Right-of-use asset 42,180 — Available for sale securities mark to market 33,140 — Acquired identifiable intangible 23,181 28,620 Depreciation 18,909 15,966 Lease financing 10,720 10,040 Other 34,826 30,566 Total deferred tax liabilities 211,391 147,036 Net deferred tax assets (liabilities) $ (26,277 ) $ 35,456
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	The significant components of the provision for income taxes attributable to continuing operations for BOK Financial are shown below (in thousands): Year Ended December 31, 2019 2018 2017 Current income tax expense: Federal $ 110,887 $ 103,748 $ 141,607 State 15,088 15,253 14,592 Total current income tax expense 125,975 119,001 156,199 Deferred income tax expense: Federal 3,416 (190 ) 25,525 State 792 250 869 Total deferred income tax expense 4,208 60 26,394 Total income tax expense $ 130,183 $ 119,061 $ 182,593
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	The reconciliations of income attributable to continuing operations at the U.S. federal statutory tax rate to income tax expense are as follows (in thousands): Year Ended December 31, 2019 2018 2017 Amount: Federal statutory tax $ 132,482 $ 118,752 $ 181,397 Tax exempt revenue (12,227 ) (8,311 ) (12,402 ) Effect of state income taxes, net of federal benefit 12,715 12,430 10,701 Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments (5,127 ) (4,559 ) (6,811 ) Other, net 2,340 749 9,708 Total income tax expense $ 130,183 $ 119,061 $ 182,593 Year Ended December 31, 2019 2018 2017 Percent of pretax income: Federal statutory tax 21.0 % 21.0 % 35.0 % Tax exempt revenue (1.9 ) (1.5 ) (2.4 ) Effect of state income taxes, net of federal benefit 2.0 2.2 2.0 Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments (0.8 ) (0.8 ) (1.3 ) Other, net 0.3 0.2 1.9 Total 20.6 % 21.1 % 35.2 %
Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands): 2019 2018 2017 Balance as of January 1 $ 18,869 $ 18,110 $ 15,841 Additions for tax for current year positions 5,649 2,649 4,645 Settlements during the period — — — Lapses of applicable statute of limitations (4,053 ) (1,890 ) (2,376 ) Balance as of December 31 $ 20,465 $ 18,869 $ 18,110

Employee Benefits (Tables)

Employee Benefits (Tables)	12 Months Ended
Employee Benefits (Tables)	Dec. 31, 2019
Retirement Benefits [Abstract]
Valuation assumptions used [Table Text Block]	2019 2018 Discount rate 4.10 % 3.30 % Expected return on plan assets 5.50 % 5.50 %

Share-Based Compensation Plans

Share-Based Compensation Plans (Tables)	12 Months Ended
Share-Based Compensation Plans (Tables)	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Share-based Payment Arrangement, Option, Activity [Table Text Block]	The following table presents stock options outstanding under these plans (in thousands, except for per share data): Number Weighted- Average Exercise Price Aggregate Intrinsic Value Options outstanding at: December 31, 2017 117,551 $ 53.26 $ 4,592 December 31, 2018 63,058 54.89 1,163 December 31, 2019 36,100 56.75 1,106 Options vested at: December 31, 2017 51,286 $ 48.62 $ 2,241 December 31, 2018 33,573 53.09 679 December 31, 2019 27,193 57.08 824
Schedule of Nonvested Share Activity [Table Text Block]	The following represents a summary of the non-vested shares for the three years ended December 31, 2019 (in thousands): Restricted Stock Restricted Stock Units Shares Weighted Average Grant Date Fair Value Units Weighted Average Grant Date Fair Value Non-vested at January 1, 2017 786,706 — Granted 177,807 $ 86.95 — — — Vested (194,419 ) 63.07 — — Forfeited (102,991 ) 78.70 — — Non-vested at December 31, 2017 667,103 — Granted 150,419 $ 85.58 — — Vested (242,215 ) 74.85 — — Forfeited (47,700 ) 75.68 — — Non-vested at December 31, 2018 527,607 — Granted 145,724 $ 76.74 46,689 $ 87.40 Vested (114,201 ) 61.28 — — Forfeited (131,952 ) 83.69 — — Non-vested at December 31, 2019 427,178 46,689

Related Parties Related Parties

Related Parties Related Parties (Tables)	12 Months Ended
Related Parties Related Parties (Tables)	Dec. 31, 2019
Related Party Transactions [Abstract]
Schedule of Related Party Transactions [Table Text Block]	Activity in loans to related parties is summarized as follows (in thousands): Year Ended December 31, 2019 2018 Beginning balance $ 75,265 $ 110,246 Advances 886,610 1,479,735 Payments (896,643 ) (1,514,841 ) Adjustments 1 9,957 125 Ending balance $ 75,189 $ 75,265 1

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
Earnings Per Share (Tables)	Dec. 31, 2019
Earnings Per Share [Abstract]
Earnings Per Share [Table Text Block]	The following table presents the computation of basic and diluted earnings per share (dollars in thousands, except per share data): Year Ended 2019 2018 2017 Numerator: Net income attributable to BOK Financial Corp. shareholders $ 500,758 $ 445,646 $ 334,644 Less: Earnings allocated to participating securities 3,227 3,737 3,561 Numerator for basic earnings per share – income available to common shareholders 497,531 441,909 331,083 Effect of reallocating undistributed earnings of participating securities — 1 2 Numerator for diluted earnings per share – income available to common shareholders $ 497,531 $ 441,910 $ 331,085 Denominator: Weighted average shares outstanding 71,250,081 67,190,257 65,440,832 Less: Participating securities included in weighted average shares outstanding 462,381 561,617 695,468 Denominator for basic earnings per common share 70,787,700 66,628,640 64,745,364 Dilutive effect of employee stock compensation plans 14,912 33,633 60,920 Denominator for diluted earnings per common share 70,802,612 66,662,273 64,806,284 Basic earnings per share $ 7.03 $ 6.63 $ 5.11 Diluted earnings per share $ 7.03 $ 6.63 $ 5.11

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
Shareholders' Equity (Tables)	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Summary of Regulatory Capital Levels [Table Text Block]	A summary of regulatory capital minimum requirements and levels follows (dollars in thousands): Minimum Capital Requirement Capital Conservation Buffer 1 Minimum Capital Requirement Including Capital Conservation Buffer Well Capitalized Bank Requirement December 31, 2019 December 31, 2018 Common Equity Tier 1 Capital (to Risk Weighted Assets): Consolidated 4.50% 2.50% 7.00% N/A $ 3,608,821 11.39 % $ 3,356,524 10.92 % BOKF, NA 4.50% N/A 4.50% 6.50% 3,414,446 10.90 % 2,894,119 10.50 % CoBiz Bank 2 4.50% N/A 4.50% 6.50% — — % 317,944 10.65 % Tier I Capital (to Risk Weighted Assets): Consolidated 6.00% 2.50% 8.50% N/A $ 3,608,821 11.39 % $ 3,356,524 10.92 % BOKF, NA 6.00% N/A 6.00% 8.00% 3,414,446 10.90 % 2,894,119 10.50 % CoBiz Bank 2 6.00% N/A 6.00% 8.00% — — % 317,944 10.65 % Total Capital (to Risk Weighted Assets): Consolidated 8.00% 2.50% 10.50% N/A $ 4,097,087 12.94 % $ 3,841,684 12.50 % BOKF, NA 8.00% N/A 8.00% 10.00% 3,692,010 11.79 % 3,103,366 11.26 % CoBiz Bank 2 8.00% N/A 8.00% 10.00% — — % 382,944 12.83 % Leverage (Tier I Capital to Average Assets): Consolidated 4.00% N/A 4.00% N/A $ 3,608,820 8.40 % $ 3,356,524 8.96 % BOKF, NA 4.00% N/A 4.00% 5.00% 3,414,446 7.98 % 2,894,119 8.56 % CoBiz Bank 2 4.00% N/A 4.00% 5.00% — — % 317,944 8.25 % 1 Capital conservation buffer was effective January 1, 2016 and phased in through 2019. The phased in capital conservation buffer was 2.50% at December 31, 2019 and 1.875% at December 31, 2018 . The fully phased in requirement of 2.50% is included in the table above. 2 CoBiz Bank was acquired by BOK Financial effective October 1, 2018 and merged into BOKF, NA during the first quarter of 2019.
Accumulated Other Comprehensive Income (Loss) [Table Text Block]	A rollforward of the components of accumulated other comprehensive income (loss) is included as follows (in thousands): Unrealized Gain (Loss) on Available for Sale Securities Employee Benefit Plans Total Balance, December 31, 2016 $ (9,087 ) $ (1,880 ) $ (10,967 ) Net change in unrealized gain (loss) (28,170 ) 2,018 (26,152 ) Reclassification adjustments included in earnings: Gain on available for sale securities, net (4,428 ) — (4,428 ) Other comprehensive income (loss), before income taxes (32,598 ) 2,018 (30,580 ) Federal and state income tax 1 (12,708 ) 785 (11,923 ) Other comprehensive income (loss), net of income taxes (19,890 ) 1,233 (18,657 ) Reclassification of stranded accumulated other comprehensive loss related to tax reform (6,408 ) (142 ) (6,550 ) Balance, December 31, 2017 (35,385 ) (789 ) (36,174 ) Transition adjustment for net unrealized gains on equity securities (2,709 ) — (2,709 ) Net change in unrealized gain (loss) (46,941 ) (1,069 ) (48,010 ) Reclassification adjustments included in earnings: Loss on available for sale securities, net 2,801 — 2,801 Other comprehensive income (loss), before income taxes (44,140 ) (1,069 ) (45,209 ) Federal and state income tax 2 (11,235 ) (272 ) (11,507 ) Other comprehensive income (loss), net of income taxes (32,905 ) (797 ) (33,702 ) Balance, December 31, 2018 (70,999 ) (1,586 ) (72,585 ) Net change in unrealized gain (loss) 239,017 2,030 241,047 Reclassification adjustments included in earnings: Gain on available for sale securities, net (5,597 ) — (5,597 ) Other comprehensive income (loss), before income taxes 233,420 2,030 235,450 Federal and state income tax 2 57,425 517 57,942 Other comprehensive income (loss), net of income taxes 175,995 1,513 177,508 Balance, December 31, 2019 $ 104,996 $ (73 ) $ 104,923 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.

Reportable Segments (Tables)

Reportable Segments (Tables)	12 Months Ended
Reportable Segments (Tables)	Dec. 31, 2019
Segment Reporting [Abstract]
Reportable Segments [Table Text Block]	Reportable segments reconciliation to the Consolidated Financial Statements for the year ended December 31, 2019 is as follows (in thousands): Commercial Consumer Wealth Management Funds Management and Other BOK Financial Consolidated Net interest and dividend revenue from external sources $ 919,148 $ 99,679 $ 61,277 $ 32,775 $ 1,112,879 Net interest revenue (expense) from internal sources (242,907 ) 95,775 38,815 108,317 — Net interest and dividend revenue 676,241 195,454 100,092 141,092 1,112,879 Provision for credit losses 39,011 6,271 (308 ) (974 ) 44,000 Net interest and dividend revenue after provision for credit losses 637,230 189,183 100,400 142,066 1,068,879 Other operating revenue 170,412 187,500 341,389 (4,931 ) 694,370 Other operating expense 252,459 230,916 277,267 371,739 1,132,381 Net direct contribution 555,183 145,767 164,522 (234,604 ) 630,868 Gain (loss) on financial instruments, net 106 30,375 2 (30,483 ) — Change in fair value of mortgage servicing rights — (53,517 ) — 53,517 — Gain (loss) on repossessed assets, net 331 496 — (827 ) — Corporate expense allocations 43,055 47,169 36,239 (126,463 ) — Net income before taxes 512,565 75,952 128,285 (85,934 ) 630,868 Federal and state income taxes 137,759 19,346 32,954 (59,876 ) 130,183 Net income 374,806 56,606 95,331 (26,058 ) 500,685 Net income attributable to non-controlling interests — — — (73 ) (73 ) Net income attributable to BOK Financial Corp. shareholders $ 374,806 $ 56,606 $ 95,331 $ (25,985 ) $ 500,758 Average assets $ 22,807,589 $ 9,301,341 $ 10,204,426 $ (219,009 ) $ 42,094,347 Reportable segments reconciliation to the Consolidated Financial Statements for the year ended December 31, 2018 is as follows (in thousands): Commercial Consumer Wealth Management Funds Management and Other BOK Financial Consolidated Net interest and dividend revenue from external sources $ 726,855 $ 83,231 $ 81,528 $ 93,253 $ 984,867 Net interest revenue (expense) from internal sources (159,954 ) 73,448 31,480 55,026 — Net interest and dividend revenue 566,901 156,679 113,008 148,279 984,867 Provision for credit losses 30,358 5,143 (288 ) (27,213 ) 8,000 Net interest and dividend revenue after provision for credit losses 536,543 151,536 113,296 175,492 976,867 Other operating revenue 162,701 178,123 296,369 (20,409 ) 616,784 Other operating expense 202,095 231,075 257,650 337,346 1,028,166 Net direct contribution 497,149 98,584 152,015 (182,263 ) 565,485 Gain (loss) on financial instruments, net 26 (25,021 ) 7 24,988 — Change in fair value of mortgage servicing rights — 4,668 — (4,668 ) — Gain (loss) on repossessed assets, net (6,532 ) 247 — 6,285 — Corporate expense allocations 36,670 44,398 35,920 (116,988 ) — Net income before taxes 453,973 34,080 116,102 (38,670 ) 565,485 Federal and state income taxes 120,458 8,681 30,075 (40,153 ) 119,061 Net income 333,515 25,399 86,027 1,483 446,424 Net income attributable to non-controlling interests — — — 778 778 Net income attributable to BOK Financial Corp. shareholders $ 333,515 $ 25,399 $ 86,027 $ 705 $ 445,646 Average assets $ 18,432,035 $ 8,303,263 $ 8,447,784 $ (245,552 ) $ 34,937,530 Reportable segments reconciliation to the Consolidated Financial Statements for the year ended December 31, 2017 is as follows (in thousands): Commercial Consumer Wealth Management Funds Management and Other BOK Financial Consolidated Net interest and dividend revenue from external sources $ 618,325 $ 84,286 $ 45,024 $ 94,066 $ 841,701 Net interest revenue (expense) from internal sources (92,055 ) 53,916 38,344 (205 ) — Net interest and dividend revenue 526,270 138,202 83,368 93,861 841,701 Provision for credit losses 13,877 4,786 (696 ) (24,967 ) (7,000 ) Net interest and dividend revenue after provision for credit losses 512,393 133,416 84,064 118,828 848,701 Other operating revenue 208,404 184,878 301,434 378 695,094 Other operating expense 235,793 241,805 254,495 293,424 1,025,517 Net direct contribution 485,004 76,489 131,003 (174,218 ) 518,278 Gain (loss) on financial instruments, net 52 (2,052 ) — 2,000 — Change in fair value of mortgage servicing rights — 172 — (172 ) — Gain on repossessed assets, net (2,681 ) 223 387 2,071 — Corporate expense allocations 28,060 49,344 32,693 (110,097 ) — Net income before taxes 454,315 25,488 98,697 (60,222 ) 518,278 Federal and state income taxes 186,518 9,915 38,848 (52,688 ) 182,593 Net income 267,797 15,573 59,849 (7,534 ) 335,685 Net loss attributable to non-controlling interests — — — 1,041 1,041 Net income attributable to BOK Financial Corp. shareholders $ 267,797 $ 15,573 $ 59,849 $ (8,575 ) $ 334,644 Average assets $ 17,766,027 $ 8,544,117 $ 7,072,622 $ (435,272 ) $ 32,947,494

