Reclassification adjustments included in earnings:

512

(33,458)

33,881

133,108

Interest revenue, Investment securities, Taxable securities

0

(112)

Other comprehensive income (loss) before income taxes

(2,487)

(2,394)

(4,916)

(11,684)

(1,975)

(35,852)

28,965

121,312

Other comprehensive income (loss), net of income taxes

(768)

(13,947)

11,241

^[1]

47,172

^[1]

(1,207)

(21,905)

17,724

74,140

Comprehensive income

84,583

53,207

281,044

256,512

Comprehensive income (loss) attributable to non-controlling interests

141

835

1,168

(270)

Comprehensive income attributable to BOK Financial Corp. shareholders

$ 84,442

$ 52,372

$ 279,876

$ 256,782

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

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Assets [Abstract]
Cash and due from banks	$ 547,203	$ 620,846	$ 535,916
Interest-bearing cash and cash equivalents	1,926,779	1,916,651	2,080,978
Trading securities	614,117	337,628	546,615
Investment securities	466,562	546,145	546,457
Available for sale securities	8,383,199	8,676,829	8,862,283
Fair value option securities	819,531	77,046	222,409
Restricted equity securities	347,542	307,240	333,391
Residential mortgage loans held for sale	275,643	301,897	447,592
Loans	17,206,834	16,989,660	16,464,786
Allowance for loan losses	(247,703)	(246,159)	(245,103)
Loans, net of allowance	16,959,131	16,743,501	16,219,683
Premises and equipment, net	320,060	325,849	318,196
Receivables	314,251	772,952	650,368
Goodwill	446,697	448,899	382,739
Intangible assets, net	39,013	46,931	41,977
Mortgage servicing rights	245,858	247,073	203,621
Real estate and other repossessed assets, net of allowance	32,535	44,287	31,941
Derivative contracts, net	352,559	689,872	655,078
Cash surrender value of bank-owned life insurance	314,201	308,430	310,211
Receivable on unsettled securities sales	230,225	7,188	19,642
Other assets	370,409	353,017	370,134
Total assets	33,005,515	32,772,281	32,779,231
Deposits [Abstract]
Noninterest-bearing demand deposits	9,185,481	9,235,720	8,681,364
Interest-bearing deposits: [Abstract]
Transaction	10,025,084	10,865,105	9,824,160
Savings	465,225	425,470	420,349
Time	2,172,289	2,221,800	2,169,631
Total deposits	21,848,079	22,748,095	21,095,504
Funds purchased	62,356	57,929	109,031
Repurchase agreements	328,189	668,661	504,573
Other borrowings	6,241,275	4,846,072	6,533,443
Subordinated debentures	144,668	144,640	144,631
Accrued interest, taxes and expense	152,029	146,704	191,276
Derivative contracts, net	336,327	664,531	573,987
Due on unsettled securities purchases	160,781	6,508	677
Other liabilities	217,372	182,784	193,698
Total liabilities	29,491,076	29,465,924	29,346,820
Shareholders' equity: [Abstract]
Common stock	4	4	4
Capital surplus	1,028,489	1,006,535	995,680
Retained earnings	2,999,005	2,823,334	2,801,931
Treasury stock	(545,441)	(544,052)	(495,031)
Accumulated other comprehensive income (loss)	6,757	(10,967)	95,727
Total shareholders’ equity	3,488,814	3,274,854	3,398,311
Non-controlling interests	25,625	31,503	34,100
Total equity	3,514,439	3,306,357	3,432,411
Total liabilities and equity	$ 33,005,515	$ 32,772,281	$ 32,779,231

Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Investment securities [Abstract]
Investment Securities, fair value	$ 489,895	$ 565,493	$ 580,310
Allowance for real estate and other repossessed assets	$ 11,738	$ 9,562	$ 9,524
Shareholders' equity: [Abstract]
Common stock, par value (in dollars per share)	$ 0.00006	$ 0.00006	$ 0.00006
Common stock, shares authorized (in shares)	2,500,000,000	2,500,000,000	2,500,000,000
Common stock, shares issued (in shares)	75,129,535	74,993,407	74,866,429
Common stock, shares outstanding (in shares)	75,129,535	74,993,407	74,866,429
Treasury stock, shares at cost (in shares)	9,672,749	9,655,975	8,955,975

Consolidated Statements of Changes in Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total Shareholders' Equity [Member]	Non-Controlling Interests [Member]
Balance, beginning of period (in shares) at Dec. 31, 2015		74,530			8,636
Balance, beginning of period at Dec. 31, 2015	$ 3,267,639	$ 4	$ 982,009	$ 2,704,121	$ (477,165)	$ 21,587	$ 3,230,556	$ 37,083
Net income (loss)	182,372			182,642			182,642	(270)
Other comprehensive income	74,140					74,140	74,140
Repurchase of common stock (in shares)					305
Repurchase of common stock	(17,771)				$ (17,771)		(17,771)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		108
Stock options exercised	5,513		5,513				5,513
Non-vested shares awarded, net (in shares)		228
Vesting of non-vested shares (in shares)					15
Vesting of non-vested shares	(95)				$ (95)		(95)
Tax effect from equity compensation, net	589		589				589
Share-based compensation	7,569		7,569				7,569
Cash dividends on common stock	(84,832)			(84,832)			(84,832)
Capital calls and distributions, net	(2,713)							(2,713)
Balance, end of period (in shares) at Sep. 30, 2016		74,866			8,956
Balance, end of period at Sep. 30, 2016	3,432,411	$ 4	995,680	2,801,931	$ (495,031)	95,727	3,398,311	34,100
Balance, beginning of period (in shares) at Dec. 31, 2016		74,993			9,656
Balance, beginning of period at Dec. 31, 2016	3,306,357	$ 4	1,006,535	2,823,334	$ (544,052)	(10,967)	3,274,854	31,503
Net income (loss)	263,320			262,152			262,152	1,168
Other comprehensive income	17,724					17,724	17,724
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		80
Stock options exercised	4,564		4,564				4,564
Non-vested shares awarded, net (in shares)		57
Vesting of non-vested shares (in shares)					17
Vesting of non-vested shares	(1,389)				$ (1,389)		(1,389)
Share-based compensation	17,390		17,390				17,390
Cash dividends on common stock	(86,481)			(86,481)			(86,481)
Capital calls and distributions, net	(7,046)							(7,046)
Balance, end of period (in shares) at Sep. 30, 2017		75,130			9,673
Balance, end of period at Sep. 30, 2017	$ 3,514,439	$ 4	$ 1,028,489	$ 2,999,005	$ (545,441)	$ 6,757	$ 3,488,814	$ 25,625

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows From Operating Activities: [Abstract]
Net income	$ 263,320	$ 182,372
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	0	65,000
Change in fair value of mortgage servicing rights due to market changes	5,726	41,944
Change in the fair value of mortgage servicing rights due to loan runoff	24,928	29,385
Net unrealized gains from derivative contracts	(3,937)	(9,755)
Share-based compensation	17,390	7,569
Depreciation and amortization	39,154	35,158
Net amortization of securities discounts and premiums	22,149	31,373
Net realized gains on financial instruments and other net gains	(1,930)	(13,663)
Net gain on mortgage loans held for sale	(35,778)	(61,775)
Mortgage loans originated for sale	(2,446,793)	(4,927,442)
Proceeds from sale of mortgage loans held for sale	2,503,759	4,855,682
Capitalized mortgage servicing rights	(29,439)	(56,345)
Change in trading and fair value option securities	(1,019,906)	(204,030)
Change in receivables	459,480	(483,836)
Change in other assets	(18,991)	(17,931)
Change in accrued interest, taxes and expense	(99)	27,780
Change in other liabilities	43,767	7,262
Net cash provided by (used in) operating activities	(177,200)	(491,252)
Cash Flows From Investing Activities: [Abstract]
Proceeds from maturities or redemptions of investment securities	94,243	65,104
Proceeds from maturities or redemptions of available for sale securities	1,345,575	1,120,917
Purchases of investment securities	(18,802)	(18,599)
Purchases of available for sale securities	(2,001,160)	(1,860,287)
Proceeds from sales of available for sale securities	966,044	1,027,379
Change in amount receivable on unsettled securities transactions	(223,037)	20,551
Loans originated, net of principal collected	(156,404)	(551,351)
Net payments on derivative asset contracts	334,709	(79,512)
Acquisitions, net of cash acquired	0	(7,700)
Proceeds from disposition of assets	162,793	131,761
Purchases of assets	(170,937)	(159,263)
Net cash provided by (used in) investing activities	333,024	(311,000)
Cash Flows From Financing Activities: [Abstract]
Net change in demand deposits, transaction deposits and savings accounts	(850,505)	243,779
Net change in time deposits	(49,511)	(236,433)
Net change in other borrowed funds	957,859	1,015,822
Repayment of subordinated debentures	0	226,550
Issuance of subordinated debentures	0	145,331
Net proceeds on derivative liability contracts	(339,566)	76,144
Net change in derivative margin accounts	(8,583)	(129,141)
Change in amount due on unsettled security transactions	154,273	(16,220)
Issuance of common and treasury stock, net	3,175	5,418
Repurchase of common stock	0	17,771
Dividends paid	(86,481)	(84,832)
Net cash provided by (used in) financing activities	(219,339)	775,547
Net increase (decrease) in cash and cash equivalents	(63,515)	(26,705)
Cash and cash equivalents at beginning of period	2,537,497	2,643,599
Cash and cash equivalents at end of period	2,473,982	2,616,894
Supplemental Cash Flow Information: [Abstract]
Cash paid for interest	89,901	61,522
Cash paid for taxes	95,967	43,096
Net loans and bank premises transferred to repossessed real estate and other assets	4,649	20,580
Residential mortgage loans guaranteed by U.S. government agencies that became eligible for repurchase during the period	101,299	79,710
Conveyance of other real estate owned guaranteed by U.S. government agencies	$ 32,033	$ 50,855

Significant Accounting Policies	9 Months Ended
Significant Accounting Policies	Sep. 30, 2017
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Significant Accounting Policies Basis of Presentation The accompanying unaudited consolidated financial statements of BOK Financial Corporation (“BOK Financial” or “the Company”) have been prepared in accordance with accounting principles for interim financial information generally accepted in the United States and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. The unaudited consolidated financial statements include accounts of BOK Financial and its subsidiaries, principally BOKF, NA (“the Bank”), BOK Financial Securities, Inc., The Milestone Group, Inc. and Cavanal Hill Investment Management Inc. Operating divisions of the Bank include Bank of Albuquerque, Bank of Arizona, Bank of Arkansas, Bank of Oklahoma, Bank of Texas, Colorado State Bank and Trust, Mobank, BOK Financial Mortgage and the TransFund electronic funds network. Certain reclassifications have been made to conform to the current period presentation. The financial information should be read in conjunction with BOK Financial’s 2016 Form 10-K filed with the Securities and Exchange Commission, which contains audited financial statements. Amounts presented as of December 31, 2016 have been derived from the audited financial statements included in BOK Financial’s 2016 Form 10-K but do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. Operating results for the nine-month period ended September 30, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017. Newly Adopted and Pending Accounting Policies Financial Accounting Standards Board (“FASB”) FASB Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers ("ASU 2014-09") On May 28, 2014, the FASB issued ASU 2014-09 to clarify the principles for recognizing revenue by providing a more robust framework that will give greater consistency and comparability in revenue recognition practices. In the new framework, an entity recognizes revenue in an amount that reflects the consideration to which the entity expects to be entitled in exchange for goods or services. The new model requires the identification of performance obligations included in contracts with customers, a determination of the transaction price and an allocation of the price to those performance obligations. The entity recognizes revenue when performance obligations are satisfied. ASU 2014-09 is effective for the Company for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. Net interest revenue from financial assets and liabilities is explicitly excluded from the scope of ASU 2014-09. Management expects that there will be no material impact on the timing of revenue recognized as our current revenue recognition policies generally conform with the principals in the standard. Management will adopt the standard in the first quarter of 2018 with a cumulative effect adjustment to opening retained earnings if such adjustment is significant. Currently, we do not anticipate any significant adjustments. FASB Accounting Standards Update No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net) ("ASU 2016-08") On March 17, 2016, the FASB Issued ASU 2016-08 to amend the principal versus agent implementation guidance in ASU 2014-09. The ASU clarifies that an entity should evaluate whether it is the principal or the agent for each specified good or service promised in a contract with a customer. ASU 2016-08 is effective for the Company for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. Management expects that interchange fees paid to issuing banks for card transactions processed related to its merchant processing services currently included in data processing and communication expense, will be netted against the amounts charged to the merchant in transaction card processing revenue. For 2016, interchange fees related to merchant processing services were approximately $27 million. FASB Accounting Standards Update No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01") On January 5, 2016, the FASB issued ASU 2016-01 over the recognition and measurement of financial assets and liabilities. The update requires equity investments, in general, to be measured at fair value with changes in fair value recognized in earnings. It also eliminates the requirement to disclose the methods and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost, requires entities to use the exit price notion when measuring fair value, requires an entity to present separately in other comprehensive income the portion of the total change in fair value of a liability resulting from a change in the instrument-specific credit risk when the fair value option has been elected, requires separate presentation of financial assets and liabilities by measurement category and form on the balance sheet or accompanying notes, clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity's other deferred tax assets, and simplifies the impairment assessment of equity investments without readily determinable fair values. The ASU is effective for the Company for interim and annual periods beginning after December 15, 2017. Upon adoption, unrealized gains and losses from equity securities will be reclassified from other comprehensive income to retained earnings. At September 30, 2017, the Company had $2.2 million of net unrealized gains included in accumulated other comprehensive income. FASB Accounting Standards Update No. 2016-02, Leases (Topic 842) ("ASU 2016-02") On February 25, 2016, the FASB issued ASU 2016-02 to increase transparency and comparability by recognizing lease assets and liabilities on the balance sheet and disclosing key information about leasing arrangements. Lessees will be required to recognize an obligation for future lease payments measured on a discounted basis and a right-of-use asset. The ASU is effective for the Company for interim and annual periods beginning after December 15, 2018 and requires transition through a modified retrospective approach for leases existing at or entered into after January 1, 2017. The Company is evaluating the impact the adoption of ASU 2016-02 will have on the Company's financial statements. FASB Accounting Standards Update No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting ("ASU 2016-09") On March 30, 2016, the FASB issued ASU 2016-09 to simplify multiple aspects of accounting for employee share-based payment transactions including accounting for income taxes, forfeitures, and statutory tax withholding requirements. The ASU became effective for annual reporting periods beginning after December 15, 2016, including interim periods within those annual reporting periods. Implementation of ASU 2016-09 decreased tax expense $2.5 million in the first nine months of 2017. FASB Accounting Standards Update No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Assets Measured at Amortized Cost ("ASU 2016-13") On June 16, 2016, the FASB issued ASU 2016-13 in order to provide more timely recording of credit losses on loans and other financial instruments. The ASU adds an impairment model (known as the current expected credit loss ("CECL") model) that is based on expected credit losses rather than incurred credit losses. It requires measurement of all expected credit losses for financial assets carried at amortized cost, including loans and investment securities, based on historical experience, current conditions, and reasonable and supportable forecasts. ASU 2016-13 also changes the recognition of other-than-temporary impairment of available for sale securities to an allowance methodology from a direct write-down methodology. ASU 2016-13 will be effective for the Company for annual reporting periods beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for annual reporting periods beginning after December 15, 2018. ASU 2016-13 will be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The Company is evaluating the impact the adoption of ASU 2016-13 will have on the Company's financial statements. FASB Accounting Standards Update No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments ("ASU 2016-15") On August 26, 2016, the FASB issued ASU 2016-15, which amends guidance in ASC 230 on the classification of certain cash receipts and payments in the statement of cash flows. The amendments address eight cash flow issues. ASU 2016-15 is effective for the Company for interim and annual reporting periods beginning after December 15, 2017. Entities generally must apply the guidance retrospectively to all periods presented. Adoption of ASU 2016-15 is not expected to have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities ("ASU 2017-12") On August 28, 2017, the FASB issued ASU 2017-12, which amends the hedge accounting recognition and presentation requirements in ASC815 in order to improve transparency and understandability of information and reduce the complexity. The update expands the types of transactions eligible for hedge accounting, eliminates the requirement to separately measure and present hedge ineffectiveness, simplifies hedge effectiveness assessments and updates documentation and presentation requirements. ASU 2017-12 is effective for the Company for fiscal years beginning after December 15, 2018, and interim periods therein; however, early adoption is permitted. The Company is evaluating the impact the adoption of ASU 2017-12 will have on the Company's financial statements.

Securities

9 Months Ended

Sep. 30, 2017

Marketable Securities [Abstract]

Securities [Text Block]

Securities

Trading Securities

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



	September 30, 2017					December 31, 2016					September 30, 2016
	Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)
U.S. government agency debentures	$	30,162	$	(101	)	$	6,234	$	(4	)	$	15,705	$	(7	)
U.S. government agency residential mortgage-backed securities	516,760		723			310,067		635			464,749		876
Municipal and other tax-exempt securities	56,148		153			14,427		50			54,856		(100		)
Other trading securities	11,047		23			6,900		57			11,305		14
Total trading securities	$	614,117	$	798		$	337,628	$	738		$	546,615	$	783

Investment Securities

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



	September 30, 2017
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss
Municipal and other tax-exempt	$	246,000	$	249,250	$	3,415	$	(165	)
U.S. government agency residential mortgage-backed securities – Other	16,926		17,458		594		(62		)
Other debt securities	203,636		223,187		20,141		(590		)
Total investment securities	$	466,562	$	489,895	$	24,150	$	(817	)


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



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


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



	September 30, 2016
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss
Municipal and other tax-exempt	$	323,225	$	327,788	$	4,745	$	(182	)
U.S. government agency residential mortgage-backed securities – Other	22,166		23,452		1,286		—
Other debt securities	201,066		229,070		28,014		(10		)
Total investment securities	$	546,457	$	580,310	$	34,045	$	(192	)


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

The amortized cost and fair values of investment securities at September 30, 2017, by contractual maturity, are as shown in the following table (dollars in thousands):



	Less than One Year			One to Five Years			Six to Ten Years			Over Ten Years			Total			Weighted Average Maturity²
Municipal and other tax-exempt:
Amortized cost	$	84,786		$	107,938		$	16,132		$	37,144		$	246,000		3.51
Fair value	84,835			108,352			16,776			39,287			249,250
Nominal yield¹	1.75		%	2.15		%	4.68		%	5.21		%	2.64		%
Other debt securities:
Amortized cost	13,546			47,077			130,494			12,519			203,636			6.40
Fair value	13,688			50,230			147,066			12,203			223,187
Nominal yield	4.10		%	4.86		%	5.75		%	4.47		%	5.35		%
Total fixed maturity securities:
Amortized cost	$	98,332		$	155,015		$	146,626		$	49,663		$	449,636		4.82
Fair value	98,523			158,582			163,842			51,490			472,437
Nominal yield	2.08		%	2.97		%	5.63		%	5.02		%	3.87		%
Residential mortgage-backed securities:
Amortized cost													$	16,926		³
Fair value													17,458
Nominal yield⁴													2.76		%
Total investment securities:
Amortized cost													$	466,562
Fair value													489,895
Nominal yield													3.83		%


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


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


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


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

Available for Sale Securities

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



	September 30, 2017
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss			OTTI²
U.S. Treasury	$	1,000	$	999	$	—	$	(1	)	$	—
Municipal and other tax-exempt	28,411		28,368		240		(283		)	—
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	3,103,869		3,108,822		25,510		(20,557		)	—
FHLMC	1,331,212		1,330,159		6,630		(7,683		)	—
GNMA	864,256		862,394		3,254		(5,116		)	—
Other	25,000		25,009		51		(42		)	—
Total U.S. government agencies	5,324,337		5,326,384		35,445		(33,398		)	—
Private issue:
Alt-A loans	35,853		46,695		10,842		—			—
Jumbo-A loans	44,944		53,299		8,355		—			—
Total private issue	80,797		99,994		19,197		—			—
Total residential mortgage-backed securities	5,405,134		5,426,378		54,642		(33,398		)	—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,899,828		2,889,346		5,577		(16,059		)	—
Other debt securities	4,400		4,153		—		(247		)	—
Perpetual preferred stock	12,562		16,245		3,683		—			—
Equity securities and mutual funds	17,803		17,710		655		(748		)	—
Total available for sale securities	$	8,369,138	$	8,383,199	$	64,797	$	(50,736	)	$	—

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

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



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

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

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



	September 30, 2016
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss			OTTI²
U.S. Treasury	$	1,000	$	1,002	$	2	$	—		$	—
Municipal and other tax-exempt	41,943		42,092		602		(453		)	—
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	3,035,041		3,101,136		67,859		(1,764		)	—
FHLMC	1,611,887		1,641,178		29,640		(349		)	—
GNMA	924,176		926,358		3,530		(1,348		)	—
Total U.S. government agencies	5,571,104		5,668,672		101,029		(3,461		)	—
Private issue:
Alt-A loans	47,039		54,065		7,230		—			(204		)
Jumbo-A loans	61,377		67,538		6,187		(26		)	—
Total private issue	108,416		121,603		13,417		(26		)	(204		)
Total residential mortgage-backed securities	5,679,520		5,790,275		114,446		(3,487		)	(204		)
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,942,988		2,986,495		45,329		(1,822		)	—
Other debt securities	4,400		4,151		—		(249		)	—
Perpetual preferred stock	15,562		19,578		4,016		—			—
Equity securities and mutual funds	17,337		18,690		1,370		(17		)	—
Total available for sale securities	$	8,702,750	$	8,862,283	$	165,765	$	(6,028	)	$	(204	)


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


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

The amortized cost and fair values of available for sale securities at September 30, 2017, by contractual maturity, are as shown in the following table (dollars in thousands):



	Less than One Year			One to Five Years			Six to Ten Years			Over Ten Years				Total			Weighted Average Maturity⁵
U.S. Treasuries:
Amortized cost	$	1,000		$	—		$	—		$	—			$	1,000		0.29
Fair value	999			—			—			—				999
Nominal yield	0.87		%	—		%	—		%	—		%		0.87		%
Municipal and other tax-exempt:
Amortized cost	$	8,754		$	4,163		$	—		$	15,494			$	28,411		9.00
Fair value	8,780			4,313			—			15,275				28,368
Nominal yield¹	3.25		%	5.13		%	—		%	2.26		%	⁶	2.99		%
Commercial mortgage-backed securities:
Amortized cost	$	59,483		$	978,565		$	1,616,383		$	245,397			$	2,899,828		6.90
Fair value	59,402			976,466			1,610,642			242,836				2,889,346
Nominal yield	1.25		%	1.85		%	1.92		%	1.92		%		1.88		%
Other debt securities:
Amortized cost	$	—		$	—		$	—		$	4,400			$	4,400		29.91
Fair value	—			—			—			4,153				4,153
Nominal yield	—		%	—		%	—		%	1.71		%	⁶	1.71		%
Total fixed maturity securities:
Amortized cost	$	69,237		$	982,728		$	1,616,383		$	265,291			$	2,933,639		6.96
Fair value	69,181			980,779			1,610,642			262,264				2,922,866
Nominal yield	1.50		%	1.86		%	1.92		%	1.93		%		1.88		%
Residential mortgage-backed securities:
Amortized cost														$	5,405,134		²
Fair value														5,426,378
Nominal yield⁴														1.99		%
Equity securities and mutual funds:
Amortized cost														$	30,365		³
Fair value														33,955
Nominal yield														—		%
Total available-for-sale securities:
Amortized cost														$	8,369,138
Fair value														8,383,199
Nominal yield														1.95		%


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


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


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


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


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


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

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



	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Proceeds	$	265,632		$	232,239		$	966,044		$	1,027,379
Gross realized gains	2,768			2,415			7,623			11,705
Gross realized losses	(281		)	(21		)	(2,707		)	(21		)
Related federal and state income tax expense	967			931			1,912			4,545

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



	Sept. 30, 2017		Dec. 31, 2016		Sept. 30, 2016
Investment:
Amortized cost	$	237,525	$	322,208	$	301,754
Fair value	241,208		323,808		307,264

Available for sale:
Amortized cost	6,559,615		7,353,116		7,098,721
Fair value	6,551,240		7,327,470		7,213,520

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

At September 30, 2017, trading securities and receivables collateralized by securities with a fair value of $224 million were pledged as collateral at the Federal Home Loan Bank (FHLB) for the trading activities of BOK Financial Securities, Inc. No trading securities were pledged as collateral as of December 31, 2016 and no trading securities were pledged as collateral at September 30, 2016.

Temporarily Impaired Securities as of September 30, 2017

(in thousands):



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investment:
Municipal and other tax-exempt	63	$	80,235	$	70	$	9,795	$	95	$	90,030	$	165
U.S. government agency residential mortgage-backed securities – Other	1	3,578		62		—		—		3,578		62
Other debt securities	28	10,022		566		427		24		10,449		590
Total investment securities	92	$	93,835	$	698	$	10,222	$	119	$	104,057	$	817



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available for sale:
U.S. Treasury	1	$	999	$	1	$	—	$	—	$	999	$	1
Municipal and other tax-exempt	11	576		1		4,785		282		5,361		283
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	81	1,054,171		10,288		480,994		10,269		1,535,165		20,557
FHLMC	42	477,823		3,546		198,478		4,137		676,301		7,683
GNMA	17	166,565		1,718		124,037		3,398		290,602		5,116
Other	1	19,958		42		—		—		19,958		42
Total U.S. government agencies	141	1,718,517		15,594		803,509		17,804		2,522,026		33,398
Private issue:
Alt-A loans	—	—		—		—		—		—		—
Jumbo-A loans	—	—		—		—		—		—		—
Total private issue	—	—		—		—		—		—		—
Total residential mortgage-backed securities	141	1,718,517		15,594		803,509		17,804		2,522,026		33,398
Commercial mortgage-backed securities guaranteed by U.S. government agencies	137	1,154,911		7,194		559,984		8,865		1,714,895		16,059
Other debt securities	2	—		—		4,153		247		4,153		247
Perpetual preferred stocks	—	—		—		—		—		—		—
Equity securities and mutual funds	91	3,672		696		1,428		52		5,100		748
Total available for sale securities	383	$	2,878,675	$	23,486	$	1,373,859	$	27,250	$	4,252,534	$	50,736

Temporarily Impaired Securities as of December 31, 2016

(In thousands)



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



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


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

Temporarily Impaired Securities as of September 30, 2016

(In thousands)



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investment:
Municipal and other tax-exempt	75	$	100,624	$	106	$	4,359	$	76	$	104,983	$	182
U.S. government agency residential mortgage-backed securities – Other	—	—		—		—		—		—		—
Other debt securities	3	444		6		856		4		1,300		10
Total investment securities	78	$	101,068	$	112	$	5,215	$	80	$	106,283	$	192



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available for sale:
U.S. Treasury	—	$	—	$	—	$	—	$	—	$	—	$	—
Municipal and other tax-exempt¹	20	2,210		3		6,396		450		8,606		453
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	14	365,201		1,712		14,229		52		379,430		1,764
FHLMC	6	122,713		91		20,306		258		143,019		349
GNMA	16	230,043		1,157		212,705		191		442,748		1,348
Total U.S. government agencies	36	717,957		2,960		247,240		501		965,197		3,461
Private issue¹:
Alt-A loans	5	8,231		141		7,773		63		16,004		204
Jumbo-A loans	1	6,583		26		—		—		6,583		26
Total private issue	6	14,814		167		7,773		63		22,587		230
Total residential mortgage-backed securities	42	732,771		3,127		255,013		564		987,784		3,691
Commercial mortgage-backed securities guaranteed by U.S. government agencies	33	372,805		1,656		60,851		166		433,656		1,822
Other debt securities	2	—		—		4,151		249		4,151		249
Perpetual preferred stocks	—	—		—		—		—		—		—
Equity securities and mutual funds	33	86		—		886		17		972		17
Total available for sale securities	130	$	1,107,872	$	4,786	$	327,297	$	1,446	$	1,435,169	$	6,232


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

For debt securities, management determines whether it intends to sell or if it is more-likely-than-not that it will be required to sell impaired securities. This determination considers current and forecasted liquidity requirements, regulatory and capital requirements and securities portfolio management. Impaired equity securities, including perpetual preferred stocks, are evaluated based on the near-term prospects of the investment in relation to the severity and duration of the impairment and management's ability and intent to hold the securities until fair value recovers. Based on this evaluation as of September 30, 2017, the Company does not intend to sell any impaired available for sale securities before fair value recovers to the current amortized cost and it is more-likely-than-not that the Company will not be required to sell impaired securities before fair value recovers, which may be maturity.