Fees and Commission Revenue Fee

Fees and Commission Revenue Fees and Commissions Revenue (Tables)	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Disaggregation of Fees and Commissions Revenue [Table Text Block]	Commercial Consumer Wealth Management Funds Management and Other Consolidated Out of Scope 1 In Scope 2 Trading revenue $ — $ — $ 88,558 $ — $ 88,558 $ 88,558 $ — Customer hedging revenue 8,422 — 9,667 852 18,941 18,941 — Retail brokerage revenue — — 16,251 (115 ) 16,136 — 16,136 Insurance brokerage revenue — — 10,131 3,730 13,861 — 13,861 Investment banking revenue 10,136 — 12,194 — 22,330 8,678 13,652 Brokerage and trading revenue 18,558 — 136,801 4,467 159,826 116,177 43,649 TransFund EFT network revenue 73,479 3,924 (82 ) 3 77,324 — 77,324 Merchant services revenue 8,607 56 — 123 8,786 — 8,786 Corporate card revenue 1,072 — 32 2 1,106 — 1,106 Transaction card revenue 83,158 3,980 (50 ) 128 87,216 — 87,216 Personal trust revenue — — 81,763 — 81,763 — 81,763 Corporate trust revenue — — 24,635 — 24,635 — 24,635 Institutional trust & retirement plan services revenue — — 44,352 — 44,352 — 44,352 Investment management services and other — — 24,725 1,550 26,275 — 26,275 Fiduciary and asset management revenue — — 175,475 1,550 177,025 — 177,025 Commercial account service charge revenue 42,251 1,713 2,137 1,804 47,905 — 47,905 Overdraft fee revenue 313 35,134 138 (229 ) 35,356 — 35,356 Check card revenue — 21,865 — 165 22,030 — 22,030 Automated service charge and other deposit fee revenue 823 6,155 168 48 7,194 — 7,194 Deposit service charges and fees 43,387 64,867 2,443 1,788 112,485 — 112,485 Mortgage production revenue — 42,724 — (4 ) 42,720 42,720 — Mortgage servicing revenue — 66,692 — (1,871 ) 64,821 64,821 — Mortgage banking revenue — 109,416 — (1,875 ) 107,541 107,541 — Other revenue 23,564 9,733 26,664 (1,853 ) 58,108 39,428 18,680 Total fees and commissions revenue $ 168,667 $ 187,996 $ 341,333 $ 4,205 $ 702,201 $ 263,146 $ 439,055 1 Out of scope revenue generally relates to financial instruments or contractual rights and obligations within the scope of other applicable accounting guidance. 2 In scope revenue represents revenue subject to FASB ASC Topic 606, Revenue from Contracts with Customers. Fees and commissions revenue by reportable segment and primary service line is as follows for the year ended December 31, 2018 . Commercial Consumer Wealth Management Funds Management and Other Consolidated Out of Scope 1 In Scope 2 Trading revenue $ — $ — $ 28,077 $ — $ 28,077 $ 28,077 $ — Customer hedging revenue 7,748 — 27,512 3,574 38,834 38,834 — Retail brokerage revenue — — 19,030 (1,078 ) 17,952 — 17,952 Insurance brokerage revenue — — — 4,198 4,198 — 4,198 Investment banking revenue 7,628 — 11,634 — 19,262 6,380 12,882 Brokerage and trading revenue 15,376 — 86,253 6,694 108,323 73,291 35,032 TransFund EFT network revenue 72,280 4,017 (82 ) 6 76,221 — 76,221 Merchant services revenue 7,666 59 — 79 7,804 — 7,804 Corporate card revenue — — — — — — — Transaction card revenue 79,946 4,076 (82 ) 85 84,025 — 84,025 Personal trust revenue — — 96,839 — 96,839 — 96,839 Corporate trust revenue — — 22,292 — 22,292 — 22,292 Institutional trust & retirement plan services revenue — — 44,400 76 44,476 — 44,476 Investment management services and other — — 19,729 1,367 21,096 — 21,096 Fiduciary and asset management revenue — — 183,260 1,443 184,703 — 184,703 Commercial account service charge revenue 41,931 1,445 2,331 1,565 47,272 — 47,272 Overdraft fee revenue 370 36,177 134 (145 ) 36,536 — 36,536 Check card revenue — 20,967 — 339 21,306 — 21,306 Automated service charge and other deposit fee revenue 282 6,621 62 74 7,039 — 7,039 Deposit service charges and fees 42,583 65,210 2,527 1,833 112,153 — 112,153 Mortgage production revenue — 31,690 — — 31,690 31,690 — Mortgage servicing revenue — 67,980 — (1,883 ) 66,097 66,097 — Mortgage banking revenue — 99,670 — (1,883 ) 97,787 97,787 — Other revenue 24,044 9,218 24,507 (1,584 ) 56,185 38,306 17,879 Total fees and commissions revenue $ 161,949 $ 178,174 $ 296,465 $ 6,588 $ 643,176 $ 209,384 $ 433,792 1 Out of scope revenue generally relates to financial instruments or contractual rights and obligations within the scope of other applicable accounting guidance. 2 In scope revenue represents revenue subject to FASB ASC Topic 606, Revenue from Contracts with Customers.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
Fair Value Measurements (Tables)	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Assets And Liabilities Measured On A Recurring Basis [Table Text Block]	The fair value of financial assets and liabilities that are measured on a recurring basis is as follows as of December 31, 2019 (in thousands): Total Quoted Prices in Active Markets for Identical Instruments Significant Other Observable Inputs Significant Unobservable Inputs Assets: Trading securities: U.S. government agency debentures $ 44,264 $ — $ 44,264 $ — Residential agency mortgage-backed securities 1,504,651 — 1,504,651 — Municipal and other tax-exempt securities 26,196 — 26,196 — Asset-backed securities 14,084 — 14,084 — Other trading securities 34,726 — 34,726 — Total trading securities 1,623,921 — 1,623,921 — Available for sale securities: U.S. Treasury 1,600 1,600 — — Municipal and other tax-exempt securities 1,861 — 1,861 — Residential agency mortgage-backed securities 8,046,096 — 8,046,096 — Residential non-agency mortgage-backed securities 41,609 — 41,609 — Commercial agency mortgage-backed securities guaranteed 3,178,005 — 3,178,005 — Other debt securities 472 — — 472 Total available for sale securities 11,269,643 1,600 11,267,571 472 Fair value option securities: U.S. Treasury 9,917 9,917 — — Residential agency mortgage-backed securities 1,088,660 — 1,088,660 — Total fair value option securities 1,098,577 9,917 1,088,660 — Residential mortgage loans held for sale 182,271 — 173,958 8,313 Mortgage servicing rights, net 1 201,886 — — 201,886 Derivative contracts, net of cash margin 2 323,375 8,944 314,431 — Liabilities: Derivative contracts, net of cash margin 2 251,128 — 251,128 — 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 7 , Mortgage Banking Activities . 2 See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts in a net asset position that were valued based on quoted prices in active markets or identical instruments (Level 1) are exchange-traded interest rate and energy derivative contracts, net of cash margin. Derivative contracts in a net liability position that were valued using quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate and agricultural derivative contracts, fully offset by cash margin. The fair value of financial assets and liabilities that are measured on a recurring basis is as follows as of December 31, 2018 (in thousands): Total Quoted Prices in Active Markets for Identical Instruments Significant Other Observable Inputs Significant Unobservable Inputs Assets: Trading securities: U.S. government agency debentures $ 63,765 $ — $ 63,765 $ — Residential agency mortgage-backed securities 1,791,584 — 1,791,584 — Municipal and other tax-exempt securities 34,507 — 34,507 — Asset-backed securities 42,656 — 42,656 — Other trading securities 24,411 — 24,411 — Total trading securities 1,956,923 — 1,956,923 — Available for sale securities: U.S. Treasury 493 493 — — Municipal and other tax-exempt securities 2,864 — 2,864 — Residential agency mortgage-backed securities 5,804,708 — 5,804,708 — Residential non-agency mortgage-backed securities 59,736 — 59,736 — Commercial agency mortgage-backed securities guaranteed 2,953,889 — 2,953,889 — Other debt securities 35,430 — 34,958 472 Total available for sale securities 8,857,120 493 8,856,155 472 Fair value option securities – Residential agency mortgage-backed securities 283,235 — 283,235 — Residential mortgage loans held for sale 149,221 — 134,014 15,207 Mortgage servicing rights, net 1 259,254 — — 259,254 Derivative contracts, net of cash margin 2 320,929 44,074 276,855 — Liabilities: Derivative contracts, net of cash margin 2 362,306 — 362,306 — 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 7 , Mortgage Banking Activities. 2 See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts in a net asset position that were valued based on quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate, energy and agricultural derivative contracts, net of cash margin. Derivative contracts in a net liability position that were valued using quoted prices in active markets for identical instruments based on quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate derivative contracts, fully offset by cash margin.
Fair Value Assets Measured On Recurring Basis Significant Unobservable Inputs [Table Text Block]	The following represents the changes related to assets measured at fair value on a recurring basis using significant unobservable inputs (in thousands): Available for Sale Securities Residential mortgage loans held for sale Municipal and other tax-exempt securities Other debt securities Balance, December 31, 2017 $ 4,802 $ 472 $ 12,299 Transfer to Level 3 from Level 2 1 — — 6,183 Purchases and capital calls — — — Redemptions and distributions (5,095 ) — — Proceeds from sales — — (2,706 ) Gain (loss) recognized in earnings: Mortgage banking revenue — — (569 ) Other comprehensive income (loss): Net change in unrealized gain (loss) 293 — — Balance, December 31, 2018 — 472 15,207 Transfer to Level 3 from Level 2 1 — — 2,449 Purchases and capital calls — — — Redemptions and distributions — — — Proceeds from sales — — (9,972 ) Gain (loss) recognized in earnings: Mortgage banking revenue — — 629 Other comprehensive income (loss): Net change in unrealized gain (loss) — — — Balance, December 31, 2019 $ — $ 472 $ 8,313 1 Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.
Fair Value Inputs, Fair Value Measured On a Recurring Basis, Quantitative Information [Table Text Block]	A summary of quantitative information about assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3) as of December 31, 2019 follows (in thousands): Quantitative Information about Level 3 Recurring Fair Value Measurements Fair Value Valuation Technique(s) Significant Unobservable Input Range (Weighted Average) Available for sale securities: Other debt securities 472 Discounted cash flows 1 Interest rate spread 7.08%-7.08% (7.08%) 3 94.4%-94.4% (94.4%) 2 Residential mortgage loans held for sale 8,313 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 95.23% 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 approximately 3% . A summary of quantitative information about Recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of December 31, 2018 follows (in thousands): Quantitative Information about Level 3 Recurring Fair Value Measurements Fair Value Valuation Technique(s) Significant Unobservable Input Range (Weighted Average) Available for sale securities: Other debt securities 472 Discounted cash flows 1 Interest rate spread 7.88%-7.88% (7.88%) 3 94.44%-94.44% (94.44%) 2 Residential mortgage loans held for sale 15,207 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 92.38% 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% .
Fair Value Assets Measured on Nonrecurring Basis [Table Text Block]	The following represents the carrying value of assets measured at fair value on a non-recurring basis and related losses recorded during the year. The carrying value represents only those assets with the balance sheet date for which the fair value was adjusted during the year: Carrying Value at December 31, 2019 Fair Value Adjustments for the Quoted Prices in Active Markets for Identical Instruments Significant Other Observable Inputs Significant Unobservable Inputs Gross charge-offs against allowance for loan losses Net losses (gains) and expenses of repossessed assets, net Impaired loans $ — $ 41 $ 55,665 $ 31,305 $ — Real estate and other repossessed assets — 5,986 1,551 — (461 ) Carrying Value at December 31, 2018 Fair Value Adjustments for the Quoted Prices in Active Markets for Identical Instruments Significant Other Observable Inputs Significant Unobservable Inputs Gross charge-offs against allowance for loan losses Net losses (gains) and expenses of repossessed assets, net Impaired loans $ — $ 1,074 $ 17,401 $ 17,434 $ — Real estate and other repossessed assets — 4,795 6,366 — 7,269
Fair Value Inputs, Fair Value Measured On a Nonrecurring Basis, Quantitative Information [Table Text Block]	A summary of quantitative information about Non-recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of December 31, 2019 follows (in thousands): Quantitative Information about Level 3 Non-recurring Fair Value Measurements Fair Value Valuation Technique(s) Significant Unobservable Input Range (Weighted Average) Impaired loans $ 55,665 Discounted cash flows Management knowledge of industry and non-real estate collateral including but not limited to recoverable oil & gas reserves, forward looking commodity prices, and estimated operating costs 4% - 94% (55%) 1 Real estate and other repossessed assets 1,551 Discounted cash flows Marketability adjustments off appraised value 2 74% - 86% (84%) 1 Represents fair value as a percentage of the unpaid principal balance. 2 Marketability adjustments include consideration of estimated costs to sell which is approximately 10% of the fair value. A summary of quantitative information about Non-recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of December 31, 2018 follows (in thousands): Quantitative Information about Level 3 Non-recurring Fair Value Measurements Fair Value Valuation Technique(s) Significant Unobservable Input Range (Weighted Average) Impaired loans $ 17,401 Discounted cash flows Management knowledge of industry and non-real estate collateral including but not limited to recoverable oil & gas reserves, forward looking commodity prices, and estimated operating costs 35% - 80% (50%) 1 Real estate and other repossessed assets 6,366 Discounted cash flows Recoverable oil and gas reserves, forward-looking commodity prices and estimated operating costs N/A 1 Represents fair value as a percentage of the unpaid principal balance.
Fair Value of Financial Instruments [Table Text Block]	The following table presents the carrying values and estimated fair values of all financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring basis or non-recurring (dollars in thousands): December 31, 2019 Carrying Value Estimated Fair Value Quoted Prices in Active Markets for Identical Instruments (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Cash and due from banks $ 735,836 $ 735,836 $ 735,836 $ — $ — Interest-bearing cash and cash equivalents 522,985 522,985 522,985 — — Trading securities: U.S. government agency debentures 44,264 44,264 — 44,264 — Residential agency mortgage-backed securities 1,504,651 1,504,651 — 1,504,651 — Municipal and other tax-exempt securities 26,196 26,196 — 26,196 — Asset-backed securities 14,084 14,084 — 14,084 — Other trading securities 34,726 34,726 — 34,726 — Total trading securities 1,623,921 1,623,921 — 1,623,921 — Investment securities: Municipal and other tax-exempt securities 93,653 96,897 — 96,897 — Residential agency mortgage-backed securities 10,676 11,164 — 11,164 — Other debt securities 189,089 206,341 — 8,206 198,135 Total investment securities 293,418 314,402 — 116,267 198,135 Available for sale securities: U.S. Treasury 1,600 1,600 1,600 — — Municipal and other tax-exempt securities 1,861 1,861 — 1,861 — Residential agency mortgage-backed securities 8,046,096 8,046,096 — 8,046,096 — Residential non-agency mortgage-backed securities 41,609 41,609 — 41,609 — Commercial agency mortgage-backed securities 3,178,005 3,178,005 — 3,178,005 — Other debt securities 472 472 — — 472 Total available for sale securities 11,269,643 11,269,643 1,600 11,267,571 472 Fair value option securities: U.S. Treasury 9,917 9,917 9,917 — — Residential agency mortgage-backed securities 1,088,660 1,088,660 — 1,088,660 — Total fair value option securities 1,098,577 1,098,577 9,917 1,088,660 — Residential mortgage loans held for sale 182,271 182,271 — 173,958 8,313 Loans: Commercial 14,031,650 13,966,221 — — 13,966,221 Commercial real estate 4,433,783 4,422,717 — — 4,422,717 Residential mortgage 2,084,172 2,098,093 — — 2,098,093 Personal 1,201,382 1,202,298 — — 1,202,298 Total loans 21,750,987 21,689,329 — — 21,689,329 Allowance for loan losses (210,759 ) — — — — Loans, net of allowance 21,540,228 21,689,329 — — 21,689,329 Mortgage servicing rights 201,886 201,886 — — 201,886 Derivative instruments with positive fair value, net of cash margin 323,375 323,375 8,944 314,431 — Deposits with no stated maturity 25,403,319 25,403,319 — — 25,403,319 Time deposits 2,217,849 2,212,467 — — 2,212,467 Other borrowed funds 8,345,405 8,315,860 — — 8,315,860 Subordinated debentures 275,923 284,627 — 284,627 — Derivative instruments with negative fair value, net of cash margin 251,128 251,128 — 251,128 — December 31, 2018 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 $ 741,749 $ 741,749 $ 741,749 $ — $ — Interest-bearing cash and cash equivalents 401,675 401,675 401,675 — — Trading securities: U.S. government agency debentures 63,765 63,765 — 63,765 — Residential agency mortgage-backed securities 1,791,584 1,791,584 — 1,791,584 — Municipal and other tax-exempt securities 34,507 34,507 — 34,507 — Asset-backed securities 42,656 42,656 — 42,656 — Other trading securities 24,411 24,411 — 24,411 — Total trading securities 1,956,923 1,956,923 — 1,956,923 — Investment securities: Municipal and other tax-exempt securities 137,296 138,562 — 138,562 — Residential agency mortgage-backed securities 12,612 12,770 — 12,770 — Other debt securities 205,279 215,966 — 7,905 208,061 Total investment securities 355,187 367,298 — 159,237 208,061 Available for sale securities: U.S. Treasury securities 493 493 493 — — Municipal and other tax-exempt securities 2,864 2,864 — 2,864 — Residential agency mortgage-backed securities 5,804,708 5,804,708 — 5,804,708 — Residential non-agency mortgage-backed securities 59,736 59,736 — 59,736 — Commercial agency mortgage-backed securities 2,953,889 2,953,889 — 2,953,889 — Other debt securities 35,430 35,430 — 34,958 472 Total available for sale securities 8,857,120 8,857,120 493 8,856,155 472 Fair value option securities – Residential agency mortgage-backed securities 283,235 283,235 — 283,235 — Residential mortgage loans held for sale 149,221 149,221 — 134,014 15,207 Loans: Commercial 13,636,078 13,526,162 — — 13,526,162 Commercial real estate 4,764,813 4,713,747 — — 4,713,747 Residential mortgage 2,230,033 2,213,951 — — 2,213,951 Personal 1,025,806 1,024,368 — — 1,024,368 Total loans 21,656,730 21,478,228 — — 21,478,228 Allowance for loan losses (207,457 ) — — — — Loans, net of allowance 21,449,273 21,478,228 — — 21,478,228 Mortgage servicing rights 259,254 259,254 — — 259,254 Derivative instruments with positive fair value, net of cash margin 320,929 320,929 44,074 276,855 — Deposits with no stated maturity 23,150,383 23,150,383 — — 23,150,383 Time deposits 2,113,380 2,073,538 — — 2,073,538 Other borrowed funds 7,142,801 7,071,953 — — 7,071,953 Subordinated debentures 275,913 261,977 — 261,977 — Derivative instruments with negative fair value, net of cash margin 362,306 362,306 — 362,306 —

Parent Company Only Financial_2

Parent Company Only Financial Statements Parent Company Only Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Condensed Balance Sheet [Table Text Block]	Balance Sheets (In thousands) December 31, 2019 2018 Assets Cash and cash equivalents $ 214,779 $ 167,093 Loan to bank subsidiary 65,220 65,228 Investment in bank subsidiaries 4,602,977 4,236,654 Investment in non-bank subsidiaries 216,542 218,007 Other assets 38,082 32,999 Total assets $ 5,137,600 $ 4,719,981 Liabilities and Shareholders’ Equity Liabilities: Other liabilities $ 5,882 $ 11,959 Subordinated debentures 275,923 275,913 Total liabilities 281,805 287,872 Shareholders’ equity: Common stock 5 5 Capital surplus 1,350,995 1,334,030 Retained earnings 3,729,778 3,369,654 Treasury stock (329,906 ) (198,995 ) Accumulated other comprehensive income (loss) 104,923 (72,585 ) Total shareholders’ equity 4,855,795 4,432,109 Total liabilities and shareholders’ equity $ 5,137,600 $ 4,719,981
Condensed Income Statement [Table Text Block]	Statements of Earnings (In thousands) Year Ended December 31, 2019 2018 2017 Dividends, interest and fees received from bank subsidiaries $ 344,007 $ 426,071 $ 150,149 Dividends, interest and fees received from non-bank subsidiaries 9,325 12,800 17,500 Other revenue 1,036 954 936 Total revenue 354,368 439,825 168,585 Interest expense 15,113 9,827 8,239 Other operating expense 2,352 12,110 2,014 Total expense 17,465 21,937 10,253 Net income before taxes, other losses, net, and equity in undistributed income of subsidiaries 336,903 417,888 158,332 Other gains (losses), net 3,310 (3,921 ) — Net income before taxes and equity in undistributed income of subsidiaries 340,213 413,967 158,332 Federal and state income taxes (4,516 ) (7,078 ) (4,305 ) Net income before equity in undistributed income of subsidiaries 344,729 421,045 162,637 Equity in undistributed income of bank subsidiaries 166,797 37,515 181,552 Equity in undistributed income of non-bank subsidiaries (10,768 ) (12,914 ) (9,545 ) Net income attributable to BOK Financial Corp. shareholders $ 500,758 $ 445,646 $ 334,644
Condensed Cash Flow Statement [Table Text Block]	Statements of Cash Flows (In thousands) Year Ended December 31, 2019 2018 2017 Cash Flows From Operating Activities: Net income $ 500,758 $ 445,646 $ 334,644 Adjustments to reconcile net income to net cash provided by operating activities: Equity in undistributed income of bank subsidiaries (166,797 ) (37,515 ) (181,552 ) Equity in undistributed income of non-bank subsidiaries 10,768 12,914 9,545 Change in other assets (5,075 ) (1,072 ) 12 Change in other liabilities 855 (13,434 ) 7,457 Net cash provided by operating activities 340,509 406,539 170,106 Cash Flows From Investing Activities: Proceeds from sales of available for sale securities — — 3,000 Investment in subsidiaries (19,837 ) (31,901 ) (4,355 ) Acquisitions, net of cash acquired — (232,680 ) — Net cash used in investing activities (19,837 ) (264,581 ) (1,355 ) Cash Flows From Financing Activities: Net change in other borrowed funds — — (7,217 ) Issuance of common and treasury stock, net (7 ) (88 ) 4,368 Dividends paid (143,496 ) (127,188 ) (116,041 ) Repurchase of common stock (129,483 ) (53,465 ) (7,403 ) Net cash used in financing activities (272,986 ) (180,741 ) (126,293 ) Net increase (decrease) in cash and cash equivalents 47,686 (38,783 ) 42,458 Cash and cash equivalents at beginning of period 167,093 205,876 163,418 Cash and cash equivalents at end of period $ 214,779 $ 167,093 $ 205,876 Cash paid for interest $ 15,099 $ 11,457 $ 6,211

Significant Accounting Polici_3

Significant Accounting Policies Goodwill and Intangible Assets (Details)	12 Months Ended
	Dec. 31, 2019
Minimum [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	3 years
Maximum [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	20 years

Significant Accounting Polici_4

Significant Accounting Policies Cash Equivalents (Details)	12 Months Ended
Significant Accounting Policies Cash Equivalents (Details)	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Maturity of Federal Funds Sold Considered Cash Equivalents	1 day
Maturity of Resell Agreement Considered Cash Equivalents, Minimum	1 day
Maturity of Resell Agreements Considered Cash Equivalents, Maximum	30 days

Significant Accounting Polici_5

Significant Accounting Policies Loans (Details)	12 Months Ended
Significant Accounting Policies Loans (Details)	Dec. 31, 2019
Loans [Abstract]
Loans, Number of Days Past Due for a Non-Risk Graded Loan to be Placed on Nonaccruing Status	90 days
Loans, Number of Days After Notification of Chapter 7 Bankruptcy Non-Risk Graded Loan is Placed on Nonaccruing Status	60 days
Loans, Minimum Number of Days After Which Past Due Non-Risk Graded Loans Are Charged Off	60 days
Loans, Maximum Number of Days After Which Past Due Non-Risk Graded Loans Are Charged Off	180 days
Loans, Number of Days After Notification of Chapter 7 Bankruptcy Non-Risk Graded Loan is Charged Off	60 days

Significant Accounting Polici_6

Significant Accounting Policies Premises and Equipment (Details)	12 Months Ended
	Dec. 31, 2019
Buildings and improvements \| Minimum [Member]
Premises and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Buildings and improvements \| Maximum [Member]
Premises and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Software and Software Development Costs [Member] \| Minimum [Member]
Premises and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Software and Software Development Costs [Member] \| Maximum [Member]
Premises and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Furniture and equipment \| Minimum [Member]
Premises and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Furniture and equipment \| Maximum [Member]
Premises and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years

Significant Accounting Polici_7

Significant Accounting Policies Share-Based Compensation (Details)	12 Months Ended
	Dec. 31, 2019
Stock Options [Member]
Share-based Compensation Arrangements by Share-based Payment Award [Line Items]
Vesting period (in years)	7 years
Restricted Stock [Member]
Share-based Compensation Arrangements by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Required Holding Period	2 years

Significant Accounting Polici_8

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

Trading Securities (Details)

Trading Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule of Trading Securities [Line Items]
Trading securities	$ 1,623,921	$ 1,956,923
Trading Securities, Net Unrealized Gain (Loss)	2,359	10,969
U.S. government agency debentures [Member]
Schedule of Trading Securities [Line Items]
Trading securities	44,264	63,765
Trading Securities, Net Unrealized Gain (Loss)	6	254
Residential agency mortgage-backed securities [Member]
Schedule of Trading Securities [Line Items]
Trading securities	1,504,651	1,791,584
Trading Securities, Net Unrealized Gain (Loss)	2,293	9,966
Municipal and other tax-exempt securities [Member]
Schedule of Trading Securities [Line Items]
Trading securities	26,196	34,507
Trading Securities, Net Unrealized Gain (Loss)	60	(1)
Asset-backed securities [Member]
Schedule of Trading Securities [Line Items]
Trading securities	14,084	42,656
Trading Securities, Net Unrealized Gain (Loss)	(21)	685
Other debt securities [Member]
Schedule of Trading Securities [Line Items]
Trading securities	34,726	24,411
Trading Securities, Net Unrealized Gain (Loss)	$ 21	$ 65

Investment (Held-to-Maturity) S

Investment (Held-to-Maturity) Securities (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Amortized Cost		$ 293,418	$ 355,187
Investment Securities, fair value		314,402	367,298
Investment Securities, Gross Unrealized Gain		21,285	14,408
Investment Securities, Gross Unrealized Loss		(301)	(2,297)
Investment Securities, Debt Maturities, Net, Amortized Cost [Abstract]
Investment Securities, Amortized Cost		293,418	355,187
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, fair value		$ 314,402	$ 367,298
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		17	146
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 1,276	$ 31,627
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		9,747	94,802
Investment Securities, Continuous Unrealized Loss Position, Fair Value		11,023	126,429
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Losses		2	133
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Losses		299	2,164
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss		301	2,297
Fixed maturity securities [Member]
Investment Securities, Debt Maturities, Net, Amortized Cost [Abstract]
Investment Securities, Debt Maturities, Less than One Year, Net Carrying Value		41,670
Investment Securities, Debt Maturities, One to Five Years, Net Carrying Value		84,027
Investment Securities, Debt Maturities, Six to Ten Years, Net Carrying Value		144,705
Investment Securities, Debt Maturities, Over Ten Years, Net Carrying Value		12,340
Investment Securities, Debt Maturities, Single Maturity Date, Carrying Value		282,742
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, Less than One Year, Fair Value		41,840
Investment Securities, Debt Maturities, One to Five Years, Fair Value		87,883
Investment Securities, Debt Maturities, Six to Ten Years, Fair Value		161,178
Investment Securities, Debt Maturities, Over Ten Years, Fair Value		12,337
Investment Securities, Debt Maturities, Single Maturity Date, Fair value		$ 303,238
Investment Securities, Debt Maturities, Weighted Average Maturity	[1]	5.10
Municipal and other tax-exempt securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Amortized Cost		$ 93,653	137,296
Investment Securities, fair value		96,897	138,562
Investment Securities, Gross Unrealized Gain		3,250	1,858
Investment Securities, Gross Unrealized Loss		(6)	(592)
Investment Securities, Debt Maturities, Net, Amortized Cost [Abstract]
Investment Securities, Amortized Cost		93,653	137,296
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, fair value		$ 96,897	$ 138,562
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		4	72
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 1,001	$ 18,255
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		1,706	66,141
Investment Securities, Continuous Unrealized Loss Position, Fair Value		2,707	84,396
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Losses		1	69
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Losses		5	523
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss		6	592
Other debt securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Amortized Cost		189,089	205,279
Investment Securities, fair value		206,341	215,966
Investment Securities, Gross Unrealized Gain		17,547	12,257
Investment Securities, Gross Unrealized Loss		(295)	(1,570)
Investment Securities, Debt Maturities, Net, Amortized Cost [Abstract]
Investment Securities, Amortized Cost		189,089	205,279
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, fair value		$ 206,341	$ 215,966
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		13	72
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 275	$ 13,372
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		8,041	23,028
Investment Securities, Continuous Unrealized Loss Position, Fair Value		8,316	36,400
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Losses		1	64
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Losses		294	1,506
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss		295	1,570
Residential agency mortgage-backed securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Amortized Cost		10,676	12,612
Investment Securities, fair value		11,164	12,770
Investment Securities, Gross Unrealized Gain		488	293
Investment Securities, Gross Unrealized Loss		0	(135)
Investment Securities, Debt Maturities, Net, Amortized Cost [Abstract]
Investment Securities, Debt Maturities, without Single Maturity Date, Net Carrying value	[2]	10,676
Investment Securities, Amortized Cost		10,676	12,612
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, without Single Maturity Date, Fair value		11,164
Investment Securities, fair value		$ 11,164	$ 12,770
Investment Securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities		5 years
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		0	2
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 0	$ 0
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0	5,633
Investment Securities, Continuous Unrealized Loss Position, Fair Value		0	5,633
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Losses		0	0
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Losses		0	135
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ 0	$ 135

[1]	Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty.
[2]	The average expected lives of residential mortgage-backed securities were 5.0 years based upon current prepayment assumptions.