Fair Value Option Securities

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

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



	September 30, 2017				December 31, 2016					September 30, 2016
	Fair Value		Net Unrealized Gain (Loss)		Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)
U.S. Treasury	$	—	$	—	$	—	$	—		$	222,409	$	(2,397	)
U.S. government agency residential mortgage-backed securities	819,531		1,671		77,046		(1,777		)	—		—
Total	$	819,531	$	1,671	$	77,046	$	(1,777	)	$	222,409	$	(2,397	)

Restricted Equity Securities

Restricted equity securities primarily include stock we are required to hold as members of the Federal Reserve system and the Federal Home Loan Banks. Restricted equity securities are carried at cost as these securities do not have a readily determined fair value because ownership of these shares are restricted and they lack a market. A summary of restricted equity securities follows (in thousands):



	Sept. 30, 2017		Dec. 31, 2016		Sept. 30, 2016
Federal Reserve stock	$	36,676	$	36,498	$	36,283
Federal Home Loan Bank stock	310,622		270,541		296,907
Other	244		201		201
Total	$	347,542	$	307,240	$	333,391

Derivatives

9 Months Ended

Sep. 30, 2017

Derivative Instrument Detail [Abstract]

Derivatives [Text Block]

Derivatives

Derivative instruments may be used by the Company as part of its internal risk management programs or may be offered to customers. All derivative instruments are carried at fair value and changes in fair value are reported in earnings as they occur. Credit risk is also considered in determining fair value.

When bilateral netting agreements or similar arrangements exist between the Company and its counterparties that create a single legal claim or obligation to pay or receive the net amount in settlement of the individual derivative contracts, the Company reports derivative assets and liabilities on a net by derivative contract type by counterparty basis.

Derivative contracts may require the Company to provide or receive cash margin as collateral for derivative assets and liabilities. Derivative assets and liabilities are reported net of cash margin when certain conditions are met. In addition, derivative contracts executed with customers under Customer Risk Management Programs may be secured by non-cash collateral in conjunction with a credit agreement with that customer. Access to collateral in the event of default is reasonably assured.

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

Customer Risk Management Programs

BOK Financial offers programs to permit its customers to manage various risks, including fluctuations in energy, cattle and other agricultural products, interest rates and foreign exchange rates with derivative contracts. Customers may also manage interest rate risk through interest rate swaps used by borrowers to modify interest rate terms of their loans or to-be-announced securities used by mortgage banking customers to hedge their loan production. Derivative contracts are executed between the customers and BOK Financial. Offsetting contracts are executed between BOK Financial and other selected counterparties to minimize the risk of changes in commodity prices, interest rates or foreign exchange rates. The counterparty contracts are identical to customer contracts, except for a fixed pricing spread or fee paid to BOK Financial as profit and compensation for administrative costs and credit risk which is recognized over the life of the contracts and included in other operating revenue – brokerage and trading revenue in the Consolidated Statements of Earnings.

Internal Risk Management Programs

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

As discussed in Note 6, certain derivative contracts not designated as hedging instruments related to mortgage loan commitments and forward sales contracts are included in Residential mortgage loans held for sale on the Consolidated Balance Sheets. See Note 6 for additional discussion of notional, fair value and impact on earnings of these contracts.

The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at September 30, 2017 (in thousands):



	Assets
	Notional¹		Gross Fair Value		Netting Adjustments			Net Fair Value Before Cash Collateral		Cash Collateral			Fair Value Net of Cash Collateral
Customer risk management programs:
Interest rate contracts
To-be-announced residential mortgage-backed securities	$	14,244,442	$	38,875	$	(9,547	)	$	29,328	$	—		$	29,328
Interest rate swaps	1,368,210		27,016		—			27,016		(2,820		)	24,196
Energy contracts	983,794		45,368		(35,166		)	10,202		(238		)	9,964
Agricultural contracts	60,745		1,870		(1,172		)	698		—			698
Foreign exchange contracts	252,525		249,788		—			249,788		—			249,788
Equity option contracts	101,841		4,871		—			4,871		(920		)	3,951
Total customer risk management programs	17,011,557		367,788		(45,885		)	321,903		(3,978		)	317,925
Internal risk management programs	11,941,260		34,634		—			34,634		—			34,634
Total derivative contracts	$	28,952,817	$	402,422	$	(45,885	)	$	356,537	$	(3,978	)	$	352,559

	Liabilities
	Notional¹		Gross Fair Value		Netting Adjustments			Net Fair Value Before Cash Collateral		Cash Collateral			Fair Value Net of Cash Collateral
Customer risk management programs:
Interest rate contracts
To-be-announced residential mortgage-backed securities	$	14,244,442	$	34,948	$	(9,547	)	$	25,401	$	(374	)	$	25,027
Interest rate swaps	1,368,230		27,056		—			27,056		(16,599		)	10,457
Energy contracts	939,350		42,744		(35,166		)	7,578		—			7,578
Agricultural contracts	60,746		1,846		(1,172		)	674		—			674
Foreign exchange contracts	249,269		245,925		—			245,925		(1,395		)	244,530
Equity option contracts	101,841		4,871		—			4,871		—			4,871
Total customer risk management programs	16,963,878		357,390		(45,885		)	311,505		(18,368		)	293,137
Internal risk management programs	9,180,531		43,190		—			43,190		—			43,190
Total derivative contracts	$	26,144,409	$	400,580	$	(45,885	)	$	354,695	$	(18,368	)	$	336,327


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

The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at December 31, 2016 (in thousands):



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

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


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

The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at September 30, 2016 (in thousands):



	Assets
	Notional¹		Gross Fair Value		Netting Adjustments			Net Fair Value Before Cash Collateral		Cash Collateral			Fair Value Net of Cash Collateral
Customer risk management programs:
Interest rate contracts
To-be-announced residential mortgage-backed securities	$	20,078,974	$	90,999	$	(38,678	)	$	52,321	$	—		$	52,321
Interest rate swaps	1,323,045		49,279		—			49,279		(794		)	48,485
Energy contracts	729,202		41,775		(28,464		)	13,311		(288		)	13,023
Agricultural contracts	53,002		3,950		(1,571		)	2,379		(1,076		)	1,303
Foreign exchange contracts	550,828		536,264		—			536,264		(7,577		)	528,687
Equity option contracts	103,464		4,654		—			4,654		(730		)	3,924
Total customer risk management programs	22,838,515		726,921		(68,713		)	658,208		(10,465		)	647,743
Internal risk management programs	2,298,038		7,335		—			7,335		—			7,335
Total derivative contracts	$	25,136,553	$	734,256	$	(68,713	)	$	665,543	$	(10,465	)	$	655,078

	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	$	19,776,883	$	86,812	$	(38,678	)	$	48,134	$	(39,042	)	$	9,092
Interest rate swaps	1,323,045		49,518		—			49,518		(34,457		)	15,061
Energy contracts	695,835		40,888		(28,464		)	12,424		(3,857		)	8,567
Agricultural contracts	52,997		3,943		(1,571		)	2,372		—			2,372
Foreign exchange contracts	550,943		536,660		—			536,660		(5,396		)	531,264
Equity option contracts	103,464		4,654		—			4,654		—			4,654
Total customer risk management programs	22,503,167		722,475		(68,713		)	653,762		(82,752		)	571,010
Internal risk management programs	1,485,691		2,977		—			2,977		—			2,977
Total derivative contracts	$	23,988,858	$	725,452	$	(68,713	)	$	656,739	$	(82,752	)	$	573,987


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

The following summarizes the pre-tax net gains (losses) on derivative instruments and where they are recorded in the income statement (in thousands):



	Three Months Ended
	September 30, 2017					September 30, 2016
	Brokerage and Trading Revenue			Gain (Loss) on Derivatives, Net		Brokerage and Trading Revenue			Gain (Loss)on Derivatives, Net
Customer risk management programs:
Interest rate contracts
To-be-announced residential mortgage-backed securities	$	9,181		$	—	$	11,584		$	—
Interest rate swaps	767			—		710			—
Energy contracts	378			—		1,222			—
Agricultural contracts	38			—		25			—
Foreign exchange contracts	164			—		218			—
Equity option contracts	—			—		—			—
Total customer risk management programs	10,528			—		13,759			—
Internal risk management programs	(711		)	1,033		(1,608		)	2,226
Total derivative contracts	$	9,817		$	1,033	$	12,151		$	2,226



	Nine Months Ended
	September 30, 2017				September 30, 2016
	Brokerage and Trading Revenue		Gain (Loss) on Derivatives, Net		Brokerage and Trading Revenue			Gain (Loss) on Derivatives, Net
Customer risk management programs:
Interest rate contracts
To-be-announced residential mortgage-backed securities	$	26,413	$	—	$	28,886		$	—
Interest rate swaps	1,891		—		1,758			—
Energy contracts	4,917		—		4,667			—
Agricultural contracts	58		—		86			—
Foreign exchange contracts	524		—		730			—
Equity option contracts	—		—		—			—
Total customer risk management programs	33,803		—		36,127			—
Internal risk management programs	5,307		3,824		(1,617		)	20,130
Total derivative contracts	$	39,110	$	3,824	$	34,510		$	20,130

Loans and Allowances for Credit Losses

9 Months Ended

Sep. 30, 2017

Loans Receivable, Net [Abstract]

Loans [Text Block]

Loans and Allowances for Credit Losses

Loans

Loans are either secured or unsecured based on the type of loan and the financial condition of the borrower. Repayment is generally expected from cash flow or proceeds from the sale of selected assets of the borrower. BOK Financial is exposed to risk of loss on loans due to the borrower’s difficulties, which may arise from any number of factors, including problems within the respective industry or local economic conditions. Access to collateral, in the event of borrower default, is reasonably assured through adherence to applicable lending laws and through sound lending standards and credit review procedures. Accounting policies for all loans, excluding residential mortgage loans guaranteed by U.S. government agencies, are as follows.

Interest is accrued at the applicable interest rate on the principal amount outstanding. Loans are placed on nonaccruing status when, in the opinion of management, full collection of principal or interest is uncertain. Internally risk graded loans are individually evaluated for nonaccruing status quarterly. Non-risk graded loans are generally placed on nonaccruing status when more than 90 days past due or within 60 days of being notified of the borrower's bankruptcy filing. Interest previously accrued but not collected is charged against interest income when the loan is placed on nonaccruing status. Payments on nonaccruing loans are applied to principal or recognized as interest income, according to management’s judgment as to the collectability of principal. Loans may be returned to accruing status when, in the opinion of management, full collection of principal and interest, including principal previously charged off, is probable based on improvements in the borrower’s financial condition or a sustained period of performance.

Loans to borrowers experiencing financial difficulties may be modified in troubled debt restructurings ("TDRs"). All TDRs are classified as nonaccruing, excluding loans guaranteed by U.S. government agencies. Modifications generally consist of extension of payment terms or interest rate concessions and may result either voluntarily through negotiations with the borrower or involuntarily through court order. Generally, principal and accrued but unpaid interest is not voluntarily forgiven.

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

All loans are charged off when the loan balance or a portion of the loan balance is no longer supported by the paying capacity of the borrower or when the required cash flow is reduced in a TDR. The charge-off amount is determined through a quarterly evaluation of available cash resources and collateral value and charge-offs are taken in the quarter in which the loss is identified. Non-risk graded loans that are past due between 60 days and 180 days, based on the loan product type, are charged off. Loans to borrowers whose personal obligation has been discharged through Chapter 7 bankruptcy proceedings are charged off within 60 days of notice of the bankruptcy filing, regardless of payment status.

Loan origination and commitment fees and direct loan acquisition and origination costs are deferred and amortized as an adjustment to yield over the life of the loan or over the commitment period, as applicable.

Qualifying residential mortgage loans guaranteed by U.S. government agencies have been sold into GNMA pools. Under certain performance conditions specified in government programs, the Company may have the right, but not the obligation to repurchase loans from GNMA pools. These loans no longer qualify for sale accounting and are recognized in the Consolidated Balance Sheets. Guaranteed loans are considered impaired because we do not expect to receive all principal and interest based on the loan's contractual terms. The principal balance continues to be guaranteed; however, interest accrues at a curtailed rate as specified in the programs. The carrying value of these loans is reduced based on an estimate of the expected cash flows discounted at the original note rate plus a liquidity spread. Guaranteed loans may be modified in TDRs in accordance with U.S. government agency guidelines. Interest continues to accrue based on the modified rate. Guaranteed loans may either be resold into GNMA pools after a performance period specified by the programs or foreclosed and conveyed to the guarantors.

Loans are disaggregated into portfolio segments and further disaggregated into classes. The portfolio segment is the level at which the Company develops and documents a systematic method for determining its allowance for credit losses. Classes are a further disaggregation of portfolio segments based on the risk characteristics of the loans and the Company’s method for monitoring and assessing credit risk.

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



	September 30, 2017								December 31, 2016
	Fixed Rate		Variable Rate		Non-accrual		Total		Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	2,225,470	$	8,393,564	$	176,900	$	10,795,934	$	2,327,085	$	7,884,786	$	178,953	$	10,390,824
Commercial real estate	564,681		2,950,486		2,975		3,518,142		624,187		3,179,338		5,521		3,809,046
Residential mortgage	1,589,013		311,231		45,506		1,945,750		1,647,357		256,255		46,220		1,949,832
Personal	153,750		793,003		255		947,008		154,971		684,697		290		839,958
Total	$	4,532,914	$	12,448,284	$	225,636	$	17,206,834	$	4,753,600	$	12,005,076	$	230,984	$	16,989,660
Accruing loans past due (90 days)¹							$	253							$	5



	September 30, 2016
	Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	1,991,423	$	7,952,276	$	176,464	$	10,120,163
Commercial real estate	565,429		3,220,819		7,350		3,793,598
Residential mortgage	1,572,288		248,053		52,452		1,872,793
Personal	104,408		573,138		686		678,232
Total	$	4,233,548	$	11,994,286	$	236,952	$	16,464,786
Accruing loans past due (90 days)¹							$	3,839


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

At September 30, 2017, $5.9 billion or 34 percent of our total loan portfolio is to businesses and individuals attributed to the Texas market and $3.4 billion or 20 percent of the total loan portfolio is to businesses and individuals attributed to the Oklahoma market. These geographic concentrations subject the loan portfolio to the general economic conditions within these areas.

Commercial

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

At September 30, 2017, commercial loans attributed to the Texas market totaled $3.7 billion or 34 percent of the commercial loan portfolio segment and commercial loans attributed to the Oklahoma market totaled $2.1 billion or 19 percent of the commercial loan portfolio segment.

The commercial loan portfolio segment is further divided into loan classes. The energy loan class totaled $2.9 billion or 17 percent of total loans at September 30, 2017, including $2.3 billion of outstanding loans to energy producers. Approximately 57 percent of committed production loans are secured by properties primarily producing oil and 43 percent are secured by properties producing natural gas. The services loan class totaled $3.0 billion or 17 percent of total loans at September 30, 2017. Approximately $1.5 billion of loans in the services category consist of loans with individual balances of less than $10 million. Businesses included in the services class include governmental, educational services, consumer services, loans to entities providing services for real estate and construction and commercial services. The healthcare loan class totaled $2.2 billion or 13 percent of total loans at September 30, 2017. The healthcare loan class consists primarily of loans for the development and operation of senior housing and care facilities, including independent living, assisted living and skilled nursing. Healthcare also includes loans to hospitals and other medical service providers.

Commercial Real Estate

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

At September 30, 2017, 35 percent of commercial real estate loans are secured by properties primarily located in the Dallas and Houston areas of Texas. An additional 13 percent of commercial real estate loans are secured by properties located primarily in the Tulsa and Oklahoma City metropolitan areas of Oklahoma.

Residential Mortgage and Personal

Residential mortgage loans provide funds for our customers to purchase or refinance their primary residence or to borrow against the equity in their home. Residential mortgage loans are secured by a first or second mortgage on the customer’s primary residence. Personal loans consist primarily of loans secured by the cash surrender value of insurance policies and marketable securities. It also includes direct loans secured by and for the purchase of automobiles, recreational and marine equipment as well as unsecured loans. Residential mortgage and personal loans are made in accordance with underwriting policies we believe to be conservative and are fully documented. Loans may be individually underwritten or credit scored based on size and other criteria. Credit scoring is assessed based on significant credit characteristics including credit history, residential and employment stability. Residential mortgage loans retained in the Company’s portfolio are primarily composed of various mortgage programs to support customer relationships including jumbo mortgage loans, non-builder construction loans and special loan programs for high net worth individuals and certain professionals. Jumbo loans may be fixed or variable rate and are fully amortizing. Jumbo loans generally conform to government sponsored entity standards, except that the loan size exceeds maximums required under these standards. These loans generally require a minimum FICO score of 720 and a maximum debt-to-income ratio (“DTI”) of 38 percent. Loan-to-value (“LTV”) ratios are tiered from 60 percent to 100 percent, depending on the market. Special mortgage programs include fixed and variable fully amortizing loans tailored to the needs of certain healthcare professionals. Variable rate loans are fully indexed at origination and may have fixed rates for three to ten years, then adjust annually thereafter.

At September 30, 2017, residential mortgage loans included $187 million of loans guaranteed by U.S. government agencies previously sold into GNMA mortgage pools. These loans either have been repurchased or are eligible to be repurchased by the Company when certain defined delinquency criteria are met. Although payments on these loans generally are past due more than 90 days, interest continues to accrue based on the government guarantee.

Home equity loans totaled $744 million at September 30, 2017. Approximately 64 percent of the home equity loan portfolio is comprised of first lien loans and 36 percent of the home equity portfolio is comprised of junior lien loans. Junior lien loans are distributed 47 percent to amortizing term loans and 53 percent to revolving lines of credit. Home equity loans generally require a minimum FICO score of 700 and a maximum DTI of 40 percent. The maximum loan amount available for our home equity loan products is generally $400 thousand. Revolving loans have a 5 year revolving period followed by a 15 year term of amortizing repayments. Interest-only home equity loans may not be extended for any additional revolving time. All other home equity loans may be extended at management's discretion for an additional 5 year revolving term, subject to an update of certain credit information.

Credit Commitments

Commitments to extend credit are agreements to lend to a customer as long as there is no violation of conditions established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. At September 30, 2017, outstanding commitments totaled $9.7 billion. Because some commitments are expected to expire before being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. BOK Financial uses the same credit policies in making commitments as it does loans.

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

Standby letters of credit are conditional commitments issued to guarantee the performance of a customer to a third party. Because the credit risk involved in issuing standby letters of credit is essentially the same as that involved in extending loan commitments, BOK Financial uses the same credit policies in evaluating the creditworthiness of the customer. Additionally, BOK Financial uses the same evaluation process in obtaining collateral on standby letters of credit as it does for loan commitments. The term of these standby letters of credit is defined in each commitment and typically corresponds with the underlying loan commitment. At September 30, 2017, outstanding standby letters of credit totaled $666 million. Commercial letters of credit are used to facilitate customer trade transactions with the drafts being drawn when the underlying transaction is consummated. At September 30, 2017, outstanding commercial letters of credit totaled $2.3 million.

Allowances for Credit Losses

BOK Financial maintains an allowance for loan losses and an accrual for off-balance sheet credit risk. The accrual for off-balance sheet credit risk is maintained at a level that is appropriate to cover estimated losses associated with credit instruments that are not currently recognized as assets such as loan commitments, standby letters of credit or guarantees. As discussed in greater detail in Note 6, the Company also has separate accruals for off-balance sheet credit risk related to residential mortgage loans previously sold with full or partial recourse and for residential mortgage loans sold to government sponsored agencies under standard representations and warranties.

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

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

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

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

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

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

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

A provision for credit losses is charged against or credited to earnings in amounts necessary to maintain an appropriate allowance for credit losses. Recoveries of loans previously charged off are added to the allowance when received.

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit for the three months ended September 30, 2017 is summarized as follows (in thousands):



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

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

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit for the nine months ended September 30, 2017 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance			Total
Allowance for loan losses:
Beginning balance	$	140,213		$	50,749		$	18,224		$	8,773		$	28,200		$	246,159
Provision for loan losses	665			4,050			82			1,168			(122		)	5,843
Loans charged off	(6,556		)	(76		)	(444		)	(3,774		)	—			(10,850		)
Recoveries	2,479			1,682			531			1,859			—			6,551
Ending balance	$	136,801		$	56,405		$	18,393		$	8,026		$	28,078		$	247,703
Allowance for off-balance sheet credit losses:
Beginning balance	$	11,063		$	123		$	50		$	8		$	—		$	11,244
Provision for off-balance sheet credit losses	(5,738		)	(88		)	(11		)	(6		)	—			(5,843		)
Ending balance	$	5,325		$	35		$	39		$	2		$	—		$	5,401

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

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit for the three months ended September 30, 2016 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	145,139		$	46,745		$	18,690		$	6,001		$	26,684	$	243,259
Provision for loan losses	2,420			2,551			(466		)	1,900			1,502		7,907
Loans charged off	(6,266		)	—			(285		)	(1,550		)	—		(8,101		)
Recoveries	177			521			650			690			—		2,038
Ending balance	$	141,470		$	49,817		$	18,589		$	7,041		$	28,186	$	245,103
Allowance for off-balance sheet credit losses:
Beginning balance	$	8,752		$	203		$	62		$	28		$	—	$	9,045
Provision for off-balance sheet credit losses	2,170			(53		)	(7		)	(17		)	—		2,093
Ending balance	$	10,922		$	150		$	55		$	11		$	—	$	11,138

Total provision for credit losses	$	4,590		$	2,498		$	(473	)	$	1,883		$	1,502	$	10,000

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit for the nine months ended September 30, 2016 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance			Total
Allowance for loan losses:
Beginning balance	$	130,334		$	41,391		$	19,509		$	4,164		$	30,126		$	225,524
Provision for loan losses	45,995			7,538			(829		)	4,809			(1,940		)	55,573
Loans charged off	(35,747		)	—			(1,104		)	(4,086		)	—			(40,937		)
Recoveries	888			888			1,013			2,154			—			4,943
Ending balance	$	141,470		$	49,817		$	18,589		$	7,041		$	28,186		$	245,103
Allowance for off-balance sheet credit losses:
Beginning balance	$	1,506		$	153		$	30		$	22		$	—		$	1,711
Provision for off-balance sheet credit losses	9,416			(3		)	25			(11		)	—			9,427
Ending balance	$	10,922		$	150		$	55		$	11		$	—		$	11,138

Total provision for credit losses	$	55,411		$	7,535		$	(804	)	$	4,798		$	(1,940	)	$	65,000

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at September 30, 2017 is as follows (in thousands):



	Collectively Measured for Impairment				Individually Measured for Impairment				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,619,034	$	123,517	$	176,900	$	13,284	$	10,795,934	$	136,801
Commercial real estate	3,515,167		56,405		2,975		—		3,518,142		56,405
Residential mortgage	1,900,244		18,393		45,506		—		1,945,750		18,393
Personal	946,753		8,026		255		—		947,008		8,026
Total	16,981,198		206,341		225,636		13,284		17,206,834		219,625

Nonspecific allowance	—		—		—		—		—		28,078

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

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2016 is as follows (in thousands):



	Collectively Measured for Impairment				Individually Measured for Impairment				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,211,871	$	139,416	$	178,953	$	797	$	10,390,824	$	140,213
Commercial real estate	3,803,525		50,749		5,521		—		3,809,046		50,749
Residential mortgage	1,903,612		18,178		46,220		46		1,949,832		18,224
Personal	839,668		8,773		290		—		839,958		8,773
Total	16,758,676		217,116		230,984		843		16,989,660		217,959

Nonspecific allowance	—		—		—		—		—		28,200

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

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at September 30, 2016 is as follows (in thousands):



	Collectively Measured for Impairment				Individually Measured for Impairment				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	9,943,699	$	134,968	$	176,464	$	6,502	$	10,120,163	$	141,470
Commercial real estate	3,786,248		49,817		7,350		—		3,793,598		49,817
Residential mortgage	1,820,341		18,527		52,452		62		1,872,793		18,589
Personal	677,546		7,041		686		—		678,232		7,041
Total	16,227,834		210,353		236,952		6,564		16,464,786		216,917

Nonspecific allowance	—		—		—		—		—		28,186

Total	$	16,227,834	$	210,353	$	236,952	$	6,564	$	16,464,786	$	245,103

Credit Quality Indicators

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

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



	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,750,657	$	135,846	$	45,277	$	955	$	10,795,934	$	136,801
Commercial real estate	3,518,142		56,405		—		—		3,518,142		56,405
Residential mortgage	226,306		3,068		1,719,444		15,325		1,945,750		18,393
Personal	856,030		6,043		90,978		1,983		947,008		8,026
Total	15,351,135		201,362		1,855,699		18,263		17,206,834		219,625

Nonspecific allowance	—		—		—		—		—		28,078

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

The allowance for loan losses and recorded investment of the related loans by portfolio segment for risk graded and non-risk graded loans at December 31, 2016 is as follows (in thousands):



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

Nonspecific allowance	—		—		—		—		—		28,200

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

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



	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,093,884	$	140,552	$	26,279	$	918	$	10,120,163	$	141,470
Commercial real estate	3,793,598		49,817		—		—		3,793,598		49,817
Residential mortgage	206,430		3,028		1,666,363		15,561		1,872,793		18,589
Personal	586,869		4,182		91,363		2,859		678,232		7,041
Total	14,680,781		197,579		1,784,005		19,338		16,464,786		216,917

Nonspecific allowance	—		—		—		—		—		28,186

Total	$	14,680,781	$	197,579	$	1,784,005	$	19,338	$	16,464,786	$	245,103

Loans are considered to be performing if they are in compliance with the original terms of the agreement and currently exhibit no factors that cause management to have doubts about the borrowers' ability to remain in compliance with the original terms of the agreement, which is consistent with the regulatory guideline of “pass.” Performing loans also include past due residential mortgages that are guaranteed by agencies of the U.S. government that continue to accrue interest based on criteria of the guarantors' programs. Other loans especially mentioned are currently performing in compliance with the original terms of the agreement but may have a potential weakness that deserves management’s close attention, consistent with regulatory guidelines.

The risk grading process identified certain loans that have a well-defined weakness (e.g. inadequate debt service coverage or liquidity or marginal capitalization; repayment may depend on collateral or other risk mitigation) that may jeopardize liquidation of the debt and represent a greater risk due to deterioration in the financial condition of the borrower. This is consistent with the regulatory guideline for “substandard.” Because the borrowers are still performing in accordance with the original terms of the loan agreements, these loans were not placed in nonaccruing status.

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

The following table summarizes the Company’s loan portfolio at September 30, 2017 by the risk grade categories (in thousands):



	Internally Risk Graded								Non-Graded
	Performing
	Pass		Other Loans Especially Mentioned		Accruing Substandard		Nonaccrual		Performing		Nonaccrual		Total
Commercial:
Energy	$	2,436,465	$	114,065	$	206,768	$	110,683	$	—	$	—	$	2,867,981
Services	2,932,577		26,372		7,390		1,174		—		—		2,967,513
Wholesale/retail	1,637,698		9,021		9,486		1,893		—		—		1,658,098
Manufacturing	486,383		7,181		16,823		9,059		—		—		519,446
Healthcare	2,150,099		31,855		33,051		24,446		—		—		2,239,451
Other commercial and industrial	458,796		52		9,820		29,500		45,132		145		543,445
Total commercial	10,102,018		188,546		283,338		176,755		45,132		145		10,795,934

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

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

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

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

The following table summarizes the Company’s loan portfolio at December 31, 2016 by the risk grade categories (in thousands):



	Internally Risk Graded								Non-Graded
	Performing
	Pass		Other Loans Especially Mentioned		Accruing Substandard		Nonaccrual		Performing		Nonaccrual		Total
Commercial:
Energy	$	1,937,790	$	119,583	$	307,996	$	132,499	$	—	$	—	$	2,497,868
Services	3,052,002		10,960		37,855		8,173		—		—		3,108,990
Wholesale/retail	1,535,463		16,886		13,062		11,407		—		—		1,576,818
Manufacturing	468,314		26,532		15,198		4,931		—		—		514,975
Healthcare	2,140,458		44,472		16,161		825		—		—		2,201,916
Other commercial and industrial	433,789		5,309		—		21,060		30,041		58		490,257
Total commercial	9,567,816		223,742		390,272		178,895		30,041		58		10,390,824

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

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

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

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

The following table summarizes the Company’s loan portfolio at September 30, 2016 by the risk grade categories (in thousands):



	Internally Risk Graded								Non-Graded
	Performing
	Pass		Other Loans Especially Mentioned		Accruing Substandard		Nonaccrual		Performing		Nonaccrual		Total
Commercial:
Energy	$	1,869,598	$	147,153	$	361,087	$	142,966	$	—	$	—	$	2,520,804
Services	2,882,065		14,861		31,196		8,477		—		—		2,936,599
Wholesale/retail	1,557,067		15,337		27,173		2,453		—		—		1,602,030
Manufacturing	470,702		8,774		19,736		274		—		—		499,486
Healthcare	2,022,757		42,224		19,210		855		—		—		2,085,046
Other commercial and industrial	415,769		2,478		10,302		21,370		26,210		69		476,198
Total commercial	9,217,958		230,827		468,704		176,395		26,210		69		10,120,163

Commercial real estate:
Residential construction and land development	155,737		—		470		3,739		—		—		159,946
Retail	794,920		4,802		406		1,249		—		—		801,377
Office	750,924		899		—		882		—		—		752,705
Multifamily	868,501		—		5,221		51		—		—		873,773
Industrial	837,945		—		—		76		—		—		838,021
Other commercial real estate	366,416		—		7		1,353		—		—		367,776
Total commercial real estate	3,774,443		5,701		6,104		7,350		—		—		3,793,598

Residential mortgage:
Permanent mortgage	200,590		1,192		2,134		2,514		739,686		23,442		969,558
Permanent mortgages guaranteed by U.S. government agencies	—		—		—		—		174,877		15,432		190,309
Home equity	—		—		—		—		701,862		11,064		712,926
Total residential mortgage	200,590		1,192		2,134		2,514		1,616,425		49,938		1,872,793

Personal	585,287		228		923		431		91,108		255		678,232

Total	$	13,778,278	$	237,948	$	477,865	$	186,690	$	1,733,743	$	50,262	$	16,464,786

Impaired Loans

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

A summary of impaired loans follows (in thousands):



	As of										For the				For the
	September 30, 2017										Three Months Ended				Nine Months Ended
			Recorded Investment								September 30, 2017				September 30, 2017
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance		Average Recorded Investment		Interest Income Recognized		Average Recorded Investment		Interest Income Recognized
Commercial:
Energy	$	133,643	$	110,683	$	45,169	$	65,514	$	4,944	$	117,338	$	—	$	121,591	$	—
Services	3,838		1,174		1,174		—		—		4,464		—		4,674		—
Wholesale/retail	8,418		1,893		1,893		—		—		6,256		—		6,650		—
Manufacturing	9,674		9,059		9,059		—		—		9,357		—		6,995		—
Healthcare	24,591		24,446		474		23,972		8,323		24,476		—		12,635		—
Other commercial and industrial	38,222		29,645		29,626		19		17		25,138		—		25,382		—
Total commercial	218,386		176,900		87,395		89,505		13,284		187,029		—		177,927		—

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

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

Personal	290		255		255		—		—		263		—		273		—

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


¹	All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At September 30, 2017, $8.9 million of these loans were nonaccruing and $178 million were accruing based on the guarantee by U.S. government agencies.

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

A summary of impaired loans at December 31, 2016 follows (in thousands):



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

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

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

Personal	332		290		290		—		—

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


¹	All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2016, $12 million of these loans were nonaccruing and $188 million were accruing based on the guarantee by U.S. government agencies.

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



											For the				For the
	As of September 30, 2016										Three Months Ended				Nine Months Ended
			Recorded Investment								September 30, 2016				September 30, 2016
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance		Average Recorded Investment		Interest Income Recognized		Average Recorded Investment		Interest Income Recognized
Commercial:
Energy	$	179,578	$	142,966	$	100,300	$	42,666	$	6,502	$	155,555	$	—	$	85,333	$	—
Services	11,858		8,477		8,477		—		—		8,932		—		9,384		—
Wholesale/retail	8,528		2,453		2,453		—		—		2,613		—		2,686		—
Manufacturing	642		274		274		—		—		284		—		303		—
Healthcare	1,168		855		855		—		—		865		—		964		—
Other commercial and industrial	29,176		21,439		21,439		—		—		10,978		—		11,031		—
Total commercial	230,950		176,464		133,798		42,666		6,502		179,227		—		109,701		—

Commercial real estate:
Residential construction and land development	6,090		3,739		3,739		—		—		4,000		—		4,074		—
Retail	1,914		1,249		1,249		—		—		1,257		—		1,284		—
Office	1,187		882		882		—		—		744		—		766		—
Multifamily	1,000		51		51		—		—		58		—		163		—
Industrial	76		76		76		—		—		76		—		76		—
Other commercial real estate	7,375		1,353		1,353		—		—		1,430		—		1,813		—
Total commercial real estate	17,642		7,350		7,350		—		—		7,565		—		8,176		—

Residential mortgage:
Permanent mortgage	32,372		25,956		25,847		109		62		26,592		292		27,470		923
Permanent mortgage guaranteed by U.S. government agencies¹	196,162		190,309		190,309		—		—		190,547		2,098		193,879		5,893
Home equity	12,099		11,064		11,064		—		—		10,578		—		10,710		—
Total residential mortgage	240,633		227,329		227,220		109		62		227,717		2,390		232,059		6,816

Personal	724		686		686		—		—		520		—		575		—

Total	$	489,949	$	411,829	$	369,054	$	42,775	$	6,564	$	415,029	$	2,390	$	350,511	$	6,816


¹	All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At September 30, 2016, $15 million of these loans were nonaccruing and $175 million were accruing based on the guarantee by U.S. government agencies.

Troubled Debt Restructurings

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



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

Commercial:
Energy	$	9,582	$	9,506	$	76	$	—	$	4,322	$	4,322
Services	720		103		617		—		7		10
Wholesale/retail	1,802		—		1,802		—		—		—
Manufacturing	180		180		—		—		—		—
Healthcare	—		—		—		—		—		—
Other commercial and industrial	20,097		19,890		207		—		—		—
Total commercial	32,381		29,679		2,702		—		4,329		4,332

Commercial real estate:
Residential construction and land development	327		91		236		—		—		—
Retail	289		289		—		—		—		—
Office	—		—		—		—		—		—
Multifamily	—		—		—		—		—		—
Industrial	—		—		—		—		—		—
Other commercial real estate	353		353		—		—		—		—
Total commercial real estate	969		733		236		—		—		—

Residential mortgage:
Permanent mortgage	14,765		10,188		4,577		—		—		—
Permanent mortgage guaranteed by U.S. government agencies	5,601		523		5,078		—		—		—
Home equity	5,625		4,213		1,412		—		39		70
Total residential mortgage	25,991		14,924		11,067		—		39		70

Personal	205		195		10		—		2		10

Total nonaccruing TDRs	$	59,546	$	45,531	$	14,015	$	—	$	4,370	$	4,412

Accruing TDRs:
Permanent mortgages guaranteed by U.S. government agencies	69,440		14,948		54,492		—		—		—

Total TDRs	$	128,986	$	60,479	$	68,507	$	—	$	4,370	$	4,412

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



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

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

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

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

Personal	237		236		1		—

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

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

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

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



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

Commercial:
Energy	$	1,746	$	—	$	1,746	$	—	$	500	$	1,000
Services	7,761		7,034		727		—		—		—
Wholesale/retail	2,327		2,287		40		—		—		—
Manufacturing	238		238		—		—		—		—
Healthcare	623		—		623		—		—		—
Other commercial and industrial	497		61		436		—		—		57
Total commercial	13,192		9,620		3,572		—		500		1,057

Commercial real estate:
Residential construction and land development	794		359		435		—		—		—
Retail	1,249		892		357		—		—		—
Office	149		149		—		—		—		—
Multifamily	—		—		—		—		—		—
Industrial	—		—		—		—		—		—
Other commercial real estate	666		666		—		—		—		—
Total commercial real estate	2,858		2,066		792		—		—		—

Residential mortgage:
Permanent mortgage	16,109		11,944		4,165		62		—		2
Permanent mortgage guaranteed by U.S. government agencies	8,220		2,331		5,889		—		—		—
Home equity	5,168		4,667		501		—		34		153
Total residential mortgage	29,497		18,942		10,555		62		34		155

Personal	273		271		2		—		9		18

Total nonaccruing TDRs	$	45,820	$	30,899	$	14,921	$	62	$	543	$	1,230

Accruing TDRs:
Permanent mortgages guaranteed by U.S. government agencies	80,306		29,020		51,286		—		—		—

Total TDRs	$	126,126	$	59,919	$	66,207	$	62	$	543	$	1,230

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



	Three Months Ended Sept. 30, 2017
	Accruing						Nonaccrual						Total
	Payment Stream		Combination & Other		Total		Payment Stream		Combination & Other		Total
Commercial:
Energy	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Services	—		—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—		—
Healthcare	—		—		—		—		—		—		—
Other commercial and industrial	—		—		—		—		60		60		60
Total commercial	—		—		—		—		60		60		60

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

Residential mortgage:
Permanent mortgage	—		—		—		969		506		1,475		1,475
Permanent mortgage guaranteed by U.S. government agencies	8,205		620		8,825		315		—		315		9,140
Home equity	—		—		—		—		469		469		469
Total residential mortgage	8,205		620		8,825		1,284		975		2,259		11,084

Personal	—		—		—		—		4		4		4

Total	$	8,205	$	620	$	8,825	$	1,284	$	1,039	$	2,323	$	11,148



	Nine Months Ended Sept. 30, 2017
	Accruing							Nonaccrual							Total
		Payment Stream		Combination & Other		Total			Payment Stream		Combination & Other		Total
Commercial:
Energy		$	—	$	—	$	—		$	7,781	$	—	$	7,781	$	7,781
Services		—		—		—			—		—		—		—
Wholesale/retail		—		—		—			—		—		—		—
Manufacturing		—		—		—			—		—		—		—
Healthcare		—		—		—			—		—		—		—
Other commercial and industrial		—		—		—			19,825		60		19,885		19,885
Total commercial		—		—		—			27,606		60		27,666		27,666

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

Residential mortgage:
Permanent mortgage		—		—		—			153		1,559		1,712		1,712
Permanent mortgage guaranteed by U.S. government agencies		18,678		2,649		21,327			443		85		528		21,855
Home equity		—		—		—			104		1,468		1,572		1,572
Total residential mortgage		18,678		2,649		21,327			700		3,112		3,812		25,139

Personal		—		—		—			—		48		48		48

Total		$	18,678	$	2,649	$	21,327		$	28,306	$	3,220	$	31,526	$	52,853

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



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

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

Residential mortgage:
Permanent mortgage	—		—		—		—		151		151		151
Permanent mortgage guaranteed by U.S. government agencies	3,527		4,211		7,738		—		287		287		8,025
Home equity	—		—		—		—		920		920		920
Total residential mortgage	3,527		4,211		7,738		—		1,358		1,358		9,096

Personal	—		—		—		—		19		19		19

Total	$	3,527	$	4,211	$	7,738	$	—	$	1,377	$	1,377	$	9,115



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

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

Residential mortgage:
Permanent mortgage	—		—		—		1,037		1,051		2,088		2,088
Permanent mortgage guaranteed by U.S. government agencies	9,687		9,350		19,037		—		982		982		20,019
Home equity	—		—		—		48		1,630		1,678		1,678
Total residential mortgage	9,687		9,350		19,037		1,085		3,663		4,748		23,785

Personal	—		—		—		—		82		82		82

Total	$	9,687	$	9,350	$	19,037	$	1,586	$	3,745	$	5,331	$	24,368

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



	Three Months Ended Sept. 30, 2017						Nine Months Ended Sept. 30, 2017
	Accruing		Nonaccrual		Total		Accruing		Nonaccrual		Total
Commercial:
Energy	$	—	$	7,857	$	7,857	$	—	$	9,582	$	9,582
Services	—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—
Healthcare	—		—		—		—		—		—
Other commercial and industrial	—		—		—		—		19,825		19,825
Total commercial	—		7,857		7,857		—		29,407		29,407

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

Residential mortgage:
Permanent mortgage	—		1,511		1,511		—		1,511		1,511
Permanent mortgage guaranteed by U.S. government agencies	23,620		878		24,498		24,349		878		25,227
Home equity	—		1,030		1,030		—		1,139		1,139
Total residential mortgage	23,620		3,419		27,039		24,349		3,528		27,877

Personal	—		10		10		—		10		10

Total	$	23,620	$	11,286	$	34,906	$	24,349	$	32,945	$	57,294

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



	Three Months Ended Sept. 30, 2016						Nine Months Ended Sept. 30, 2016
	Accruing		Nonaccrual		Total		Accruing		Nonaccrual		Total
Commercial:
Energy	$	—	$	1,746	$	1,746	$	—	$	1,746	$	1,746
Services	—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—
Healthcare	—		—		—		—		—		—
Other commercial and industrial	—		—		—		—		—		—
Total commercial	—		1,746		1,746		—		1,746		1,746

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

Residential mortgage:
Permanent mortgage	—		298		298		—		542		542
Permanent mortgage guaranteed by U.S. government agencies	17,491		1,095		18,586		19,352		1,121		20,473
Home equity	—		258		258		—		258		258
Total residential mortgage	17,491		1,651		19,142		19,352		1,921		21,273

Personal	—		11		11		—		11		11

Total	$	17,491	$	3,408	$	20,899	$	19,352	$	3,678	$	23,030

Nonaccrual & Past Due Loans

Past due status for all loan classes is based on the actual number of days since the last payment was due according to the contractual terms of the loans.

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



			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	2,752,259	$	—	$	5,039	$	—	$	110,683	$	2,867,981
Services	2,963,746		2,343		250		—		1,174		2,967,513
Wholesale/retail	1,654,018		1,748		409		30		1,893		1,658,098
Manufacturing	508,231		—		2,156		—		9,059		519,446
Healthcare	2,214,849		156		—		—		24,446		2,239,451
Other commercial and industrial	513,748		52		—		—		29,645		543,445
Total commercial	10,606,851		4,299		7,854		30		176,900		10,795,934

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

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

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

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

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



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

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

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

Personal	838,811		589		263	5		290		839,958

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

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



			Past Due
	Current		30 to 59 Days		60 to 89 Days	90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	2,365,850	$	11,988	—	$	—	$	142,966	$	2,520,804
Services	2,923,874		502		39	3,707		8,477		2,936,599
Wholesale/retail	1,599,356		221		—	—		2,453		1,602,030
Manufacturing	499,212		—		—	—		274		499,486
Healthcare	2,083,556		635		—	—		855		2,085,046
Other commercial and industrial	454,538		34		68	119		21,439		476,198
Total commercial	9,926,386		13,380		107	3,826		176,464		10,120,163

Commercial real estate:
Residential construction and land development	156,207		—		—	—		3,739		159,946
Retail	796,362		3,766		—	—		1,249		801,377
Office	751,823		—		—	—		882		752,705
Multifamily	868,591		—		5,131	—		51		873,773
Industrial	837,945		—		—	—		76		838,021
Other commercial real estate	366,416		7		—	—		1,353		367,776
Total commercial real estate	3,777,344		3,773		5,131	—		7,350		3,793,598

Residential mortgage:
Permanent mortgage	939,853		3,547		202	—		25,956		969,558
Permanent mortgages guaranteed by U.S. government agencies	41,150		17,364		12,963	103,400		15,432		190,309
Home equity	700,031		1,526		305	—		11,064		712,926
Total residential mortgage	1,681,034		22,437		13,470	103,400		52,452		1,872,793

Personal	677,194		191		148	13		686		678,232

Total	$	16,061,958	$	39,781	18,856	$	107,239	$	236,952	$	16,464,786

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

Mortgage Banking Activities [Text Block]

Acquisitions	9 Months Ended
Acquisitions	Sep. 30, 2017
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	Acquisitions On December 1, 2016, the Company acquired MBT Bancshares (“MBT”), parent company of Missouri Bank and Trust of Kansas City (“Mobank”) following regulatory approval of the transaction. Mobank operated four banking branches in the Kansas City, Mo. area. BOK Financial paid $102.5 million in an all-cash deal for all outstanding shares of MBT stock. MBT was merged into BOK Financial and Mobank became a wholly owned subsidiary of BOK Financial on December 1, 2016. On February 21, 2017, Mobank was merged with the Bank of Kansas City division of BOKF, NA. All branches in the Kansas City market will operate under the Mobank name. The preliminary purchase price allocation was updated in the first quarter of 2017 resulting in a $2.0 million increase in identifiable intangibles, $1.5 million decrease in premises and equipment and other repossessed assets, and a $526 thousand decrease in goodwill.

Mortgage Banking Activities

9 Months Ended

Sep. 30, 2017

Mortgage Banking [Abstract]

Mortgage Banking Activities

Residential Mortgage Loan Production

The Company originates, markets and services conventional and government-sponsored residential mortgage loans. Generally, conforming fixed rate residential mortgage loans are held for sale in the secondary market and non-conforming and adjustable-rate residential mortgage loans are retained for investment. Residential mortgage loans originated for sale by the Company are carried at fair value based on sales commitments and market quotes. Changes in the fair value of mortgage loans held for sale are included in Other operating revenue – Mortgage banking revenue. Residential mortgage loans held for sale also includes the fair value of residential mortgage loan commitments and forward sale commitments which are considered derivative contracts that have not been designated as hedging instruments for accounting purposes. The volume of mortgage loans originated for sale and secondary market prices are the primary drivers of originating and marketing revenue.

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

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



	September 30, 2017				December 31, 2016				September 30, 2016
	Unpaid Principal Balance/ Notional		Fair Value		Unpaid Principal Balance/ Notional		Fair Value		Unpaid Principal Balance/ Notional		Fair Value
Residential mortgage loans held for sale	$	261,868	$	265,783	$	286,414	$	286,971	$	422,523	$	433,040
Residential mortgage loan commitments	334,337		9,066		318,359		9,733		630,804		18,598
Forward sales contracts	524,878		794		569,543		5,193		929,907		(4,046		)
			$	275,643			$	301,897			$	447,592

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

Mortgage banking revenue was as follows (in thousands):



	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Production revenue:
Net realized gains on sale of mortgage loans	$	12,041		$	23,110		$	32,443		$	47,424
Net change in unrealized gain on mortgage loans held for sale	(1,492		)	(2,518		)	3,335			4,649
Net change in the fair value of mortgage loan commitments	(1,927		)	(6,901		)	(667		)	10,464
Net change in the fair value of forward sales contracts	(293		)	8,267			(4,399		)	(4,846		)
Total production revenue	8,329			21,958			30,712			57,691
Servicing revenue	16,561			16,558			49,645			47,809
Total mortgage banking revenue	$	24,890		$	38,516		$	80,357		$	105,500

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

Residential Mortgage Servicing

Mortgage servicing rights may be originated or purchased. Both originated and purchased mortgage servicing rights are initially recognized at fair value. The Company has elected to carry all mortgage servicing rights at fair value. Changes in the fair value are recognized in earnings as they occur. The unpaid principal balance of loans serviced for others is the primary driver of servicing revenue.

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



	September 30, 2017			December 31, 2016			September 30, 2016
Number of residential mortgage loans serviced for others	137,359			139,340			139,587
Outstanding principal balance of residential mortgage loans serviced for others	$	22,063,121		$	21,997,568		$	21,851,536
Weighted average interest rate	3.95		%	3.97		%	4.01		%
Remaining term (in months)	298			301			302

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



	Purchased			Originated			Total
Balance, June 30, 2017	$	7,995		$	237,244		$	245,239
Additions, net	—			9,925			9,925
Change in fair value due to principal payments	(470		)	(8,197		)	(8,667		)
Change in fair value due to market assumption changes	303			(942		)	(639		)
Balance, September 30, 2017	$	7,828		$	238,030		$	245,858



	Purchased			Originated			Total
Balance, December 31, 2016	$	8,909		$	238,164		$	247,073
Additions, net	—			29,439			29,439
Change in fair value due to principal payments	(1,443		)	(23,485		)	(24,928		)
Change in fair value due to market assumption changes	362			(6,088		)	(5,726		)
Balance, September 30, 2017	$	7,828		$	238,030		$	245,858

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



	Purchased			Originated			Total
Balance, June 30, 2016	$	4,067		$	186,680		$	190,747
Additions, net	—			21,990			21,990
Change in fair value due to scheduled payments and full-balance payoffs	(753		)	(10,690		)	(11,443		)
Change in fair value due to market assumption changes	251			2,076			2,327
Balance, September 30, 2016	$	3,565		$	200,056		$	203,621



	Purchased			Originated			Total
Balance, December 31, 2015	$	9,911		$	208,694		$	218,605
Additions, net	—			56,345			56,345
Change in fair value due to scheduled payments and full-balance payoffs	(2,109		)	(27,276		)	(29,385		)
Change in fair value due to market assumption changes	(4,237		)	(37,707		)	(41,944		)
Balance, September 30, 2016	$	3,565		$	200,056		$	203,621

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

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



	September 30, 2017	December 31, 2016	September 30, 2016
Discount rate – risk-free rate plus a market premium	9.84%	10.08%	10.08%
Prepayment rate - based upon loan interest rate, original term and loan type	8.71%-15.43%	8.98%-16.91%	9.16%-47.15%
Loan servicing costs – annually per loan based upon loan type:
Performing loans	$65-$120	$63 - $120	$63 - $120
Delinquent loans	$150-$500	$150 - $500	$150 - $500
Loans in foreclosure	$1,000-$4,250	$650 - $4,250	$650 - $4,250
Escrow earnings rate – indexed to rates paid on deposit accounts with comparable average life	2.00%	1.98%	1.18%
Primary/secondary mortgage rate spread	105 bps	105 bps	115 bps

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

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



			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Total
FHLMC	$	8,021,016	$	78,542	$	13,100	$	26,171	$	8,138,829
FNMA	6,635,428		76,065		10,398		20,596		6,742,487
GNMA	6,376,127		215,506		59,659		20,925		6,672,217
Other	502,768		3,492		1,167		2,161		509,588
Total	$	21,535,339	$	373,605	$	84,324	$	69,853	$	22,063,121

Commitments and Contingent Liabilities

9 Months Ended

Sep. 30, 2017

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingent Liabilities [Text Block]

Commitments and Contingent Liabilities

Litigation Contingencies

As a member of Visa, BOK Financial is obligated for a proportionate share of certain covered litigation losses incurred by Visa under a retrospective responsibility plan. A contingent liability was recognized for the Company’s share of Visa’s covered litigation liabilities. Visa funded an escrow account to cover litigation claims, including covered litigation losses under the retrospective responsibility plan, with proceeds from its initial public offering in 2008 and from available cash.

BOK Financial currently owns 252,233 Visa Class B shares which are convertible into 415,755 shares of Visa Class A shares after the final settlement of all covered litigation. Class B shares may be diluted in the future if the escrow fund is not adequate to cover future covered litigation costs. Therefore, no value has been currently assigned to the Class B shares and no value may be assigned until the Class B shares are converted into a known number of Class A shares.