Available for Sale Securities (

Available for Sale Securities (Details) $ in Thousands		12 Months Ended
Available for Sale Securities (Details) $ in Thousands		Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Available for Sale Securities [Line Items]
Available for sale securities, Amortized Cost		$ 11,131,494	$ 8,952,391
Available for sale securities		11,269,643	8,857,120
Available for sale securities, Gross Unrealized Gain		158,435	42,986
Available for sale securities, Gross Unrealized Loss		(20,286)	(138,257)
Available for Sale Securities, Realized Gain (Loss) [Abstract]
Proceeds from sales of available for sale securities		1,211,718	745,643	$ 1,309,215
Available for sale securities, Gross realized gains		14,996	7,117	10,223
Available for sale securities, Gross realized losses		(9,399)	(9,918)	(5,795)
Available for sale securities, Related federal and state income tax expense		1,425	(713)	$ 1,722
Available for sale securities, Pledged as Collateral, Fair Value		10,100,000	9,100,000
Fixed maturity securities [Member]
Available for Sale Securities, Debt Maturities, Amortized Cost, Rolling Maturity [Abstract]
Available for sale securities, Debt Maturities, Less than One Year, Amortized Cost		5,105
Available for sale securities, Debt Maturities, One to Five Years, Amortized Cost		1,113,463
Available for sale securities, Debt Maturities, Six to Ten Years, Amortized Cost		1,455,340
Available for sale securities, Debt Maturities, Over Ten Years, Amortized Cost		575,321
Available for sale securities, Maturity, Allocated and Single Maturity Date, Amortized Cost		3,149,229
Available for Sale Securities, Maturity, Fair Value, Rolling Maturity [Abstract]
Available for sale securities, Debt Maturities, Less Than One Year, Fair Value		5,114
Available for sale securities, Debt Maturities, One to Five Years, Fair Value		1,122,392
Available for sale securities, Debt Maturities, Six to Ten Years, Fair Value		1,474,002
Available for sale securities, Debt Maturities, Over Ten Years, Fair Value		580,430
Available for sale securities, Debt Maturities, Single Maturity Date, Fair value		$ 3,181,938
Available for sale securities, Debt Maturities, Weighted Average Maturity	[1]	8.15
U.S. Treasury [Member]
Available for Sale Securities [Line Items]
Available for sale securities, Amortized Cost		$ 1,598	496
Available for sale securities		1,600	493
Available for sale securities, Gross Unrealized Gain		2	0
Available for sale securities, Gross Unrealized Loss		0	(3)
Municipal and other tax-exempt securities [Member]
Available for Sale Securities [Line Items]
Available for sale securities, Amortized Cost		1,789	2,782
Available for sale securities		1,861	2,864
Available for sale securities, Gross Unrealized Gain		72	82
Available for sale securities, Gross Unrealized Loss		0	0
Commercial agency mortgage-backed securities [Member]
Available for Sale Securities [Line Items]
Available for sale securities, Amortized Cost		3,145,342	2,986,297
Available for sale securities		3,178,005	2,953,889
Available for sale securities, Gross Unrealized Gain		37,808	7,955
Available for sale securities, Gross Unrealized Loss		(5,145)	(40,363)
Other debt securities [Member]
Available for Sale Securities [Line Items]
Available for sale securities, Amortized Cost		500	35,545
Available for sale securities		472	35,430
Available for sale securities, Gross Unrealized Gain		0	12
Available for sale securities, Gross Unrealized Loss		(28)	(127)
Residential Mortgage Backed Securities [Member]
Available for Sale Securities, Debt Maturities, Amortized Cost, Rolling Maturity [Abstract]
Available for sale securities, Maturity, without Single Maturity Date, Amortized Cost	[2]	7,982,265
Available for Sale Securities, Maturity, Fair Value, Rolling Maturity [Abstract]
Available for sale securities, Debt Maturities, without Single Maturity Date, Fair value		$ 8,087,705
Available for sale securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities		4 years
Residential agency mortgage-backed securities [Member]
Available for Sale Securities [Line Items]
Available for sale securities, Amortized Cost		$ 7,956,297	5,886,323
Available for sale securities		8,046,096	5,804,708
Available for sale securities, Gross Unrealized Gain		104,912	16,149
Available for sale securities, Gross Unrealized Loss		(15,113)	(97,764)
Residential non-agency mortgage-backed securities [Member]
Available for Sale Securities [Line Items]
Available for sale securities, Amortized Cost		25,968	40,948
Available for sale securities		41,609	59,736
Available for sale securities, Gross Unrealized Gain		15,641	18,788
Available for sale securities, Gross Unrealized Loss		$ 0	$ 0

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

Securities Available for sale,

Securities Available for sale, Unrealized Loss Position, Fair Value (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	203	490
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 2,182,644	$ 700,064
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	897,351	5,631,803
Available for sale securities, Unrealized Loss Position, Fair Value	3,079,995	6,331,867
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	10,928	1,615
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	9,358	136,642
Available for sale securities, Unrealized Loss Position, Accumulated Loss	20,286	138,257
Other than Temporary Impairment Loss, Available for sale, Recognized in Earnings	0	0
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Credit Losses on Debt Securities Held	$ 36,000	$ 45,000
U.S. Treasury [Member]
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		1
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value		$ 0
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value		493
Available for sale securities, Unrealized Loss Position, Fair Value		493
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		0
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		3
Available for sale securities, Unrealized Loss Position, Accumulated Loss		$ 3
Residential agency mortgage-backed securities [Member]
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	133	289
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 1,352,597	$ 510,824
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	686,002	3,641,370
Available for sale securities, Unrealized Loss Position, Fair Value	2,038,599	4,152,194
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	6,690	1,158
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	8,423	96,606
Available for sale securities, Unrealized Loss Position, Accumulated Loss	$ 15,113	$ 97,764
Commercial agency mortgage-backed securities [Member]
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	69	197
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 830,047	$ 179,258
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	210,877	1,969,504
Available for sale securities, Unrealized Loss Position, Fair Value	1,040,924	2,148,762
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4,238	394
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	907	39,969
Available for sale securities, Unrealized Loss Position, Accumulated Loss	$ 5,145	$ 40,363
Other debt securities [Member]
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	1	3
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 0	$ 9,982
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	472	20,436
Available for sale securities, Unrealized Loss Position, Fair Value	472	30,418
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	63
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	28	64
Available for sale securities, Unrealized Loss Position, Accumulated Loss	$ 28	$ 127

Securities Fair Value Option Se

Securities Fair Value Option Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value Option Securities [Line Items]
Fair value option securities	$ 1,098,577	$ 283,235
Fair Value Option Securities Unrealized Gain or Loss	14,061	2,766
U.S. Treasury [Member]
Fair Value Option Securities [Line Items]
Fair value option securities	9,917	0
Fair Value Option Securities Unrealized Gain or Loss	(48)	0
Residential agency mortgage-backed securities [Member]
Fair Value Option Securities [Line Items]
Fair value option securities	1,088,660	283,235
Fair Value Option Securities Unrealized Gain or Loss	$ 14,109	$ 2,766

Derivatives, Fair Value of Deri

Derivatives, Fair Value of Derivatives Contracts (Details) - USD ($) $ in Thousands	Dec. 31, 2019		Dec. 31, 2018
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Fair Value, Net of Cash Collateral	$ 323,375		$ 320,929
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Fair Value, Net of Cash Collateral	251,128		362,306
Not Designated as Hedging Instrument [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	75,917,378	[1]	30,272,764	[2]
Derivative Liabilities, Notional	70,400,171	[1]	33,838,893	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	549,555		571,793
Derivative Assets, Netting Adjustments	(225,482)		(135,530)
Derivative Assets, Net Fair Value Before Cash Collateral	324,073		436,263
Derivative Assets, Cash Collateral	(698)		(115,334)
Derivative Assets, Fair Value, Net of Cash Collateral	323,375		320,929
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Gross Fair Value	528,921		574,347
Derivative Liabilities, Netting Adjustments	(225,482)		(135,530)
Derivative Liabilities, Net Fair Value Before Cash Collateral	303,439		438,817
Derivative Liabilities, Cash Collateral	(52,311)		(76,511)
Derivative Liabilities, Fair Value, Net of Cash Collateral	251,128		362,306
Not Designated as Hedging Instrument [Member] \| Total customer risk management programs [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	4,927,266	[1]	14,362,776	[2]
Derivative Liabilities, Notional	4,875,382	[1]	14,204,251	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	411,768		521,383
Derivative Assets, Netting Adjustments	(109,452)		(94,659)
Derivative Assets, Net Fair Value Before Cash Collateral	302,316		426,724
Derivative Assets, Cash Collateral	(698)		(115,334)
Derivative Assets, Fair Value, Net of Cash Collateral	301,618		311,390
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Gross Fair Value	400,265		507,925
Derivative Liabilities, Netting Adjustments	(109,452)		(94,659)
Derivative Liabilities, Net Fair Value Before Cash Collateral	290,813		413,266
Derivative Liabilities, Cash Collateral	(51,448)		(69,196)
Derivative Liabilities, Fair Value, Net of Cash Collateral	239,365		344,070
Not Designated as Hedging Instrument [Member] \| To-be-announced residential mortgage-backed securities [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	0	[1]	10,671,151	[2]
Derivative Liabilities, Notional	0	[1]	10,558,151	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	0		92,231
Derivative Assets, Netting Adjustments	0		(26,787)
Derivative Assets, Net Fair Value Before Cash Collateral	0		65,444
Derivative Assets, Cash Collateral	0		0
Derivative Assets, Fair Value, Net of Cash Collateral	0		65,444
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Gross Fair Value	0		90,388
Derivative Liabilities, Netting Adjustments	0		(26,787)
Derivative Liabilities, Net Fair Value Before Cash Collateral	0		63,601
Derivative Liabilities, Cash Collateral	0		(63,596)
Derivative Liabilities, Fair Value, Net of Cash Collateral	0		5
Not Designated as Hedging Instrument [Member] \| Interest rate swaps [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	2,464,478	[1]	1,924,131	[2]
Derivative Liabilities, Notional	2,464,478	[1]	1,924,131	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	49,100		36,112
Derivative Assets, Netting Adjustments	(1,839)		(6,688)
Derivative Assets, Net Fair Value Before Cash Collateral	47,261		29,424
Derivative Assets, Cash Collateral	0		(7,934)
Derivative Assets, Fair Value, Net of Cash Collateral	47,261		21,490
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Gross Fair Value	49,194		36,288
Derivative Liabilities, Netting Adjustments	(1,839)		(6,688)
Derivative Liabilities, Net Fair Value Before Cash Collateral	47,355		29,600
Derivative Liabilities, Cash Collateral	(43,932)		(4,110)
Derivative Liabilities, Fair Value, Net of Cash Collateral	3,423		25,490
Not Designated as Hedging Instrument [Member] \| Energy contracts [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	2,151,096	[1]	1,472,209	[2]
Derivative Liabilities, Notional	2,105,391	[1]	1,434,247	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	144,906		206,418
Derivative Assets, Netting Adjustments	(107,591)		(60,983)
Derivative Assets, Net Fair Value Before Cash Collateral	37,315		145,435
Derivative Assets, Cash Collateral	(38)		(106,752)
Derivative Assets, Fair Value, Net of Cash Collateral	37,277		38,683
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Gross Fair Value	139,311		202,494
Derivative Liabilities, Netting Adjustments	(107,591)		(60,983)
Derivative Liabilities, Net Fair Value Before Cash Collateral	31,720		141,511
Derivative Liabilities, Cash Collateral	(6,031)		(1,490)
Derivative Liabilities, Fair Value, Net of Cash Collateral	25,689		140,021
Not Designated as Hedging Instrument [Member] \| Agricultural contracts [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	16,118	[1]	21,210	[2]
Derivative Liabilities, Notional	16,139	[1]	21,214	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	1,522		842
Derivative Assets, Netting Adjustments	(22)		(201)
Derivative Assets, Net Fair Value Before Cash Collateral	1,500		641
Derivative Assets, Cash Collateral	0		0
Derivative Assets, Fair Value, Net of Cash Collateral	1,500		641
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Gross Fair Value	1,507		812
Derivative Liabilities, Netting Adjustments	(22)		(201)
Derivative Liabilities, Net Fair Value Before Cash Collateral	1,485		611
Derivative Liabilities, Cash Collateral	(1,485)		0
Derivative Liabilities, Fair Value, Net of Cash Collateral	0		611
Not Designated as Hedging Instrument [Member] \| Foreign exchange contracts [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	214,119	[1]	184,990	[2]
Derivative Liabilities, Notional	207,919	[1]	177,423	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	213,007		183,759
Derivative Assets, Netting Adjustments	0		0
Derivative Assets, Net Fair Value Before Cash Collateral	213,007		183,759
Derivative Assets, Cash Collateral	0		0
Derivative Assets, Fair Value, Net of Cash Collateral	213,007		183,759
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Gross Fair Value	207,020		175,922
Derivative Liabilities, Netting Adjustments	0		0
Derivative Liabilities, Net Fair Value Before Cash Collateral	207,020		175,922
Derivative Liabilities, Cash Collateral	0		0
Derivative Liabilities, Fair Value, Net of Cash Collateral	207,020		175,922
Not Designated as Hedging Instrument [Member] \| Equity option contracts [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	81,455	[1]	89,085	[2]
Derivative Liabilities, Notional	81,455	[1]	89,085	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	3,233		2,021
Derivative Assets, Netting Adjustments	0		0
Derivative Assets, Net Fair Value Before Cash Collateral	3,233		2,021
Derivative Assets, Cash Collateral	(660)		(648)
Derivative Assets, Fair Value, Net of Cash Collateral	2,573		1,373
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Gross Fair Value	3,233		2,021
Derivative Liabilities, Netting Adjustments	0		0
Derivative Liabilities, Net Fair Value Before Cash Collateral	3,233		2,021
Derivative Liabilities, Cash Collateral	0		0
Derivative Liabilities, Fair Value, Net of Cash Collateral	3,233		2,021
Not Designated as Hedging Instrument [Member] \| Trading [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	69,721,932	[1]	15,356,909	[2]
Derivative Liabilities, Notional	65,144,388	[1]	19,374,294	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	131,561		45,346
Derivative Assets, Netting Adjustments	(115,949)		(39,521)
Derivative Assets, Net Fair Value Before Cash Collateral	15,612		5,825
Derivative Assets, Cash Collateral	0		0
Derivative Assets, Fair Value, Net of Cash Collateral	15,612		5,825
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Gross Fair Value	125,535		56,983
Derivative Liabilities, Netting Adjustments	(115,949)		(39,521)
Derivative Liabilities, Net Fair Value Before Cash Collateral	9,586		17,462
Derivative Liabilities, Cash Collateral	0		0
Derivative Liabilities, Fair Value, Net of Cash Collateral	9,586		17,462
Not Designated as Hedging Instrument [Member] \| Internal risk management programs [Member]
Notional Amount of Derivatives [Abstract]
Derivative Assets, Notional	1,268,180	[1]	553,079	[2]
Derivative Liabilities, Notional	380,401	[1]	260,348	[2]
Derivative Assets, Fair Value, Net [Abstract]
Derivative Assets, Gross Fair Value	6,226		5,064
Derivative Assets, Netting Adjustments	(81)		(1,350)
Derivative Assets, Net Fair Value Before Cash Collateral	6,145		3,714
Derivative Assets, Cash Collateral	0		0
Derivative Assets, Fair Value, Net of Cash Collateral	6,145		3,714
Derivative Liabilities, Fair Value, Net [Abstract]
Derivative Liabilities, Gross Fair Value	3,121		9,439
Derivative Liabilities, Netting Adjustments	(81)		(1,350)
Derivative Liabilities, Net Fair Value Before Cash Collateral	3,040		8,089
Derivative Liabilities, Cash Collateral	(863)		(7,315)
Derivative Liabilities, Fair Value, Net of Cash Collateral	$ 2,177		$ 774

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

Loans and Allowances for Cred_3

Loans and Allowances for Credit Losses, Loans by Portfolio Segment (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Loans receivables disclosure [Abstract]
Loans receivables with fixed rate of interest		$ 6,134,362	$ 5,749,373
Loans receivables with variable rate of interest		15,435,674	15,744,110
Loan receivable non-accrual		180,951	163,247
Total		21,750,987	21,656,730
Accruing loans past due (90 days)	[1]	7,680	1,338
Foregone interest on nonaccrual loans		17,409	15,502
Credit Commitments [Abstract]
Outstanding commitments to extend credit		11,100,000
Outstanding standby letters of credit		646,000
Geographic Concentration Risk [Member] \| Texas [Member]
Loans receivables disclosure [Abstract]
Total		$ 6,800,000	$ 6,400,000
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Texas (in hundredths)		31.00%	30.00%
Geographic Concentration Risk [Member] \| Oklahoma [Member]
Loans receivables disclosure [Abstract]
Total		$ 3,500,000	$ 3,500,000
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Oklahoma (in hundredths)		16.00%	16.00%
Geographic Concentration Risk [Member] \| Colorado [Member]
Loans receivables disclosure [Abstract]
Total		$ 2,800,000
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Colorado (in hundredths)		13.00%
Commercial [Member]
Loans receivables disclosure [Abstract]
Loans receivables with fixed rate of interest		$ 3,231,485	$ 2,251,188
Loans receivables with variable rate of interest		10,684,749	11,285,049
Loan receivable non-accrual		115,416	99,841
Total		14,031,650	13,636,078
Credit Commitments [Abstract]
Outstanding commercial letters of credit		1,200
Commercial [Member] \| Geographic Concentration Risk [Member] \| Texas [Member]
Loans receivables disclosure [Abstract]
Total		$ 4,700,000	$ 4,100,000
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Texas (in hundredths)		33.00%	30.00%
Commercial [Member] \| Geographic Concentration Risk [Member] \| Oklahoma [Member]
Loans receivables disclosure [Abstract]
Total		$ 2,000,000	$ 2,200,000
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Oklahoma (in hundredths)		14.00%	16.00%
Commercial [Member] \| Geographic Concentration Risk [Member] \| Colorado [Member]
Loans receivables disclosure [Abstract]
Total		$ 2,000,000
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Colorado (in hundredths)		14.00%
Commercial [Member] \| Services [Member]
Loans receivables disclosure [Abstract]
Total		$ 3,122,163	$ 3,258,192
Commercial [Member] \| Services [Member] \| Credit Concentration Risk [Member]
Loans receivables disclosure [Abstract]
Total		$ 3,100,000	$ 3,300,000
Loans receivable, other information [Abstract]
Percentage of loan class to total loans		14.00%	15.00%
Amount of loans with individual balances less than $10 million		$ 1,500,000	$ 2,300,000
Maximum loan amount for certain individual loans in category		10,000	10,000
Commercial [Member] \| Energy [Member]
Loans receivables disclosure [Abstract]
Total		3,973,377	3,590,333
Commercial [Member] \| Energy [Member] \| Credit Concentration Risk [Member]
Loans receivables disclosure [Abstract]
Total		$ 4,000,000	$ 3,600,000
Loans receivable, other information [Abstract]
Percentage of loan class to total loans		18.00%	17.00%
Commercial [Member] \| Energy Producers [Member] \| Credit Concentration Risk [Member]
Loans receivables disclosure [Abstract]
Total		$ 3,100,000	$ 2,900,000
Loans receivable, other information [Abstract]
Percentage of committed energy production loans secured by oil		58.00%	57.00%
Percentage of committed energy production loans secured by natural gas		42.00%	43.00%
Commercial [Member] \| Healthcare [Member]
Loans receivables disclosure [Abstract]
Total		$ 3,033,916	$ 2,799,277
Commercial [Member] \| Healthcare [Member] \| Credit Concentration Risk [Member]
Loans receivables disclosure [Abstract]
Total		$ 3,000,000	$ 2,800,000
Loans receivable, other information [Abstract]
Percentage of loan class to total loans		14.00%	13.00%
Commercial Real Estate [Member]
Loans receivables disclosure [Abstract]
Loans receivables with fixed rate of interest		$ 1,056,321	$ 1,477,274
Loans receivables with variable rate of interest		3,349,836	3,265,918
Loan receivable non-accrual		27,626	21,621
Total		$ 4,433,783	$ 4,764,813
Commercial Real Estate [Member] \| Geographic Concentration Risk [Member] \| Texas [Member]
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Texas (in hundredths)		24.00%	26.00%
Commercial Real Estate [Member] \| Geographic Concentration Risk [Member] \| Oklahoma [Member]
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Oklahoma (in hundredths)			9.00%
Commercial Real Estate [Member] \| Geographic Concentration Risk [Member] \| Colorado [Member]
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Colorado (in hundredths)		11.00%
Residential Mortgage [Member]
Loans receivables disclosure [Abstract]
Loans receivables with fixed rate of interest		$ 1,652,653	$ 1,830,224
Loans receivables with variable rate of interest		393,897	358,254
Loan receivable non-accrual		37,622	41,555
Total		$ 2,084,172	$ 2,230,033
Residential Mortgage [Member] \| Geographic Concentration Risk [Member] \| Texas [Member]
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Texas (in hundredths)		28.00%	28.00%
Residential Mortgage [Member] \| Geographic Concentration Risk [Member] \| Oklahoma [Member]
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Oklahoma (in hundredths)		28.00%	26.00%
Residential Mortgage [Member] \| Geographic Concentration Risk [Member] \| Colorado [Member]
Loans receivable, other information [Abstract]
Percentage of loan portfolio secured by property in Colorado (in hundredths)		15.00%	19.00%
Residential Mortgage [Member] \| Permanent mortgage [Member]
Loans receivables disclosure [Abstract]
Total		$ 1,057,321	$ 1,122,610
Loans receivable, other information [Abstract]
Minimum FICO required for jumbo loan approval		720
Maximum debt-to-income ratio on jumbo loans (in hundredths)		38.00%
Minimum loan-to-value ratio on jumbo loans (in hundredths)		60.00%
Maximum loan-to-value ratio on jumbo loans (in hundredths)		100.00%
Minimum period for fixed rate on variable rate jumbo loans (in years)		3 years
Maximum period for fixed rate on variable rate jumbo loans (in years)		10 years
Residential Mortgage [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Loans receivables disclosure [Abstract]
Total		$ 197,794	190,866
Residential Mortgage [Member] \| Home equity [Member]
Loans receivables disclosure [Abstract]
Total		829,057	$ 916,557
Loans receivable, other information [Abstract]
Maximum loan amount for certain individual loans in category		$ 400
Percentage of home equity portfolio comprised of first lien loans		63.00%	65.00%
Percentage of home equity portfolio comprised of junior lien loans		37.00%	35.00%
Percentage of junior lien home equity loans that are amortizing term loans		35.00%	36.00%
Percentage of junior lien home equity loans that are revolving lines of credit		65.00%	64.00%
Home equity loans, description		Home equity loans generally require a minimum FICO score of 700 and a maximum DTI of 40%.
Home equity loans, revolving period		5 years
Home equity loans, amortization period following revolving period		15 years
Home equity loans, discretionary additional revolving period		5 years
Personal [Member]
Loans receivables disclosure [Abstract]
Loans receivables with fixed rate of interest		$ 193,903	$ 190,687
Loans receivables with variable rate of interest		1,007,192	834,889
Loan receivable non-accrual		287	230
Total		$ 1,201,382	$ 1,025,806

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

Derivatives, Derivatives Instru

Derivatives, Derivatives Instruments Gain (Loss) in Income Statement (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Trading Activity, Gains and Losses, Net [Line Items]
Brokerage and Trading Revenue	$ 32,940	$ 25,192	$ 48,761
Gain (Loss) on Derivatives, Net	14,951	(422)	779
To-be-announced residential mortgage-backed securities [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokerage and Trading Revenue	9,579	27,190	34,532
Gain (Loss) on Derivatives, Net	0	0	0
Interest rate swaps [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokerage and Trading Revenue	3,647	2,614	2,647
Gain (Loss) on Derivatives, Net	0	0	0
Energy contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokerage and Trading Revenue	5,064	8,443	5,536
Gain (Loss) on Derivatives, Net	0	0	0
Agricultural contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokerage and Trading Revenue	28	53	79
Gain (Loss) on Derivatives, Net	0	0	0
Foreign exchange contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokerage and Trading Revenue	623	535	1,352
Gain (Loss) on Derivatives, Net	0	0	0
Equity option contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokerage and Trading Revenue	0	0	0
Gain (Loss) on Derivatives, Net	0	0	0
Total customer risk management programs [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokerage and Trading Revenue	18,941	38,835	44,146
Gain (Loss) on Derivatives, Net	0	0	0
Trading [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokerage and Trading Revenue	13,999	(13,643)	4,615
Gain (Loss) on Derivatives, Net	0	0	0
Internal risk management programs [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Brokerage and Trading Revenue	0	0	0
Gain (Loss) on Derivatives, Net	$ 14,951	$ (422)	$ 779