On June 24, 2015, the Bank received a complaint alleging that an employee had colluded with a bond issuer and an individual in misusing revenues pledged to municipal bonds for which the Bank served as trustee under the bond indenture. The Company conducted an investigation and concluded that employees in one of its Corporate Trust offices had, with respect to a single group of affiliated bond issuances, violated Company policies and procedures by waiving financial covenants, granting forbearances and accepting without disclosure to the bondholders, debt service payments from sources other than pledged revenues. The relationship manager was terminated. The Company reported the circumstances to, and cooperated with an investigation by, the Securities and Exchange Commission ("SEC"). On December 28, 2015, in an action brought by the SEC, the United States District Court for the District of New Jersey entered a judgment against the principals involved in issuing the bonds, precluding the principals from denying the alleged violations of the federal securities laws and requiring the principals to pay all outstanding principal, accrued interest, and other amounts required under the bond documents (now estimated to be approximately $48 million, less the value of the facilities securing repayment of the bonds), subject to oversight by a court appointed monitor. On September 7, 2016, the Bank agreed, and the SEC entered, a consent order finding that the Bank had violated Section 17(a) of the Securities Act of 1933 and Section 10(b) of the Securities Exchange Act and requiring the Bank to disgorge $1,067,721 of fees and pay a civil penalty of $600,000. The Bank has disgorged the fees and paid the penalty.

On August 26, 2016, the Bank was sued in the United States District Court for New Jersey by two bondholders in a putative class action on behalf of all holders of the bonds alleging the Bank participated in the fraudulent sale of securities by the principals. On September 14, 2016, the Bank was sued in the District Court of Tulsa County, Oklahoma by 19 bondholders alleging the Bank participated in the fraudulent sale of securities by the principals. Management has been advised by counsel that the Bank has valid defenses to the claims.

On September 15, 2017, the principal filed for protection under Chapter 11 of the United States Bankruptcy Code in the United States Bankruptcy Court for the Northern District of Georgia. The obligation of the principal to pay all principal and interest on the bonds is non-dischargeable in bankruptcy. The Bank expects the Court ordered payment plan will result in the payment of the bonds by the principals. Accordingly, no loss is probable at this time and no provision for loss has been made. If the payment plan does not result in payment of the bonds, a loss could become probable. A reasonable estimate cannot be made at this time though the amount could be material to the Company.

On March 14, 2017, the Bank was sued in the United States District Court for the Northern District of Oklahoma by bondholders in a second putative class action representing a different set of municipal securities. The bondholders in this second action allege two individuals purchased facilities from the principals who are the subject of the SEC New Jersey proceedings by means of the fraudulent sale of $60 million of municipal securities for which the Bank also served as indenture trustee. The bondholders allege the Bank failed to disclose that the seller of the purchased facilities had engaged in the conduct complained of in the New Jersey action. The Bank properly performed all duties as indenture trustee of this second set of municipal securities, timely commenced proceedings against the issuer of the securities when default occurred, is cooperating with the SEC in actions against the two principals, is not a target of the SEC proceedings, and has been advised by counsel that the Bank has valid defenses to the claims of these bondholders. It is the opinion of management that no loss is probable at this time.

The County of Bernalillo, New Mexico, commenced arbitration pursuant to the Arbitration Rules of FINRA seeking recovery of $5.6 million alleging that various municipal bonds purchased by the elected County Treasurer of Bernalillo County, New Mexico, from BOK Financial Securities, Inc. were unsuitable. The arbitration was conducted in July 2017. The arbitration panel found the County of Bernalillo’s complaint frivolous and awarded BOK Financial Securities, Inc. attorney fees and costs. The County has sued in the United States District Court for New Mexico to set aside the award of fees and costs to BOK Financial Securities but not the finding that the County's complaint was frivolous.

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

On March 7, 2017, a plaintiff filed a putative class action in the United States District Court for the Northern District of Texas alleging an extended overdraft fee charged by BOKF, NA is interest and exceeds permitted rates. BOKF, NA was previously sued in a class action in the United States District Court for the Northern District of Oklahoma making the same allegations. Pursuant to a motion to dismiss, the Northern District of Oklahoma Court action was dismissed. Other courts considering the question whether extended overdraft fees are interest have likewise determined such fees are not interest. BOKF, NA has moved to dismiss the action. Management is advised by counsel that a loss is not probable and that the loss, if any, cannot be reasonably estimated.

In the ordinary course of business, BOK Financial and its subsidiaries are subject to legal actions and complaints. Management believes, based upon the opinion of counsel, that the actions and liability or loss, if any, resulting from the final outcomes of the proceedings, will not have a material effect on the Company’s financial condition, results of operations or cash flows.

Alternative Investment Commitments

The Company sponsors two private equity funds and invests in several tax credit entities and other funds as permitted by banking regulations. Consolidation of these investments is based on the variable interest model determined by the nature of the entity. Variable interest entities are generally defined as entities that either do not have sufficient equity to finance their activities without support from other parties or whose equity investors lack a controlling financial interest. Variable interest entities are consolidated based on the determination that the Company is the primary beneficiary including the power to direct the activities that most significantly impact the variable interest's economic performance and the obligation to absorb losses of the variable interest or the right to receive benefits of the variable interest that could be significant to the variable interest.

BOKF Equity, LLC, an indirect wholly-owned subsidiary, is the general partner of two consolidated private equity funds (“the Funds”). The Funds provide alternative investment opportunities to certain customers, some of which are related parties, through unaffiliated limited partnerships. These unaffiliated limited partnerships generally invest in distressed assets, asset buy-outs or venture capital companies. As general partner, BOKF Equity, LLC has the power to direct activities that most significantly affect the Funds' performance and contingent obligations to make additional investments totaling $3.4 million at September 30, 2017. Substantially all of the obligations are offset by limited partner commitments. The Company does not accrue its contingent liability to fund investments. The Volcker Rule in Title VI of the Dodd-Frank Act will limit both the amount and structure of these types of investments.

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

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

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

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



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

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



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

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



	September 30, 2016
	Loans		Other assets		Other liabilities		Other borrowings		Non-controlling interests
Consolidated:
Private equity funds	$	—	$	18,420	$	—	$	—	$	15,946
Tax credit entities	10,000		11,740		—		10,964		10,000
Other	—		30,978		2,346		1,063		8,154
Total consolidated	$	10,000	$	61,138	$	2,346	$	12,027	$	34,100

Unconsolidated:
Tax credit entities	$	39,849	$	129,715	$	57,026	$	—	$	—
Other	—		30,272		13,653		—		—
Total unconsolidated	$	39,849	$	159,987	$	70,679	$	—	$	—

Other Commitments and Contingencies

At September 30, 2017, Cavanal Hill Funds’ assets included U.S. Treasury, cash management and tax-free money market funds. Assets of these funds consist of highly-rated, short-term obligations of the U.S. Treasury, corporate issuers and U.S. states and municipalities. The net asset value of units in these funds was $1.00 at September 30, 2017. An investment in these funds is not insured by the Federal Deposit Insurance Corporation or guaranteed by BOK Financial or any of its subsidiaries. BOK Financial may, but is not obligated to purchase assets from these funds to maintain the net asset value at $1.00. No assets were purchased from the funds in 2017 or 2016.

Shareholders' Equity

9 Months Ended

Sep. 30, 2017

Stockholders' Equity Note [Abstract]

Shareholders' Equity [Text Block]

Shareholders' Equity

On October 31, 2017, the Company declared a quarterly cash dividend of $0.45 per common share on or about November 27, 2017 to shareholders of record as of November 13, 2017.

Dividends declared were $0.44 per share and $1.32 per share during the three and nine months ended September 30, 2017 and $0.43 per share and $1.29 per share during the three and nine months ended September 30, 2016.

Accumulated Other Comprehensive Income (Loss)

AOCI includes unrealized gains and losses on available for sale ("AFS") securities and non-credit related unrealized losses on AFS securities for which an other-than-temporary impairment has been recorded in earnings. AOCI also includes unrealized gains on AFS securities that were transferred from AFS to investment securities in the third quarter of 2011. Such amounts are being amortized over the estimated remaining life of the security as an adjustment to yield, offsetting the related amortization of premium on the transferred securities. Unrealized losses on employee benefit plans will be reclassified into income as pension plan costs are recognized over the remaining service period of plan participants. Gains and losses in AOCI are net of deferred income taxes.

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



	Unrealized Gain (Loss) on
	Available for Sale Securities			Investment Securities Transferred from AFS			Employee Benefit Plans			Total
Balance, December 31, 2015	$	23,284		$	68		$	(1,765	)	$	21,587
Net change in unrealized gain (loss)	133,108			—			—			133,108
Reclassification adjustments included in earnings:
Interest revenue, Investment securities, Taxable securities	—			(112		)	—			(112		)
Gain on available for sale securities, net	(11,684		)	—			—			(11,684		)
Other comprehensive income (loss), before income taxes	121,424			(112		)	—			121,312
Federal and state income taxes¹	47,216			(44		)	—			47,172
Other comprehensive income (loss), net of income taxes	74,208			(68		)	—			74,140
Balance, September 30, 2016	$	97,492		$	—		$	(1,765	)	$	95,727

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


¹	Calculated using a 39 percent effective tax rate.

Earnings Per Share

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Earnings Per Share [Text Block]

Earnings Per Share



(In thousands, except share and per share amounts)	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Numerator:
Net income attributable to BOK Financial Corp. shareholders	$	85,649	$	74,277	$	262,152	$	182,642
Less: Earnings allocated to participating securities	888		916		2,817		2,275
Numerator for basic earnings per share – income available to common shareholders	84,761		73,361		259,335		180,367
Effect of reallocating undistributed earnings of participating securities	1		1		2		1
Numerator for diluted earnings per share – income available to common shareholders	$	84,762	$	73,362	$	259,337	$	180,368

Denominator:
Weighted average shares outstanding	65,423,258		65,895,430		65,432,313		66,031,497
Less: Participating securities included in weighted average shares outstanding	680,436		810,038		702,922		822,723
Denominator for basic earnings per common share	64,742,822		65,085,392		64,729,391		65,208,774
Dilutive effect of employee stock compensation plans¹	62,350		72,449		64,502		54,792
Denominator for diluted earnings per common share	64,805,172		65,157,841		64,793,893		65,263,566

Basic earnings per share	$	1.31	$	1.13	$	4.01	$	2.77
Diluted earnings per share	$	1.31	$	1.13	$	4.00	$	2.76
¹ Excludes employee stock options with exercise prices greater than current market price.	—		—		—		—

Reportable Segments

9 Months Ended

Sep. 30, 2017

Segment Reporting [Abstract]

Reportable Segments [Text Block]

Reportable Segments

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



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	157,080		$	25,576		$	11,169		$	24,627		$	218,452
Net interest revenue (expense) from internal sources	(24,173		)	12,213			9,604			2,356			—
Net interest revenue	132,907			37,789			20,773			26,983			218,452
Provision for credit losses	3,217			1,315			(623		)	(3,909		)	—
Net interest revenue after provision for credit losses	129,690			36,474			21,396			30,892			218,452
Other operating revenue	54,091			47,033			75,707			(1,121		)	175,710
Other operating expense	56,952			56,785			61,791			90,406			265,934
Net direct contribution	126,829			26,722			35,312			(60,635		)	128,228
Gain on financial instruments, net	4			1,686			—			(1,690		)	—
Change in fair value of mortgage servicing rights	—			(639		)	—			639			—
Gain (loss) on repossessed assets, net	(4,126		)	292			—			3,834			—
Corporate expense allocations	8,650			17,039			9,819			(35,508		)	—
Net income before taxes	114,057			11,022			25,493			(22,344		)	128,228
Federal and state income taxes	44,368			4,288			9,917			(16,135		)	42,438
Net income	69,689			6,734			15,576			(6,209		)	85,790
Net income attributable to non-controlling interests	—			—			—			141			141
Net income attributable to BOK Financial Corp. shareholders	$	69,689		$	6,734		$	15,576		$	(6,350	)	$	85,649

Average assets	$	17,558,390		$	9,115,319		$	6,992,021		$	(657,560	)	$	33,008,170

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



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	435,946		$	70,208		$	33,130		$	85,554		$	624,838
Net interest revenue (expense) from internal sources	(61,803		)	35,002			28,784			(1,983		)	—
Net interest revenue	374,143			105,210			61,914			83,571			624,838
Provision for credit losses	2,983			3,512			(676		)	(5,819		)	—
Net interest revenue after provision for credit losses	371,160			101,698			62,590			89,390			624,838
Other operating revenue	156,139			146,440			225,434			245			528,258
Other operating expense	168,517			166,027			182,816			244,170			761,530
Net direct contribution	358,782			82,111			105,208			(154,535		)	391,566
Gain on financial instruments, net	46			5,242			—			(5,288		)	—
Change in fair value of mortgage servicing rights	—			(5,726		)	—			5,726			—
Gain (loss) on repossessed assets, net	(2,728		)	253			—			2,475			—
Corporate expense allocations	26,144			50,947			30,438			(107,529		)	—
Net income before taxes	329,956			30,933			74,770			(44,093		)	391,566
Federal and state income taxes	128,353			12,033			29,086			(41,226		)	128,246
Net income	201,603			18,900			45,684			(2,867		)	263,320
Net income attributable to non-controlling interests	—			—			—			1,168			1,168
Net income attributable to BOK Financial Corp. shareholders	$	201,603		$	18,900		$	45,684		$	(4,035	)	$	262,152

Average assets	$	17,525,658		$	8,871,470		$	6,971,369		$	(591,059	)	$	32,777,438

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



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	123,599		$	22,098		$	9,274		$	32,875		$	187,846
Net interest revenue (expense) from internal sources	(15,052		)	9,263			$	7,401		(1,612		)	—
Net interest revenue	108,547			31,361			16,675			31,263			187,846
Provision for credit losses	5,601			1,157			(89		)	3,331			10,000
Net interest revenue after provision for credit losses	102,946			30,204			16,764			27,932			177,846
Other operating revenue	49,642			60,603			73,523			3,542			187,310
Other operating expense	53,375			60,964			64,426			79,323			258,088
Net direct contribution	99,213			29,843			25,861			(47,849		)	107,068
Gain (loss) on financial instruments, net	—			(1,087		)	(42		)	1,129			—
Change in fair value of mortgage servicing rights	—			2,327			—			(2,327		)	—
Gain on repossessed assets, net	1,486			161			—			(1,647		)	—
Corporate expense allocations	9,054			16,905			10,912			(36,871		)	—
Net income before taxes	91,645			14,339			14,907			(13,823		)	107,068
Federal and state income taxes	35,650			5,578			5,799			(15,071		)	31,956
Net income	55,995			8,761			9,108			1,248			75,112
Net income attributable to non-controlling interests	—			—			—			835			835
Net income attributable to BOK Financial Corp. shareholders	$	55,995		$	8,761		$	9,108		$	413		$	74,277

Average assets	$	16,934,587		$	8,827,816		$	6,413,735		$	470,335		$	32,646,473

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



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	358,713		$	65,897		$	21,620		$	106,800		$	553,030
Net interest revenue (expense) from internal sources	(44,259		)	27,492			$	22,258		(5,491		)	—
Net interest revenue	314,454			93,389			43,878			101,309			553,030
Provision for credit losses	34,024			4,177			(479		)	27,278			65,000
Net interest revenue after provision for credit losses	280,430			89,212			44,357			74,031			488,030
Other operating revenue	146,248			172,072			218,042			(6,096		)	530,266
Other operating expense	162,039			179,487			186,524			223,993			752,043
Net direct contribution	264,639			81,797			75,875			(156,058		)	266,253
Gain (loss) on financial instruments, net	—			30,539			(42		)	(30,497		)	—
Change in fair value of mortgage servicing rights	—			(41,944		)	—			41,944			—
Gain on repossessed assets, net	806			566			—			(1,372		)	—
Corporate expense allocations	26,681			49,513			31,864			(108,058		)	—
Net income before taxes	238,764			21,445			43,969			(37,925		)	266,253
Federal and state income taxes	92,879			8,342			17,104			(34,444		)	83,881
Net income	145,885			13,103			26,865			(3,481		)	182,372
Net loss attributable to non-controlling interests	—			—			—			(270		)	(270		)
Net income attributable to BOK Financial Corp. shareholders	$	145,885		$	13,103		$	26,865		$	(3,211	)	$	182,642

Average assets	$	16,958,999		$	8,763,564		$	5,916,545		$	410,075		$	32,049,183

Fair Value Measurements

9 Months Ended

Sep. 30, 2017

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. Certain assets and liabilities are recorded in the Company’s financial statements at fair value. Some are recorded on a recurring basis and some on a non-recurring basis.

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

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

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


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


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


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


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

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

Transfers between levels are recognized as of the end of the reporting period. There were no transfers in or out of quoted prices in active markets for identical instruments to significant other observable inputs or significant unobservable inputs during the three and nine months ended September 30, 2017 and 2016, respectively. Transfers between significant other observable inputs and significant unobservable inputs during the three and nine months ended September 30, 2017 and 2016 are included in the summary of changes in recurring fair values measured using unobservable inputs.

The underlying methods used by the third-party pricing services are considered in determining the primary inputs used to determine fair values. Management has evaluated the methodologies employed by the third-party pricing services by comparing the price provided by the pricing service with other sources, including brokers' quotes, sales or purchases of similar instruments and discounted cash flows to establish a basis for reliance on the pricing service values. Significant differences between the pricing service provided value and other sources are discussed with the pricing service to understand the basis for their values. Based on all observable inputs, management may adjust prices obtained from third-party pricing services to more appropriately reflect the prices that would be received to sell assets or paid to transfer liabilities in orderly transactions in the current market. No significant adjustments were made to prices provided by third-party pricing services at September 30, 2017, December 31, 2016 or September 30, 2016.

Assets and Liabilities Measured at Fair Value on a Recurring Basis

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



	Total		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Trading securities:
U.S. government agency debentures	$	30,162	$	—	$	30,162	$	—
U.S. government agency residential mortgage-backed securities	516,760		—		516,760		—
Municipal and other tax-exempt securities	56,148		—		56,148		—
Other trading securities	11,047		—		11,047		—
Total trading securities	614,117		—		614,117		—
Available for sale securities:
U.S. Treasury	999		999		—		—
Municipal and other tax-exempt securities	28,368		—		23,583		4,785
U.S. government agency residential mortgage-backed securities	5,326,384		—		5,326,384		—
Privately issued residential mortgage-backed securities	99,994		—		99,994		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,889,346		—		2,889,346		—
Other debt securities	4,153		—		—		4,153
Perpetual preferred stock	16,245		—		16,245		—
Equity securities and mutual funds	17,710		2,578		15,132		—
Total available for sale securities	8,383,199		3,577		8,370,684		8,938
Fair value option securities – U.S. government agency residential mortgage-backed securities	819,531		—		819,531		—
Residential mortgage loans held for sale	275,643		—		263,543		12,100
Mortgage servicing rights¹	245,858		—		—		245,858
Derivative contracts, net of cash collateral²	352,559		8,498		344,061		—
Liabilities:
Derivative contracts, net of cash collateral²	336,327		6,903		329,424		—


¹	A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 6, Mortgage Banking Activities.

²

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

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



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


¹	A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 6, Mortgage Banking Activities.

²

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

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



	Total		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Trading securities:
U.S. government agency debentures	$	15,705	$	—	$	15,705	$	—
U.S. government agency residential mortgage-backed securities	464,749		—		464,749		—
Municipal and other tax-exempt securities	54,856		—		54,856		—
Other trading securities	11,305		—		11,305		—
Total trading securities	546,615		—		546,615		—
Available for sale securities:
U.S. Treasury	1,002		1,002		—		—
Municipal and other tax-exempt securities	42,092		—		36,379		5,713
U.S. government agency residential mortgage-backed securities	5,668,672		—		5,668,672		—
Privately issued residential mortgage-backed securities	121,603		—		121,603		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,986,495		—		2,986,495		—
Other debt securities	4,151		—		—		4,151
Perpetual preferred stock	19,578		—		19,578		—
Equity securities and mutual funds	18,690		3,544		15,146		—
Total available for sale securities	8,862,283		4,546		8,847,873		9,864
Fair value option securities:
U.S. Treasury	222,409		222,409		—		—
U.S. government agency residential mortgage-backed securities	—		—		—		—
Total fair value option securities	222,409		222,409		—		—
Residential mortgage loans held for sale	447,592		—		438,291		9,301
Mortgage servicing rights¹	203,621		—		—		203,621
Derivative contracts, net of cash collateral²	655,078		5,575		649,503		—
Liabilities:
Derivative contracts, net of cash collateral²	573,987		1,308		572,679		—


¹	A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 6, Mortgage Banking Activities.

²

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

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

Securities

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

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

Derivatives

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

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

We also consider our own credit risk in determining the fair value of derivative contracts. Changes in our credit rating would affect the fair value of our derivative liabilities. In the event of a credit downgrade, the fair value of our derivative liabilities would increase. The change in the fair value would be recognized in earnings in the current period.

Residential Mortgage Loans Held for Sale

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

Other Assets - Private Equity Funds

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

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

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



	Available for Sale Securities
	Municipal and other tax-exempt securities		Other debt securities		Residential mortgage loans held for sale
Balance, June 30, 2017	$	4,655	$	4,152	$	12,735
Transfer to Level 3 from Level 2¹	—		—		176
Purchases	—		—		—
Proceeds from sales	—		—		(847		)
Redemptions and distributions	—		—		—
Gain recognized in earnings:
Mortgage banking revenue	—		—		36
Other comprehensive income:
Net change in unrealized gain	130		1		—
Balance, September 30, 2017	$	4,785	$	4,153	$	12,100


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



	Available for Sale Securities
	Municipal and other tax-exempt			Other debt securities		Residential mortgage loans held for sale
Balance, December 31, 2016	$	5,789		$	4,152	$	11,617
Transfer to Level 3 from Level 2¹	—			—		2,916
Purchases	—			—		—
Proceeds from sales	—			—		(2,549		)
Redemptions and distributions	(1,100		)	—		—
Gain (loss) recognized in earnings:
Mortgage banking revenue	—			—		116
Other comprehensive income (loss):
Net change in unrealized gain (loss)	96			1		—
Balance, September 30, 2017	$	4,785		$	4,153	$	12,100


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

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



	Available for Sale Securities
	Municipal and other tax-exempt securities			Other debt securities		Residential mortgage loans held for sale
Balance, June 30, 2016	$	9,600		$	4,151	$	9,749
Transfer to Level 3 from Level 2¹	—			—		442
Purchases	—			—		—
Proceeds from sales	—			—		(1,003		)
Redemptions and distributions	(3,975		)	—		—
Gain (loss) recognized in earnings:
Mortgage banking revenue	—			—		113
Other comprehensive income (loss):
Net change in unrealized gain (loss)	88			—		—
Balance, September 30, 2016	$	5,713		$	4,151	$	9,301


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



	Available for Sale Securities
	Municipal and other tax-exempt			Other debt securities		Residential mortgage loans held for sale
Balance, December 31, 2015	$	9,610		$	4,151	$	7,874
Transfer to Level 3 from Level 2¹	—			—		3,982
Purchases	—			—		—
Proceeds from sales	—			—		(2,365		)
Redemptions and distributions	(3,975		)	—		—
Gain (loss) recognized in earnings
Mortgage banking revenue	—			—		(190		)
Other comprehensive income (loss):
Net change in unrealized gain (loss)	78			—		—
Balance, September 30, 2016	$	5,713		$	4,151	$	9,301


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

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



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

Available for sale securities
Municipal and other tax-exempt securities	$	5,095	$	5,067	$	4,785	Discounted cash flows	¹	Interest rate spread	6.05%-6.05% (6.05%)	²
										92.25%-95.02% (93.91%)	³
Other debt securities	4,400		4,400		4,153		Discounted cash flows	¹	Interest rate spread	6.65%-6.73% (6.72%)	⁴
										94.38% - 94.38 (94.38%)	³

Residential mortgage loans held for sale	N/A		12,612		12,100		Quoted prices of loans sold in securitization transactions, with a liquidity discount applied		Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.	95.94%


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


²	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 352 to 467 basis points over average yields for comparable tax-exempt securities.


³	Represents fair value as a percentage of par value.


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

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



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

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


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


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


³	Represents fair value as a percentage of par value.


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

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



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

Available for sale securities
Municipal and other tax-exempt securities	$	6,195	$	6,162	$	5,713	Discounted cash flows	¹	Interest rate spread	5.60%-5.90% (5.85%)	²
										90.00%-93.79% (92.22%)	³
Other debt securities	4,400		4,400		4,151		Discounted cash flows	¹	Interest rate spread	5.98%-6.03% (6.02%)	⁴
										94.34% - 94.34 (94.34%)	³

Residential mortgage loans held for sale	N/A		9,957		9,301		Quoted prices of loans sold in securitization transactions, with a liquidity discount applied		Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.	93.41%


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


²	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 437 to 484 basis points over average yields for comparable tax-exempt securities.


³	Represents fair value as a percentage of par value.