Loans and Allowances for Cred_4

Loans and Allowances for Credit Losses, Activity in Allowance for Credit Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Allowance for loan losses [Roll Forward]
Beginning balance	$ 207,457	$ 230,682	$ 246,159
Provision for loan losses	44,205	9,944	510
Loans charged off	(50,977)	(43,583)	(25,599)
Recoveries	10,074	10,414	9,612
Ending balance	210,759	207,457	230,682
Accrual for off-balance sheet credit losses [Roll Forward]
Beginning balance	1,790	3,734	11,244
Provision for off-balance sheet credit risk	(205)	(1,944)	(7,510)
Ending balance	1,585	1,790	3,734
Total provision for credit losses	44,000	8,000	(7,000)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment				$ 21,570,036	$ 21,493,483
Individually measured for impairment, recorded investment				180,951	163,247
Total				21,750,987	21,656,730
Related allowance [Abstract]
Collectively measured for impairment, related allowance				176,150	180,957
Individually measured for impairment, related allowance				17,414	8,732
Total measured for impairment, related allowance	210,759	207,457	230,682	210,759	207,457
Commercial [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	102,226	124,269	140,213
Provision for loan losses	57,125	12,521	(595)
Loans charged off	(43,185)	(37,880)	(19,810)
Recoveries	2,021	3,316	4,461
Ending balance	118,187	102,226	124,269
Accrual for off-balance sheet credit losses [Roll Forward]
Beginning balance	1,655	3,644	11,063
Provision for off-balance sheet credit risk	(221)	(1,989)	(7,419)
Ending balance	1,434	1,655	3,644
Total provision for credit losses	56,904	10,532	(8,014)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment				13,916,234	13,536,237
Individually measured for impairment, recorded investment				115,416	99,841
Total				14,031,650	13,636,078
Related allowance [Abstract]
Collectively measured for impairment, related allowance				100,773	93,494
Individually measured for impairment, related allowance				17,414	8,732
Total measured for impairment, related allowance	118,187	102,226	140,213	118,187	102,226
Commercial Real Estate [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	60,026	56,621	50,749
Provision for loan losses	(12,046)	(147)	4,008
Loans charged off	(1,161)	0	(76)
Recoveries	4,986	3,552	1,940
Ending balance	51,805	60,026	56,621
Accrual for off-balance sheet credit losses [Roll Forward]
Beginning balance	52	45	123
Provision for off-balance sheet credit risk	55	7	(78)
Ending balance	107	52	45
Total provision for credit losses	(11,991)	(140)	3,930
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment				4,406,157	4,743,192
Individually measured for impairment, recorded investment				27,626	21,621
Total				4,433,783	4,764,813
Related allowance [Abstract]
Collectively measured for impairment, related allowance				51,805	60,026
Individually measured for impairment, related allowance				0	0
Total measured for impairment, related allowance	60,026	60,026	56,621	51,805	60,026
Residential Mortgage [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	17,964	18,451	18,224
Provision for loan losses	(3,838)	(1,156)	116
Loans charged off	(288)	(378)	(649)
Recoveries	562	1,047	760
Ending balance	14,400	17,964	18,451
Accrual for off-balance sheet credit losses [Roll Forward]
Beginning balance	52	43	50
Provision for off-balance sheet credit risk	(8)	9	(7)
Ending balance	44	52	43
Total provision for credit losses	(3,846)	(1,147)	109
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment				2,046,550	2,188,478
Individually measured for impairment, recorded investment				37,622	41,555
Total				2,084,172	2,230,033
Related allowance [Abstract]
Collectively measured for impairment, related allowance				14,400	17,964
Individually measured for impairment, related allowance				0	0
Total measured for impairment, related allowance	17,964	17,964	18,451	14,400	17,964
Personal [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	9,473	9,124	8,773
Provision for loan losses	3,537	3,175	2,964
Loans charged off	(6,343)	(5,325)	(5,064)
Recoveries	2,505	2,499	2,451
Ending balance	9,172	9,473	9,124
Accrual for off-balance sheet credit losses [Roll Forward]
Beginning balance	31	2	8
Provision for off-balance sheet credit risk	(31)	29	(6)
Ending balance	0	31	2
Total provision for credit losses	3,506	3,204	2,958
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment				1,201,095	1,025,576
Individually measured for impairment, recorded investment				287	230
Total				1,201,382	1,025,806
Related allowance [Abstract]
Collectively measured for impairment, related allowance				9,172	9,473
Individually measured for impairment, related allowance				0	0
Total measured for impairment, related allowance	9,172	9,473	8,773	9,172	9,473
Specific Allowance [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	189,689
Ending balance	193,564	189,689
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment				21,570,036	21,493,483
Individually measured for impairment, recorded investment				180,951	163,247
Total				21,750,987	21,656,730
Related allowance [Abstract]
Collectively measured for impairment, related allowance				176,150	180,957
Individually measured for impairment, related allowance				17,414	8,732
Total measured for impairment, related allowance	189,689	189,689		193,564	189,689
Nonspecific Allowance [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	17,768	22,217	28,200
Provision for loan losses	(573)	(4,449)	(5,983)
Loans charged off	0	0	0
Recoveries	0	0	0
Ending balance	17,195	17,768	22,217
Accrual for off-balance sheet credit losses [Roll Forward]
Beginning balance	0	0	0
Provision for off-balance sheet credit risk	0	0	0
Ending balance	0	0	0
Total provision for credit losses	(573)	(4,449)	(5,983)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment				0	0
Individually measured for impairment, recorded investment				0	0
Total				0	0
Related allowance [Abstract]
Collectively measured for impairment, related allowance				0	0
Individually measured for impairment, related allowance				0	0
Total measured for impairment, related allowance	$ 17,195	$ 22,217	$ 22,217	$ 17,195	$ 17,768

Loans and Allowances for Cred_5

Loans and Allowances for Credit Losses, Credit Quality Indicators (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	$ 19,826,731	$ 19,805,403
Non-Graded, Recorded Investment	1,924,256	1,851,327
Total	21,750,987	21,656,730
Related Allowance [Abstract]
Internally Risk Graded, Related Allowance	179,129	171,272
Non-Graded, Related Allowance	14,435	18,417
Total, Related Allowance	210,759	207,457	$ 230,682	$ 246,159
Commercial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	13,997,538	13,586,654
Non-Graded, Recorded Investment	34,112	49,424
Total	14,031,650	13,636,078
Related Allowance [Abstract]
Internally Risk Graded, Related Allowance	117,236	101,303
Non-Graded, Related Allowance	951	923
Total, Related Allowance	118,187	102,226	124,269	140,213
Commercial [Member] \| Energy [Member]
Recorded Investment [Abstract]
Total	3,973,377	3,590,333
Commercial [Member] \| Services [Member]
Recorded Investment [Abstract]
Total	3,122,163	3,258,192
Commercial [Member] \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Total	1,760,866	1,621,158
Commercial [Member] \| Manufacturing [Member]
Recorded Investment [Abstract]
Total	665,449	730,521
Commercial [Member] \| Healthcare [Member]
Recorded Investment [Abstract]
Total	3,033,916	2,799,277
Commercial [Member] \| Public finance [Member]
Recorded Investment [Abstract]
Total	709,868	804,550
Commercial [Member] \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Total	766,011	832,047
Commercial Real Estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	4,433,783	4,764,813
Non-Graded, Recorded Investment	0	0
Total	4,433,783	4,764,813
Related Allowance [Abstract]
Internally Risk Graded, Related Allowance	51,805	60,026
Non-Graded, Related Allowance	0	0
Total, Related Allowance	51,805	60,026	56,621	50,749
Commercial Real Estate [Member] \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Total	150,879	148,584
Commercial Real Estate [Member] \| Retail [Member]
Recorded Investment [Abstract]
Total	775,521	919,082
Commercial Real Estate [Member] \| Office [Member]
Recorded Investment [Abstract]
Total	928,379	1,072,920
Commercial Real Estate [Member] \| Multifamily [Member]
Recorded Investment [Abstract]
Total	1,265,562	1,288,065
Commercial Real Estate [Member] \| Industrial [Member]
Recorded Investment [Abstract]
Total	856,117	778,106
Commercial Real Estate [Member] \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Total	457,325	558,056
Residential Mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	279,113	505,046
Non-Graded, Recorded Investment	1,805,059	1,724,987
Total	2,084,172	2,230,033
Related Allowance [Abstract]
Internally Risk Graded, Related Allowance	3,085	3,310
Non-Graded, Related Allowance	11,315	14,654
Total, Related Allowance	14,400	17,964	18,451	18,224
Residential Mortgage [Member] \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Total	1,057,321	1,122,610
Residential Mortgage [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Recorded Investment [Abstract]
Total	197,794	190,866
Residential Mortgage [Member] \| Home equity [Member]
Recorded Investment [Abstract]
Total	829,057	916,557
Personal [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,116,297	948,890
Non-Graded, Recorded Investment	85,085	76,916
Total	1,201,382	1,025,806
Related Allowance [Abstract]
Internally Risk Graded, Related Allowance	7,003	6,633
Non-Graded, Related Allowance	2,169	2,840
Total, Related Allowance	9,172	9,473	9,124	8,773
Specific Allowance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	19,826,731	19,805,403
Non-Graded, Recorded Investment	1,924,256	1,851,327
Total	21,750,987	21,656,730
Related Allowance [Abstract]
Internally Risk Graded, Related Allowance	179,129	171,272
Non-Graded, Related Allowance	14,435	18,417
Total, Related Allowance	193,564	189,689
Nonspecific Allowance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	0
Non-Graded, Recorded Investment	0	0
Total	0	0
Related Allowance [Abstract]
Internally Risk Graded, Related Allowance	0	0
Non-Graded, Related Allowance	0	0
Total, Related Allowance	17,195	17,768	$ 22,217	$ 28,200
Performing Financial Instruments [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	1,886,858	1,811,557
Performing Financial Instruments [Member] \| Commercial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	34,075	49,371
Performing Financial Instruments [Member] \| Commercial [Member] \| Energy [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Commercial [Member] \| Services [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Commercial [Member] \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Commercial [Member] \| Manufacturing [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Commercial [Member] \| Healthcare [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Commercial [Member] \| Public finance [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Commercial [Member] \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	34,075	49,371
Performing Financial Instruments [Member] \| Commercial Real Estate [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Commercial Real Estate [Member] \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Commercial Real Estate [Member] \| Retail [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Commercial Real Estate [Member] \| Office [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Commercial Real Estate [Member] \| Multifamily [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Commercial Real Estate [Member] \| Industrial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Commercial Real Estate [Member] \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Residential Mortgage [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	1,767,930	1,685,424
Performing Financial Instruments [Member] \| Residential Mortgage [Member] \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	758,260	819,199
Performing Financial Instruments [Member] \| Residential Mortgage [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	191,694	183,734
Performing Financial Instruments [Member] \| Residential Mortgage [Member] \| Home equity [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	817,976	682,491
Performing Financial Instruments [Member] \| Personal [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	84,853	76,762
Performing Financial Instruments [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	19,312,702	19,285,126
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	13,538,705	13,135,068
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial [Member] \| Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	3,700,406	3,414,039
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial [Member] \| Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	3,050,946	3,167,203
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial [Member] \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,749,023	1,593,902
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial [Member] \| Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	623,219	668,438
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial [Member] \| Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,995,514	2,730,121
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial [Member] \| Public finance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	709,868	804,550
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial [Member] \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	709,729	756,815
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial Real Estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	4,381,663	4,712,826
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial Real Estate [Member] \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	150,529	148,234
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial Real Estate [Member] \| Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	743,343	885,588
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial Real Estate [Member] \| Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	923,202	1,059,334
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial Real Estate [Member] \| Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,257,005	1,287,471
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial Real Estate [Member] \| Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	852,539	776,898
Performing Financial Instruments [Member] \| Pass [Member] \| Commercial Real Estate [Member] \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	455,045	555,301
Performing Financial Instruments [Member] \| Pass [Member] \| Residential Mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	276,138	492,976
Performing Financial Instruments [Member] \| Pass [Member] \| Residential Mortgage [Member] \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	276,138	269,678
Performing Financial Instruments [Member] \| Pass [Member] \| Residential Mortgage [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Pass [Member] \| Residential Mortgage [Member] \| Home equity [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	223,298
Performing Financial Instruments [Member] \| Pass [Member] \| Personal [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,116,196	944,256
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	210,149	181,960
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	187,881	157,866
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial [Member] \| Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	117,298	42,176
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial [Member] \| Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	29,943	49,761
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial [Member] \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	5,281	18,809
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial [Member] \| Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	18,214	30,934
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial [Member] \| Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	13,117	14,920
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial [Member] \| Public finance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial [Member] \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	4,028	1,266
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial Real Estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	22,145	23,927
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial Real Estate [Member] \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial Real Estate [Member] \| Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	12,067	11,926
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial Real Estate [Member] \| Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	5,177	10,532
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial Real Estate [Member] \| Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,604	281
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial Real Estate [Member] \| Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,658	0
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Commercial Real Estate [Member] \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,639	1,188
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Residential Mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	78	52
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Residential Mortgage [Member] \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	78	52
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Residential Mortgage [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Residential Mortgage [Member] \| Home equity [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Other Loans Especially Mentioned [Member] \| Personal [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	45	115
Performing Financial Instruments [Member] \| Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	160,326	214,840
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	155,573	193,932
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial [Member] \| Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	63,951	86,624
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial [Member] \| Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	33,791	32,661
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial [Member] \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	5,399	7,131
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial [Member] \| Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	13,883	22,230
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial [Member] \| Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	20,805	37,698
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial [Member] \| Public finance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial [Member] \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	17,744	7,588
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial Real Estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,349	6,439
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial Real Estate [Member] \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial Real Estate [Member] \| Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,243	1,289
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial Real Estate [Member] \| Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	3,054
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial Real Estate [Member] \| Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	95	12
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial Real Estate [Member] \| Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,011	1,208
Performing Financial Instruments [Member] \| Substandard [Member] \| Commercial Real Estate [Member] \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	876
Performing Financial Instruments [Member] \| Substandard [Member] \| Residential Mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,404	10,026
Performing Financial Instruments [Member] \| Substandard [Member] \| Residential Mortgage [Member] \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,404	9,730
Performing Financial Instruments [Member] \| Substandard [Member] \| Residential Mortgage [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	0
Performing Financial Instruments [Member] \| Substandard [Member] \| Residential Mortgage [Member] \| Home equity [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	296
Performing Financial Instruments [Member] \| Substandard [Member] \| Personal [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	4,443
Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	143,554	123,476
Non-Graded, Recorded Investment	37,398	39,771
Nonaccrual [Member] \| Commercial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	115,379	99,788
Non-Graded, Recorded Investment	37	53
Nonaccrual [Member] \| Commercial [Member] \| Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	91,722	47,494
Non-Graded, Recorded Investment	0	0
Nonaccrual [Member] \| Commercial [Member] \| Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	7,483	8,567
Non-Graded, Recorded Investment	0	0
Nonaccrual [Member] \| Commercial [Member] \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,163	1,316
Non-Graded, Recorded Investment	0	0
Nonaccrual [Member] \| Commercial [Member] \| Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	10,133	8,919
Non-Graded, Recorded Investment	0	0
Nonaccrual [Member] \| Commercial [Member] \| Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	4,480	16,538
Non-Graded, Recorded Investment	0	0
Nonaccrual [Member] \| Commercial [Member] \| Public finance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	0
Non-Graded, Recorded Investment	0	0
Nonaccrual [Member] \| Commercial [Member] \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	398	16,954
Non-Graded, Recorded Investment	37	53
Nonaccrual [Member] \| Commercial Real Estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	27,626	21,621
Non-Graded, Recorded Investment	0	0
Nonaccrual [Member] \| Commercial Real Estate [Member] \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	350	350
Non-Graded, Recorded Investment	0	0
Nonaccrual [Member] \| Commercial Real Estate [Member] \| Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	18,868	20,279
Non-Graded, Recorded Investment	0	0
Nonaccrual [Member] \| Commercial Real Estate [Member] \| Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	0
Non-Graded, Recorded Investment	0	0
Nonaccrual [Member] \| Commercial Real Estate [Member] \| Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	6,858	301
Non-Graded, Recorded Investment	0	0
Nonaccrual [Member] \| Commercial Real Estate [Member] \| Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	909	0
Non-Graded, Recorded Investment	0	0
Nonaccrual [Member] \| Commercial Real Estate [Member] \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	641	691
Non-Graded, Recorded Investment	0	0
Nonaccrual [Member] \| Residential Mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	493	1,991
Non-Graded, Recorded Investment	37,129	39,564
Nonaccrual [Member] \| Residential Mortgage [Member] \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	493	1,991
Non-Graded, Recorded Investment	19,948	21,960
Nonaccrual [Member] \| Residential Mortgage [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	0
Non-Graded, Recorded Investment	6,100	7,132
Nonaccrual [Member] \| Residential Mortgage [Member] \| Home equity [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0	0
Non-Graded, Recorded Investment	11,081	10,472
Nonaccrual [Member] \| Personal [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	56	76
Non-Graded, Recorded Investment	232	154
Residential Mortgage [Member] \| Performing Financial Instruments [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	192,000	184,000
Residential Mortgage [Member] \| Nonaccrual [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	$ 6,100	$ 7,100

Loans and Allowances for Cred_6

Loans and Allowances for Credit Losses, Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	$ 467,714		$ 423,787
Impaired loans, recorded investment, total	372,645		346,981
Impaired loans, recorded investment with no related allowance	323,505		311,526
Impaired loans, recorded investment with related allowance	49,140		35,455
Impaired loans, related allowance	17,414		8,732
Impaired loans, average recorded investment	354,262		345,107
Impaired loans, interest income recognized	8,931		8,405
Commercial [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	195,193		156,163
Impaired loans, recorded investment, total	115,416		99,841
Impaired loans, recorded investment with no related allowance	66,276		64,386
Impaired loans, recorded investment with related allowance	49,140		35,455
Impaired loans, related allowance	17,414		8,732
Impaired loans, average recorded investment	101,399		115,460
Impaired loans, interest income recognized	0		0
Commercial [Member] \| Energy [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	149,441		79,675
Impaired loans, recorded investment, total	91,722		47,494
Impaired loans, recorded investment with no related allowance	44,244		18,639
Impaired loans, recorded investment with related allowance	47,478		28,855
Impaired loans, related allowance	16,854		5,362
Impaired loans, average recorded investment	69,119		69,645
Impaired loans, interest income recognized	0		0
Commercial [Member] \| Services [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	10,923		13,437
Impaired loans, recorded investment, total	7,483		8,567
Impaired loans, recorded investment with no related allowance	6,301		8,489
Impaired loans, recorded investment with related allowance	1,182		78
Impaired loans, related allowance	240		74
Impaired loans, average recorded investment	5,854		4,509
Impaired loans, interest income recognized	0		0
Commercial [Member] \| Wholesale/retail [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	1,980		1,722
Impaired loans, recorded investment, total	1,163		1,316
Impaired loans, recorded investment with no related allowance	902		1,015
Impaired loans, recorded investment with related allowance	261		301
Impaired loans, related allowance	101		101
Impaired loans, average recorded investment	916		1,784
Impaired loans, interest income recognized	0		0
Commercial [Member] \| Manufacturing [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	10,848		10,055
Impaired loans, recorded investment, total	10,133		8,919
Impaired loans, recorded investment with no related allowance	9,914		8,673
Impaired loans, recorded investment with related allowance	219		246
Impaired loans, related allowance	219		246
Impaired loans, average recorded investment	9,144		7,249
Impaired loans, interest income recognized	0		0
Commercial [Member] \| Healthcare [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	13,774		24,319
Impaired loans, recorded investment, total	4,480		16,538
Impaired loans, recorded investment with no related allowance	4,480		10,563
Impaired loans, recorded investment with related allowance	0		5,975
Impaired loans, related allowance	0		2,949
Impaired loans, average recorded investment	7,798		14,297
Impaired loans, interest income recognized	0		0
Commercial [Member] \| Public finance [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	0		0
Impaired loans, recorded investment, total	0		0
Impaired loans, recorded investment with no related allowance	0		0
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	0		0
Impaired loans, interest income recognized	0		0
Commercial [Member] \| Other commercial and industrial [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	8,227		26,955
Impaired loans, recorded investment, total	435		17,007
Impaired loans, recorded investment with no related allowance	435		17,007
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	8,568		17,976
Impaired loans, interest income recognized	0		0
Commercial Real Estate [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	30,139		30,138
Impaired loans, recorded investment, total	27,626		21,621
Impaired loans, recorded investment with no related allowance	27,626		21,621
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	24,623		12,238
Impaired loans, interest income recognized	0		0
Commercial Real Estate [Member] \| Residential construction and land development [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	1,306		1,306
Impaired loans, recorded investment, total	350		350
Impaired loans, recorded investment with no related allowance	350		350
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	350		1,091
Impaired loans, interest income recognized	0		0
Commercial Real Estate [Member] \| Retail [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	20,265		27,680
Impaired loans, recorded investment, total	18,868		20,279
Impaired loans, recorded investment with no related allowance	18,868		20,279
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	19,573		10,278
Impaired loans, interest income recognized	0		0
Commercial Real Estate [Member] \| Office [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	0		0
Impaired loans, recorded investment, total	0		0
Impaired loans, recorded investment with no related allowance	0		0
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	0		137
Impaired loans, interest income recognized	0		0
Commercial Real Estate [Member] \| Multifamily [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	6,858		301
Impaired loans, recorded investment, total	6,858		301
Impaired loans, recorded investment with no related allowance	6,858		301
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	3,580		151
Impaired loans, interest income recognized	0		0
Commercial Real Estate [Member] \| Industrial [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	909		0
Impaired loans, recorded investment, total	909		0
Impaired loans, recorded investment with no related allowance	909		0
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	454		0
Impaired loans, interest income recognized	0		0
Commercial Real Estate [Member] \| Other commercial real estate [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	801		851
Impaired loans, recorded investment, total	641		691
Impaired loans, recorded investment with no related allowance	641		691
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	666		581
Impaired loans, interest income recognized	0		0
Residential Mortgage [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	242,022		237,208
Impaired loans, recorded investment, total	229,316		225,289
Impaired loans, recorded investment with no related allowance	229,316		225,289
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	227,981		217,159
Impaired loans, interest income recognized	8,931		8,405
Residential Mortgage [Member] \| Permanent mortgage [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	24,868		28,716
Impaired loans, recorded investment, total	20,441		23,951
Impaired loans, recorded investment with no related allowance	20,441		23,951
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	22,196		24,572
Impaired loans, interest income recognized	1,198		1,233
Residential Mortgage [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	204,187	[1]	196,296	[2]
Impaired loans, recorded investment, total	197,794	[1]	190,866	[2]
Impaired loans, recorded investment with no related allowance	197,794	[1]	190,866	[2]
Impaired loans, recorded investment with related allowance	0	[1]	0	[2]
Impaired loans, related allowance	0	[1]	0	[2]
Impaired loans, average recorded investment	195,009	[1]	180,813	[2]
Impaired loans, interest income recognized	7,733	[1]	7,172	[2]
Residential Mortgage [Member] \| Home equity [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	12,967		12,196
Impaired loans, recorded investment, total	11,081		10,472
Impaired loans, recorded investment with no related allowance	11,081		10,472
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	10,776		11,774
Impaired loans, interest income recognized	0		0
Personal [Member]
Impaired loans [Abstract]
Impaired loans, unpaid principal balance	360		278
Impaired loans, recorded investment, total	287		230
Impaired loans, recorded investment with no related allowance	287		230
Impaired loans, recorded investment with related allowance	0		0
Impaired loans, related allowance	0		0
Impaired loans, average recorded investment	259		250
Impaired loans, interest income recognized	$ 0		$ 0

[1]	All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2019 , $6.1 million of these loans are nonaccruing and $192 million are accruing based on the guarantee by U.S. government agencies.
[2]	All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2018 , $7.1 million of these loans are nonaccruing and $184 million are accruing based on the guarantee by U.S. government agencies.

Loans and Allowances for Cred_7

Loans and Allowances for Credit Losses, Troubled Debt Restructurings (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Troubled Debt Restructuring [Line Items]
Troubled Debt Restructuring, Recorded Investment	$ 132	$ 166
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	57	71
Troubled Debt Restructuring, Charge-offs	18.6	16.1
Troubled Debt Restructurings, Recorded Balance Modified During The Period	37	75
Residential Mortgage [Member] \| Accruing [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Troubled Debt Restructuring, Recorded Investment	$ 92	$ 86

Loans and Allowances for Cred_8

Loans and Allowances for Credit Losses, By Aging Category (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Financing receivable, recorded investment, aging [Abstract]
Current	$ 21,392,306,000	$ 21,308,989,000
Nonaccrual	180,951,000	163,247,000
Total	21,750,987,000	21,656,730,000
Commercial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	13,899,429,000	13,521,894,000
Nonaccrual	115,416,000	99,841,000
Total	14,031,650,000	13,636,078,000
Commercial [Member] \| Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	3,881,244,000	3,542,839,000
Nonaccrual	91,722,000	47,494,000
Total	3,973,377,000	3,590,333,000
Commercial [Member] \| Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	3,105,621,000	3,237,578,000
Nonaccrual	7,483,000	8,567,000
Total	3,122,163,000	3,258,192,000
Commercial [Member] \| Wholesale/retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,758,878,000	1,619,290,000
Nonaccrual	1,163,000	1,316,000
Total	1,760,866,000	1,621,158,000
Commercial [Member] \| Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	654,329,000	721,204,000
Nonaccrual	10,133,000	8,919,000
Total	665,449,000	730,521,000
Commercial [Member] \| Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	3,027,329,000	2,781,944,000
Nonaccrual	4,480,000	16,538,000
Total	3,033,916,000	2,799,277,000
Commercial [Member] \| Public finance [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	707,638,000	804,550,000
Nonaccrual	0	0
Total	709,868,000	804,550,000
Commercial [Member] \| Other commercial and industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	764,390,000	814,489,000
Nonaccrual	435,000	17,007,000
Total	766,011,000	832,047,000
Commercial Real Estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	4,400,576,000	4,725,669,000
Nonaccrual	27,626,000	21,621,000
Total	4,433,783,000	4,764,813,000
Commercial Real Estate [Member] \| Residential construction and land development [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	147,379,000	147,705,000
Nonaccrual	350,000	350,000
Total	150,879,000	148,584,000
Commercial Real Estate [Member] \| Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	756,653,000	884,424,000
Nonaccrual	18,868,000	20,279,000
Total	775,521,000	919,082,000
Commercial Real Estate [Member] \| Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	928,379,000	1,072,920,000
Nonaccrual	0	0
Total	928,379,000	1,072,920,000
Commercial Real Estate [Member] \| Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,258,704,000	1,287,483,000
Nonaccrual	6,858,000	301,000
Total	1,265,562,000	1,288,065,000
Commercial Real Estate [Member] \| Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	855,208,000	776,898,000
Nonaccrual	909,000	0
Total	856,117,000	778,106,000
Commercial Real Estate [Member] \| Other commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	454,253,000	556,239,000
Nonaccrual	641,000	691,000
Total	457,325,000	558,056,000
Residential Mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,895,939,000	2,037,128,000
Nonaccrual	37,622,000	41,555,000
Total	2,084,172,000	2,230,033,000
Residential Mortgage [Member] \| Permanent mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,034,716,000	1,095,097,000
Nonaccrual	20,441,000	23,951,000
Total	1,057,321,000	1,122,610,000
Residential Mortgage [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	46,898,000	37,459,000
Nonaccrual	6,100,000	7,132,000
Total	197,794,000	190,866,000
Residential Mortgage [Member] \| Home equity [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	814,325,000	904,572,000
Nonaccrual	11,081,000	10,472,000
Total	829,057,000	916,557,000
Personal [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,196,362,000	1,024,298,000
Nonaccrual	287,000	230,000
Total	1,201,382,000	1,025,806,000
30 to 59 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	47,084,000	53,350,000
30 to 59 Days Past Due [Member] \| Commercial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	7,943,000	7,675,000
30 to 59 Days Past Due [Member] \| Commercial [Member] \| Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	401,000	0
30 to 59 Days Past Due [Member] \| Commercial [Member] \| Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	1,737,000	6,009,000
30 to 59 Days Past Due [Member] \| Commercial [Member] \| Wholesale/retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	712,000	515,000
30 to 59 Days Past Due [Member] \| Commercial [Member] \| Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	410,000	392,000
30 to 59 Days Past Due [Member] \| Commercial [Member] \| Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	2,039,000	241,000
30 to 59 Days Past Due [Member] \| Commercial [Member] \| Public finance [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	2,230,000	0
30 to 59 Days Past Due [Member] \| Commercial [Member] \| Other commercial and industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	414,000	518,000
30 to 59 Days Past Due [Member] \| Commercial Real Estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	4,920,000	16,529,000
30 to 59 Days Past Due [Member] \| Commercial Real Estate [Member] \| Residential construction and land development [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	3,093,000	249,000
30 to 59 Days Past Due [Member] \| Commercial Real Estate [Member] \| Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	14,379,000
30 to 59 Days Past Due [Member] \| Commercial Real Estate [Member] \| Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
30 to 59 Days Past Due [Member] \| Commercial Real Estate [Member] \| Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	281,000
30 to 59 Days Past Due [Member] \| Commercial Real Estate [Member] \| Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	1,208,000
30 to 59 Days Past Due [Member] \| Commercial Real Estate [Member] \| Other commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	1,827,000	412,000
30 to 59 Days Past Due [Member] \| Residential Mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	29,557,000	28,667,000
30 to 59 Days Past Due [Member] \| Residential Mortgage [Member] \| Permanent mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	2,011,000	3,196,000
30 to 59 Days Past Due [Member] \| Residential Mortgage [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	24,203,000	24,369,000
30 to 59 Days Past Due [Member] \| Residential Mortgage [Member] \| Home equity [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	3,343,000	1,102,000
30 to 59 Days Past Due [Member] \| Personal [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	4,664,000	479,000
60 to 89 Days Past Due [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	20,560,000	24,245,000
60 to 89 Days Past Due [Member] \| Commercial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	1,608,000	6,106,000
60 to 89 Days Past Due [Member] \| Commercial [Member] \| Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	10,000	0
60 to 89 Days Past Due [Member] \| Commercial [Member] \| Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	523,000	6,038,000
60 to 89 Days Past Due [Member] \| Commercial [Member] \| Wholesale/retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	113,000	37,000
60 to 89 Days Past Due [Member] \| Commercial [Member] \| Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	190,000	6,000
60 to 89 Days Past Due [Member] \| Commercial [Member] \| Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
60 to 89 Days Past Due [Member] \| Commercial [Member] \| Public finance [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
60 to 89 Days Past Due [Member] \| Commercial [Member] \| Other commercial and industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	772,000	25,000
60 to 89 Days Past Due [Member] \| Commercial Real Estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	250,000	280,000
60 to 89 Days Past Due [Member] \| Commercial Real Estate [Member] \| Residential construction and land development [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	280,000
60 to 89 Days Past Due [Member] \| Commercial Real Estate [Member] \| Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
60 to 89 Days Past Due [Member] \| Commercial Real Estate [Member] \| Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
60 to 89 Days Past Due [Member] \| Commercial Real Estate [Member] \| Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
60 to 89 Days Past Due [Member] \| Commercial Real Estate [Member] \| Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
60 to 89 Days Past Due [Member] \| Commercial Real Estate [Member] \| Other commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	250,000	0
60 to 89 Days Past Due [Member] \| Residential Mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	18,648,000	17,063,000
60 to 89 Days Past Due [Member] \| Residential Mortgage [Member] \| Permanent mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	153,000	366,000
60 to 89 Days Past Due [Member] \| Residential Mortgage [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	18,187,000	16,345,000
60 to 89 Days Past Due [Member] \| Residential Mortgage [Member] \| Home equity [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	308,000	352,000
60 to 89 Days Past Due [Member] \| Personal [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	54,000	796,000
90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	110,086,000	106,899,000
90 Days or More [Member] \| Commercial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	7,254,000	562,000
90 Days or More [Member] \| Commercial [Member] \| Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
90 Days or More [Member] \| Commercial [Member] \| Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	6,799,000	0
90 Days or More [Member] \| Commercial [Member] \| Wholesale/retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
90 Days or More [Member] \| Commercial [Member] \| Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	387,000	0
90 Days or More [Member] \| Commercial [Member] \| Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	68,000	554,000
90 Days or More [Member] \| Commercial [Member] \| Public finance [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
90 Days or More [Member] \| Commercial [Member] \| Other commercial and industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	8,000
90 Days or More [Member] \| Commercial Real Estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	411,000	714,000
90 Days or More [Member] \| Commercial Real Estate [Member] \| Residential construction and land development [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	57,000	0
90 Days or More [Member] \| Commercial Real Estate [Member] \| Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
90 Days or More [Member] \| Commercial Real Estate [Member] \| Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
90 Days or More [Member] \| Commercial Real Estate [Member] \| Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
90 Days or More [Member] \| Commercial Real Estate [Member] \| Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
90 Days or More [Member] \| Commercial Real Estate [Member] \| Other commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	354,000	714,000
90 Days or More [Member] \| Residential Mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	102,406,000	105,620,000
90 Days or More [Member] \| Residential Mortgage [Member] \| Permanent mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0
90 Days or More [Member] \| Residential Mortgage [Member] \| Permanent mortgages guaranteed by U.S. government agencies [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	102,406,000	105,561,000
90 Days or More [Member] \| Residential Mortgage [Member] \| Home equity [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	59,000
90 Days or More [Member] \| Personal [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	$ 15,000	$ 3,000

Premises and Equipment and Le_3

Premises and Equipment and Leases Premises and Equipment and Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Premises and Equipment [Line Items]
Premises and equipment	$ 779,050	$ 645,017
Less accumulated depreciation	243,531	314,984
Premises and equipment, net of accumulated depreciation	535,519	330,033
Depreciation Expense	51,600	51,200	$ 47,700
Operating Lease, Right-of-Use Asset	$ 180,000
Lease, Cost [Abstract]
Operating Lease, Weighted Average Remaining Lease Term	11 years 1 month 6 days
Operating Lease, Weighted Average Discount Rate, Percent	3.20%
Operating Lease, costs recognized as occupancy and equipment expense	$ 24,200
Operating Lease, operating cash flows	23,300
Lease, Cost	43,000	28,500	$ 27,500
Short-term Lease, Cost	12,600
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Operating Leases, Payments Due, Next Twelve Months	27,500
Operating Leases, Payments, Due in Two Years	25,700
Operating Leases, Payments, Due in Three Years	20,100
Operating Leases, Payments, Due in Four Years	18,900
Operating Lease, Payments, Due Year Five	18,200
Operating Leases, Payments, Due after Five Years	127,000
Land
Premises and Equipment [Line Items]
Premises and equipment	69,960	70,575
Buildings and improvements
Premises and Equipment [Line Items]
Premises and equipment	421,952	266,733
Software and related integration
Premises and Equipment [Line Items]
Premises and equipment	98,487	150,207
Furniture and equipment
Premises and Equipment [Line Items]
Premises and equipment	135,153	129,988
Construction in progress
Premises and Equipment [Line Items]
Premises and equipment	$ 53,498	$ 27,514

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets Acquisitions (Details) - USD ($) shares in Millions, $ in Millions	Oct. 01, 2018	May 01, 2018	Dec. 31, 2019
CoBiz Financial Inc. [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition	Oct. 1, 2018
Name of Acquired Entity			CoBiz Financial, Inc. ("CoBiz")
Consideration Transferred			$ 944
Cash payments to acquire businesses			$ 243
Stock Issued During Period, Shares, Acquisitions			7.2
Equity interests issued			$ 701
Goodwill Recognized, Description			synergies expected to be gained through consolidation of administrative functions resulting in cost savings.
Switchgrass Holdings LLC [Member]
Business Acquisition [Line Items]
Effective Date of Acquisition		May 1, 2018
Name of Acquired Entity			Switchgrass Holdings, LLC
Cash payments to acquire businesses			$ 14
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest [Abstract]
Intangible assets			$ 6.7

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net		$ 125,271	$ 134,849
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2020		20,297
2021		18,599
2022		16,320
2023		14,443
2024		12,663
Thereafter		42,949
Goodwill [Roll Forward]
Goodwill, Beginning Balance		1,049,263	447,430
Goodwill recognized during period	[1]		601,833
Adjustment	[1]	(1,172)
Goodwill, Ending Balance		1,048,091	1,049,263
Commercial [Member]
Goodwill [Roll Forward]
Goodwill, Beginning Balance		313,270	313,270
Goodwill recognized during period	[1]		0
Adjustment	[1]	600,661
Goodwill, Ending Balance		913,931	313,270
Consumer [Member]
Goodwill [Roll Forward]
Goodwill, Beginning Balance		43,458	43,458
Goodwill recognized during period	[1]		0
Adjustment	[1]	0
Goodwill, Ending Balance		43,458	43,458
Wealth Management [Member]
Goodwill [Roll Forward]
Goodwill, Beginning Balance		90,702	90,702
Goodwill recognized during period	[1]		0
Adjustment	[1]	0
Goodwill, Ending Balance		90,702	90,702
Funds Management and Other [Member]
Goodwill [Roll Forward]
Goodwill, Beginning Balance		601,833	0
Goodwill recognized during period	[1]		601,833
Adjustment	[1]	(601,833)
Goodwill, Ending Balance		0	601,833
Core deposits premiums [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross		103,200	103,200
Accumulated amortization		19,364	5,032
Finite-lived intangible assets, net		83,836	98,168
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2020		12,892
2021		11,893
2022		10,981
2023		10,145
2024		9,379
Thereafter		28,546
Other identifiable intangible assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross		74,372	63,497
Accumulated amortization		32,937	26,816
Finite-lived intangible assets, net		41,435	$ 36,681
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2020		7,405
2021		6,706
2022		5,339
2023		4,298
2024		3,284
Thereafter		$ 14,403

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

Mortgage Banking Activities, Co

Mortgage Banking Activities, Components of Loans Held For Sale (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Residential Mortgage Loans Held For Sale [Line Items]
Number of days for past due for a residential mortgage loan to be considered nonperforming (in days)	90 days	90 days
Residential mortgage loans held for sale, nonperforming	$ 0	$ 0
Credit losses recognized on residential mortgage loans held for sale	0	0	$ 0
Components of Residential Mortgage Loans Held for Sale [Abstract]
Unpaid principal balance	175,117	145,057
Residential mortgage loans held for sale, Fair value	177,703	146,971
Residential mortgage loans held for sale	$ 182,271	$ 149,221
Not Designated as Hedging Instrument [Member] \| Residential mortgage loan commitments [Member]
Schedule of Residential Mortgage Loans Held For Sale [Line Items]
General number of days outstanding for residential mortgage commitments, minimum (in days)	60 days	60 days
General number of days outstanding for residential mortgage commitments, maximum (in days)	90 days	90 days
Components of Residential Mortgage Loans Held for Sale [Abstract]
Derivative, Notional Amount	$ 158,460	$ 160,848
Derivative, Net fair value	$ 5,233	$ 5,378
Not Designated as Hedging Instrument [Member] \| Forward sales contracts [Member]
Schedule of Residential Mortgage Loans Held For Sale [Line Items]
General number of days for delivery of loans, for which the price is set by forward sales contracts, minimum (in days)	60 days	60 days
General number of days for delivery of loans, for which the price is set by forward sales contracts, maximum (in days)	90 days	90 days
Components of Residential Mortgage Loans Held for Sale [Abstract]
Derivative, Notional Amount	$ 315,203	$ 274,000
Derivative, Net fair value	$ (665)	$ (3,128)

Mortgage Banking Activities, Mo

Mortgage Banking Activities, Mortgage Banking Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Mortgage Banking Revenue [Abstract]
Net realized gains on sales of mortgage loans	$ 39,730	$ 36,379	$ 45,128
Net change in unrealized gain on mortgage loans held for sale	672	(674)	2,031
Net change in fair value of mortgage loan commitments	(145)	(1,145)	(3,210)
Net change in the fair value of forward sales contracts	2,463	(2,870)	(5,451)
Total mortgage production revenue	42,720	31,690	38,498
Servicing revenue	64,821	66,097	66,221
Total mortgage banking revenue	$ 107,541	$ 97,787	$ 104,719

Mortgage Banking Activities, _2

Mortgage Banking Activities, Mortgage Servicing Rights (Details)	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Summary of Mortgage Servicing Rights [Abstract]
Number of residential mortgage loans serviced for others	126,828	132,463	136,528
Outstanding principal balance of residential mortgage loans serviced for others	$ 20,727,106,000	$ 21,658,335,000	$ 22,046,632,000
Weighted average interest rate (in hundredths)	3.98%	3.99%	3.94%
Remaining contractual term (in months)	289 months	293 months	297 months
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance	$ 259,254,000	$ 252,867,000	$ 247,073,000
Additions, net	35,128,000	35,247,000	39,149,000
Change in fair value due to loan runoff	(38,979,000)	(33,528,000)	(33,527,000)
Change in fair value due to market changes	(53,517,000)	4,668,000	172,000
Ending balance	$ 201,886,000	$ 259,254,000	$ 252,867,000
Servicing Assets at Fair Value, Assumptions Used to Estimate Fair Value [Abstract]
Discount rate - risk-free rate plus a market premium (in hundredths)	9.81%	9.90%
Prepayment rate - based upon loan interest rate, original term and loan type, minimum	8.28%	8.05%
Prepayment rate - based upon loan interest rate, original term and loan type, maximum	16.05%	15.74%
Loan servicing costs - annually per loan based upon loan type, performing, minimum (in dollars per loan)	$ 68	$ 67
Loan servicing costs - annually per loan based upon loan type, performing, maximum (in dollars per loan)	94	93
Loan servicing costs - annually per loan based upon loan type, delinquent, minimum (in dollars per loan)	150	150
Loan servicing costs - annually per loan based upon loan type, delinquent, maximum (in dollars per loan)	500	500
Loan servicing costs - annually per loan based upon loan type, foreclosure, minimum (in dollars per loan)	1,000	1,000
Loan servicing costs - annually per loan based upon loan type, foreclosure, maximum (in dollars per loan)	$ 4,000	$ 4,000
Primary secondary mortgage rate spread (in basis points)	104	105
Escrow earnings rate - indexed to rates paid on deposit accounts with comparable average life	1.73%	2.57%
Delinquency rate	2.73%	2.74%

Deposits (Details)

Deposits (Details) - USD ($) $ in Thousands	12 Months Ended
Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest expense on deposits [Abstract]
Transaction deposits	$ 132,854	$ 65,859	$ 28,627
Savings	677	439	359
Time Deposit, Interest Expense [Abstract]
Certificates of deposits under $100,000	8,299	5,751	7,702
Certificates of deposits $100,000 and over	29,288	19,739	12,393
Other time deposits	4,420	3,729	4,722
Total time	42,007	29,219	24,817
Total	175,538	95,517	$ 53,803
Time Deposit Information [Abstract]
Time deposits in denomination of $250,000 or more	845,000	756,000
Time Deposit Maturities [Abstract]
2020	1,500,000
2021	230,000
2022	104,000
2023	103,000
2024	55,000
Thereafter	228,000
Other Deposits Information [Abstract]
Overdrawn customer transaction deposits reclassified as loan balances	$ 8,700	$ 27,000

Other Borrowed Funds (Details)

Other Borrowed Funds (Details) - USD ($) $ in Thousands		12 Months Ended
Other Borrowed Funds (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Borrowed Funds [Line Items]
Balance		$ 8,621,328	$ 7,418,714	$ 5,854,537
Average Balance		$ 10,261,592	$ 7,298,229	$ 6,559,101
Rate		2.37%	2.03%	1.18%
Other borrowed funds, Maturities [Abstract]
2020		$ 8,335,742
2021		1,244
2022		575
2023		1,454
2024		3,599
Thereafter		278,714
Funds purchased [Member]
Other Borrowed Funds [Line Items]
Balance		$ 3,390,528	$ 402,450	$ 58,628
Rate		1.53%	2.34%	1.00%
Average Balance		$ 2,438,376	$ 419,322	$ 58,064
Rate		2.08%	1.89%	0.73%
Maximum Outstanding At Any Month End		$ 3,390,528	$ 949,531	$ 80,967
Repurchase agreements [Member]
Other Borrowed Funds [Line Items]
Balance		$ 427,822	$ 615,961	$ 516,335
Rate		0.50%	0.36%	0.17%
Average Balance		$ 399,785	$ 464,582	$ 433,791
Rate		0.57%	0.28%	0.10%
Maximum Outstanding At Any Month End		$ 427,822	$ 615,961	$ 536,094
Other Borrowings [Member]
Other Borrowed Funds [Line Items]
Balance		4,527,055	6,124,390	5,134,897
Average Balance		$ 7,147,356	$ 6,236,441	$ 5,919,292
Rate		2.45%	2.07%	1.15%
Federal Home Loan Bank advances [Member]
Other Borrowed Funds [Line Items]
Balance		$ 4,500,000	$ 6,100,000	$ 5,100,000
Rate		1.79%	2.65%	1.47%
Average Balance		$ 7,122,466	$ 6,207,142	$ 5,882,466
Rate		2.44%	2.06%	1.13%
Maximum Outstanding At Any Month End		$ 8,000,000	$ 6,500,000	$ 6,200,000
GNMA repurchase liability [Member]
Other Borrowed Funds [Line Items]
Balance		$ 15,417	$ 15,552	$ 19,947
Rate		4.32%	4.43%	4.22%
Average Balance		$ 13,746	$ 14,783	$ 20,509
Rate		4.47%	4.47%	4.59%
Maximum Outstanding At Any Month End		$ 19,581	$ 16,529	$ 24,139
Other [Member]
Other Borrowed Funds [Line Items]
Balance		$ 11,638	$ 8,838	$ 14,950
Rate		5.09%	2.90%	2.61%
Average Balance		$ 11,144	$ 14,516	$ 16,317
Rate		5.30%	2.67%	3.35%
Maximum Outstanding At Any Month End		$ 34,676	$ 20,422	$ 18,610
Subordinated debentures [Member]
Other Borrowed Funds [Line Items]
Balance	[1]	$ 275,923	$ 275,913	$ 144,677
Rate	[1]	5.15%	5.34%	5.60%
Average Balance	[1]	$ 276,075	$ 177,884	$ 147,954
Rate	[1]	5.47%	5.52%	5.57%
Maximum Outstanding At Any Month End	[1]	$ 275,923	$ 275,913	$ 151,875
Subordinated debentures [Member] \| Subordinated debentures, 2016 issuance [Member]
Other borrowed funds, Other Disclosures [Abstract]
Amount of debt issuance		$ 150,000
Maturity date		Jun. 30, 2056
Stated interest rate		5.375%
Debt Instrument, Call Date, Earliest		Jun. 30, 2021
Subordinated debentures [Member] \| Subordinated debentures-acquired, 2015 Issuance [Member]
Other borrowed funds, Other Disclosures [Abstract]
Amount of debt issuance		$ 60,000
Maturity date		Jun. 25, 2030
Interest rate description		three-month LIBOR plus 3.17%
Stated interest rate		5.625%
Debt Instrument, Call Date, Earliest		Jun. 25, 2025
Subordinated debentures [Member] \| Junior subordinated debentures-acquired, 2003 issuance [Member]
Other borrowed funds, Other Disclosures [Abstract]
Amount of debt issuance		$ 21,000
Maturity date		Sep. 17, 2033
Interest rate description		three-month LIBOR plus 2.95%
Subordinated debentures [Member] \| Junior subordinated debentures-acquired, 2004 issuance [Member]
Other borrowed funds, Other Disclosures [Abstract]
Amount of debt issuance		$ 31,000
Maturity date		Jul. 23, 2034
Interest rate description		three-month LIBOR plus 2.60%
Subordinated debentures [Member] \| Junior subordinated debentures-acquired, 2005 issuance [Member]
Other borrowed funds, Other Disclosures [Abstract]
Amount of debt issuance		$ 20,000
Maturity date		Sep. 30, 2035
Interest rate description		three-month LIBOR plus 1.45%
U.S. government agency mortgage-backed securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amortized Cost		$ 431,939	636,864
Fair Value		435,898	628,229
Repurchase Liability		$ 427,822	$ 615,961
Average Rate (in hundredths)		0.50%	0.36%
U.S. government agency mortgage-backed securities [Member] \| Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amortized Cost		$ 431,939	$ 636,864
Fair Value		435,898	628,229
Repurchase Liability		$ 427,822	$ 615,961
Average Rate (in hundredths)		0.50%	0.36%
U.S. government agency mortgage-backed securities [Member] \| Long-term [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amortized Cost		$ 0	$ 0
Fair Value		0	0
Repurchase Liability		$ 0	$ 0
Average Rate (in hundredths)		0.00%	0.00%
Subsidiaries [Member] \| Funds purchased [Member]
Other borrowed funds, Other Disclosures [Abstract]
Number of days to maturity, minimum		1 day
Number of days to maturity, maximum		90 days
Subsidiaries [Member] \| Repurchase agreements [Member]
Other borrowed funds, Other Disclosures [Abstract]
Number of days to maturity, maximum		90 days
Subsidiaries [Member] \| Federal Home Loan Bank advances [Member]
Other borrowed funds, Other Disclosures [Abstract]
Federal Home Loan Banks, Letters of credit issued to secure public funds		$ 661,000
Unused credit available pursuant to the FHLB's collateral policies		4,900,000
Subsidiaries [Member] \| BOK Financial Securities, Inc. [Member] \| Other [Member]
Other Borrowed Funds [Line Items]
Balance		$ 0	$ 0

[1]	Parent Company only.