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

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

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

The following represents the carrying value of assets measured at fair value on a non-recurring basis (and related losses) during the period. The carrying value represents only those assets with a balance at September 30, 2017 for which the fair value was adjusted during the nine months ended September 30, 2017:



							Fair Value Adjustments for the
	Carrying Value at September 30, 2017						Three Months Ended September 30, 2017 Recognized in:				Nine Months Ended September 30, 2017 Recognized in:
	Quoted Prices in Active Markets for Identical Instruments		Significant Other Observable Inputs		Significant Unobservable Inputs		Gross charge-offs against allowance for loan losses		Net losses and expenses of repossessed assets, net		Gross charge-offs against allowance for loan losses		Net losses and expenses of repossessed assets, net
Impaired loans	$	—	$	423	$	10,960	$	4,397	$	—	$	5,058	$	—
Real estate and other repossessed assets	—		4,392		6,845		—		4,683		—		4,915

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



	Carrying Value at September 30, 2016						Fair Value Adjustments for the Three Months Ended September 30, 2016 Recognized in:				Nine Months Ended September 30, 2016 Recognized in:
	Quoted Prices in Active Markets for Identical Instruments		Significant Other Observable Inputs		Significant Unobservable Inputs		Gross charge-offs against allowance for loan losses		Net losses and expenses of repossessed assets, net		Gross charge-offs against allowance for loan losses		Net losses and expenses of repossessed assets, net
Impaired loans	$	—	$	436	$	23,089	$	6,334	$	—	$	30,200	$	—
Real estate and other repossessed assets	—		6,048		1,927		—		480		—		1,260

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

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



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


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

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



	Fair Value		Valuation Technique(s)	Unobservable Input	Range (Weighted Average)
Impaired loans	$	23,089	Discounted cash flows	Recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs	23% - 59% (43%)¹
Real estate and other repossessed assets	1,927		Appraised value, as adjusted	Marketability adjustments off appraised value2	68% - 80% (71%)


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


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

Fair Value of Financial Instruments

The following table presents the carrying values and estimated fair values of all financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis as of September 30, 2017 (dollars in thousands):



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

The following table presents the carrying values and estimated fair values of all financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis as of December 31, 2016 (dollars in thousands):



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

The following table presents the carrying values and estimated fair values of all financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis as of September 30, 2016 (dollars in thousands):



	Carrying Value			Estimated Fair Value		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and due from banks	$	535,916		$	535,916	$	535,916	$	—	$	—
Interest-bearing cash and cash equivalents	2,080,978			2,080,978		2,080,978		—		—
Trading securities:								—
U.S. government agency debentures	15,705			15,705		—		15,705		—
U.S. government agency residential mortgage-backed securities	464,749			464,749		—		464,749		—
Municipal and other tax-exempt securities	54,856			54,856		—		54,856		—
Other trading securities	11,305			11,305		—		11,305		—
Total trading securities	546,615			546,615		—		546,615		—
Investment securities:
Municipal and other tax-exempt securities	323,225			327,788		—		327,788		—
U.S. government agency residential mortgage-backed securities	22,166			23,452		—		23,452		—
Other debt securities	201,066			229,070		—		229,070		—
Total investment securities	546,457			580,310		—		580,310		—
Available for sale securities:
U.S. Treasury	1,002			1,002		1,002		—		—
Municipal and other tax-exempt securities	42,092			42,092		—		36,379		5,713
U.S. government agency residential mortgage-backed securities	5,668,672			5,668,672		—		5,668,672		—
Privately issued residential mortgage-backed securities	121,603			121,603		—		121,603		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,986,495			2,986,495		—		2,986,495		—
Other debt securities	4,151			4,151		—		—		4,151
Perpetual preferred stock	19,578			19,578		—		19,578		—
Equity securities and mutual funds	18,690			18,690		3,544		15,146		—
Total available for sale securities	8,862,283			8,862,283		4,546		8,847,873		9,864
Fair value option securities:
U.S. Treasury	222,409			222,409		222,409		—		—
U.S. government agency residential mortgage-backed securities	—			—		—		—		—
Total fair value option securities	222,409			222,409		222,409		—		—
Residential mortgage loans held for sale	447,592			447,592		—		438,291		9,301
Loans:
Commercial	10,120,163			9,926,548		—		—		9,926,548
Commercial real estate	3,793,598			3,769,427		—		—		3,769,427
Residential mortgage	1,872,793			1,905,786		—		—		1,905,786
Personal	678,232			671,421		—		—		671,421
Total loans	16,464,786			16,273,182		—		—		16,273,182
Allowance for loan losses	(245,103		)	—		—		—		—
Loans, net of allowance	16,219,683			16,273,182		—		—		16,273,182
Mortgage servicing rights	203,621			203,621		—		—		203,621
Derivative instruments with positive fair value, net of cash collateral	655,078			655,078		5,575		649,503		—
Deposits with no stated maturity	18,925,873			18,925,873		—		—		18,925,873
Time deposits	2,169,631			2,163,947		—		—		2,163,947
Other borrowed funds	7,147,047			7,079,737		—		—		7,079,737
Subordinated debentures	144,631			148,360		—		148,360		—
Derivative instruments with negative fair value, net of cash collateral	573,987			573,987		1,308		572,679		—

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

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

Cash and Cash Equivalents

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

Securities

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

Loans

The fair value of loans, excluding loans held for sale, are based on discounted cash flow analyses using interest rates and credit and liquidity spreads currently being offered for loans with similar remaining terms to maturity and risk, adjusted for the impact of interest rate floors and ceilings, which are classified as Significant Unobservable Inputs. The fair values of loans were estimated to approximate their discounted cash flows less loan loss allowances allocated to these loans of $220 million at September 30, 2017, $218 million at December 31, 2016 and $217 million at September 30, 2016. A summary of assumptions used in determining the fair value of loans follows:



	Range of Contractual Yields	Average Re-pricing (in years)	Discount Rate
September 30, 2017:
Commercial	0.38% - 30.00%	0.62	0.78% - 4.59%
Commercial real estate	0.38% - 18.00%	0.77	1.04% - 4.38%
Residential mortgage	1.74% - 18.00%	2.12	1.79% - 4.09%
Personal	0.25% - 21.00%	0.24	0.55% - 4.78%

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

September 30, 2016:
Commercial	0.38% - 30.00%	0.69	0.54% - 3.93%
Commercial real estate	0.38% - 18.00%	0.72	0.80% - 3.90%
Residential mortgage	1.74% - 18.00%	1.95	1.57% - 3.55%
Personal	0.25% - 21.00%	0.35	0.75% - 4.15%

Deposits

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

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



	Range of Contractual Yields	Average Re-pricing (in years)	Discount Rate
September 30, 2017	0.03% - 9.64%	1.95	1.86% - 2.18%
December 31, 2016	0.02% - 9.65%	1.96	1.57% - 2.00%
September 30, 2016	0.03% - 9.65%	2.10	1.37% - 1.66%

Other Borrowings and Subordinated Debentures

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



	Range of Contractual Yields	Average Re-pricing (in years)	Discount Rate
September 30, 2017:
Other borrowed funds	0.25% - 6.25%	0.02	1.06% - 3.70%
Subordinated debentures	5.38%	16.85	4.96%

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

September 30, 2016:
Other borrowed funds	0.25% - 3.81%	0.02	0.29% - 2.99%
Subordinated debentures	5.38%	18.37	5.38%

Off-Balance Sheet Instruments

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

Fair Value Election

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

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

Income Tax Disclosure [Text Block]

Federal and State Income Taxes Federal and State Income Taxes

9 Months Ended

Sep. 30, 2017

Income Tax Disclosure [Abstract]

Federal and State Income Taxes

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



	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Amount:
Federal statutory tax	$	44,880		$	37,474		$	137,048		$	93,189
Tax exempt revenue	(3,001		)	(2,391		)	(9,336		)	(7,491		)
Effect of state income taxes, net of federal benefit	2,486			1,364			7,875			5,222
Utilization of tax credits:
Low-income housing tax credit, net of amortization	(23		)	(623		)	(2,272		)	(2,505		)
Other tax credits	(364		)	(522		)	(1,091		)	(1,564		)
Bank-owned life insurance	(705		)	(813		)	(2,252		)	(2,414		)
Share-based compensation	(169		)	—			(2,470		)	—
Other, net	(666		)	(2,533		)	744			(556		)
Total income tax expense	$	42,438		$	31,956		$	128,246		$	83,881



	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Percent of pretax income:
Federal statutory tax	35.0	%	35.0	%	35.0	%	35.0	%
Tax exempt revenue	(2.3	)	(2.2	)	(2.4	)	(2.8	)
Effect of state income taxes, net of federal benefit	1.9		1.3		2.0		2.0
Utilization of tax credits:
Low-income housing tax credit, net of amortization	—		(0.6	)	(0.6	)	(0.9	)
Other tax credits	(0.3	)	(0.5	)	(0.3	)	(0.6	)
Bank-owned life insurance	(0.5	)	(0.8	)	(0.6	)	(0.9	)
Share-based compensation	(0.1	)	—		(0.6	)	—
Other, net	(0.6	)	(2.4	)	0.3		(0.3	)
Total	33.1	%	29.8	%	32.8	%	31.5	%

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company evaluated events from the date of the consolidated financial statements on September 30, 2017 through the issuance of those consolidated financial statements included in this Quarterly Report on Form 10-Q. No events were identified requiring recognition in and/or disclosure in the consolidated financial statements.

Significant Accounting Policies (Policies)	9 Months Ended
Significant Accounting Policies (Policies)	Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	The accompanying unaudited consolidated financial statements of BOK Financial Corporation (“BOK Financial” or “the Company”) have been prepared in accordance with accounting principles for interim financial information generally accepted in the United States and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included.
Principles of Consolidation [Policy Text Block]	The unaudited consolidated financial statements include accounts of BOK Financial and its subsidiaries, principally BOKF, NA (“the Bank”), BOK Financial Securities, Inc., The Milestone Group, Inc. and Cavanal Hill Investment Management Inc. Operating divisions of the Bank include Bank of Albuquerque, Bank of Arizona, Bank of Arkansas, Bank of Oklahoma, Bank of Texas, Colorado State Bank and Trust, Mobank, BOK Financial Mortgage and the TransFund electronic funds network.
Reclassification, Policy [Policy Text Block]	Certain reclassifications have been made to conform to the current period presentation.
Newly Adopted and Pending Accounting Policies [Policy Text Block]	Newly Adopted and Pending Accounting Policies Financial Accounting Standards Board (“FASB”) FASB Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers ("ASU 2014-09") On May 28, 2014, the FASB issued ASU 2014-09 to clarify the principles for recognizing revenue by providing a more robust framework that will give greater consistency and comparability in revenue recognition practices. In the new framework, an entity recognizes revenue in an amount that reflects the consideration to which the entity expects to be entitled in exchange for goods or services. The new model requires the identification of performance obligations included in contracts with customers, a determination of the transaction price and an allocation of the price to those performance obligations. The entity recognizes revenue when performance obligations are satisfied. ASU 2014-09 is effective for the Company for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. Net interest revenue from financial assets and liabilities is explicitly excluded from the scope of ASU 2014-09. Management expects that there will be no material impact on the timing of revenue recognized as our current revenue recognition policies generally conform with the principals in the standard. Management will adopt the standard in the first quarter of 2018 with a cumulative effect adjustment to opening retained earnings if such adjustment is significant. Currently, we do not anticipate any significant adjustments. FASB Accounting Standards Update No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net) ("ASU 2016-08") On March 17, 2016, the FASB Issued ASU 2016-08 to amend the principal versus agent implementation guidance in ASU 2014-09. The ASU clarifies that an entity should evaluate whether it is the principal or the agent for each specified good or service promised in a contract with a customer. ASU 2016-08 is effective for the Company for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. Management expects that interchange fees paid to issuing banks for card transactions processed related to its merchant processing services currently included in data processing and communication expense, will be netted against the amounts charged to the merchant in transaction card processing revenue. For 2016, interchange fees related to merchant processing services were approximately $27 million. FASB Accounting Standards Update No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01") On January 5, 2016, the FASB issued ASU 2016-01 over the recognition and measurement of financial assets and liabilities. The update requires equity investments, in general, to be measured at fair value with changes in fair value recognized in earnings. It also eliminates the requirement to disclose the methods and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost, requires entities to use the exit price notion when measuring fair value, requires an entity to present separately in other comprehensive income the portion of the total change in fair value of a liability resulting from a change in the instrument-specific credit risk when the fair value option has been elected, requires separate presentation of financial assets and liabilities by measurement category and form on the balance sheet or accompanying notes, clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity's other deferred tax assets, and simplifies the impairment assessment of equity investments without readily determinable fair values. The ASU is effective for the Company for interim and annual periods beginning after December 15, 2017. Upon adoption, unrealized gains and losses from equity securities will be reclassified from other comprehensive income to retained earnings. At September 30, 2017, the Company had $2.2 million of net unrealized gains included in accumulated other comprehensive income. FASB Accounting Standards Update No. 2016-02, Leases (Topic 842) ("ASU 2016-02") On February 25, 2016, the FASB issued ASU 2016-02 to increase transparency and comparability by recognizing lease assets and liabilities on the balance sheet and disclosing key information about leasing arrangements. Lessees will be required to recognize an obligation for future lease payments measured on a discounted basis and a right-of-use asset. The ASU is effective for the Company for interim and annual periods beginning after December 15, 2018 and requires transition through a modified retrospective approach for leases existing at or entered into after January 1, 2017. The Company is evaluating the impact the adoption of ASU 2016-02 will have on the Company's financial statements. FASB Accounting Standards Update No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting ("ASU 2016-09") On March 30, 2016, the FASB issued ASU 2016-09 to simplify multiple aspects of accounting for employee share-based payment transactions including accounting for income taxes, forfeitures, and statutory tax withholding requirements. The ASU became effective for annual reporting periods beginning after December 15, 2016, including interim periods within those annual reporting periods. Implementation of ASU 2016-09 decreased tax expense $2.5 million in the first nine months of 2017. FASB Accounting Standards Update No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Assets Measured at Amortized Cost ("ASU 2016-13") On June 16, 2016, the FASB issued ASU 2016-13 in order to provide more timely recording of credit losses on loans and other financial instruments. The ASU adds an impairment model (known as the current expected credit loss ("CECL") model) that is based on expected credit losses rather than incurred credit losses. It requires measurement of all expected credit losses for financial assets carried at amortized cost, including loans and investment securities, based on historical experience, current conditions, and reasonable and supportable forecasts. ASU 2016-13 also changes the recognition of other-than-temporary impairment of available for sale securities to an allowance methodology from a direct write-down methodology. ASU 2016-13 will be effective for the Company for annual reporting periods beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for annual reporting periods beginning after December 15, 2018. ASU 2016-13 will be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The Company is evaluating the impact the adoption of ASU 2016-13 will have on the Company's financial statements. FASB Accounting Standards Update No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments ("ASU 2016-15") On August 26, 2016, the FASB issued ASU 2016-15, which amends guidance in ASC 230 on the classification of certain cash receipts and payments in the statement of cash flows. The amendments address eight cash flow issues. ASU 2016-15 is effective for the Company for interim and annual reporting periods beginning after December 15, 2017. Entities generally must apply the guidance retrospectively to all periods presented. Adoption of ASU 2016-15 is not expected to have a material impact on the Company's financial statements. FASB Accounting Standards Update No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities ("ASU 2017-12") On August 28, 2017, the FASB issued ASU 2017-12, which amends the hedge accounting recognition and presentation requirements in ASC815 in order to improve transparency and understandability of information and reduce the complexity. The update expands the types of transactions eligible for hedge accounting, eliminates the requirement to separately measure and present hedge ineffectiveness, simplifies hedge effectiveness assessments and updates documentation and presentation requirements. ASU 2017-12 is effective for the Company for fiscal years beginning after December 15, 2018, and interim periods therein; however, early adoption is permitted. The Company is evaluating the impact the adoption of ASU 2017-12 will have on the Company's financial statements.
Derivatives, Policy [Policy Text Block]	Derivative instruments may be used by the Company as part of its internal risk management programs or may be offered to customers. All derivative instruments are carried at fair value and changes in fair value are reported in earnings as they occur. Credit risk is also considered in determining fair value. When bilateral netting agreements or similar arrangements exist between the Company and its counterparties that create a single legal claim or obligation to pay or receive the net amount in settlement of the individual derivative contracts, the Company reports derivative assets and liabilities on a net by derivative contract type by counterparty basis. Derivative contracts may require the Company to provide or receive cash margin as collateral for derivative assets and liabilities. Derivative assets and liabilities are reported net of cash margin when certain conditions are met. In addition, derivative contracts executed with customers under Customer Risk Management Programs may be secured by non-cash collateral in conjunction with a credit agreement with that customer. Access to collateral in the event of default is reasonably assured. None of these derivative contracts have been designated as hedging instruments for accounting purposes. Customer Risk Management Programs BOK Financial offers programs to permit its customers to manage various risks, including fluctuations in energy, cattle and other agricultural products, interest rates and foreign exchange rates with derivative contracts. Customers may also manage interest rate risk through interest rate swaps used by borrowers to modify interest rate terms of their loans or to-be-announced securities used by mortgage banking customers to hedge their loan production. Derivative contracts are executed between the customers and BOK Financial. Offsetting contracts are executed between BOK Financial and other selected counterparties to minimize the risk of changes in commodity prices, interest rates or foreign exchange rates. The counterparty contracts are identical to customer contracts, except for a fixed pricing spread or fee paid to BOK Financial as profit and compensation for administrative costs and credit risk which is recognized over the life of the contracts and included in other operating revenue – brokerage and trading revenue in the Consolidated Statements of Earnings. Internal Risk Management Programs BOK Financial may use derivative contracts in managing its interest rate sensitivity, as part of its economic hedge of the change in the fair value of mortgage servicing rights and as an economic hedge of trading securities. As of September 30, 2017, derivative contracts under the internal risk management programs were primarily used as part of the economic hedges of the change in the fair value of the mortgage servicing rights and trading securities. As discussed in Note 6, certain derivative contracts not designated as hedging instruments related to mortgage loan commitments and forward sales contracts are included in Residential mortgage loans held for sale on the Consolidated Balance Sheets. See Note 6 for additional discussion of notional, fair value and impact on earnings of these contracts.
Loans and Allowances for Credit Losses, Loans [Policy Text Block]	Loans Loans are either secured or unsecured based on the type of loan and the financial condition of the borrower. Repayment is generally expected from cash flow or proceeds from the sale of selected assets of the borrower. BOK Financial is exposed to risk of loss on loans due to the borrower’s difficulties, which may arise from any number of factors, including problems within the respective industry or local economic conditions. Access to collateral, in the event of borrower default, is reasonably assured through adherence to applicable lending laws and through sound lending standards and credit review procedures. Accounting policies for all loans, excluding residential mortgage loans guaranteed by U.S. government agencies, are as follows. Interest is accrued at the applicable interest rate on the principal amount outstanding. Loans are placed on nonaccruing status when, in the opinion of management, full collection of principal or interest is uncertain. Internally risk graded loans are individually evaluated for nonaccruing status quarterly. Non-risk graded loans are generally placed on nonaccruing status when more than 90 days past due or within 60 days of being notified of the borrower's bankruptcy filing. Interest previously accrued but not collected is charged against interest income when the loan is placed on nonaccruing status. Payments on nonaccruing loans are applied to principal or recognized as interest income, according to management’s judgment as to the collectability of principal. Loans may be returned to accruing status when, in the opinion of management, full collection of principal and interest, including principal previously charged off, is probable based on improvements in the borrower’s financial condition or a sustained period of performance. Loans to borrowers experiencing financial difficulties may be modified in troubled debt restructurings ("TDRs"). All TDRs are classified as nonaccruing, excluding loans guaranteed by U.S. government agencies. Modifications generally consist of extension of payment terms or interest rate concessions and may result either voluntarily through negotiations with the borrower or involuntarily through court order. Generally, principal and accrued but unpaid interest is not voluntarily forgiven. Performing loans may be renewed under the current collateral value, debt service ratio and other underwriting standards. Nonaccruing loans may be renewed and will remain classified as nonaccruing. All loans are charged off when the loan balance or a portion of the loan balance is no longer supported by the paying capacity of the borrower or when the required cash flow is reduced in a TDR. The charge-off amount is determined through a quarterly evaluation of available cash resources and collateral value and charge-offs are taken in the quarter in which the loss is identified. Non-risk graded loans that are past due between 60 days and 180 days, based on the loan product type, are charged off. Loans to borrowers whose personal obligation has been discharged through Chapter 7 bankruptcy proceedings are charged off within 60 days of notice of the bankruptcy filing, regardless of payment status. Loan origination and commitment fees and direct loan acquisition and origination costs are deferred and amortized as an adjustment to yield over the life of the loan or over the commitment period, as applicable. Qualifying residential mortgage loans guaranteed by U.S. government agencies have been sold into GNMA pools. Under certain performance conditions specified in government programs, the Company may have the right, but not the obligation to repurchase loans from GNMA pools. These loans no longer qualify for sale accounting and are recognized in the Consolidated Balance Sheets. Guaranteed loans are considered impaired because we do not expect to receive all principal and interest based on the loan's contractual terms. The principal balance continues to be guaranteed; however, interest accrues at a curtailed rate as specified in the programs. The carrying value of these loans is reduced based on an estimate of the expected cash flows discounted at the original note rate plus a liquidity spread. Guaranteed loans may be modified in TDRs in accordance with U.S. government agency guidelines. Interest continues to accrue based on the modified rate. Guaranteed loans may either be resold into GNMA pools after a performance period specified by the programs or foreclosed and conveyed to the guarantors. Loans are disaggregated into portfolio segments and further disaggregated into classes. The portfolio segment is the level at which the Company develops and documents a systematic method for determining its allowance for credit losses. Classes are a further disaggregation of portfolio segments based on the risk characteristics of the loans and the Company’s method for monitoring and assessing credit risk.
Loans and Allowances for Credit Losses, Allowances for Credit Losses [Policy Text Block]	Allowances for Credit Losses BOK Financial maintains an allowance for loan losses and an accrual for off-balance sheet credit risk. The accrual for off-balance sheet credit risk is maintained at a level that is appropriate to cover estimated losses associated with credit instruments that are not currently recognized as assets such as loan commitments, standby letters of credit or guarantees. As discussed in greater detail in Note 6, the Company also has separate accruals for off-balance sheet credit risk related to residential mortgage loans previously sold with full or partial recourse and for residential mortgage loans sold to government sponsored agencies under standard representations and warranties. The appropriateness of the allowance for loan losses and accrual for off-balance sheet credit losses (collectively "allowance for credit losses") is assessed by management based on an ongoing quarterly evaluation of the probable estimated losses inherent in the portfolio, including probable losses on both outstanding loans and unused commitments. The allowance for loan losses consists of specific allowances attributed to impaired loans that have not yet been charged down to amounts we expect to recover, general allowances for unimpaired loans based on estimated loss rates by loan class and nonspecific allowances based on general economic conditions, risk concentration and related factors. There have been no material changes in the approach or techniques utilized in developing the allowance for loan losses and the accrual for off-balance sheet credit losses for the three and nine months ended September 30, 2017. Loans are considered to be impaired when it becomes probable that BOK Financial will be unable to collect all amounts due according to the contractual terms of the loan agreements. Internally risk graded loans are evaluated individually for impairment. Substantially all commercial and commercial real estate loans and certain residential mortgage and consumer loans are risk graded based on evaluation of the borrowers' ability to repay. Certain commercial loans and most residential mortgage and consumer loans are small balance, homogeneous pools of loans that are not risk graded. Non-risk graded loans are identified as impaired based on performance status. Generally, non-risk graded loans 90 days or more past due or modified in a TDR or in bankruptcy are considered to be impaired. Specific allowances for impaired loans are measured by an evaluation of estimated future cash flows discounted at the loans’ initial effective interest rate or the fair value of collateral for certain collateral dependent loans. Collateral value of real property is generally based on third party appraisals that conform to Uniform Standards of Professional Appraisal Practice, less estimated selling costs. Appraised values are on an "as-is" basis and are generally not adjusted by the Company. Updated appraisals are obtained at least annually or more frequently if market conditions indicate collateral values have declined. Collateral value of mineral rights is generally determined by our internal staff of engineers based on projected cash flows under current market conditions. Collateral values and available cash resources that support impaired loans are evaluated quarterly. Historical statistics may be used as a practical way to estimate impairment in limited situations, such as when a collateral dependent loan is identified as impaired at the end of a reporting period, until an updated appraisal of collateral value is received or a full assessment of future cash flows is completed. Estimates of future cash flows and collateral values require significant judgments and may be volatile. General allowances for unimpaired loans are based on estimated loss rates by loan class. The gross loss rate for each loan class is determined by the greater of the current gross loss rate based on the most recent twelve months or a ten-year gross loss rate. Recoveries are not directly considered in the estimation of loss rates. Recoveries generally do not follow predictable patterns and are not received until well after the charge-off date as a result of protracted legal actions. For risk graded loans, gross loss rates are adjusted for changes in risk grading. For each loan class, the current weighted average risk grade is compared to the long-term average risk grade. This comparison determines whether credit risk in each loan class is increasing or decreasing. Loss rates are adjusted upward or downward in proportion to changes in average risk grading. General allowances for unimpaired loans also consider inherent risks identified for each loan class. Inherent risks consider loss rates that most appropriately represent the current credit cycle and other factors attributable to specific loan classes which have not yet been represented in the gross loss rates or risk grading. These factors include changes in commodity prices or engineering imprecision, which may affect the value of reserves that secure our energy loan portfolio, construction risk that may affect commercial real estate loans, changes in regulations and public policy that may disproportionately impact health care loans and changes in loan products. Nonspecific allowances are maintained for risks beyond factors specific to a particular loan or loan class. These factors include trends in the economy of our primary lending areas, concentrations in large balance loans and other relevant factors. An accrual for off-balance sheet credit losses is included in Other liabilities in the Consolidated Balance Sheets. The appropriateness of this accrual is determined in the same manner as the allowance for loan losses. A provision for credit losses is charged against or credited to earnings in amounts necessary to maintain an appropriate allowance for credit losses. Recoveries of loans previously charged off are added to the allowance when received.