Federal and State Income Taxe_2

Federal and State Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets [Abstract]
Credit loss reserves	$ 50,611	$ 49,804
Lease liability	46,084	0
Deferred compensation	25,976	25,608
Purchased loan discount	18,042	27,283
Unearned fees	9,080	9,814
Share-based compensation	7,392	4,434
Valuation adjustments	1,545	9,619
Available for sale securities mark to market	0	24,441
Other	26,384	31,489
Total deferred tax assets	185,114	182,492
Valuation Allowance [Abstract]
Valuation allowance	0	0
Deferred tax liabilities [Abstract]
Mortgage servicing rights	48,435	61,844
Right-of-use asset	42,180	0
Available for sale securities mark to market	33,140	0
Acquired identifiable intangible	23,181	28,620
Depreciation	18,909	15,966
Lease financing	10,720	10,040
Other	34,826	30,566
Total deferred tax liabilities	211,391	147,036
Net deferred tax assets, net	26,277	35,456
Current income tax expense [Abstract]
Federal	110,887	103,748	$ 141,607
State	15,088	15,253	14,592
Total current income tax expense	125,975	119,001	156,199
Deferred income tax expense [Abstract]
Federal	3,416	(190)	25,525
State	792	250	869
Total deferred income tax expense	4,208	60	26,394
Total income tax expense	130,183	119,061	182,593
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal statutory tax	132,482	118,752	181,397
Tax exempt revenue	(12,227)	(8,311)	(12,402)
Effect of state income taxes, net of federal benefit	12,715	12,430	10,701
Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments	(5,127)	(4,559)	(6,811)
Other, net	2,340	749	9,708
Total income tax expense	$ 130,183	$ 119,061	$ 182,593
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory tax (in thousandths)	21.00%	21.00%	35.00%
Tax exempt revenue (in thousandths)	(1.90%)	(1.50%)	(2.40%)
Effect of state income taxes, net of federal benefit (in thousandths)	2.00%	2.20%	2.00%
Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments (in thousandths)	(0.80%)	(0.80%)	(1.30%)
Other, net (in thousandths)	0.30%	0.20%	1.90%
Total (in thousandths)	20.60%	21.10%	35.20%
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of January 1	$ 18,869	$ 18,110	$ 15,841
Additions for tax for current year positions	5,649	2,649	4,645
Settlements during the period	0	0	0
Lapses of applicable statute of limitations	(4,053)	(1,890)	(2,376)
Balance as of December 31	20,465	18,869	18,110
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	14,700
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	2,200	1,700	$ 1,200
Unrecognized Tax Benefits, Penalties and Interest Accrued	$ 5,600	$ 5,000
Unrecognized Tax Benefits, Number of Reporting Periods Open for Examination, Federal	3
Unrecognized Tax Benefits, Number of Reporting Periods Open for Examination, State, Minimum	3
Unrecognized Tax Benefits, Number of Reporting Periods Open for Examination, State, Maximum	6

Employee Benefits (Details)

Employee Benefits (Details) - USD ($)	12 Months Ended
Employee Benefits (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
BOK Financial Pension Plan [Member]
BOK Financial Pension Plan [Abstract]
Interest percentage added to the five-year trailing average of five-year Treasury Securities	1.50%
Interest percentage accrued on employee account balances, Minimum	3.00%
Interest percentage accrued on employee account balances, Maximum	5.00%
Quarterly variable interest percentage accrued on employee account balances, minimum	3.32%
Quarterly variable interest percentage accrued on employee account balances, maximum	3.40%
Defined Benefit Plan, Benefit Obligation	$ 24,500,000	$ 24,500,000
Defined Benefit Plan, Plan Assets, Amount	36,400,000	33,600,000
Net periodic benefit cost (credit)	(815,000)	$ (583,000)	$ (704,000)
Total estimated future benefit payments	$ 27,800,000
BOK Financial Pension Plan Weighted-average Assumptions [Abstract]
Discount rate (in hundredths)	4.10%	3.30%
Expected return on plan assets (in hundredths)	5.50%	5.50%
BOK Financial Pension Plan [Member] \| Equity Securities [Member]
BOK Financial Pension Plan [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	60.00%
BOK Financial Pension Plan [Member] \| Bonds [Member]
BOK Financial Pension Plan [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	40.00%
BOK Financial 401(k) Plan [Member]
BOK Financial 401(k) Plan [Abstract]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	6.00%
Defined Contribution Plan, Minimum Years of Service for Employees to Obtain Maximum Employer Matching	4 years
Defined Contribution Plan, Maximum Years of Service for Employees to Obtain Minimum Employer Matching	15 years
Contributions Non-Elective Annual Contributions For Qualified Employees	$ 750
Defined Contribution Plan, Annual Base Employee Compensation to Qualify for Non-Elective Employer Contributions, Maximum	$ 40,000
Defined Contribution Plan, Vesting Period for Employer Contributions	5 years
Defined Contribution Plan, Cost	$ 27,600,000	$ 25,100,000	$ 22,800,000
BOK Financial 401(k) Plan [Member] \| Minimum [Member]
BOK Financial 401(k) Plan [Abstract]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	50.00%
BOK Financial 401(k) Plan [Member] \| Maximum [Member]
BOK Financial 401(k) Plan [Abstract]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	200.00%

Share-Based Compensation Plan_2

Share-Based Compensation Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Options [Member]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Outstanding, Number of Options [Abstract]
Number of options outstanding, Ending balance (in shares)	36,100	63,058	117,551
Options vested (in shares)	27,193	33,573	51,286
Share-based Compensation Arrangements by Share-based Payment Award, Options, Weighted Average Exercise Price [Abstract]
Options outstanding, weighted average exercise price, ending balance (in dollars per share)	$ 56.75	$ 54.89	$ 53.26
Options vested, weighted average exercise price (in dollars per share)	$ 57.08	$ 53.09	$ 48.62
Share-based Compensation Arrangements by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options outstanding, aggregate intrinsic value	$ 1,106	$ 1,163	$ 4,592
Options vested, aggregate intrinsic value	824	679	2,241
Options exercised, aggregate intrinsic value	$ 761	$ 2,300	$ 3,500
Weighted average remaining contractual life of options outstanding (in years)	1 year 9 months 3 days
Weighted average remaining contractual life of options vested (in years)	1 year 4 months 6 days
Restricted Stock [Member]
Share-based Compensation Arrangements by Share-based Payment Award, Restricted Stock, Nonvested, Number of Shares [Roll Forward]
Non-vested shares awarded, beginning of period (in shares)	527,607	667,103	786,706
Non-vested shares that were granted during the period (in shares)	145,724	150,419	177,807
Non-vested shares that vested during period (in shares)	(114,201)	(242,215)	(194,419)
Non-vested shares that forfeited during period (in shares)	(131,952)	(47,700)	(102,991)
Non-vested shares awarded, end of period (in shares)	427,178	527,607	667,103
Share-based Compensation Arrangements by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted Average Grant Date Fair Value, Granted	$ 76.74	$ 85.58	$ 86.95
Weighted Average Grant Date Fair Value, Vested	61.28	74.85	63.07
Weighted average grant date fair value non-vested share awards forfeited (in dollars per share)	$ 83.69	$ 75.68	$ 78.70
Share-based Compensation Costs, Including Costs That May Be Recognized As Future Expense [Abstract]
Share-based Compensation Expense Recognized	$ 15,100	$ 3,600	$ 23,200
Unrecognized compensation cost of unvested awards, for future periods	14,900
Unrecognized compensation cost of unvested awards, Amount to be expensed in 2020	9,400
Unrecognized compensation cost of unvested awards, Amount to be expensed in 2021	5,300
Unrecognized compensation cost of unvested awards, Amount to be expensed in 2022	$ 144
Number of shares with required performance obligations	222,164
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangements by Share-based Payment Award, Restricted Stock, Nonvested, Number of Shares [Roll Forward]
Non-vested shares awarded, beginning of period (in shares)	0	0	0
Non-vested shares that were granted during the period (in shares)	46,689	0	0
Non-vested shares that vested during period (in shares)	0	0	0
Non-vested shares that forfeited during period (in shares)	0	0	0
Non-vested shares awarded, end of period (in shares)	46,689	0	0
Share-based Compensation Arrangements by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted Average Grant Date Fair Value, Granted	$ 87.40	$ 0	$ 0
Weighted Average Grant Date Fair Value, Vested	0	0	0
Weighted average grant date fair value non-vested share awards forfeited (in dollars per share)	$ 0	$ 0	$ 0

Related Parties Related Parti_2

Related Parties Related Parties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Directors and Senior Management [Member]
Loans and Leases Receivable, Related Parties [Roll Forward]
Beginning balance	$ 75,265	$ 110,246
Advances	886,610	1,479,735
Payments	(896,643)	(1,514,841)
Adjustments	9,957	125
Ending balance	75,189	75,265
Director [Member]
Loan Commitments and Equity Investments [Abstract]
Related Party Transaction, Expenses from Transactions with Related Party	$ 10,000
Executive Officer [Member]
Loan Commitments and Equity Investments [Abstract]
Percentage of investment funds' assets held by clients	84.00%
Assets Held in Cavanal Hill Funds	$ 3,700,000
Subsidiaries [Member] \| BOKF, NA [Member] \| Affiliated Entity [Member]
Loan Commitments and Equity Investments [Abstract]
Maximum percentage of unimpaired capital on loan commitments and equity investments to a single affiliate (in hundredths)	10.00%
Maximum percentage of unimpaired capital on loan commitments and equity investments to all affiliates (in hundredths)	20.00%
Maximum loan commitments and equity investments to a single affiliate	$ 370,000
Maximum loan commitments and equity investments to all affiliates	739,000
Largest loan commitment and equity investment to a single affiliate	257,000
Aggregate loan commitment and equity investment to all affiliates	392,000	313,000
Outstanding amounts to all affiliates	5,000	$ 883
Largest amount outstanding to a single affiliate	$ 4,300

Commitments and Contingent Li_2

Commitments and Contingent Liabilities (Details)	12 Months Ended
Commitments and Contingent Liabilities (Details)	Dec. 31, 2019USD ($)shares	Dec. 31, 2018USD ($)
Other Commitments [Abstract]
The Net Asset Value of Units in Mutual Funds (per unit)	1
Minimum Average Cash Balance Required to be Maintained at Federal Reserve by Subsidiary Bank	$ 618,000,000	$ 1,200,000,000
Misuse of Revenues Pledged to Municipal Bonds [Member] \| Judicial Ruling [Member]
Litigation Settlement [Abstract]
Disgorged fees	1,067,721
Litigation Settlement, Expense	$ 600,000
Misuse of Revenues Pledged to Municipal Bonds [Member] \| Pending Litigation [Member]
Litigation Settlement [Abstract]
Loss Contingency, Number of Plaintiffs	2
Alleged total of judgment against nursing home operator	$ 8,000,000
Bank Participation in Fraudulent Sale of Securities by Principals [Member] \| Pending Litigation [Member]
Litigation Settlement [Abstract]
Loss Contingency, Number of Plaintiffs	19
Principal amount of entered judgment against the principal individual and his wife	$ 36,805,051
Pre-judgment interest amount of entered judgment against the principal individual and his wife	10,937,831
Outstanding principal accrued interest and other amounts upon sale of facilities securing payment of the bonds	$ 20,000,000
Purchase of facilities from principals subject to SEC New Jersey proceedings [Member] \| Pending Litigation [Member]
Litigation Settlement [Abstract]
Number of individuals who purchased facilities from the principals subject to SEC New Jersey proceedings	2
Outstanding principal, accrued interest and other amounts required by bond documents	$ 60,000,000
Number of principals in SEC New Jersey proceedings	2
Visa Membership [Member]
Loss Contingencies [Line Items]
Number of Visa Class B Shares Owned by Entity (in shares) \| shares	252,233
Number of Visa Class A Shares Visa Class B Shares Are Convertible To (in shares) \| shares	409,324

Commitments and Contingent Li_3

Commitments and Contingent Liabilities Variable Interest Entities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Other Assets [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	$ 259	$ 237
Other Liabilities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	$ 82	$ 74

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator: [Abstract]:
Net income attributable to BOK Financial Corp. shareholders	$ 500,758	$ 445,646	$ 334,644
Less: Earnings allocated to participating securities	3,227	3,737	3,561
Numerator for basic earnings per share - income available to common shareholders	497,531	441,909	331,083
Effect of reallocating undistributed earnings of participating securities	0	1	2
Numerator for diluted earnings per share - income available to common shareholders	$ 497,531	$ 441,910	$ 331,085
Denominator: [Abstract]
Weighted average shares outstanding	71,250,081	67,190,257	65,440,832
Less: Participating securities included in weighted average shares outstanding (in shares)	462,381	561,617	695,468
Denominator for basic earnings per common share (in shares)	70,787,700	66,628,640	64,745,364
Dilutive effect of employee stock compensation plans (in shares)	14,912	33,633	60,920
Denominator for diluted earnings per common share (in shares)	70,802,612	66,662,273	64,806,284
Basic (in dollars per share)	$ 7.03	$ 6.63	$ 5.11
Diluted earnings per share (per share)	$ 7.03	$ 6.63	$ 5.11

Shareholders' Equity (Details)

Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common Stock [Abstract]
Common stock, shares authorized (in shares)	2,500,000,000	2,500,000,000
Common stock, par value (in dollars per share)	$ 0.00006	$ 0.00006
Perpetual preferred stock [Member]
Preferred Stock [Abstract]
Preferred stock, authorized (in shares)	1,000,000,000
Preferred stock at par value (in dollars per share)	$ 0.00005
Preferred stock conversion rate	one share of Common Stock for each 36 shares of Series A Preferred Stock at the option of the holder
Preferred stock, Rate of annual cumulative dividends (in hundredths)	10.00%
Preferred stock, Liquidation preference per share	$ 0.06
Preferred stock, Aggregate liquidation preference	$ 15
Preferred Stock, Shares Outstanding	0	0	0
Common Stock [Member]
Common Stock [Abstract]
Common stock, shares authorized (in shares)	2,500,000,000
Common stock, par value (in dollars per share)	$ 0.00006
Common stock, number of vote per share	$ 1

Shareholders' Equity Regulatory

Shareholders' Equity Regulatory Capital (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Common Equity Tier 1 Capital [Abstract]
Minimum Capital Requirements, Common Equity Tier 1 to Risk Weighted Assets		4.50%	4.50%
Capital Conservation Buffer, Common Equity Tier 1 to Risk Weighted Assets	[1]	2.50%	2.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Common Equity Tier 1 to Risk Weighted Assets		7.00%	7.00%
Common Equity Tier 1 Capital		$ 3,608,821	$ 3,356,524
Common Equity Tier 1 Capital to Risk Weighted Assets		11.39%	10.92%
Tier I Capital (to Risk Weighted Assets) [Abstract]
Minimum Capital Requirement, Tier 1 Capital to Risk Weighted Assets		6.00%	6.00%
Capital Conservation Buffer, Tier 1 Capital to Risk Weighted Assets	[1]	2.50%	2.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Tier One to Risk Weighted Assets		8.50%	8.50%
Tier 1 Capital		$ 3,608,821	$ 3,356,524
Tier 1 Capital to Risk Weighted Assets		11.39%	10.92%
Total Capital (to Risk Weighted Assets) [Abstract]
Minimum Capital Requirement, Total Capital to Risk Weighted Assets		8.00%	8.00%
Capital Conservation Buffer, Total Capital to Risk Weighted Assets	[1]	2.50%	2.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Total Capital to Risk Weighted Assets		10.50%	10.50%
Total Capital		$ 4,097,087	$ 3,841,684
Total Capital to Risk Weighted Assets		12.94%	12.50%
Tier 1 Capital (to Average Assets) [Abstract]
Minimum Capital Requirement, Tier 1 Capital to Average Assets		4.00%	4.00%
Minimum Capital Requirements Including Capital Conservation Buffer, Tier 1 Capital to Average Assets		4.00%	4.00%
Tier 1 Leverage Capital		$ 3,608,820	$ 3,356,524
Tier 1 Capital to Average Assets		8.40%	8.96%
Phased in Capital Conservation Buffer		2.50%	1.875%
Fully Phased In Capital Conservation Buffer		2.50%
Subsidiaries [Member] \| BOKF, NA [Member]
Common Equity Tier 1 Capital [Abstract]
Common Equity Tier 1 Capital Ratio Required to be Well Capitalized		6.50%	6.50%
Minimum Capital Requirements, Common Equity Tier 1 to Risk Weighted Assets		4.50%	4.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Common Equity Tier 1 to Risk Weighted Assets		4.50%	4.50%
Common Equity Tier 1 Capital		$ 3,414,446	$ 2,894,119
Common Equity Tier 1 Capital to Risk Weighted Assets		10.90%	10.50%
Tier I Capital (to Risk Weighted Assets) [Abstract]
Tier I Capital Ratio Required to be Well Capitalized		8.00%	8.00%
Minimum Capital Requirement, Tier 1 Capital to Risk Weighted Assets		6.00%	6.00%
Minimum Capital Requirement Including Capital Conservation Buffer, Tier One to Risk Weighted Assets		6.00%	6.00%
Tier 1 Capital		$ 3,414,446	$ 2,894,119
Tier 1 Capital to Risk Weighted Assets		10.90%	10.50%
Total Capital (to Risk Weighted Assets) [Abstract]
Total Capital Ratio Required to be Well Capitalized		10.00%	10.00%
Minimum Capital Requirement, Total Capital to Risk Weighted Assets		8.00%	8.00%
Minimum Capital Requirement Including Capital Conservation Buffer, Total Capital to Risk Weighted Assets		8.00%	8.00%
Total Capital		$ 3,692,010	$ 3,103,366
Total Capital to Risk Weighted Assets		11.79%	11.26%
Tier 1 Capital (to Average Assets) [Abstract]
Leverage Ratio Required to be Well Capitalized		5.00%	5.00%
Minimum Capital Requirement, Tier 1 Capital to Average Assets		4.00%	4.00%
Minimum Capital Requirements Including Capital Conservation Buffer, Tier 1 Capital to Average Assets		4.00%	4.00%
Tier 1 Leverage Capital		$ 3,414,446	$ 2,894,119
Tier 1 Capital to Average Assets		7.98%	8.56%
Subsidiaries [Member] \| CoBiz Bank [Member]
Common Equity Tier 1 Capital [Abstract]
Common Equity Tier 1 Capital Ratio Required to be Well Capitalized	[2]	6.50%	6.50%
Minimum Capital Requirements, Common Equity Tier 1 to Risk Weighted Assets	[2]	4.50%	4.50%
Minimum Capital Requirement Including Capital Conservation Buffer, Common Equity Tier 1 to Risk Weighted Assets	[2]	4.50%	4.50%
Common Equity Tier 1 Capital	[2]	$ 0	$ 317,944
Common Equity Tier 1 Capital to Risk Weighted Assets	[2]	0.00%	10.65%
Tier I Capital (to Risk Weighted Assets) [Abstract]
Tier I Capital Ratio Required to be Well Capitalized	[2]	8.00%	8.00%
Minimum Capital Requirement, Tier 1 Capital to Risk Weighted Assets	[2]	6.00%	6.00%
Minimum Capital Requirement Including Capital Conservation Buffer, Tier One to Risk Weighted Assets	[2]	6.00%	6.00%
Tier 1 Capital	[2]	$ 0	$ 317,944
Tier 1 Capital to Risk Weighted Assets	[2]	0.00%	10.65%
Total Capital (to Risk Weighted Assets) [Abstract]
Total Capital Ratio Required to be Well Capitalized	[2]	10.00%	10.00%
Minimum Capital Requirement, Total Capital to Risk Weighted Assets	[2]	8.00%	8.00%
Minimum Capital Requirement Including Capital Conservation Buffer, Total Capital to Risk Weighted Assets	[2]	8.00%	8.00%
Total Capital	[2]	$ 0	$ 382,944
Total Capital to Risk Weighted Assets	[2]	0.00%	12.83%
Tier 1 Capital (to Average Assets) [Abstract]
Leverage Ratio Required to be Well Capitalized	[2]	5.00%	5.00%
Minimum Capital Requirement, Tier 1 Capital to Average Assets	[2]	4.00%	4.00%
Minimum Capital Requirements Including Capital Conservation Buffer, Tier 1 Capital to Average Assets	[2]	4.00%	4.00%
Tier 1 Leverage Capital	[2]	$ 0	$ 317,944
Tier 1 Capital to Average Assets	[2]	0.00%	8.25%

[1]	Capital conservation buffer was effective January 1, 2016 and phased in through 2019. The phased in capital conservation buffer was 2.50% at December 31, 2019 and 1.875% at December 31, 2018 . The fully phased in requirement of 2.50%
[2]	CoBiz Bank was acquired by BOK Financial effective October 1, 2018 and merged into BOKF, NA during the first quarter of 2019.

Shareholders' Equity Accumulate

Shareholders' Equity Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ (72,585)		$ (36,174)		$ (10,967)
Reclassification of stranded accumulated other comprehensive loss to retained earnings related to tax reform					(6,550)
Transition adjustment of new accounting principle			2,862		(2,709)
Net change in unrealized gain (loss)	241,047		(48,010)		(26,152)
Reclassification adjustments included in earnings: [Abstract]
Loss (gain) on available for sale securities, net	(5,597)		2,801		(4,428)
Other comprehensive income (loss), before income taxes	235,450		(45,209)		(30,580)
Federal and state income taxes	57,942	[1]	(11,507)	[1]	(11,923)	[2]
Other comprehensive income (loss), net of income taxes	177,508		(33,702)		(18,657)
Ending balance	104,923		(72,585)		(36,174)
Unrealized Gain (Loss) on Available for Sale Securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(70,999)		(35,385)		(9,087)
Reclassification of stranded accumulated other comprehensive loss to retained earnings related to tax reform					(6,408)
Transition adjustment of new accounting principle					(2,709)
Net change in unrealized gain (loss)	239,017		(46,941)		(28,170)
Reclassification adjustments included in earnings: [Abstract]
Loss (gain) on available for sale securities, net	(5,597)		2,801		(4,428)
Other comprehensive income (loss), before income taxes	233,420		(44,140)		(32,598)
Federal and state income taxes	57,425	[1]	(11,235)	[1]	(12,708)	[2]
Other comprehensive income (loss), net of income taxes	175,995		(32,905)		(19,890)
Ending balance	104,996		(70,999)		(35,385)
Unrealized Gain (Loss) on Employee Benefit Plans [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(1,586)		(789)		(1,880)
Reclassification of stranded accumulated other comprehensive loss to retained earnings related to tax reform					(142)
Transition adjustment of new accounting principle					0
Net change in unrealized gain (loss)	2,030		(1,069)		2,018
Reclassification adjustments included in earnings: [Abstract]
Loss (gain) on available for sale securities, net	0		0		0
Other comprehensive income (loss), before income taxes	2,030		(1,069)		2,018
Federal and state income taxes	517	[1]	(272)	[1]	785	[2]
Other comprehensive income (loss), net of income taxes	1,513		(797)		1,233
Ending balance	$ (73)		$ (1,586)		$ (789)

[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.