Securities (Tables)

9 Months Ended

Sep. 30, 2017

Marketable Securities [Abstract]

Trading Securities [Table Text Block]

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



	September 30, 2017					December 31, 2016					September 30, 2016
	Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)
U.S. government agency debentures	$	30,162	$	(101	)	$	6,234	$	(4	)	$	15,705	$	(7	)
U.S. government agency residential mortgage-backed securities	516,760		723			310,067		635			464,749		876
Municipal and other tax-exempt securities	56,148		153			14,427		50			54,856		(100		)
Other trading securities	11,047		23			6,900		57			11,305		14
Total trading securities	$	614,117	$	798		$	337,628	$	738		$	546,615	$	783

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

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



	September 30, 2017
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss
Municipal and other tax-exempt	$	246,000	$	249,250	$	3,415	$	(165	)
U.S. government agency residential mortgage-backed securities – Other	16,926		17,458		594		(62		)
Other debt securities	203,636		223,187		20,141		(590		)
Total investment securities	$	466,562	$	489,895	$	24,150	$	(817	)


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



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


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



	September 30, 2016
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss
Municipal and other tax-exempt	$	323,225	$	327,788	$	4,745	$	(182	)
U.S. government agency residential mortgage-backed securities – Other	22,166		23,452		1,286		—
Other debt securities	201,066		229,070		28,014		(10		)
Total investment securities	$	546,457	$	580,310	$	34,045	$	(192	)


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

The amortized cost and fair values of investment securities at September 30, 2017, by contractual maturity, are as shown in the following table (dollars in thousands):



	Less than One Year			One to Five Years			Six to Ten Years			Over Ten Years			Total			Weighted Average Maturity²
Municipal and other tax-exempt:
Amortized cost	$	84,786		$	107,938		$	16,132		$	37,144		$	246,000		3.51
Fair value	84,835			108,352			16,776			39,287			249,250
Nominal yield¹	1.75		%	2.15		%	4.68		%	5.21		%	2.64		%
Other debt securities:
Amortized cost	13,546			47,077			130,494			12,519			203,636			6.40
Fair value	13,688			50,230			147,066			12,203			223,187
Nominal yield	4.10		%	4.86		%	5.75		%	4.47		%	5.35		%
Total fixed maturity securities:
Amortized cost	$	98,332		$	155,015		$	146,626		$	49,663		$	449,636		4.82
Fair value	98,523			158,582			163,842			51,490			472,437
Nominal yield	2.08		%	2.97		%	5.63		%	5.02		%	3.87		%
Residential mortgage-backed securities:
Amortized cost													$	16,926		³
Fair value													17,458
Nominal yield⁴													2.76		%
Total investment securities:
Amortized cost													$	466,562
Fair value													489,895
Nominal yield													3.83		%


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


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


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


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

Available For Sale Securities [Table Text Block]

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



	September 30, 2017
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss			OTTI²
U.S. Treasury	$	1,000	$	999	$	—	$	(1	)	$	—
Municipal and other tax-exempt	28,411		28,368		240		(283		)	—
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	3,103,869		3,108,822		25,510		(20,557		)	—
FHLMC	1,331,212		1,330,159		6,630		(7,683		)	—
GNMA	864,256		862,394		3,254		(5,116		)	—
Other	25,000		25,009		51		(42		)	—
Total U.S. government agencies	5,324,337		5,326,384		35,445		(33,398		)	—
Private issue:
Alt-A loans	35,853		46,695		10,842		—			—
Jumbo-A loans	44,944		53,299		8,355		—			—
Total private issue	80,797		99,994		19,197		—			—
Total residential mortgage-backed securities	5,405,134		5,426,378		54,642		(33,398		)	—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,899,828		2,889,346		5,577		(16,059		)	—
Other debt securities	4,400		4,153		—		(247		)	—
Perpetual preferred stock	12,562		16,245		3,683		—			—
Equity securities and mutual funds	17,803		17,710		655		(748		)	—
Total available for sale securities	$	8,369,138	$	8,383,199	$	64,797	$	(50,736	)	$	—

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

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



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

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

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



	September 30, 2016
	Amortized		Fair		Gross Unrealized¹
	Cost		Value		Gain		Loss			OTTI²
U.S. Treasury	$	1,000	$	1,002	$	2	$	—		$	—
Municipal and other tax-exempt	41,943		42,092		602		(453		)	—
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	3,035,041		3,101,136		67,859		(1,764		)	—
FHLMC	1,611,887		1,641,178		29,640		(349		)	—
GNMA	924,176		926,358		3,530		(1,348		)	—
Total U.S. government agencies	5,571,104		5,668,672		101,029		(3,461		)	—
Private issue:
Alt-A loans	47,039		54,065		7,230		—			(204		)
Jumbo-A loans	61,377		67,538		6,187		(26		)	—
Total private issue	108,416		121,603		13,417		(26		)	(204		)
Total residential mortgage-backed securities	5,679,520		5,790,275		114,446		(3,487		)	(204		)
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,942,988		2,986,495		45,329		(1,822		)	—
Other debt securities	4,400		4,151		—		(249		)	—
Perpetual preferred stock	15,562		19,578		4,016		—			—
Equity securities and mutual funds	17,337		18,690		1,370		(17		)	—
Total available for sale securities	$	8,702,750	$	8,862,283	$	165,765	$	(6,028	)	$	(204	)


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


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

The amortized cost and fair values of available for sale securities at September 30, 2017, by contractual maturity, are as shown in the following table (dollars in thousands):



	Less than One Year			One to Five Years			Six to Ten Years			Over Ten Years				Total			Weighted Average Maturity⁵
U.S. Treasuries:
Amortized cost	$	1,000		$	—		$	—		$	—			$	1,000		0.29
Fair value	999			—			—			—				999
Nominal yield	0.87		%	—		%	—		%	—		%		0.87		%
Municipal and other tax-exempt:
Amortized cost	$	8,754		$	4,163		$	—		$	15,494			$	28,411		9.00
Fair value	8,780			4,313			—			15,275				28,368
Nominal yield¹	3.25		%	5.13		%	—		%	2.26		%	⁶	2.99		%
Commercial mortgage-backed securities:
Amortized cost	$	59,483		$	978,565		$	1,616,383		$	245,397			$	2,899,828		6.90
Fair value	59,402			976,466			1,610,642			242,836				2,889,346
Nominal yield	1.25		%	1.85		%	1.92		%	1.92		%		1.88		%
Other debt securities:
Amortized cost	$	—		$	—		$	—		$	4,400			$	4,400		29.91
Fair value	—			—			—			4,153				4,153
Nominal yield	—		%	—		%	—		%	1.71		%	⁶	1.71		%
Total fixed maturity securities:
Amortized cost	$	69,237		$	982,728		$	1,616,383		$	265,291			$	2,933,639		6.96
Fair value	69,181			980,779			1,610,642			262,264				2,922,866
Nominal yield	1.50		%	1.86		%	1.92		%	1.93		%		1.88		%
Residential mortgage-backed securities:
Amortized cost														$	5,405,134		²
Fair value														5,426,378
Nominal yield⁴														1.99		%
Equity securities and mutual funds:
Amortized cost														$	30,365		³
Fair value														33,955
Nominal yield														—		%
Total available-for-sale securities:
Amortized cost														$	8,369,138
Fair value														8,383,199
Nominal yield														1.95		%


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


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


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


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


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


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

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



	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Proceeds	$	265,632		$	232,239		$	966,044		$	1,027,379
Gross realized gains	2,768			2,415			7,623			11,705
Gross realized losses	(281		)	(21		)	(2,707		)	(21		)
Related federal and state income tax expense	967			931			1,912			4,545

Securities Pledged As Collateral [Table Text Block]

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



	Sept. 30, 2017		Dec. 31, 2016		Sept. 30, 2016
Investment:
Amortized cost	$	237,525	$	322,208	$	301,754
Fair value	241,208		323,808		307,264

Available for sale:
Amortized cost	6,559,615		7,353,116		7,098,721
Fair value	6,551,240		7,327,470		7,213,520

Schedule of Unrealized Loss on Investments [Table Text Block]

Temporarily Impaired Securities as of September 30, 2017

(in thousands):



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investment:
Municipal and other tax-exempt	63	$	80,235	$	70	$	9,795	$	95	$	90,030	$	165
U.S. government agency residential mortgage-backed securities – Other	1	3,578		62		—		—		3,578		62
Other debt securities	28	10,022		566		427		24		10,449		590
Total investment securities	92	$	93,835	$	698	$	10,222	$	119	$	104,057	$	817



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available for sale:
U.S. Treasury	1	$	999	$	1	$	—	$	—	$	999	$	1
Municipal and other tax-exempt	11	576		1		4,785		282		5,361		283
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	81	1,054,171		10,288		480,994		10,269		1,535,165		20,557
FHLMC	42	477,823		3,546		198,478		4,137		676,301		7,683
GNMA	17	166,565		1,718		124,037		3,398		290,602		5,116
Other	1	19,958		42		—		—		19,958		42
Total U.S. government agencies	141	1,718,517		15,594		803,509		17,804		2,522,026		33,398
Private issue:
Alt-A loans	—	—		—		—		—		—		—
Jumbo-A loans	—	—		—		—		—		—		—
Total private issue	—	—		—		—		—		—		—
Total residential mortgage-backed securities	141	1,718,517		15,594		803,509		17,804		2,522,026		33,398
Commercial mortgage-backed securities guaranteed by U.S. government agencies	137	1,154,911		7,194		559,984		8,865		1,714,895		16,059
Other debt securities	2	—		—		4,153		247		4,153		247
Perpetual preferred stocks	—	—		—		—		—		—		—
Equity securities and mutual funds	91	3,672		696		1,428		52		5,100		748
Total available for sale securities	383	$	2,878,675	$	23,486	$	1,373,859	$	27,250	$	4,252,534	$	50,736

Temporarily Impaired Securities as of December 31, 2016

(In thousands)



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



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


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

Temporarily Impaired Securities as of September 30, 2016

(In thousands)



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Investment:
Municipal and other tax-exempt	75	$	100,624	$	106	$	4,359	$	76	$	104,983	$	182
U.S. government agency residential mortgage-backed securities – Other	—	—		—		—		—		—		—
Other debt securities	3	444		6		856		4		1,300		10
Total investment securities	78	$	101,068	$	112	$	5,215	$	80	$	106,283	$	192



	Number of Securities	Less Than 12 Months				12 Months or Longer				Total
	Number of Securities	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available for sale:
U.S. Treasury	—	$	—	$	—	$	—	$	—	$	—	$	—
Municipal and other tax-exempt¹	20	2,210		3		6,396		450		8,606		453
Residential mortgage-backed securities:
U. S. government agencies:
FNMA	14	365,201		1,712		14,229		52		379,430		1,764
FHLMC	6	122,713		91		20,306		258		143,019		349
GNMA	16	230,043		1,157		212,705		191		442,748		1,348
Total U.S. government agencies	36	717,957		2,960		247,240		501		965,197		3,461
Private issue¹:
Alt-A loans	5	8,231		141		7,773		63		16,004		204
Jumbo-A loans	1	6,583		26		—		—		6,583		26
Total private issue	6	14,814		167		7,773		63		22,587		230
Total residential mortgage-backed securities	42	732,771		3,127		255,013		564		987,784		3,691
Commercial mortgage-backed securities guaranteed by U.S. government agencies	33	372,805		1,656		60,851		166		433,656		1,822
Other debt securities	2	—		—		4,151		249		4,151		249
Perpetual preferred stocks	—	—		—		—		—		—		—
Equity securities and mutual funds	33	86		—		886		17		972		17
Total available for sale securities	130	$	1,107,872	$	4,786	$	327,297	$	1,446	$	1,435,169	$	6,232


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

Fair Value Option Securities [Table Text Block]

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



	September 30, 2017				December 31, 2016					September 30, 2016
	Fair Value		Net Unrealized Gain (Loss)		Fair Value		Net Unrealized Gain (Loss)			Fair Value		Net Unrealized Gain (Loss)
U.S. Treasury	$	—	$	—	$	—	$	—		$	222,409	$	(2,397	)
U.S. government agency residential mortgage-backed securities	819,531		1,671		77,046		(1,777		)	—		—
Total	$	819,531	$	1,671	$	77,046	$	(1,777	)	$	222,409	$	(2,397	)

Schedule of Restricted Equity Securities [Table Text Block]



	Sept. 30, 2017		Dec. 31, 2016		Sept. 30, 2016
Federal Reserve stock	$	36,676	$	36,498	$	36,283
Federal Home Loan Bank stock	310,622		270,541		296,907
Other	244		201		201
Total	$	347,542	$	307,240	$	333,391

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

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

Derivative Instrument Detail [Abstract]

Derivatives (Tables)

9 Months Ended

Sep. 30, 2017

Derivative Contracts [Table Text Block]

The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at September 30, 2017 (in thousands):



	Assets
	Notional¹		Gross Fair Value		Netting Adjustments			Net Fair Value Before Cash Collateral		Cash Collateral			Fair Value Net of Cash Collateral
Customer risk management programs:
Interest rate contracts
To-be-announced residential mortgage-backed securities	$	14,244,442	$	38,875	$	(9,547	)	$	29,328	$	—		$	29,328
Interest rate swaps	1,368,210		27,016		—			27,016		(2,820		)	24,196
Energy contracts	983,794		45,368		(35,166		)	10,202		(238		)	9,964
Agricultural contracts	60,745		1,870		(1,172		)	698		—			698
Foreign exchange contracts	252,525		249,788		—			249,788		—			249,788
Equity option contracts	101,841		4,871		—			4,871		(920		)	3,951
Total customer risk management programs	17,011,557		367,788		(45,885		)	321,903		(3,978		)	317,925
Internal risk management programs	11,941,260		34,634		—			34,634		—			34,634
Total derivative contracts	$	28,952,817	$	402,422	$	(45,885	)	$	356,537	$	(3,978	)	$	352,559

	Liabilities
	Notional¹		Gross Fair Value		Netting Adjustments			Net Fair Value Before Cash Collateral		Cash Collateral			Fair Value Net of Cash Collateral
Customer risk management programs:
Interest rate contracts
To-be-announced residential mortgage-backed securities	$	14,244,442	$	34,948	$	(9,547	)	$	25,401	$	(374	)	$	25,027
Interest rate swaps	1,368,230		27,056		—			27,056		(16,599		)	10,457
Energy contracts	939,350		42,744		(35,166		)	7,578		—			7,578
Agricultural contracts	60,746		1,846		(1,172		)	674		—			674
Foreign exchange contracts	249,269		245,925		—			245,925		(1,395		)	244,530
Equity option contracts	101,841		4,871		—			4,871		—			4,871
Total customer risk management programs	16,963,878		357,390		(45,885		)	311,505		(18,368		)	293,137
Internal risk management programs	9,180,531		43,190		—			43,190		—			43,190
Total derivative contracts	$	26,144,409	$	400,580	$	(45,885	)	$	354,695	$	(18,368	)	$	336,327


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

The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at December 31, 2016 (in thousands):



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

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


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

The following table summarizes the fair values of derivative contracts recorded as “derivative contracts” assets and liabilities in the balance sheet at September 30, 2016 (in thousands):



	Assets
	Notional¹		Gross Fair Value		Netting Adjustments			Net Fair Value Before Cash Collateral		Cash Collateral			Fair Value Net of Cash Collateral
Customer risk management programs:
Interest rate contracts
To-be-announced residential mortgage-backed securities	$	20,078,974	$	90,999	$	(38,678	)	$	52,321	$	—		$	52,321
Interest rate swaps	1,323,045		49,279		—			49,279		(794		)	48,485
Energy contracts	729,202		41,775		(28,464		)	13,311		(288		)	13,023
Agricultural contracts	53,002		3,950		(1,571		)	2,379		(1,076		)	1,303
Foreign exchange contracts	550,828		536,264		—			536,264		(7,577		)	528,687
Equity option contracts	103,464		4,654		—			4,654		(730		)	3,924
Total customer risk management programs	22,838,515		726,921		(68,713		)	658,208		(10,465		)	647,743
Internal risk management programs	2,298,038		7,335		—			7,335		—			7,335
Total derivative contracts	$	25,136,553	$	734,256	$	(68,713	)	$	665,543	$	(10,465	)	$	655,078

	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	$	19,776,883	$	86,812	$	(38,678	)	$	48,134	$	(39,042	)	$	9,092
Interest rate swaps	1,323,045		49,518		—			49,518		(34,457		)	15,061
Energy contracts	695,835		40,888		(28,464		)	12,424		(3,857		)	8,567
Agricultural contracts	52,997		3,943		(1,571		)	2,372		—			2,372
Foreign exchange contracts	550,943		536,660		—			536,660		(5,396		)	531,264
Equity option contracts	103,464		4,654		—			4,654		—			4,654
Total customer risk management programs	22,503,167		722,475		(68,713		)	653,762		(82,752		)	571,010
Internal risk management programs	1,485,691		2,977		—			2,977		—			2,977
Total derivative contracts	$	23,988,858	$	725,452	$	(68,713	)	$	656,739	$	(82,752	)	$	573,987


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

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

The following summarizes the pre-tax net gains (losses) on derivative instruments and where they are recorded in the income statement (in thousands):



	Three Months Ended
	September 30, 2017					September 30, 2016
	Brokerage and Trading Revenue			Gain (Loss) on Derivatives, Net		Brokerage and Trading Revenue			Gain (Loss)on Derivatives, Net
Customer risk management programs:
Interest rate contracts
To-be-announced residential mortgage-backed securities	$	9,181		$	—	$	11,584		$	—
Interest rate swaps	767			—		710			—
Energy contracts	378			—		1,222			—
Agricultural contracts	38			—		25			—
Foreign exchange contracts	164			—		218			—
Equity option contracts	—			—		—			—
Total customer risk management programs	10,528			—		13,759			—
Internal risk management programs	(711		)	1,033		(1,608		)	2,226
Total derivative contracts	$	9,817		$	1,033	$	12,151		$	2,226



	Nine Months Ended
	September 30, 2017				September 30, 2016
	Brokerage and Trading Revenue		Gain (Loss) on Derivatives, Net		Brokerage and Trading Revenue			Gain (Loss) on Derivatives, Net
Customer risk management programs:
Interest rate contracts
To-be-announced residential mortgage-backed securities	$	26,413	$	—	$	28,886		$	—
Interest rate swaps	1,891		—		1,758			—
Energy contracts	4,917		—		4,667			—
Agricultural contracts	58		—		86			—
Foreign exchange contracts	524		—		730			—
Equity option contracts	—		—		—			—
Total customer risk management programs	33,803		—		36,127			—
Internal risk management programs	5,307		3,824		(1,617		)	20,130
Total derivative contracts	$	39,110	$	3,824	$	34,510		$	20,130

Loans and Allowances for Credit Losses (Tables)

9 Months Ended

Sep. 30, 2017

Loans Receivable, Net [Abstract]

Schedule of Loans by Portfolio Segment [Table Text Block]

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



	September 30, 2017								December 31, 2016
	Fixed Rate		Variable Rate		Non-accrual		Total		Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	2,225,470	$	8,393,564	$	176,900	$	10,795,934	$	2,327,085	$	7,884,786	$	178,953	$	10,390,824
Commercial real estate	564,681		2,950,486		2,975		3,518,142		624,187		3,179,338		5,521		3,809,046
Residential mortgage	1,589,013		311,231		45,506		1,945,750		1,647,357		256,255		46,220		1,949,832
Personal	153,750		793,003		255		947,008		154,971		684,697		290		839,958
Total	$	4,532,914	$	12,448,284	$	225,636	$	17,206,834	$	4,753,600	$	12,005,076	$	230,984	$	16,989,660
Accruing loans past due (90 days)¹							$	253							$	5



	September 30, 2016
	Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	1,991,423	$	7,952,276	$	176,464	$	10,120,163
Commercial real estate	565,429		3,220,819		7,350		3,793,598
Residential mortgage	1,572,288		248,053		52,452		1,872,793
Personal	104,408		573,138		686		678,232
Total	$	4,233,548	$	11,994,286	$	236,952	$	16,464,786
Accruing loans past due (90 days)¹							$	3,839


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

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

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit for the three months ended September 30, 2017 is summarized as follows (in thousands):



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

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

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit for the nine months ended September 30, 2017 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance			Total
Allowance for loan losses:
Beginning balance	$	140,213		$	50,749		$	18,224		$	8,773		$	28,200		$	246,159
Provision for loan losses	665			4,050			82			1,168			(122		)	5,843
Loans charged off	(6,556		)	(76		)	(444		)	(3,774		)	—			(10,850		)
Recoveries	2,479			1,682			531			1,859			—			6,551
Ending balance	$	136,801		$	56,405		$	18,393		$	8,026		$	28,078		$	247,703
Allowance for off-balance sheet credit losses:
Beginning balance	$	11,063		$	123		$	50		$	8		$	—		$	11,244
Provision for off-balance sheet credit losses	(5,738		)	(88		)	(11		)	(6		)	—			(5,843		)
Ending balance	$	5,325		$	35		$	39		$	2		$	—		$	5,401

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

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit for the three months ended September 30, 2016 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance		Total
Allowance for loan losses:
Beginning balance	$	145,139		$	46,745		$	18,690		$	6,001		$	26,684	$	243,259
Provision for loan losses	2,420			2,551			(466		)	1,900			1,502		7,907
Loans charged off	(6,266		)	—			(285		)	(1,550		)	—		(8,101		)
Recoveries	177			521			650			690			—		2,038
Ending balance	$	141,470		$	49,817		$	18,589		$	7,041		$	28,186	$	245,103
Allowance for off-balance sheet credit losses:
Beginning balance	$	8,752		$	203		$	62		$	28		$	—	$	9,045
Provision for off-balance sheet credit losses	2,170			(53		)	(7		)	(17		)	—		2,093
Ending balance	$	10,922		$	150		$	55		$	11		$	—	$	11,138

Total provision for credit losses	$	4,590		$	2,498		$	(473	)	$	1,883		$	1,502	$	10,000

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit for the nine months ended September 30, 2016 is summarized as follows (in thousands):



	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance			Total
Allowance for loan losses:
Beginning balance	$	130,334		$	41,391		$	19,509		$	4,164		$	30,126		$	225,524
Provision for loan losses	45,995			7,538			(829		)	4,809			(1,940		)	55,573
Loans charged off	(35,747		)	—			(1,104		)	(4,086		)	—			(40,937		)
Recoveries	888			888			1,013			2,154			—			4,943
Ending balance	$	141,470		$	49,817		$	18,589		$	7,041		$	28,186		$	245,103
Allowance for off-balance sheet credit losses:
Beginning balance	$	1,506		$	153		$	30		$	22		$	—		$	1,711
Provision for off-balance sheet credit losses	9,416			(3		)	25			(11		)	—			9,427
Ending balance	$	10,922		$	150		$	55		$	11		$	—		$	11,138

Total provision for credit losses	$	55,411		$	7,535		$	(804	)	$	4,798		$	(1,940	)	$	65,000

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at September 30, 2017 is as follows (in thousands):



	Collectively Measured for Impairment				Individually Measured for Impairment				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,619,034	$	123,517	$	176,900	$	13,284	$	10,795,934	$	136,801
Commercial real estate	3,515,167		56,405		2,975		—		3,518,142		56,405
Residential mortgage	1,900,244		18,393		45,506		—		1,945,750		18,393
Personal	946,753		8,026		255		—		947,008		8,026
Total	16,981,198		206,341		225,636		13,284		17,206,834		219,625

Nonspecific allowance	—		—		—		—		—		28,078

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

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2016 is as follows (in thousands):



	Collectively Measured for Impairment				Individually Measured for Impairment				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,211,871	$	139,416	$	178,953	$	797	$	10,390,824	$	140,213
Commercial real estate	3,803,525		50,749		5,521		—		3,809,046		50,749
Residential mortgage	1,903,612		18,178		46,220		46		1,949,832		18,224
Personal	839,668		8,773		290		—		839,958		8,773
Total	16,758,676		217,116		230,984		843		16,989,660		217,959

Nonspecific allowance	—		—		—		—		—		28,200

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

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at September 30, 2016 is as follows (in thousands):



	Collectively Measured for Impairment				Individually Measured for Impairment				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	9,943,699	$	134,968	$	176,464	$	6,502	$	10,120,163	$	141,470
Commercial real estate	3,786,248		49,817		7,350		—		3,793,598		49,817
Residential mortgage	1,820,341		18,527		52,452		62		1,872,793		18,589
Personal	677,546		7,041		686		—		678,232		7,041
Total	16,227,834		210,353		236,952		6,564		16,464,786		216,917

Nonspecific allowance	—		—		—		—		—		28,186

Total	$	16,227,834	$	210,353	$	236,952	$	6,564	$	16,464,786	$	245,103

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

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



	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,750,657	$	135,846	$	45,277	$	955	$	10,795,934	$	136,801
Commercial real estate	3,518,142		56,405		—		—		3,518,142		56,405
Residential mortgage	226,306		3,068		1,719,444		15,325		1,945,750		18,393
Personal	856,030		6,043		90,978		1,983		947,008		8,026
Total	15,351,135		201,362		1,855,699		18,263		17,206,834		219,625

Nonspecific allowance	—		—		—		—		—		28,078

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

The allowance for loan losses and recorded investment of the related loans by portfolio segment for risk graded and non-risk graded loans at December 31, 2016 is as follows (in thousands):



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

Nonspecific allowance	—		—		—		—		—		28,200

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

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



	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,093,884	$	140,552	$	26,279	$	918	$	10,120,163	$	141,470
Commercial real estate	3,793,598		49,817		—		—		3,793,598		49,817
Residential mortgage	206,430		3,028		1,666,363		15,561		1,872,793		18,589
Personal	586,869		4,182		91,363		2,859		678,232		7,041
Total	14,680,781		197,579		1,784,005		19,338		16,464,786		216,917

Nonspecific allowance	—		—		—		—		—		28,186

Total	$	14,680,781	$	197,579	$	1,784,005	$	19,338	$	16,464,786	$	245,103

Schedule of Credit Quality Indicators [Table Text Block]

The following table summarizes the Company’s loan portfolio at September 30, 2017 by the risk grade categories (in thousands):



	Internally Risk Graded								Non-Graded
	Performing
	Pass		Other Loans Especially Mentioned		Accruing Substandard		Nonaccrual		Performing		Nonaccrual		Total
Commercial:
Energy	$	2,436,465	$	114,065	$	206,768	$	110,683	$	—	$	—	$	2,867,981
Services	2,932,577		26,372		7,390		1,174		—		—		2,967,513
Wholesale/retail	1,637,698		9,021		9,486		1,893		—		—		1,658,098
Manufacturing	486,383		7,181		16,823		9,059		—		—		519,446
Healthcare	2,150,099		31,855		33,051		24,446		—		—		2,239,451
Other commercial and industrial	458,796		52		9,820		29,500		45,132		145		543,445
Total commercial	10,102,018		188,546		283,338		176,755		45,132		145		10,795,934

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

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

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

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

The following table summarizes the Company’s loan portfolio at December 31, 2016 by the risk grade categories (in thousands):



	Internally Risk Graded								Non-Graded
	Performing
	Pass		Other Loans Especially Mentioned		Accruing Substandard		Nonaccrual		Performing		Nonaccrual		Total
Commercial:
Energy	$	1,937,790	$	119,583	$	307,996	$	132,499	$	—	$	—	$	2,497,868
Services	3,052,002		10,960		37,855		8,173		—		—		3,108,990
Wholesale/retail	1,535,463		16,886		13,062		11,407		—		—		1,576,818
Manufacturing	468,314		26,532		15,198		4,931		—		—		514,975
Healthcare	2,140,458		44,472		16,161		825		—		—		2,201,916
Other commercial and industrial	433,789		5,309		—		21,060		30,041		58		490,257
Total commercial	9,567,816		223,742		390,272		178,895		30,041		58		10,390,824

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

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

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

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

The following table summarizes the Company’s loan portfolio at September 30, 2016 by the risk grade categories (in thousands):



	Internally Risk Graded								Non-Graded
	Performing
	Pass		Other Loans Especially Mentioned		Accruing Substandard		Nonaccrual		Performing		Nonaccrual		Total
Commercial:
Energy	$	1,869,598	$	147,153	$	361,087	$	142,966	$	—	$	—	$	2,520,804
Services	2,882,065		14,861		31,196		8,477		—		—		2,936,599
Wholesale/retail	1,557,067		15,337		27,173		2,453		—		—		1,602,030
Manufacturing	470,702		8,774		19,736		274		—		—		499,486
Healthcare	2,022,757		42,224		19,210		855		—		—		2,085,046
Other commercial and industrial	415,769		2,478		10,302		21,370		26,210		69		476,198
Total commercial	9,217,958		230,827		468,704		176,395		26,210		69		10,120,163

Commercial real estate:
Residential construction and land development	155,737		—		470		3,739		—		—		159,946
Retail	794,920		4,802		406		1,249		—		—		801,377
Office	750,924		899		—		882		—		—		752,705
Multifamily	868,501		—		5,221		51		—		—		873,773
Industrial	837,945		—		—		76		—		—		838,021
Other commercial real estate	366,416		—		7		1,353		—		—		367,776
Total commercial real estate	3,774,443		5,701		6,104		7,350		—		—		3,793,598

Residential mortgage:
Permanent mortgage	200,590		1,192		2,134		2,514		739,686		23,442		969,558
Permanent mortgages guaranteed by U.S. government agencies	—		—		—		—		174,877		15,432		190,309
Home equity	—		—		—		—		701,862		11,064		712,926
Total residential mortgage	200,590		1,192		2,134		2,514		1,616,425		49,938		1,872,793

Personal	585,287		228		923		431		91,108		255		678,232

Total	$	13,778,278	$	237,948	$	477,865	$	186,690	$	1,733,743	$	50,262	$	16,464,786

Summary of Impaired Loans [Table Text Block]

Impaired Loans

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

A summary of impaired loans follows (in thousands):



	As of										For the				For the
	September 30, 2017										Three Months Ended				Nine Months Ended
			Recorded Investment								September 30, 2017				September 30, 2017
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance		Average Recorded Investment		Interest Income Recognized		Average Recorded Investment		Interest Income Recognized
Commercial:
Energy	$	133,643	$	110,683	$	45,169	$	65,514	$	4,944	$	117,338	$	—	$	121,591	$	—
Services	3,838		1,174		1,174		—		—		4,464		—		4,674		—
Wholesale/retail	8,418		1,893		1,893		—		—		6,256		—		6,650		—
Manufacturing	9,674		9,059		9,059		—		—		9,357		—		6,995		—
Healthcare	24,591		24,446		474		23,972		8,323		24,476		—		12,635		—
Other commercial and industrial	38,222		29,645		29,626		19		17		25,138		—		25,382		—
Total commercial	218,386		176,900		87,395		89,505		13,284		187,029		—		177,927		—

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

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

Personal	290		255		255		—		—		263		—		273		—

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


¹	All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At September 30, 2017, $8.9 million of these loans were nonaccruing and $178 million were accruing based on the guarantee by U.S. government agencies.