Reportable Segments (Details)

Reportable Segments (Details) - USD ($) $ in Thousands	12 Months Ended
Reportable Segments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	$ 1,112,879	$ 984,867	$ 841,701
Net interest revenue (expense) from internal sources	0	0	0
Net interest and dividend revenue	1,112,879	984,867	841,701
Provision for credit losses	44,000	8,000	(7,000)
Net interest and dividend revenue after provision for credit losses	1,068,879	976,867	848,701
Other operating revenue	694,370	616,784	695,094
Other operating expense	1,132,381	1,028,166	1,025,517
Net direct contribution	630,868	565,485	518,278
Gain (loss) on financial instruments, net	0	0	0
Change in fair value of mortgage servicing rights	0	0	0
Gain (loss) on repossessed assets, net	0	0	0
Corporate expense allocations	0	0	0
Net income before taxes	630,868	565,485	518,278
Federal and state income taxes	130,183	119,061	182,593
Net income	500,685	446,424	335,685
Net income (loss) attributable to Non-controlling interests	(73)	778	1,041
Net income attributable to BOK Financial Corp. shareholders	500,758	445,646	334,644
Average assets	42,094,347	34,937,530	32,947,494
Operating Segments [Member] \| Commercial [Member]
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	919,148	726,855	618,325
Net interest revenue (expense) from internal sources	(242,907)	(159,954)	(92,055)
Net interest and dividend revenue	676,241	566,901	526,270
Provision for credit losses	39,011	30,358	13,877
Net interest and dividend revenue after provision for credit losses	637,230	536,543	512,393
Other operating revenue	170,412	162,701	208,404
Other operating expense	252,459	202,095	235,793
Net direct contribution	555,183	497,149	485,004
Gain (loss) on financial instruments, net	106	26	52
Change in fair value of mortgage servicing rights	0	0	0
Gain (loss) on repossessed assets, net	331	(6,532)	(2,681)
Corporate expense allocations	43,055	36,670	28,060
Net income before taxes	512,565	453,973	454,315
Federal and state income taxes	137,759	120,458	186,518
Net income	374,806	333,515	267,797
Net income (loss) attributable to Non-controlling interests	0	0	0
Net income attributable to BOK Financial Corp. shareholders	374,806	333,515	267,797
Average assets	22,807,589	18,432,035	17,766,027
Operating Segments [Member] \| Consumer [Member]
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	99,679	83,231	84,286
Net interest revenue (expense) from internal sources	95,775	73,448	53,916
Net interest and dividend revenue	195,454	156,679	138,202
Provision for credit losses	6,271	5,143	4,786
Net interest and dividend revenue after provision for credit losses	189,183	151,536	133,416
Other operating revenue	187,500	178,123	184,878
Other operating expense	230,916	231,075	241,805
Net direct contribution	145,767	98,584	76,489
Gain (loss) on financial instruments, net	30,375	(25,021)	(2,052)
Change in fair value of mortgage servicing rights	(53,517)	4,668	172
Gain (loss) on repossessed assets, net	496	247	223
Corporate expense allocations	47,169	44,398	49,344
Net income before taxes	75,952	34,080	25,488
Federal and state income taxes	19,346	8,681	9,915
Net income	56,606	25,399	15,573
Net income (loss) attributable to Non-controlling interests	0	0	0
Net income attributable to BOK Financial Corp. shareholders	56,606	25,399	15,573
Average assets	9,301,341	8,303,263	8,544,117
Operating Segments [Member] \| Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	61,277	81,528	45,024
Net interest revenue (expense) from internal sources	38,815	31,480	38,344
Net interest and dividend revenue	100,092	113,008	83,368
Provision for credit losses	(308)	(288)	(696)
Net interest and dividend revenue after provision for credit losses	100,400	113,296	84,064
Other operating revenue	341,389	296,369	301,434
Other operating expense	277,267	257,650	254,495
Net direct contribution	164,522	152,015	131,003
Gain (loss) on financial instruments, net	2	7	0
Change in fair value of mortgage servicing rights	0	0	0
Gain (loss) on repossessed assets, net	0	0	387
Corporate expense allocations	36,239	35,920	32,693
Net income before taxes	128,285	116,102	98,697
Federal and state income taxes	32,954	30,075	38,848
Net income	95,331	86,027	59,849
Net income (loss) attributable to Non-controlling interests	0	0	0
Net income attributable to BOK Financial Corp. shareholders	95,331	86,027	59,849
Average assets	10,204,426	8,447,784	7,072,622
Funds Management and Other [Member]
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	32,775	93,253	94,066
Net interest revenue (expense) from internal sources	108,317	55,026	(205)
Net interest and dividend revenue	141,092	148,279	93,861
Provision for credit losses	(974)	(27,213)	(24,967)
Net interest and dividend revenue after provision for credit losses	142,066	175,492	118,828
Other operating revenue	(4,931)	(20,409)	378
Other operating expense	371,739	337,346	293,424
Net direct contribution	(234,604)	(182,263)	(174,218)
Gain (loss) on financial instruments, net	(30,483)	24,988	2,000
Change in fair value of mortgage servicing rights	53,517	(4,668)	(172)
Gain (loss) on repossessed assets, net	(827)	6,285	2,071
Corporate expense allocations	(126,463)	(116,988)	(110,097)
Net income before taxes	(85,934)	(38,670)	(60,222)
Federal and state income taxes	(59,876)	(40,153)	(52,688)
Net income	(26,058)	1,483	(7,534)
Net income (loss) attributable to Non-controlling interests	(73)	778	1,041
Net income attributable to BOK Financial Corp. shareholders	(25,985)	705	(8,575)
Average assets	$ (219,009)	$ (245,552)	$ (435,272)

Fees and Commission Revenue F_2

Fees and Commission Revenue Fees and Commissions (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		$ 702,201	$ 643,176	$ 681,014
Fees and commissions revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		702,201	643,176
Fees and commissions revenue not from contracts with customers	[1]	263,146	209,384
Fees and commissions revenue from contracts with customers	[2]	439,055	433,792
Brokerage and trading revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		159,826	108,323	131,601
Fees and commissions revenue not from contracts with customers	[1]	116,177	73,291
Fees and commissions revenue from contracts with customers	[2]	43,649	35,032
Trading Revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		88,558	28,077
Fees and commissions revenue not from contracts with customers	[1]	88,558	28,077
Fees and commissions revenue from contracts with customers	[2]	0	0
Customer hedging revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		18,941	38,834
Fees and commissions revenue not from contracts with customers	[1]	18,941	38,834
Fees and commissions revenue from contracts with customers	[2]	0	0
Retail brokerage revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		16,136	17,952
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	16,136	17,952
Insurance brokerage revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		13,861	4,198
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	13,861	4,198
Investment banking revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		22,330	19,262
Fees and commissions revenue not from contracts with customers	[1]	8,678	6,380
Fees and commissions revenue from contracts with customers	[2]	13,652	12,882
Transaction card revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		87,216	84,025	119,988
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	87,216	84,025
TransFund EFT network revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		77,324	76,221
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	77,324	76,221
Merchant services revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		8,786	7,804
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	8,786	7,804
Corporate card revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		1,106	0
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	1,106	0
Fiduciary and asset management revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		177,025	184,703	162,889
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	177,025	184,703
Personal trust revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		81,763	96,839
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	81,763	96,839
Corporate trust revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		24,635	22,292
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	24,635	22,292
Institutional trust & retirement plan services revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		44,352	44,476
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	44,352	44,476
Investment management services and other [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		26,275	21,096
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	26,275	21,096
Deposit service charges and fees [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		112,485	112,153	112,079
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	112,485	112,153
Commercial account service charge revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		47,905	47,272
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	47,905	47,272
Overdraft fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		35,356	36,536
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	35,356	36,536
Check card fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		22,030	21,306
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	22,030	21,306
Automated service charge and other deposit fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		7,194	7,039
Fees and commissions revenue not from contracts with customers	[1]	0	0
Fees and commissions revenue from contracts with customers	[2]	7,194	7,039
Mortgage banking revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		107,541	97,787	104,719
Fees and commissions revenue not from contracts with customers	[1]	107,541	97,787
Fees and commissions revenue from contracts with customers	[2]	0	0
Mortgage production revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		42,720	31,690
Fees and commissions revenue not from contracts with customers	[1]	42,720	31,690
Fees and commissions revenue from contracts with customers	[2]	0	0
Mortgage servicing revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		64,821	66,097
Fees and commissions revenue not from contracts with customers	[1]	64,821	66,097
Fees and commissions revenue from contracts with customers	[2]	0	0
Other revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		58,108	56,185	$ 49,738
Fees and commissions revenue not from contracts with customers	[1]	39,428	38,306
Fees and commissions revenue from contracts with customers	[2]	18,680	17,879
Operating Segments [Member] \| Commercial [Member] \| Fees and commissions revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		168,667	161,949
Operating Segments [Member] \| Commercial [Member] \| Brokerage and trading revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		18,558	15,376
Operating Segments [Member] \| Commercial [Member] \| Trading Revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Commercial [Member] \| Customer hedging revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		8,422	7,748
Operating Segments [Member] \| Commercial [Member] \| Retail brokerage revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Commercial [Member] \| Insurance brokerage revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Commercial [Member] \| Investment banking revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		10,136	7,628
Operating Segments [Member] \| Commercial [Member] \| Transaction card revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		83,158	79,946
Operating Segments [Member] \| Commercial [Member] \| TransFund EFT network revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		73,479	72,280
Operating Segments [Member] \| Commercial [Member] \| Merchant services revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		8,607	7,666
Operating Segments [Member] \| Commercial [Member] \| Corporate card revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		1,072	0
Operating Segments [Member] \| Commercial [Member] \| Fiduciary and asset management revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Commercial [Member] \| Personal trust revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Commercial [Member] \| Corporate trust revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Commercial [Member] \| Institutional trust & retirement plan services revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Commercial [Member] \| Investment management services and other [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Commercial [Member] \| Deposit service charges and fees [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		43,387	42,583
Operating Segments [Member] \| Commercial [Member] \| Commercial account service charge revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		42,251	41,931
Operating Segments [Member] \| Commercial [Member] \| Overdraft fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		313	370
Operating Segments [Member] \| Commercial [Member] \| Check card fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Commercial [Member] \| Automated service charge and other deposit fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		823	282
Operating Segments [Member] \| Commercial [Member] \| Mortgage banking revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Commercial [Member] \| Mortgage production revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Commercial [Member] \| Mortgage servicing revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Commercial [Member] \| Other revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		23,564	24,044
Operating Segments [Member] \| Consumer [Member] \| Fees and commissions revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		187,996	178,174
Operating Segments [Member] \| Consumer [Member] \| Brokerage and trading revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Consumer [Member] \| Trading Revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Consumer [Member] \| Customer hedging revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Consumer [Member] \| Retail brokerage revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Consumer [Member] \| Insurance brokerage revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Consumer [Member] \| Investment banking revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Consumer [Member] \| Transaction card revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		3,980	4,076
Operating Segments [Member] \| Consumer [Member] \| TransFund EFT network revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		3,924	4,017
Operating Segments [Member] \| Consumer [Member] \| Merchant services revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		56	59
Operating Segments [Member] \| Consumer [Member] \| Corporate card revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Consumer [Member] \| Fiduciary and asset management revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Consumer [Member] \| Personal trust revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Consumer [Member] \| Corporate trust revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Consumer [Member] \| Institutional trust & retirement plan services revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Consumer [Member] \| Investment management services and other [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Consumer [Member] \| Deposit service charges and fees [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		64,867	65,210
Operating Segments [Member] \| Consumer [Member] \| Commercial account service charge revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		1,713	1,445
Operating Segments [Member] \| Consumer [Member] \| Overdraft fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		35,134	36,177
Operating Segments [Member] \| Consumer [Member] \| Check card fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		21,865	20,967
Operating Segments [Member] \| Consumer [Member] \| Automated service charge and other deposit fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		6,155	6,621
Operating Segments [Member] \| Consumer [Member] \| Mortgage banking revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		109,416	99,670
Operating Segments [Member] \| Consumer [Member] \| Mortgage production revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		42,724	31,690
Operating Segments [Member] \| Consumer [Member] \| Mortgage servicing revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		66,692	67,980
Operating Segments [Member] \| Consumer [Member] \| Other revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		9,733	9,218
Operating Segments [Member] \| Wealth Management [Member] \| Fees and commissions revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		341,333	296,465
Operating Segments [Member] \| Wealth Management [Member] \| Brokerage and trading revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		136,801	86,253
Operating Segments [Member] \| Wealth Management [Member] \| Trading Revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		88,558	28,077
Operating Segments [Member] \| Wealth Management [Member] \| Customer hedging revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		9,667	27,512
Operating Segments [Member] \| Wealth Management [Member] \| Retail brokerage revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		16,251	19,030
Operating Segments [Member] \| Wealth Management [Member] \| Insurance brokerage revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		10,131	0
Operating Segments [Member] \| Wealth Management [Member] \| Investment banking revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		12,194	11,634
Operating Segments [Member] \| Wealth Management [Member] \| Transaction card revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		(50)	(82)
Operating Segments [Member] \| Wealth Management [Member] \| TransFund EFT network revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		(82)	(82)
Operating Segments [Member] \| Wealth Management [Member] \| Merchant services revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Wealth Management [Member] \| Corporate card revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		32	0
Operating Segments [Member] \| Wealth Management [Member] \| Fiduciary and asset management revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		175,475	183,260
Operating Segments [Member] \| Wealth Management [Member] \| Personal trust revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		81,763	96,839
Operating Segments [Member] \| Wealth Management [Member] \| Corporate trust revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		24,635	22,292
Operating Segments [Member] \| Wealth Management [Member] \| Institutional trust & retirement plan services revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		44,352	44,400
Operating Segments [Member] \| Wealth Management [Member] \| Investment management services and other [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		24,725	19,729
Operating Segments [Member] \| Wealth Management [Member] \| Deposit service charges and fees [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		2,443	2,527
Operating Segments [Member] \| Wealth Management [Member] \| Commercial account service charge revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		2,137	2,331
Operating Segments [Member] \| Wealth Management [Member] \| Overdraft fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		138	134
Operating Segments [Member] \| Wealth Management [Member] \| Check card fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Wealth Management [Member] \| Automated service charge and other deposit fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		168	62
Operating Segments [Member] \| Wealth Management [Member] \| Mortgage banking revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Wealth Management [Member] \| Mortgage production revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Wealth Management [Member] \| Mortgage servicing revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Operating Segments [Member] \| Wealth Management [Member] \| Other revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		26,664	24,507
Funds Management and Other [Member] \| Fees and commissions revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		4,205	6,588
Funds Management and Other [Member] \| Brokerage and trading revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		4,467	6,694
Funds Management and Other [Member] \| Trading Revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Funds Management and Other [Member] \| Customer hedging revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		852	3,574
Funds Management and Other [Member] \| Retail brokerage revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		(115)	(1,078)
Funds Management and Other [Member] \| Insurance brokerage revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		3,730	4,198
Funds Management and Other [Member] \| Investment banking revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Funds Management and Other [Member] \| Transaction card revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		128	85
Funds Management and Other [Member] \| TransFund EFT network revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		3	6
Funds Management and Other [Member] \| Merchant services revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		123	79
Funds Management and Other [Member] \| Corporate card revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		2	0
Funds Management and Other [Member] \| Fiduciary and asset management revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		1,550	1,443
Funds Management and Other [Member] \| Personal trust revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Funds Management and Other [Member] \| Corporate trust revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	0
Funds Management and Other [Member] \| Institutional trust & retirement plan services revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		0	76
Funds Management and Other [Member] \| Investment management services and other [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		1,550	1,367
Funds Management and Other [Member] \| Deposit service charges and fees [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		1,788	1,833
Funds Management and Other [Member] \| Commercial account service charge revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		1,804	1,565
Funds Management and Other [Member] \| Overdraft fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		(229)	(145)
Funds Management and Other [Member] \| Check card fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		165	339
Funds Management and Other [Member] \| Automated service charge and other deposit fee revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		48	74
Funds Management and Other [Member] \| Mortgage banking revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		(1,875)	(1,883)
Funds Management and Other [Member] \| Mortgage production revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		(4)	0
Funds Management and Other [Member] \| Mortgage servicing revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		(1,871)	(1,883)
Funds Management and Other [Member] \| Other revenue [Member]
Disaggregation of Revenue [Line Items]
Fess and commissions revenue		$ (1,853)	$ (1,584)

[1]	Out of scope revenue generally relates to financial instruments or contractual rights and obligations within the scope of other applicable accounting guidance.
[2]	In scope revenue represents revenue subject to FASB ASC Topic 606, Revenue from Contracts with Customers.

Fair Value Measurements, Fair V

Fair Value Measurements, Fair Value Of Financial Instruments as Measured On a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016
Assets [Abstract]
Trading securities	$ 1,623,921		$ 1,956,923
Available for sale securities	11,269,643		8,857,120
Fair value option securities	1,098,577		283,235
Mortgage servicing rights	201,886		259,254		$ 252,867	$ 247,073
Derivative contracts, net of cash margin, Assets, Fair Value	323,375		320,929
Liabilities [Abstract]
Derivative contracts, net of cash margin, Liabilities, Fair Value	251,128		362,306
U.S. government agency debentures [Member]
Assets [Abstract]
Trading securities	44,264		63,765
Residential agency mortgage-backed securities [Member]
Assets [Abstract]
Trading securities	1,504,651		1,791,584
Available for sale securities	8,046,096		5,804,708
Fair value option securities	1,088,660		283,235
Municipal and other tax-exempt securities [Member]
Assets [Abstract]
Trading securities	26,196		34,507
Available for sale securities	1,861		2,864
Asset-backed securities [Member]
Assets [Abstract]
Trading securities	14,084		42,656
U.S. Treasury [Member]
Assets [Abstract]
Available for sale securities	1,600		493
Fair value option securities	9,917		0
Residential non-agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	41,609		59,736
Commercial agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	3,178,005		2,953,889
Other debt securities [Member]
Assets [Abstract]
Trading securities	34,726		24,411
Available for sale securities	472		35,430
Fair Value, Recurring [Member]
Assets [Abstract]
Trading securities	1,623,921		1,956,923
Available for sale securities	11,269,643		8,857,120
Fair value option securities	1,098,577
Residential mortgage loans held for sale	182,271		149,221
Mortgage servicing rights	201,886	[1]	259,254	[2]
Derivative contracts, net of cash margin, Assets, Fair Value	323,375	[3]	320,929	[4]
Liabilities [Abstract]
Derivative contracts, net of cash margin, Liabilities, Fair Value	251,128	[3]	362,306	[4]
Fair Value, Recurring [Member] \| U.S. government agency debentures [Member]
Assets [Abstract]
Trading securities	44,264		63,765
Fair Value, Recurring [Member] \| Residential agency mortgage-backed securities [Member]
Assets [Abstract]
Trading securities	1,504,651		1,791,584
Available for sale securities	8,046,096		5,804,708
Fair value option securities	1,088,660		283,235
Fair Value, Recurring [Member] \| Municipal and other tax-exempt securities [Member]
Assets [Abstract]
Trading securities	26,196		34,507
Available for sale securities	1,861		2,864
Fair Value, Recurring [Member] \| Asset-backed securities [Member]
Assets [Abstract]
Trading securities	14,084		42,656
Fair Value, Recurring [Member] \| U.S. Treasury [Member]
Assets [Abstract]
Available for sale securities	1,600		493
Fair value option securities	9,917
Fair Value, Recurring [Member] \| Residential non-agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	41,609		59,736
Fair Value, Recurring [Member] \| Commercial agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	3,178,005		2,953,889
Fair Value, Recurring [Member] \| Other debt securities [Member]
Assets [Abstract]
Trading securities	34,726		24,411
Available for sale securities	472		35,430
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets [Abstract]
Trading securities	0		0
Available for sale securities	1,600		493
Fair value option securities	9,917
Residential mortgage loans held for sale	0		0
Mortgage servicing rights	0	[1]	0	[2]
Derivative contracts, net of cash margin, Assets, Fair Value	8,944	[3]	44,074	[4]
Liabilities [Abstract]
Derivative contracts, net of cash margin, Liabilities, Fair Value	0	[3]	0	[4]
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| U.S. government agency debentures [Member]
Assets [Abstract]
Trading securities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Residential agency mortgage-backed securities [Member]
Assets [Abstract]
Trading securities	0		0
Available for sale securities	0		0
Fair value option securities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Municipal and other tax-exempt securities [Member]
Assets [Abstract]
Trading securities	0		0
Available for sale securities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Asset-backed securities [Member]
Assets [Abstract]
Trading securities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| U.S. Treasury [Member]
Assets [Abstract]
Available for sale securities	1,600		493
Fair value option securities	9,917
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Residential non-agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Commercial agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Other debt securities [Member]
Assets [Abstract]
Trading securities	0		0
Available for sale securities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets [Abstract]
Trading securities	1,623,921		1,956,923
Available for sale securities	11,267,571		8,856,155
Fair value option securities	1,088,660
Residential mortgage loans held for sale	173,958		134,014
Mortgage servicing rights	0	[1]	0	[2]
Derivative contracts, net of cash margin, Assets, Fair Value	314,431	[3]	276,855	[4]
Liabilities [Abstract]
Derivative contracts, net of cash margin, Liabilities, Fair Value	251,128	[3]	362,306	[4]
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| U.S. government agency debentures [Member]
Assets [Abstract]
Trading securities	44,264		63,765
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Residential agency mortgage-backed securities [Member]
Assets [Abstract]
Trading securities	1,504,651		1,791,584
Available for sale securities	8,046,096		5,804,708
Fair value option securities	1,088,660		283,235
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Municipal and other tax-exempt securities [Member]
Assets [Abstract]
Trading securities	26,196		34,507
Available for sale securities	1,861		2,864
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Asset-backed securities [Member]
Assets [Abstract]
Trading securities	14,084		42,656
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| U.S. Treasury [Member]
Assets [Abstract]
Available for sale securities	0		0
Fair value option securities	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Residential non-agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	41,609		59,736
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Commercial agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	3,178,005		2,953,889
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Other debt securities [Member]
Assets [Abstract]
Trading securities	34,726		24,411
Available for sale securities	0		34,958
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets [Abstract]
Trading securities	0		0
Available for sale securities	472		472
Fair value option securities	0
Residential mortgage loans held for sale	8,313		15,207
Mortgage servicing rights	201,886	[1]	259,254	[2]
Derivative contracts, net of cash margin, Assets, Fair Value	0	[3]	0	[4]
Liabilities [Abstract]
Derivative contracts, net of cash margin, Liabilities, Fair Value	0	[3]	0	[4]
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| U.S. government agency debentures [Member]
Assets [Abstract]
Trading securities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Residential agency mortgage-backed securities [Member]
Assets [Abstract]
Trading securities	0		0
Available for sale securities	0		0
Fair value option securities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Municipal and other tax-exempt securities [Member]
Assets [Abstract]
Trading securities	0		0
Available for sale securities			0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Asset-backed securities [Member]
Assets [Abstract]
Trading securities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| U.S. Treasury [Member]
Assets [Abstract]
Available for sale securities	0		0
Fair value option securities	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Residential non-agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Commercial agency mortgage-backed securities [Member]
Assets [Abstract]
Available for sale securities	0		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Other debt securities [Member]
Assets [Abstract]
Trading securities	0		0
Available for sale securities	$ 472		$ 472

[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 7 , Mortgage Banking Activities .
[2]	A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 7 , Mortgage Banking Activities.
[3]	See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts in a net asset position that were valued based on quoted prices in active markets or identical instruments (Level 1) are exchange-traded interest rate and energy derivative contracts, net of cash margin. Derivative contracts in a net liability position that were valued using quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate and agricultural derivative contracts, fully offset by cash margin.
[4]	See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts in a net asset position that were valued based on quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate, energy and agricultural derivative contracts, net of cash margin. Derivative contracts in a net liability position that were valued using quoted prices in active markets for identical instruments based on quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate derivative contracts, fully offset by cash margin.