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

A summary of impaired loans at December 31, 2016 follows (in thousands):



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

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

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

Personal	332		290		290		—		—

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


¹	All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2016, $12 million of these loans were nonaccruing and $188 million were accruing based on the guarantee by U.S. government agencies.

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



											For the				For the
	As of September 30, 2016										Three Months Ended				Nine Months Ended
			Recorded Investment								September 30, 2016				September 30, 2016
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance		Average Recorded Investment		Interest Income Recognized		Average Recorded Investment		Interest Income Recognized
Commercial:
Energy	$	179,578	$	142,966	$	100,300	$	42,666	$	6,502	$	155,555	$	—	$	85,333	$	—
Services	11,858		8,477		8,477		—		—		8,932		—		9,384		—
Wholesale/retail	8,528		2,453		2,453		—		—		2,613		—		2,686		—
Manufacturing	642		274		274		—		—		284		—		303		—
Healthcare	1,168		855		855		—		—		865		—		964		—
Other commercial and industrial	29,176		21,439		21,439		—		—		10,978		—		11,031		—
Total commercial	230,950		176,464		133,798		42,666		6,502		179,227		—		109,701		—

Commercial real estate:
Residential construction and land development	6,090		3,739		3,739		—		—		4,000		—		4,074		—
Retail	1,914		1,249		1,249		—		—		1,257		—		1,284		—
Office	1,187		882		882		—		—		744		—		766		—
Multifamily	1,000		51		51		—		—		58		—		163		—
Industrial	76		76		76		—		—		76		—		76		—
Other commercial real estate	7,375		1,353		1,353		—		—		1,430		—		1,813		—
Total commercial real estate	17,642		7,350		7,350		—		—		7,565		—		8,176		—

Residential mortgage:
Permanent mortgage	32,372		25,956		25,847		109		62		26,592		292		27,470		923
Permanent mortgage guaranteed by U.S. government agencies¹	196,162		190,309		190,309		—		—		190,547		2,098		193,879		5,893
Home equity	12,099		11,064		11,064		—		—		10,578		—		10,710		—
Total residential mortgage	240,633		227,329		227,220		109		62		227,717		2,390		232,059		6,816

Personal	724		686		686		—		—		520		—		575		—

Total	$	489,949	$	411,829	$	369,054	$	42,775	$	6,564	$	415,029	$	2,390	$	350,511	$	6,816


¹	All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At September 30, 2016, $15 million of these loans were nonaccruing and $175 million were accruing based on the guarantee by U.S. government agencies.

Troubled Debt Restructurings [Table Text Block]

Troubled Debt Restructurings

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



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

Commercial:
Energy	$	9,582	$	9,506	$	76	$	—	$	4,322	$	4,322
Services	720		103		617		—		7		10
Wholesale/retail	1,802		—		1,802		—		—		—
Manufacturing	180		180		—		—		—		—
Healthcare	—		—		—		—		—		—
Other commercial and industrial	20,097		19,890		207		—		—		—
Total commercial	32,381		29,679		2,702		—		4,329		4,332

Commercial real estate:
Residential construction and land development	327		91		236		—		—		—
Retail	289		289		—		—		—		—
Office	—		—		—		—		—		—
Multifamily	—		—		—		—		—		—
Industrial	—		—		—		—		—		—
Other commercial real estate	353		353		—		—		—		—
Total commercial real estate	969		733		236		—		—		—

Residential mortgage:
Permanent mortgage	14,765		10,188		4,577		—		—		—
Permanent mortgage guaranteed by U.S. government agencies	5,601		523		5,078		—		—		—
Home equity	5,625		4,213		1,412		—		39		70
Total residential mortgage	25,991		14,924		11,067		—		39		70

Personal	205		195		10		—		2		10

Total nonaccruing TDRs	$	59,546	$	45,531	$	14,015	$	—	$	4,370	$	4,412

Accruing TDRs:
Permanent mortgages guaranteed by U.S. government agencies	69,440		14,948		54,492		—		—		—

Total TDRs	$	128,986	$	60,479	$	68,507	$	—	$	4,370	$	4,412

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



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

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

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

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

Personal	237		236		1		—

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

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

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

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



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

Commercial:
Energy	$	1,746	$	—	$	1,746	$	—	$	500	$	1,000
Services	7,761		7,034		727		—		—		—
Wholesale/retail	2,327		2,287		40		—		—		—
Manufacturing	238		238		—		—		—		—
Healthcare	623		—		623		—		—		—
Other commercial and industrial	497		61		436		—		—		57
Total commercial	13,192		9,620		3,572		—		500		1,057

Commercial real estate:
Residential construction and land development	794		359		435		—		—		—
Retail	1,249		892		357		—		—		—
Office	149		149		—		—		—		—
Multifamily	—		—		—		—		—		—
Industrial	—		—		—		—		—		—
Other commercial real estate	666		666		—		—		—		—
Total commercial real estate	2,858		2,066		792		—		—		—

Residential mortgage:
Permanent mortgage	16,109		11,944		4,165		62		—		2
Permanent mortgage guaranteed by U.S. government agencies	8,220		2,331		5,889		—		—		—
Home equity	5,168		4,667		501		—		34		153
Total residential mortgage	29,497		18,942		10,555		62		34		155

Personal	273		271		2		—		9		18

Total nonaccruing TDRs	$	45,820	$	30,899	$	14,921	$	62	$	543	$	1,230

Accruing TDRs:
Permanent mortgages guaranteed by U.S. government agencies	80,306		29,020		51,286		—		—		—

Total TDRs	$	126,126	$	59,919	$	66,207	$	62	$	543	$	1,230

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



	Three Months Ended Sept. 30, 2017
	Accruing						Nonaccrual						Total
	Payment Stream		Combination & Other		Total		Payment Stream		Combination & Other		Total
Commercial:
Energy	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Services	—		—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—		—
Healthcare	—		—		—		—		—		—		—
Other commercial and industrial	—		—		—		—		60		60		60
Total commercial	—		—		—		—		60		60		60

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

Residential mortgage:
Permanent mortgage	—		—		—		969		506		1,475		1,475
Permanent mortgage guaranteed by U.S. government agencies	8,205		620		8,825		315		—		315		9,140
Home equity	—		—		—		—		469		469		469
Total residential mortgage	8,205		620		8,825		1,284		975		2,259		11,084

Personal	—		—		—		—		4		4		4

Total	$	8,205	$	620	$	8,825	$	1,284	$	1,039	$	2,323	$	11,148



	Nine Months Ended Sept. 30, 2017
	Accruing							Nonaccrual							Total
		Payment Stream		Combination & Other		Total			Payment Stream		Combination & Other		Total
Commercial:
Energy		$	—	$	—	$	—		$	7,781	$	—	$	7,781	$	7,781
Services		—		—		—			—		—		—		—
Wholesale/retail		—		—		—			—		—		—		—
Manufacturing		—		—		—			—		—		—		—
Healthcare		—		—		—			—		—		—		—
Other commercial and industrial		—		—		—			19,825		60		19,885		19,885
Total commercial		—		—		—			27,606		60		27,666		27,666

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

Residential mortgage:
Permanent mortgage		—		—		—			153		1,559		1,712		1,712
Permanent mortgage guaranteed by U.S. government agencies		18,678		2,649		21,327			443		85		528		21,855
Home equity		—		—		—			104		1,468		1,572		1,572
Total residential mortgage		18,678		2,649		21,327			700		3,112		3,812		25,139

Personal		—		—		—			—		48		48		48

Total		$	18,678	$	2,649	$	21,327		$	28,306	$	3,220	$	31,526	$	52,853

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



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

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

Residential mortgage:
Permanent mortgage	—		—		—		—		151		151		151
Permanent mortgage guaranteed by U.S. government agencies	3,527		4,211		7,738		—		287		287		8,025
Home equity	—		—		—		—		920		920		920
Total residential mortgage	3,527		4,211		7,738		—		1,358		1,358		9,096

Personal	—		—		—		—		19		19		19

Total	$	3,527	$	4,211	$	7,738	$	—	$	1,377	$	1,377	$	9,115



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

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

Residential mortgage:
Permanent mortgage	—		—		—		1,037		1,051		2,088		2,088
Permanent mortgage guaranteed by U.S. government agencies	9,687		9,350		19,037		—		982		982		20,019
Home equity	—		—		—		48		1,630		1,678		1,678
Total residential mortgage	9,687		9,350		19,037		1,085		3,663		4,748		23,785

Personal	—		—		—		—		82		82		82

Total	$	9,687	$	9,350	$	19,037	$	1,586	$	3,745	$	5,331	$	24,368

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



	Three Months Ended Sept. 30, 2017						Nine Months Ended Sept. 30, 2017
	Accruing		Nonaccrual		Total		Accruing		Nonaccrual		Total
Commercial:
Energy	$	—	$	7,857	$	7,857	$	—	$	9,582	$	9,582
Services	—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—
Healthcare	—		—		—		—		—		—
Other commercial and industrial	—		—		—		—		19,825		19,825
Total commercial	—		7,857		7,857		—		29,407		29,407

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

Residential mortgage:
Permanent mortgage	—		1,511		1,511		—		1,511		1,511
Permanent mortgage guaranteed by U.S. government agencies	23,620		878		24,498		24,349		878		25,227
Home equity	—		1,030		1,030		—		1,139		1,139
Total residential mortgage	23,620		3,419		27,039		24,349		3,528		27,877

Personal	—		10		10		—		10		10

Total	$	23,620	$	11,286	$	34,906	$	24,349	$	32,945	$	57,294

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



	Three Months Ended Sept. 30, 2016						Nine Months Ended Sept. 30, 2016
	Accruing		Nonaccrual		Total		Accruing		Nonaccrual		Total
Commercial:
Energy	$	—	$	1,746	$	1,746	$	—	$	1,746	$	1,746
Services	—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—
Healthcare	—		—		—		—		—		—
Other commercial and industrial	—		—		—		—		—		—
Total commercial	—		1,746		1,746		—		1,746		1,746

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

Residential mortgage:
Permanent mortgage	—		298		298		—		542		542
Permanent mortgage guaranteed by U.S. government agencies	17,491		1,095		18,586		19,352		1,121		20,473
Home equity	—		258		258		—		258		258
Total residential mortgage	17,491		1,651		19,142		19,352		1,921		21,273

Personal	—		11		11		—		11		11

Total	$	17,491	$	3,408	$	20,899	$	19,352	$	3,678	$	23,030

Summary of Loans by Aging Status [Table Text Block]

Nonaccrual & Past Due Loans

Past due status for all loan classes is based on the actual number of days since the last payment was due according to the contractual terms of the loans.

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



			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	2,752,259	$	—	$	5,039	$	—	$	110,683	$	2,867,981
Services	2,963,746		2,343		250		—		1,174		2,967,513
Wholesale/retail	1,654,018		1,748		409		30		1,893		1,658,098
Manufacturing	508,231		—		2,156		—		9,059		519,446
Healthcare	2,214,849		156		—		—		24,446		2,239,451
Other commercial and industrial	513,748		52		—		—		29,645		543,445
Total commercial	10,606,851		4,299		7,854		30		176,900		10,795,934

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

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

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

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

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



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

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

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

Personal	838,811		589		263	5		290		839,958

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

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



			Past Due
	Current		30 to 59 Days		60 to 89 Days	90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	2,365,850	$	11,988	—	$	—	$	142,966	$	2,520,804
Services	2,923,874		502		39	3,707		8,477		2,936,599
Wholesale/retail	1,599,356		221		—	—		2,453		1,602,030
Manufacturing	499,212		—		—	—		274		499,486
Healthcare	2,083,556		635		—	—		855		2,085,046
Other commercial and industrial	454,538		34		68	119		21,439		476,198
Total commercial	9,926,386		13,380		107	3,826		176,464		10,120,163

Commercial real estate:
Residential construction and land development	156,207		—		—	—		3,739		159,946
Retail	796,362		3,766		—	—		1,249		801,377
Office	751,823		—		—	—		882		752,705
Multifamily	868,591		—		5,131	—		51		873,773
Industrial	837,945		—		—	—		76		838,021
Other commercial real estate	366,416		7		—	—		1,353		367,776
Total commercial real estate	3,777,344		3,773		5,131	—		7,350		3,793,598

Residential mortgage:
Permanent mortgage	939,853		3,547		202	—		25,956		969,558
Permanent mortgages guaranteed by U.S. government agencies	41,150		17,364		12,963	103,400		15,432		190,309
Home equity	700,031		1,526		305	—		11,064		712,926
Total residential mortgage	1,681,034		22,437		13,470	103,400		52,452		1,872,793

Personal	677,194		191		148	13		686		678,232

Total	$	16,061,958	$	39,781	18,856	$	107,239	$	236,952	$	16,464,786

Mortgage Banking Activities (Tables)

9 Months Ended

Sep. 30, 2017

Mortgage Banking [Abstract]

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



	September 30, 2017				December 31, 2016				September 30, 2016
	Unpaid Principal Balance/ Notional		Fair Value		Unpaid Principal Balance/ Notional		Fair Value		Unpaid Principal Balance/ Notional		Fair Value
Residential mortgage loans held for sale	$	261,868	$	265,783	$	286,414	$	286,971	$	422,523	$	433,040
Residential mortgage loan commitments	334,337		9,066		318,359		9,733		630,804		18,598
Forward sales contracts	524,878		794		569,543		5,193		929,907		(4,046		)
			$	275,643			$	301,897			$	447,592

Mortgage Banking Revenue [Table Text Block]

Mortgage banking revenue was as follows (in thousands):



	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Production revenue:
Net realized gains on sale of mortgage loans	$	12,041		$	23,110		$	32,443		$	47,424
Net change in unrealized gain on mortgage loans held for sale	(1,492		)	(2,518		)	3,335			4,649
Net change in the fair value of mortgage loan commitments	(1,927		)	(6,901		)	(667		)	10,464
Net change in the fair value of forward sales contracts	(293		)	8,267			(4,399		)	(4,846		)
Total production revenue	8,329			21,958			30,712			57,691
Servicing revenue	16,561			16,558			49,645			47,809
Total mortgage banking revenue	$	24,890		$	38,516		$	80,357		$	105,500

Summary of Mortgage Servicing Rights [Table Text Block]

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



	September 30, 2017			December 31, 2016			September 30, 2016
Number of residential mortgage loans serviced for others	137,359			139,340			139,587
Outstanding principal balance of residential mortgage loans serviced for others	$	22,063,121		$	21,997,568		$	21,851,536
Weighted average interest rate	3.95		%	3.97		%	4.01		%
Remaining term (in months)	298			301			302

Activity in Capitalized Mortgage Servicing Rights [Table Text Block]

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



	Purchased			Originated			Total
Balance, June 30, 2017	$	7,995		$	237,244		$	245,239
Additions, net	—			9,925			9,925
Change in fair value due to principal payments	(470		)	(8,197		)	(8,667		)
Change in fair value due to market assumption changes	303			(942		)	(639		)
Balance, September 30, 2017	$	7,828		$	238,030		$	245,858



	Purchased			Originated			Total
Balance, December 31, 2016	$	8,909		$	238,164		$	247,073
Additions, net	—			29,439			29,439
Change in fair value due to principal payments	(1,443		)	(23,485		)	(24,928		)
Change in fair value due to market assumption changes	362			(6,088		)	(5,726		)
Balance, September 30, 2017	$	7,828		$	238,030		$	245,858

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



	Purchased			Originated			Total
Balance, June 30, 2016	$	4,067		$	186,680		$	190,747
Additions, net	—			21,990			21,990
Change in fair value due to scheduled payments and full-balance payoffs	(753		)	(10,690		)	(11,443		)
Change in fair value due to market assumption changes	251			2,076			2,327
Balance, September 30, 2016	$	3,565		$	200,056		$	203,621



	Purchased			Originated			Total
Balance, December 31, 2015	$	9,911		$	208,694		$	218,605
Additions, net	—			56,345			56,345
Change in fair value due to scheduled payments and full-balance payoffs	(2,109		)	(27,276		)	(29,385		)
Change in fair value due to market assumption changes	(4,237		)	(37,707		)	(41,944		)
Balance, September 30, 2016	$	3,565		$	200,056		$	203,621

Assumptions to Value Mortgage Servicing Rights [Table Text Block]

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



	September 30, 2017	December 31, 2016	September 30, 2016
Discount rate – risk-free rate plus a market premium	9.84%	10.08%	10.08%
Prepayment rate - based upon loan interest rate, original term and loan type	8.71%-15.43%	8.98%-16.91%	9.16%-47.15%
Loan servicing costs – annually per loan based upon loan type:
Performing loans	$65-$120	$63 - $120	$63 - $120
Delinquent loans	$150-$500	$150 - $500	$150 - $500
Loans in foreclosure	$1,000-$4,250	$650 - $4,250	$650 - $4,250
Escrow earnings rate – indexed to rates paid on deposit accounts with comparable average life	2.00%	1.98%	1.18%
Primary/secondary mortgage rate spread	105 bps	105 bps	115 bps

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

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



			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Total
FHLMC	$	8,021,016	$	78,542	$	13,100	$	26,171	$	8,138,829
FNMA	6,635,428		76,065		10,398		20,596		6,742,487
GNMA	6,376,127		215,506		59,659		20,925		6,672,217
Other	502,768		3,492		1,167		2,161		509,588
Total	$	21,535,339	$	373,605	$	84,324	$	69,853	$	22,063,121

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

9 Months Ended

Sep. 30, 2017

Commitments and Contingencies Disclosure [Abstract]

Schedule of Variable Interest Entities [Table Text Block]

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



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

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



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

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



	September 30, 2016
	Loans		Other assets		Other liabilities		Other borrowings		Non-controlling interests
Consolidated:
Private equity funds	$	—	$	18,420	$	—	$	—	$	15,946
Tax credit entities	10,000		11,740		—		10,964		10,000
Other	—		30,978		2,346		1,063		8,154
Total consolidated	$	10,000	$	61,138	$	2,346	$	12,027	$	34,100

Unconsolidated:
Tax credit entities	$	39,849	$	129,715	$	57,026	$	—	$	—
Other	—		30,272		13,653		—		—
Total unconsolidated	$	39,849	$	159,987	$	70,679	$	—	$	—

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

Stockholders' Equity Note [Abstract]

Shareholders' Equity (Tables)

9 Months Ended

Sep. 30, 2017

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

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



	Unrealized Gain (Loss) on
	Available for Sale Securities			Investment Securities Transferred from AFS			Employee Benefit Plans			Total
Balance, December 31, 2015	$	23,284		$	68		$	(1,765	)	$	21,587
Net change in unrealized gain (loss)	133,108			—			—			133,108
Reclassification adjustments included in earnings:
Interest revenue, Investment securities, Taxable securities	—			(112		)	—			(112		)
Gain on available for sale securities, net	(11,684		)	—			—			(11,684		)
Other comprehensive income (loss), before income taxes	121,424			(112		)	—			121,312
Federal and state income taxes¹	47,216			(44		)	—			47,172
Other comprehensive income (loss), net of income taxes	74,208			(68		)	—			74,140
Balance, September 30, 2016	$	97,492		$	—		$	(1,765	)	$	95,727

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


¹	Calculated using a 39 percent effective tax rate.

Earnings Per Share (Tables)

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Earnings Per Share [Table Text Block]



(In thousands, except share and per share amounts)	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Numerator:
Net income attributable to BOK Financial Corp. shareholders	$	85,649	$	74,277	$	262,152	$	182,642
Less: Earnings allocated to participating securities	888		916		2,817		2,275
Numerator for basic earnings per share – income available to common shareholders	84,761		73,361		259,335		180,367
Effect of reallocating undistributed earnings of participating securities	1		1		2		1
Numerator for diluted earnings per share – income available to common shareholders	$	84,762	$	73,362	$	259,337	$	180,368

Denominator:
Weighted average shares outstanding	65,423,258		65,895,430		65,432,313		66,031,497
Less: Participating securities included in weighted average shares outstanding	680,436		810,038		702,922		822,723
Denominator for basic earnings per common share	64,742,822		65,085,392		64,729,391		65,208,774
Dilutive effect of employee stock compensation plans¹	62,350		72,449		64,502		54,792
Denominator for diluted earnings per common share	64,805,172		65,157,841		64,793,893		65,263,566

Basic earnings per share	$	1.31	$	1.13	$	4.01	$	2.77
Diluted earnings per share	$	1.31	$	1.13	$	4.00	$	2.76
¹ Excludes employee stock options with exercise prices greater than current market price.	—		—		—		—

Reportable Segments (Tables)

9 Months Ended

Sep. 30, 2017

Segment Reporting [Abstract]

Reportable Segments [Table Text Block]

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



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	157,080		$	25,576		$	11,169		$	24,627		$	218,452
Net interest revenue (expense) from internal sources	(24,173		)	12,213			9,604			2,356			—
Net interest revenue	132,907			37,789			20,773			26,983			218,452
Provision for credit losses	3,217			1,315			(623		)	(3,909		)	—
Net interest revenue after provision for credit losses	129,690			36,474			21,396			30,892			218,452
Other operating revenue	54,091			47,033			75,707			(1,121		)	175,710
Other operating expense	56,952			56,785			61,791			90,406			265,934
Net direct contribution	126,829			26,722			35,312			(60,635		)	128,228
Gain on financial instruments, net	4			1,686			—			(1,690		)	—
Change in fair value of mortgage servicing rights	—			(639		)	—			639			—
Gain (loss) on repossessed assets, net	(4,126		)	292			—			3,834			—
Corporate expense allocations	8,650			17,039			9,819			(35,508		)	—
Net income before taxes	114,057			11,022			25,493			(22,344		)	128,228
Federal and state income taxes	44,368			4,288			9,917			(16,135		)	42,438
Net income	69,689			6,734			15,576			(6,209		)	85,790
Net income attributable to non-controlling interests	—			—			—			141			141
Net income attributable to BOK Financial Corp. shareholders	$	69,689		$	6,734		$	15,576		$	(6,350	)	$	85,649

Average assets	$	17,558,390		$	9,115,319		$	6,992,021		$	(657,560	)	$	33,008,170

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



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	435,946		$	70,208		$	33,130		$	85,554		$	624,838
Net interest revenue (expense) from internal sources	(61,803		)	35,002			28,784			(1,983		)	—
Net interest revenue	374,143			105,210			61,914			83,571			624,838
Provision for credit losses	2,983			3,512			(676		)	(5,819		)	—
Net interest revenue after provision for credit losses	371,160			101,698			62,590			89,390			624,838
Other operating revenue	156,139			146,440			225,434			245			528,258
Other operating expense	168,517			166,027			182,816			244,170			761,530
Net direct contribution	358,782			82,111			105,208			(154,535		)	391,566
Gain on financial instruments, net	46			5,242			—			(5,288		)	—
Change in fair value of mortgage servicing rights	—			(5,726		)	—			5,726			—
Gain (loss) on repossessed assets, net	(2,728		)	253			—			2,475			—
Corporate expense allocations	26,144			50,947			30,438			(107,529		)	—
Net income before taxes	329,956			30,933			74,770			(44,093		)	391,566
Federal and state income taxes	128,353			12,033			29,086			(41,226		)	128,246
Net income	201,603			18,900			45,684			(2,867		)	263,320
Net income attributable to non-controlling interests	—			—			—			1,168			1,168
Net income attributable to BOK Financial Corp. shareholders	$	201,603		$	18,900		$	45,684		$	(4,035	)	$	262,152

Average assets	$	17,525,658		$	8,871,470		$	6,971,369		$	(591,059	)	$	32,777,438

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



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	123,599		$	22,098		$	9,274		$	32,875		$	187,846
Net interest revenue (expense) from internal sources	(15,052		)	9,263			$	7,401		(1,612		)	—
Net interest revenue	108,547			31,361			16,675			31,263			187,846
Provision for credit losses	5,601			1,157			(89		)	3,331			10,000
Net interest revenue after provision for credit losses	102,946			30,204			16,764			27,932			177,846
Other operating revenue	49,642			60,603			73,523			3,542			187,310
Other operating expense	53,375			60,964			64,426			79,323			258,088
Net direct contribution	99,213			29,843			25,861			(47,849		)	107,068
Gain (loss) on financial instruments, net	—			(1,087		)	(42		)	1,129			—
Change in fair value of mortgage servicing rights	—			2,327			—			(2,327		)	—
Gain on repossessed assets, net	1,486			161			—			(1,647		)	—
Corporate expense allocations	9,054			16,905			10,912			(36,871		)	—
Net income before taxes	91,645			14,339			14,907			(13,823		)	107,068
Federal and state income taxes	35,650			5,578			5,799			(15,071		)	31,956
Net income	55,995			8,761			9,108			1,248			75,112
Net income attributable to non-controlling interests	—			—			—			835			835
Net income attributable to BOK Financial Corp. shareholders	$	55,995		$	8,761		$	9,108		$	413		$	74,277

Average assets	$	16,934,587		$	8,827,816		$	6,413,735		$	470,335		$	32,646,473

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



	Commercial			Consumer			Wealth Management			Funds Management and Other			BOK Financial Consolidated
Net interest revenue from external sources	$	358,713		$	65,897		$	21,620		$	106,800		$	553,030
Net interest revenue (expense) from internal sources	(44,259		)	27,492			$	22,258		(5,491		)	—
Net interest revenue	314,454			93,389			43,878			101,309			553,030
Provision for credit losses	34,024			4,177			(479		)	27,278			65,000
Net interest revenue after provision for credit losses	280,430			89,212			44,357			74,031			488,030
Other operating revenue	146,248			172,072			218,042			(6,096		)	530,266
Other operating expense	162,039			179,487			186,524			223,993			752,043
Net direct contribution	264,639			81,797			75,875			(156,058		)	266,253
Gain (loss) on financial instruments, net	—			30,539			(42		)	(30,497		)	—
Change in fair value of mortgage servicing rights	—			(41,944		)	—			41,944			—
Gain on repossessed assets, net	806			566			—			(1,372		)	—
Corporate expense allocations	26,681			49,513			31,864			(108,058		)	—
Net income before taxes	238,764			21,445			43,969			(37,925		)	266,253
Federal and state income taxes	92,879			8,342			17,104			(34,444		)	83,881
Net income	145,885			13,103			26,865			(3,481		)	182,372
Net loss attributable to non-controlling interests	—			—			—			(270		)	(270		)
Net income attributable to BOK Financial Corp. shareholders	$	145,885		$	13,103		$	26,865		$	(3,211	)	$	182,642

Average assets	$	16,958,999		$	8,763,564		$	5,916,545		$	410,075		$	32,049,183

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

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

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



	Total		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Trading securities:
U.S. government agency debentures	$	30,162	$	—	$	30,162	$	—
U.S. government agency residential mortgage-backed securities	516,760		—		516,760		—
Municipal and other tax-exempt securities	56,148		—		56,148		—
Other trading securities	11,047		—		11,047		—
Total trading securities	614,117		—		614,117		—
Available for sale securities:
U.S. Treasury	999		999		—		—
Municipal and other tax-exempt securities	28,368		—		23,583		4,785
U.S. government agency residential mortgage-backed securities	5,326,384		—		5,326,384		—
Privately issued residential mortgage-backed securities	99,994		—		99,994		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,889,346		—		2,889,346		—
Other debt securities	4,153		—		—		4,153
Perpetual preferred stock	16,245		—		16,245		—
Equity securities and mutual funds	17,710		2,578		15,132		—
Total available for sale securities	8,383,199		3,577		8,370,684		8,938
Fair value option securities – U.S. government agency residential mortgage-backed securities	819,531		—		819,531		—
Residential mortgage loans held for sale	275,643		—		263,543		12,100
Mortgage servicing rights¹	245,858		—		—		245,858
Derivative contracts, net of cash collateral²	352,559		8,498		344,061		—
Liabilities:
Derivative contracts, net of cash collateral²	336,327		6,903		329,424		—


¹	A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 6, Mortgage Banking Activities.