Fair Value Measurements, Measur

Fair Value Measurements, Measured On Recurring Basis Significant Unobservable Inputs (Details) - Fair Value, Recurring [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($)		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Available-for-sale securities [Member] \| Municipal and other tax-exempt securities [Member]
Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]
Balance, beginning of period		$ 0	$ 4,802,000
Transfer to Level 3 from Level 2	[1]	0	0
Purchases		0	0
Redemptions and distributions		0	(5,095,000)
Proceeds from sales		0	0
Other comprehensive income (loss)		0	293,000
Balance, end of period		0	0
Available-for-sale securities [Member] \| Municipal and other tax-exempt securities [Member] \| Mortgage banking revenue [Member]
Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]
Gain (loss) recognized in earnings		0	0
Available-for-sale securities [Member] \| Other debt securities [Member]
Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]
Balance, beginning of period		472,000	472,000
Transfer to Level 3 from Level 2	[1]	0	0
Purchases		0	0
Redemptions and distributions		0	0
Proceeds from sales		0	0
Other comprehensive income (loss)		0	0
Balance, end of period		472,000	472,000
Available-for-sale securities [Member] \| Other debt securities [Member] \| Mortgage banking revenue [Member]
Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]
Gain (loss) recognized in earnings		0	0
Residential mortgage loans held for sale [Member]
Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]
Balance, beginning of period		15,207,000	12,299,000
Transfer to Level 3 from Level 2	[1]	2,449,000	6,183,000
Purchases		0	0
Redemptions and distributions		0	0
Proceeds from sales		(9,972,000)	(2,706,000)
Other comprehensive income (loss)		0	0
Balance, end of period		8,313,000	15,207,000
Residential mortgage loans held for sale [Member] \| Mortgage banking revenue [Member]
Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]
Gain (loss) recognized in earnings		$ 629,000	$ (569,000)

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

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Measurements, Financial Instruments Measured On a Recurring Basis, Quantitative Information (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available for sale securities	$ 11,269,643	$ 8,857,120
Other debt securities [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available for sale securities	472	35,430
Fair Value, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available for sale securities	11,269,643	8,857,120
Residential mortgage loans held for sale	182,271	149,221
Fair Value, Recurring [Member] \| Other debt securities [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available for sale securities	472	35,430
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available for sale securities	472	472
Residential mortgage loans held for sale	8,313	15,207
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Other debt securities [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available for sale securities	$ 472	$ 472
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Available-for-sale securities [Member] \| Other debt securities [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Average Yields On Comparable Short-term Taxable Securities	3.00%	3.00%
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Residential mortgage loans held for sale [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Liquidity Discount on Mortgage Loans Qualifying for Sale to US Govt Agencies	95.23%	92.38%
Discounted Cash Flow [Member] \| Interest Rate Spread [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Available-for-sale securities [Member] \| Other debt securities [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available for sale securities	$ 472	$ 472
Quoted prices of loans sold in securitization transactions, with a liquidity discount applied [Member] \| Liquidity discount [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Residential mortgage loans held for sale [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential mortgage loans held for sale	$ 8,313	$ 15,207
Minimum [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Available-for-sale securities [Member] \| Other debt securities [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range of Interest Rates used to Value Securities	7.08%	7.88%
Range of fair value as a percentage of par value	94.40%	94.44%
Maximum [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Available-for-sale securities [Member] \| Other debt securities [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range of Interest Rates used to Value Securities	7.08%	7.88%
Range of fair value as a percentage of par value	94.40%	94.44%
Weighted Average [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Available-for-sale securities [Member] \| Other debt securities [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range of Interest Rates used to Value Securities	7.08%	7.88%
Range of fair value as a percentage of par value	94.40%	94.44%

Fair Value Measurements, Fair_2

Fair Value Measurements, Fair Value Measured On a Nonrecurring Basis (Details) - Fair Value, Nonrecurring [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross charge-offs against allowance for loan losses	$ 31,305	$ 17,434
Net losses and expenses of repossessed assets, net	0	0
Real estate and other repossessed assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross charge-offs against allowance for loan losses	0	0
Net losses and expenses of repossessed assets, net	(461)	7,269
Fair Value, Inputs, Level 1 [Member] \| Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 [Member] \| Real estate and other repossessed assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member] \| Pension Plan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Plan Assets, Amount	36,000	34,000
Fair Value, Inputs, Level 2 [Member] \| Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	41	1,074
Fair Value, Inputs, Level 2 [Member] \| Real estate and other repossessed assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	5,986	4,795
Fair Value, Inputs, Level 3 [Member] \| Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	55,665	17,401
Fair Value, Inputs, Level 3 [Member] \| Real estate and other repossessed assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 1,551	$ 6,366

Fair Value Measurements Fair _2

Fair Value Measurements Fair Value Measurement, Measured On Non-Recurring Basis, Signfiicant Unobservable Inputs, Quantitative Information (Details) - Fair Value, Nonrecurring [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Impaired Loans [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 55,665	$ 17,401
Real estate and other repossessed assets [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	1,551	6,366
Discounted Cash Flow [Member] \| Impaired Loans [Member] \| Management knowledge of Industry [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	55,665	17,401
Discounted Cash Flow [Member] \| Real estate and other repossessed assets [Member] \| Marketability adjustments off appraised value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure	$ 1,551
Discounted Cash Flow [Member] \| Real estate and other repossessed assets [Member] \| Recoverable oil and gas reserves, forward-looking commodity prices, and estimated operating costs [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets, Fair Value Disclosure		$ 6,366
Minimum [Member] \| Impaired Loans [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value of Impaired Loans as Percentage of Unpaid Principal Balance	4.00%	35.00%
Minimum [Member] \| Real estate and other repossessed assets [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Measurement, Percentage of appraised value	74.00%
Maximum [Member] \| Impaired Loans [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value of Impaired Loans as Percentage of Unpaid Principal Balance	94.00%	80.00%
Maximum [Member] \| Real estate and other repossessed assets [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Measurement, Percentage of appraised value	86.00%
Weighted Average [Member] \| Impaired Loans [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value of Impaired Loans as Percentage of Unpaid Principal Balance	55.00%	50.00%
Weighted Average [Member] \| Real estate and other repossessed assets [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Measurement, Percentage of appraised value	84.00%

Fair Value Measurements, Financ

Fair Value Measurements, Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	$ 1,623,921	$ 1,956,923
Investment securities	293,418	355,187
Available for sale securities	11,269,643	8,857,120
Fair value option securities	1,098,577	283,235
Residential mortgage loans held for sale	182,271	149,221
Loans	21,750,987	21,656,730
Allowance for loan losses	(210,759)	(207,457)	$ (230,682)	$ (246,159)
Loans, net of allowance	21,540,228	21,449,273
Mortgage servicing rights	201,886	259,254	252,867	247,073
Derivative contracts, net of cash margin, Assets, Fair Value	323,375	320,929
Time deposits	2,217,849	2,113,380
Subordinated debentures	275,923	275,913
Derivative contracts, net of cash margin, Liabilities, Fair Value	251,128	362,306
Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	14,031,650	13,636,078
Allowance for loan losses	(118,187)	(102,226)	(124,269)	(140,213)
Commercial Real Estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	4,433,783	4,764,813
Allowance for loan losses	(51,805)	(60,026)	(56,621)	(50,749)
Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,084,172	2,230,033
Allowance for loan losses	(14,400)	(17,964)	(18,451)	(18,224)
Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,201,382	1,025,806
Allowance for loan losses	(9,172)	(9,473)	$ (9,124)	$ (8,773)
U.S. government agency debentures [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	44,264	63,765
Residential agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	1,504,651	1,791,584
Investment securities	10,676	12,612
Available for sale securities	8,046,096	5,804,708
Fair value option securities	1,088,660	283,235
Municipal and other tax-exempt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	26,196	34,507
Investment securities	93,653	137,296
Available for sale securities	1,861	2,864
U.S. Treasury [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	1,600	493
Fair value option securities	9,917	0
Residential non-agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	41,609	59,736
Commercial agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	3,178,005	2,953,889
Other debt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	34,726	24,411
Investment securities	189,089	205,279
Available for sale securities	472	35,430
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	735,836	741,749
Interest-bearing cash and cash equivalents	522,985	401,675
Trading securities	1,623,921	1,956,923
Investment securities	314,402	367,298
Available for sale securities	11,269,643	8,857,120
Fair value option securities	1,098,577
Residential mortgage loans held for sale	182,271	149,221
Loans	21,689,329	21,478,228
Allowance for loan losses	0	0
Loans, net of allowance	21,689,329	21,478,228
Mortgage servicing rights	201,886	259,254
Derivative contracts, net of cash margin, Assets, Fair Value	323,375	320,929
Deposits with no stated maturity	25,403,319	23,150,383
Time deposits	2,212,467	2,073,538
Other borrowed funds	8,315,860	7,071,953
Subordinated debentures	284,627	261,977
Derivative contracts, net of cash margin, Liabilities, Fair Value	251,128	362,306
Estimate of Fair Value Measurement [Member] \| Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	13,966,221	13,526,162
Estimate of Fair Value Measurement [Member] \| Commercial Real Estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	4,422,717	4,713,747
Estimate of Fair Value Measurement [Member] \| Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,098,093	2,213,951
Estimate of Fair Value Measurement [Member] \| Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,202,298	1,024,368
Estimate of Fair Value Measurement [Member] \| U.S. government agency debentures [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	44,264	63,765
Estimate of Fair Value Measurement [Member] \| Residential agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	1,504,651	1,791,584
Investment securities	11,164	12,770
Available for sale securities	8,046,096	5,804,708
Fair value option securities	1,088,660	283,235
Estimate of Fair Value Measurement [Member] \| Municipal and other tax-exempt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	26,196	34,507
Investment securities	96,897	138,562
Available for sale securities	1,861	2,864
Estimate of Fair Value Measurement [Member] \| Asset-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	14,084	42,656
Estimate of Fair Value Measurement [Member] \| Other trading securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	34,726	24,411
Estimate of Fair Value Measurement [Member] \| U.S. Treasury [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	1,600	493
Fair value option securities	9,917
Estimate of Fair Value Measurement [Member] \| Residential non-agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	41,609	59,736
Estimate of Fair Value Measurement [Member] \| Commercial agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	3,178,005	2,953,889
Estimate of Fair Value Measurement [Member] \| Other debt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	206,341	215,966
Available for sale securities	472	35,430
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	735,836	741,749
Interest-bearing cash and cash equivalents	522,985	401,675
Trading securities	1,623,921	1,956,923
Investment securities	293,418	355,187
Available for sale securities	11,269,643	8,857,120
Fair value option securities	1,098,577
Residential mortgage loans held for sale	182,271	149,221
Loans	21,750,987	21,656,730
Allowance for loan losses	(210,759)	(207,457)
Loans, net of allowance	21,540,228	21,449,273
Mortgage servicing rights	201,886	259,254
Derivative contracts, net of cash margin, Assets, Fair Value	323,375	320,929
Deposits with no stated maturity	25,403,319	23,150,383
Time deposits	2,217,849	2,113,380
Other borrowed funds	8,345,405	7,142,801
Subordinated debentures	275,923	275,913
Derivative contracts, net of cash margin, Liabilities, Fair Value	251,128	362,306
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	14,031,650	13,636,078
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Commercial Real Estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	4,433,783	4,764,813
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,084,172	2,230,033
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,201,382	1,025,806
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| U.S. government agency debentures [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	44,264	63,765
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Residential agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	1,504,651	1,791,584
Investment securities	10,676	12,612
Available for sale securities	8,046,096	5,804,708
Fair value option securities	1,088,660	283,235
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Municipal and other tax-exempt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	26,196	34,507
Investment securities	93,653	137,296
Available for sale securities	1,861	2,864
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Asset-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	14,084	42,656
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Other trading securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	34,726	24,411
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| U.S. Treasury [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	1,600	493
Fair value option securities	9,917
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Residential non-agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	41,609	59,736
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Commercial agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	3,178,005	2,953,889
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Other debt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	189,089	205,279
Available for sale securities	472	35,430
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	735,836	741,749
Interest-bearing cash and cash equivalents	522,985	401,675
Trading securities	0	0
Investment securities	0	0
Available for sale securities	1,600	493
Fair value option securities	9,917
Residential mortgage loans held for sale	0	0
Loans	0	0
Allowance for loan losses	0	0
Loans, net of allowance	0	0
Mortgage servicing rights	0	0
Derivative contracts, net of cash margin, Assets, Fair Value	8,944	44,074
Deposits with no stated maturity	0	0
Time deposits	0	0
Other borrowed funds	0	0
Subordinated debentures	0	0
Derivative contracts, net of cash margin, Liabilities, Fair Value	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial Real Estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| U.S. government agency debentures [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Investment securities	0	0
Available for sale securities	0	0
Fair value option securities	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Municipal and other tax-exempt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Investment securities	0	0
Available for sale securities	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Asset-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Other trading securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| U.S. Treasury [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	1,600	493
Fair value option securities	9,917
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential non-agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0	0
Fair Value, Inputs, Level 1 [Member] \| Estimate of Fair Value Measurement [Member] \| Other debt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	0	0
Available for sale securities	0	0
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	0	0
Interest-bearing cash and cash equivalents	0	0
Trading securities	1,623,921	1,956,923
Investment securities	116,267	159,237
Available for sale securities	11,267,571	8,856,155
Fair value option securities	1,088,660
Residential mortgage loans held for sale	173,958	134,014
Loans	0	0
Allowance for loan losses	0	0
Loans, net of allowance	0	0
Mortgage servicing rights	0	0
Derivative contracts, net of cash margin, Assets, Fair Value	314,431	276,855
Deposits with no stated maturity	0	0
Time deposits	0	0
Other borrowed funds	0	0
Subordinated debentures	284,627	261,977
Derivative contracts, net of cash margin, Liabilities, Fair Value	251,128	362,306
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial Real Estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| U.S. government agency debentures [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	44,264	63,765
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	1,504,651	1,791,584
Investment securities	11,164	12,770
Available for sale securities	8,046,096	5,804,708
Fair value option securities	1,088,660	283,235
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Municipal and other tax-exempt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	26,196	34,507
Investment securities	96,897	138,562
Available for sale securities	1,861	2,864
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Asset-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	14,084	42,656
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Other trading securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	34,726	24,411
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| U.S. Treasury [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0	0
Fair value option securities	0
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential non-agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	41,609	59,736
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	3,178,005	2,953,889
Fair Value, Inputs, Level 2 [Member] \| Estimate of Fair Value Measurement [Member] \| Other debt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	8,206	7,905
Available for sale securities	0	34,958
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	0	0
Interest-bearing cash and cash equivalents	0	0
Trading securities	0	0
Investment securities	198,135	208,061
Available for sale securities	472	472
Fair value option securities	0
Residential mortgage loans held for sale	8,313	15,207
Loans	21,689,329	21,478,228
Allowance for loan losses	0	0
Loans, net of allowance	21,689,329	21,478,228
Mortgage servicing rights	201,886	259,254
Derivative contracts, net of cash margin, Assets, Fair Value	0	0
Deposits with no stated maturity	25,403,319	23,150,383
Time deposits	2,212,467	2,073,538
Other borrowed funds	8,315,860	7,071,953
Subordinated debentures	0	0
Derivative contracts, net of cash margin, Liabilities, Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	13,966,221	13,526,162
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial Real Estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	4,422,717	4,713,747
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential Mortgage [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,098,093	2,213,951
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,202,298	1,024,368
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| U.S. government agency debentures [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Investment securities	0	0
Available for sale securities	0	0
Fair value option securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Municipal and other tax-exempt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Investment securities	0	0
Available for sale securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Asset-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Other trading securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| U.S. Treasury [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0	0
Fair value option securities	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Residential non-agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Commercial agency mortgage-backed securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Estimate of Fair Value Measurement [Member] \| Other debt securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	198,135	208,061
Available for sale securities	$ 472	$ 472

Parent Company Only Financial_3

Parent Company Only Financial Statements Parent Company Only Financial Statements, Condensed Balance Sheet Statement (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets [Abstract]
Cash and cash equivalents	$ 1,258,821	$ 1,143,424	$ 2,317,054	$ 2,537,497
Loan to bank subsidiary	21,540,228	21,449,273
Other assets	547,995	446,891
Total assets	42,172,021	38,020,504
Liabilities [Abstract]
Other liabilities	372,230	183,480
Subordinated debentures	275,923	275,913
Total liabilities	37,308,102	33,577,459
Shareholders' equity: [Abstract]
Common stock	5	5
Capital surplus	1,350,995	1,334,030
Retained earnings	3,729,778	3,369,654
Treasury stock	(329,906)	(198,995)
Accumulated other comprehensive income (loss)	104,923	(72,585)	(36,174)	(10,967)
Total shareholders’ equity	4,855,795	4,432,109
Total liabilities and shareholders’ equity	42,172,021	38,020,504
Parent Company [Member]
Assets [Abstract]
Cash and cash equivalents	214,779	167,093	$ 205,876	$ 163,418
Loan to bank subsidiary	65,220	65,228
Investment in bank subsidiaries	4,602,977	4,236,654
Investment in non-bank subsidiaries	216,542	218,007
Other assets	38,082	32,999
Total assets	5,137,600	4,719,981
Liabilities [Abstract]
Other liabilities	5,882	11,959
Subordinated debentures	275,923	275,913
Total liabilities	281,805	287,872
Shareholders' equity: [Abstract]
Common stock	5	5
Capital surplus	1,350,995	1,334,030
Retained earnings	3,729,778	3,369,654
Treasury stock	329,906	198,995
Accumulated other comprehensive income (loss)	104,923	(72,585)
Total shareholders’ equity	4,855,795	4,432,109
Total liabilities and shareholders’ equity	$ 5,137,600	$ 4,719,981

Parent Company Only Financial_4

Parent Company Only Financial Statements Parent Company Only Financial Statements, Condensed Income Statements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Income Statements, Captions [Line Items]
Interest expense	$ 419,079	$ 243,559	$ 131,050
Other operating expense	1,132,381	1,028,166	1,025,517
Other gains (losses), net	(9,351)	2,265	(11,434)
Federal and state income taxes	130,183	119,061	182,593
Net income attributable to BOK Financial Corp. shareholders	500,758	445,646	334,644
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Total revenue	354,368	439,825	168,585
Interest expense	15,113	9,827	8,239
Other operating expense	2,352	12,110	2,014
Total expense	17,465	21,937	10,253
Net income before taxes, other losses, net, and equity in undistributed income of subsidiaries	336,903	417,888	158,332
Other gains (losses), net	3,310	(3,921)	0
Net income before taxes, other losses, net, and equity in undistributed income of subsidiaries	340,213	413,967	158,332
Federal and state income taxes	(4,516)	(7,078)	(4,305)
Net income before equity in undistributed income of subsidiaries	344,729	421,045	162,637
Equity in undistributed income of bank subsidiaries	166,797	37,515	181,552
Equity in undistributed income of non-bank subsidiaries	(10,768)	(12,914)	(9,545)
Net income attributable to BOK Financial Corp. shareholders	500,758	445,646	334,644
Parent Company [Member] \| Dividends, interest and fees received from bank susidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Total revenue	344,007	426,071	150,149
Parent Company [Member] \| Diviidends, interest and fees received from non-bank subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Total revenue	9,325	12,800	17,500
Parent Company [Member] \| Other revenue [Member]
Condensed Income Statements, Captions [Line Items]
Total revenue	$ 1,036	$ 954	$ 936

Parent Company Only Financial_5

Parent Company Only Financial Statements Parent Company Only Financial Statements, Condensed Cash Flow Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flows From Operating Activities: [Abstract]
Net income	$ 500,685	$ 446,424	$ 335,685
Adjustments to reconcile net income to net cash provided by operating activities: [Abstract]
Change in other assets	18,955	27,507	(5,506)
Change in other liabilities	57,569	(139,346)	182,184
Net cash provided by operating activities	(473,679)	(552,006)	214,931
Cash Flows From Investing Activities: [Abstract]
Proceeds from sales of available for sale securities	1,211,718	745,643	1,309,215
Acquisitions, net of cash acquired	0	(175,755)	0
Net cash used in investing activities	(2,323,737)	(1,807,631)	739,556
Cash Flows From Financing Activities: [Abstract]
Net change in other borrowed funds	1,110,970	1,295,484	(10,909)
Issuance of common and treasury stock, net	(7)	(88)	4,368
Dividends paid	(143,496)	(127,188)	(116,041)
Repurchase of common stock	(129,483)	(53,465)	(7,403)
Net cash used in financing activities	2,912,813	1,186,007	(1,174,930)
Net increase (decrease) in cash and cash equivalents	115,397	(1,173,630)	(220,443)
Cash and cash equivalents at beginning of period	1,143,424	2,317,054	2,537,497
Cash and cash equivalents at end of period	1,258,821	1,143,424	2,317,054
Cash paid for interest	417,070	243,121	127,513
Parent Company [Member]
Cash Flows From Operating Activities: [Abstract]
Net income	500,758	445,646	334,644
Adjustments to reconcile net income to net cash provided by operating activities: [Abstract]
Equity in undistributed income of bank subsidiaries	(166,797)	(37,515)	(181,552)
Equity in undistributed income of non-bank subsidiaries	(10,768)	(12,914)	(9,545)
Change in other assets	5,075	1,072	(12)
Change in other liabilities	855	(13,434)	7,457
Net cash provided by operating activities	340,509	406,539	170,106
Cash Flows From Investing Activities: [Abstract]
Proceeds from sales of available for sale securities	0	0	3,000
Investment in subsidiaries	(19,837)	(31,901)	(4,355)
Acquisitions, net of cash acquired	0	(232,680)	0
Net cash used in investing activities	(19,837)	(264,581)	(1,355)
Cash Flows From Financing Activities: [Abstract]
Net change in other borrowed funds	0	0	(7,217)
Issuance of common and treasury stock, net	(7)	(88)	4,368
Dividends paid	143,496	127,188	116,041
Repurchase of common stock	129,483	53,465	7,403
Net cash used in financing activities	(272,986)	(180,741)	(126,293)
Net increase (decrease) in cash and cash equivalents	47,686	(38,783)	42,458
Cash and cash equivalents at beginning of period	167,093	205,876	163,418
Cash and cash equivalents at end of period	214,779	167,093	205,876
Cash paid for interest	$ 15,099	$ 11,457	$ 6,211