²

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

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



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


¹	A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 6, Mortgage Banking Activities.

²

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

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



	Total		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Trading securities:
U.S. government agency debentures	$	15,705	$	—	$	15,705	$	—
U.S. government agency residential mortgage-backed securities	464,749		—		464,749		—
Municipal and other tax-exempt securities	54,856		—		54,856		—
Other trading securities	11,305		—		11,305		—
Total trading securities	546,615		—		546,615		—
Available for sale securities:
U.S. Treasury	1,002		1,002		—		—
Municipal and other tax-exempt securities	42,092		—		36,379		5,713
U.S. government agency residential mortgage-backed securities	5,668,672		—		5,668,672		—
Privately issued residential mortgage-backed securities	121,603		—		121,603		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,986,495		—		2,986,495		—
Other debt securities	4,151		—		—		4,151
Perpetual preferred stock	19,578		—		19,578		—
Equity securities and mutual funds	18,690		3,544		15,146		—
Total available for sale securities	8,862,283		4,546		8,847,873		9,864
Fair value option securities:
U.S. Treasury	222,409		222,409		—		—
U.S. government agency residential mortgage-backed securities	—		—		—		—
Total fair value option securities	222,409		222,409		—		—
Residential mortgage loans held for sale	447,592		—		438,291		9,301
Mortgage servicing rights¹	203,621		—		—		203,621
Derivative contracts, net of cash collateral²	655,078		5,575		649,503		—
Liabilities:
Derivative contracts, net of cash collateral²	573,987		1,308		572,679		—


¹	A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 6, Mortgage Banking Activities.

²

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

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

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



	Available for Sale Securities
	Municipal and other tax-exempt securities		Other debt securities		Residential mortgage loans held for sale
Balance, June 30, 2017	$	4,655	$	4,152	$	12,735
Transfer to Level 3 from Level 2¹	—		—		176
Purchases	—		—		—
Proceeds from sales	—		—		(847		)
Redemptions and distributions	—		—		—
Gain recognized in earnings:
Mortgage banking revenue	—		—		36
Other comprehensive income:
Net change in unrealized gain	130		1		—
Balance, September 30, 2017	$	4,785	$	4,153	$	12,100


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



	Available for Sale Securities
	Municipal and other tax-exempt			Other debt securities		Residential mortgage loans held for sale
Balance, December 31, 2016	$	5,789		$	4,152	$	11,617
Transfer to Level 3 from Level 2¹	—			—		2,916
Purchases	—			—		—
Proceeds from sales	—			—		(2,549		)
Redemptions and distributions	(1,100		)	—		—
Gain (loss) recognized in earnings:
Mortgage banking revenue	—			—		116
Other comprehensive income (loss):
Net change in unrealized gain (loss)	96			1		—
Balance, September 30, 2017	$	4,785		$	4,153	$	12,100


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

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



	Available for Sale Securities
	Municipal and other tax-exempt securities			Other debt securities		Residential mortgage loans held for sale
Balance, June 30, 2016	$	9,600		$	4,151	$	9,749
Transfer to Level 3 from Level 2¹	—			—		442
Purchases	—			—		—
Proceeds from sales	—			—		(1,003		)
Redemptions and distributions	(3,975		)	—		—
Gain (loss) recognized in earnings:
Mortgage banking revenue	—			—		113
Other comprehensive income (loss):
Net change in unrealized gain (loss)	88			—		—
Balance, September 30, 2016	$	5,713		$	4,151	$	9,301


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



	Available for Sale Securities
	Municipal and other tax-exempt			Other debt securities		Residential mortgage loans held for sale
Balance, December 31, 2015	$	9,610		$	4,151	$	7,874
Transfer to Level 3 from Level 2¹	—			—		3,982
Purchases	—			—		—
Proceeds from sales	—			—		(2,365		)
Redemptions and distributions	(3,975		)	—		—
Gain (loss) recognized in earnings
Mortgage banking revenue	—			—		(190		)
Other comprehensive income (loss):
Net change in unrealized gain (loss)	78			—		—
Balance, September 30, 2016	$	5,713		$	4,151	$	9,301


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 September 30, 2017 follows (in thousands):



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

Available for sale securities
Municipal and other tax-exempt securities	$	5,095	$	5,067	$	4,785	Discounted cash flows	¹	Interest rate spread	6.05%-6.05% (6.05%)	²
										92.25%-95.02% (93.91%)	³
Other debt securities	4,400		4,400		4,153		Discounted cash flows	¹	Interest rate spread	6.65%-6.73% (6.72%)	⁴
										94.38% - 94.38 (94.38%)	³

Residential mortgage loans held for sale	N/A		12,612		12,100		Quoted prices of loans sold in securitization transactions, with a liquidity discount applied		Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.	95.94%


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


²	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 352 to 467 basis points over average yields for comparable tax-exempt securities.


³	Represents fair value as a percentage of par value.


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

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



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

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


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


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


³	Represents fair value as a percentage of par value.


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

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



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

Available for sale securities
Municipal and other tax-exempt securities	$	6,195	$	6,162	$	5,713	Discounted cash flows	¹	Interest rate spread	5.60%-5.90% (5.85%)	²
										90.00%-93.79% (92.22%)	³
Other debt securities	4,400		4,400		4,151		Discounted cash flows	¹	Interest rate spread	5.98%-6.03% (6.02%)	⁴
										94.34% - 94.34 (94.34%)	³

Residential mortgage loans held for sale	N/A		9,957		9,301		Quoted prices of loans sold in securitization transactions, with a liquidity discount applied		Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.	93.41%


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


²	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 437 to 484 basis points over average yields for comparable tax-exempt securities.


³	Represents fair value as a percentage of par value.


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

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

The following represents the carrying value of assets measured at fair value on a non-recurring basis (and related losses) during the period. The carrying value represents only those assets with a balance at September 30, 2017 for which the fair value was adjusted during the nine months ended September 30, 2017:



							Fair Value Adjustments for the
	Carrying Value at September 30, 2017						Three Months Ended September 30, 2017 Recognized in:				Nine Months Ended September 30, 2017 Recognized in:
	Quoted Prices in Active Markets for Identical Instruments		Significant Other Observable Inputs		Significant Unobservable Inputs		Gross charge-offs against allowance for loan losses		Net losses and expenses of repossessed assets, net		Gross charge-offs against allowance for loan losses		Net losses and expenses of repossessed assets, net
Impaired loans	$	—	$	423	$	10,960	$	4,397	$	—	$	5,058	$	—
Real estate and other repossessed assets	—		4,392		6,845		—		4,683		—		4,915

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



	Carrying Value at September 30, 2016						Fair Value Adjustments for the Three Months Ended September 30, 2016 Recognized in:				Nine Months Ended September 30, 2016 Recognized in:
	Quoted Prices in Active Markets for Identical Instruments		Significant Other Observable Inputs		Significant Unobservable Inputs		Gross charge-offs against allowance for loan losses		Net losses and expenses of repossessed assets, net		Gross charge-offs against allowance for loan losses		Net losses and expenses of repossessed assets, net
Impaired loans	$	—	$	436	$	23,089	$	6,334	$	—	$	30,200	$	—
Real estate and other repossessed assets	—		6,048		1,927		—		480		—		1,260

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 September 30, 2017 follows (in thousands):



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


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

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



	Fair Value		Valuation Technique(s)	Unobservable Input	Range (Weighted Average)
Impaired loans	$	23,089	Discounted cash flows	Recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs	23% - 59% (43%)¹
Real estate and other repossessed assets	1,927		Appraised value, as adjusted	Marketability adjustments off appraised value2	68% - 80% (71%)


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


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

Fair Value of Financial Instruments [Table Text Block]

The following table presents the carrying values and estimated fair values of all financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis as of September 30, 2017 (dollars in thousands):



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

The following table presents the carrying values and estimated fair values of all financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis as of December 31, 2016 (dollars in thousands):



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

The following table presents the carrying values and estimated fair values of all financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis as of September 30, 2016 (dollars in thousands):



	Carrying Value			Estimated Fair Value		Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and due from banks	$	535,916		$	535,916	$	535,916	$	—	$	—
Interest-bearing cash and cash equivalents	2,080,978			2,080,978		2,080,978		—		—
Trading securities:								—
U.S. government agency debentures	15,705			15,705		—		15,705		—
U.S. government agency residential mortgage-backed securities	464,749			464,749		—		464,749		—
Municipal and other tax-exempt securities	54,856			54,856		—		54,856		—
Other trading securities	11,305			11,305		—		11,305		—
Total trading securities	546,615			546,615		—		546,615		—
Investment securities:
Municipal and other tax-exempt securities	323,225			327,788		—		327,788		—
U.S. government agency residential mortgage-backed securities	22,166			23,452		—		23,452		—
Other debt securities	201,066			229,070		—		229,070		—
Total investment securities	546,457			580,310		—		580,310		—
Available for sale securities:
U.S. Treasury	1,002			1,002		1,002		—		—
Municipal and other tax-exempt securities	42,092			42,092		—		36,379		5,713
U.S. government agency residential mortgage-backed securities	5,668,672			5,668,672		—		5,668,672		—
Privately issued residential mortgage-backed securities	121,603			121,603		—		121,603		—
Commercial mortgage-backed securities guaranteed by U.S. government agencies	2,986,495			2,986,495		—		2,986,495		—
Other debt securities	4,151			4,151		—		—		4,151
Perpetual preferred stock	19,578			19,578		—		19,578		—
Equity securities and mutual funds	18,690			18,690		3,544		15,146		—
Total available for sale securities	8,862,283			8,862,283		4,546		8,847,873		9,864
Fair value option securities:
U.S. Treasury	222,409			222,409		222,409		—		—
U.S. government agency residential mortgage-backed securities	—			—		—		—		—
Total fair value option securities	222,409			222,409		222,409		—		—
Residential mortgage loans held for sale	447,592			447,592		—		438,291		9,301
Loans:
Commercial	10,120,163			9,926,548		—		—		9,926,548
Commercial real estate	3,793,598			3,769,427		—		—		3,769,427
Residential mortgage	1,872,793			1,905,786		—		—		1,905,786
Personal	678,232			671,421		—		—		671,421
Total loans	16,464,786			16,273,182		—		—		16,273,182
Allowance for loan losses	(245,103		)	—		—		—		—
Loans, net of allowance	16,219,683			16,273,182		—		—		16,273,182
Mortgage servicing rights	203,621			203,621		—		—		203,621
Derivative instruments with positive fair value, net of cash collateral	655,078			655,078		5,575		649,503		—
Deposits with no stated maturity	18,925,873			18,925,873		—		—		18,925,873
Time deposits	2,169,631			2,163,947		—		—		2,163,947
Other borrowed funds	7,147,047			7,079,737		—		—		7,079,737
Subordinated debentures	144,631			148,360		—		148,360		—
Derivative instruments with negative fair value, net of cash collateral	573,987			573,987		1,308		572,679		—

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



	Range of Contractual Yields				Average Re-pricing (in years)	Discount Rate
	Minimum		Maximum		Average	Minimum		Maximum
September 30, 2017
Commercial	0.38	%	30.00	%	0.62	0.78	%	4.59	%
Commercial real estate	0.38	%	18.00	%	0.77	1.04	%	4.38	%
Residential mortgage	1.74	%	18.00	%	2.12	1.79	%	4.09	%
Consumer	0.25	%	21.00	%	0.24	0.55	%	4.78	%

Time deposits	0.03	%	9.64	%	1.95	1.86	%	2.18	%
Other borrowings	0.25	%	6.25	%	0.02	1.06	%	3.70	%
Subordinated debentures	5.38	%	5.38	%	16.85	4.96	%	4.96	%

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

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

September 30, 2016
Commercial	0.38	%	30.00	%	0.69	0.54	%	3.93	%
Commercial real estate	0.38	%	18.00	%	0.72	0.80	%	3.90	%
Residential mortgage	1.74	%	18.00	%	1.95	1.57	%	3.55	%
Consumer	0.25	%	21.00	%	0.35	0.75	%	4.15	%

Time deposits	0.03	%	9.65	%	2.10	1.37	%	1.66	%
Other borrowings	0.25	%	3.81	%	0.02	0.29	%	2.99	%
Subordinated debentures	5.38	%	5.38	%	18.37	5.38	%	5.38	%

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

9 Months Ended

Sep. 30, 2017

Income Tax Disclosure [Abstract]

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):



	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Amount:
Federal statutory tax	$	44,880		$	37,474		$	137,048		$	93,189
Tax exempt revenue	(3,001		)	(2,391		)	(9,336		)	(7,491		)
Effect of state income taxes, net of federal benefit	2,486			1,364			7,875			5,222
Utilization of tax credits:
Low-income housing tax credit, net of amortization	(23		)	(623		)	(2,272		)	(2,505		)
Other tax credits	(364		)	(522		)	(1,091		)	(1,564		)
Bank-owned life insurance	(705		)	(813		)	(2,252		)	(2,414		)
Share-based compensation	(169		)	—			(2,470		)	—
Other, net	(666		)	(2,533		)	744			(556		)
Total income tax expense	$	42,438		$	31,956		$	128,246		$	83,881



	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Percent of pretax income:
Federal statutory tax	35.0	%	35.0	%	35.0	%	35.0	%
Tax exempt revenue	(2.3	)	(2.2	)	(2.4	)	(2.8	)
Effect of state income taxes, net of federal benefit	1.9		1.3		2.0		2.0
Utilization of tax credits:
Low-income housing tax credit, net of amortization	—		(0.6	)	(0.6	)	(0.9	)
Other tax credits	(0.3	)	(0.5	)	(0.3	)	(0.6	)
Bank-owned life insurance	(0.5	)	(0.8	)	(0.6	)	(0.9	)
Share-based compensation	(0.1	)	—		(0.6	)	—
Other, net	(0.6	)	(2.4	)	0.3		(0.3	)
Total	33.1	%	29.8	%	32.8	%	31.5	%

Significant Accounting Policies Loans and Allowance for Credit Losses (Details)	9 Months Ended
	Sep. 30, 2017
Loans and Allowance for Credit Losses [Abstract]
Loans, Number of Days Past Due for a Non-Risk Graded Loan to be Placed on Nonaccruing Status	90 days
Loans, Number of Days After Notification of Chapter 7 Bankruptcy Non-Risk Graded Loan is Placed on Nonaccruing Status	60 days
Loans and Allowances for Credit Losses, Minimum No of Days After Which Past Due Non-Risk Graded Loans Are Charged Off	60 days
Loans and Allowances for Credit Losses, Maximum No of Days After Which Past Due Non-Risk Graded Loans Are Charged Off	180 days
Loans, Number of Days After Notification of Chapter 7 Bankruptcy Non-Risk Graded Loan is Charged Off	60 days

Significant Accounting Policies Newly Adopted and Pending Accounting Pronouncements (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Interchange fees related to transaction card processing revenue	$ 27

Trading Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	$ 614,117	$ 337,628	$ 546,615
Trading Securities, Net Unrealized Gain (Loss)	798	738	783
Trading Securities, Pledged as Collateral [Abstract]
Trading Securities Pledged as Collateral	224,000	0	0
U.S. government agency debentures
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	30,162	6,234	15,705
Trading Securities, Net Unrealized Gain (Loss)	(101)	(4)	(7)
U.S. government agency residential mortgage-backed securities
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	516,760	310,067	464,749
Trading Securities, Net Unrealized Gain (Loss)	723	635	876
Municipal and other tax-exempt securities
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	56,148	14,427	54,856
Trading Securities, Net Unrealized Gain (Loss)	153	50	(100)
Other trading securities
Schedule of Trading Securities [Line Items]
Trading Securities, Fair Value	11,047	6,900	11,305
Trading Securities, Net Unrealized Gain (Loss)	$ 23	$ 57	$ 14

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

9 Months Ended

Sep. 30, 2017

USD ($)

Dec. 31, 2016

USD ($)

Sep. 30, 2016

USD ($)

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

$ 466,562

$ 546,145

$ 546,457

489,895

565,493

580,310

24,150

^[1]

21,154

^[2]

34,045

^[3]

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

(817)

^[1]

(1,806)

^[2]

(192)

^[3]

Investments Securities, Debt Maturities, Amortized Cost

466,562

546,145

546,457

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

Investment Securities, Debt Maturities, Nominal Yield [Abstract]

$ 489,895

565,493

580,310

Investment Securities, Debt Maturities, Nominal Yield

3.83%

Investment Securities, Pledged as Collateral [Abstract]

Investment Securities, Pledged as Collateral, Amortized Cost

$ 237,525

322,208

301,754

Investment Securities, Pledged as Collateral, Fair Value

$ 241,208

$ 323,808

$ 307,264

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

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

92

193

78

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

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

$ 93,835

$ 236,070

$ 101,068

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

10,222

5,188

5,215

Investment Securities, Continuous Unrealized Loss Position, Fair Value

104,057

241,258

106,283

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

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

698

1,709

112

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

119

97

80

Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss

817

1,806

192

Fixed Maturity Securities [Member]

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

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

98,332

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

155,015

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

146,626

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

49,663

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

449,636

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

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

98,523

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

158,582

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

163,842

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

51,490

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

$ 472,437

Investment Securities, Debt Maturities, Nominal Yield [Abstract]

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

2.08%

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

2.97%

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

5.63%

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

5.02%

Investment Securities, Debt Maturities, Nominal Yield

3.87%

Investment Securities, Debt Maturities, Weighted Average Maturity

^[4]

4.82

Municipal and other tax-exempt securities

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

$ 246,000

320,364

323,225

249,250

321,225

327,788

3,415

^[1]

2,272

^[2]

4,745

^[3]

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

(165)

^[1]

(1,411)

^[2]

(182)

^[3]

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

84,786

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

107,938

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

16,132

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

37,144

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

246,000

Investments Securities, Debt Maturities, Amortized Cost

246,000

320,364

323,225

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

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

84,835

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

108,352

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

16,776

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

39,287

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

249,250

Investment Securities, Debt Maturities, Nominal Yield [Abstract]

$ 249,250

$ 321,225

$ 327,788

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

^[5]

1.75%

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

^[5]

2.15%

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

^[5]

4.68%

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

^[5]

5.21%

Investment Securities, Debt Maturities, Nominal Yield

^[5]

2.64%

Investment Securities, Debt Maturities, Weighted Average Maturity

^[4]

3.51

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

39.00%

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

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

63

151

75

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

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

$ 80,235

$ 219,892

$ 100,624

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

9,795

4,333

4,359

Investment Securities, Continuous Unrealized Loss Position, Fair Value

90,030

224,225

104,983

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

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

70

1,316

106

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

95

76

Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss

165

1,411

182

Other debt securities

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

203,636

205,004

201,066

223,187

222,795

229,070

20,141

^[1]

18,115

^[2]

28,014

^[3]

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

(590)

^[1]

(324)

^[2]

(10)

^[3]

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

13,546

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

47,077

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

130,494

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

12,519

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

203,636

Investments Securities, Debt Maturities, Amortized Cost

203,636

205,004

201,066

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

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

13,688

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

50,230

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

147,066

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

12,203

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

223,187

Investment Securities, Debt Maturities, Nominal Yield [Abstract]

$ 223,187

$ 222,795

$ 229,070

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

4.10%

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

4.86%

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

5.75%

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

4.47%

Investment Securities, Debt Maturities, Nominal Yield

5.35%

Investment Securities, Debt Maturities, Weighted Average Maturity

^[4]

6.40

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

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

28

41

3

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

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

$ 10,022

$ 11,820

$ 444

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

427

855

856

Investment Securities, Continuous Unrealized Loss Position, Fair Value

10,449

12,675

1,300

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

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

566

322

6

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

24

2

4

Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss

590

324

10

U.S. government agency residential mortgage-backed securities

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

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

16,926

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

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

$ 17,458

Investment Securities, Debt Maturities, Nominal Yield [Abstract]

Investment Securities, Debt Maturities, Nominal Yield

^[6]

2.76%

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

4 years 255 days

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

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

$ 16,926

20,777

22,166

17,458

21,473

23,452

594

^[1]

767

^[2]

1,286

^[3]

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

(62)

^[1]

(71)

^[2]

0

^[3]

Investments Securities, Debt Maturities, Amortized Cost

16,926

20,777

22,166

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

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

$ 17,458

$ 21,473

$ 23,452

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

1

0

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

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

$ 3,578

$ 4,358

$ 0

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

0

Investment Securities, Continuous Unrealized Loss Position, Fair Value

3,578

4,358

0

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

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

62

71

0

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

0

Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss

$ 62

$ 71

$ 0

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

Available for Sale Securities (Details)
$ in Thousands

3 Months Ended

9 Months Ended

Sep. 30, 2017

USD ($)

Sep. 30, 2016

USD ($)

Sep. 30, 2017

USD ($)

Sep. 30, 2016

USD ($)

Dec. 31, 2016

USD ($)

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

$ 8,369,138

$ 8,702,750

$ 8,369,138

$ 8,702,750

$ 8,691,728

Available-for-sale Securities, Gross Unrealized Gain

8,383,199

8,862,283

8,383,199

8,862,283

8,676,829

64,797

^[1]

165,765

^[2]

64,797

^[1]

165,765

^[2]

60,165

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(50,736)

^[1]

(6,028)

^[2]

(50,736)

^[1]

(6,028)

^[2]

(74,846)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

(204)

^[5]

0

^[4]

(204)

^[5]

(218)

^[6]

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

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

8,369,138

8,702,750

8,369,138

8,702,750

8,691,728

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

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

$ 8,383,199

8,862,283

$ 8,383,199

8,862,283

8,676,829

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

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

1.95%

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

Available-for-sale Securities, Proceeds

$ 265,632

232,239

$ 966,044

1,027,379

Available-for-sale Securities, Gross realized gains

2,768

2,415

7,623

11,705

Available-for-sale Securities, Gross realized losses

(281)

(21)

(2,707)

(21)

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

967

931

1,912

4,545

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

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

6,559,615

7,098,721

6,559,615

7,098,721

7,353,116

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

$ 6,551,240

$ 7,213,520

$ 6,551,240

$ 7,213,520

$ 7,327,470

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

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

383

130

383

130

488

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

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

$ 2,878,675

$ 1,107,872

$ 2,878,675

$ 1,107,872

$ 5,231,605

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

1,373,859

327,297

1,373,859

327,297

178,249

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

4,252,534

1,435,169

4,252,534

1,435,169

5,409,854

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

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

23,486

4,786

23,486

4,786

70,818

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

27,250

1,446

27,250

1,446

4,246

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

50,736

6,232

50,736

6,232

75,064

Fixed Maturity Securities [Member]

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

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

69,237

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

982,728

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

1,616,383

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

265,291

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

2,933,639

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

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

69,181

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

980,779

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

1,610,642

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

262,264

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

$ 2,922,866

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

Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield

1.50%

Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield

1.86%

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield

1.92%

Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield

1.93%

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

1.88%

Available-for-sale Securities, Debt Maturities, Weighted Average Maturity

^[7]

6.96

U.S. Treasury

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

$ 1,000

1,000

$ 1,000

1,000

Available-for-sale Securities, Gross Unrealized Gain

999

1,002

999

1,002

999

0

^[1]

2

^[2]

0

^[1]

2

^[2]

0

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(1)

^[1]

0

^[2]

(1)

^[1]

0

^[2]

(1)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

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

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

1,000

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

0

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

0

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

0

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

1,000

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

1,000

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

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

999

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

0

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

0

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

0

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

999

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

$ 999

$ 1,002

$ 999

$ 1,002

$ 999

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

Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield

0.87%

Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield

0.00%

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield

0.00%

Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield

0.00%

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

0.87%

Available-for-sale Securities, Debt Maturities, Weighted Average Maturity

^[7]

0.29

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

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

1

0

1

0

1

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

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

$ 999

$ 0

$ 999

$ 0

$ 999

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

0

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

999

0

999

0

999

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

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

1

0

1

0

1

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

0

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

1

0

1

0

1

Municipal and other tax-exempt securities

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

28,411

41,943

28,411

41,943

41,050

Available-for-sale Securities, Gross Unrealized Gain

28,368

42,092

28,368

42,092

40,993

240

^[1]

602

^[2]

240

^[1]

602

^[2]

343

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(283)

^[1]

(453)

^[2]

(283)

^[1]

(453)

^[2]

(400)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

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

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

8,754

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

4,163

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

0

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

15,494

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

28,411

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

28,411

41,943

28,411

41,943

41,050

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

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

8,780

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

4,313

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

0

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

15,275

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

28,368

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

$ 28,368

$ 42,092

$ 28,368

$ 42,092

$ 40,993

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

Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield

^[8]

3.25%

Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield

^[8]

5.13%

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield

^[8]

0.00%

Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield

^[8],[9]

2.26%

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

^[8]

2.99%

Available-for-sale Securities, Debt Maturities, Weighted Average Maturity

^[7]

9.00

Available-for-sale Securities, Debt Maturities, Effective tax rate for nominal yield calculation

39.00%

Available-for-sale Securities, Debt Maturities, Number of days for interest rates to reset

35 days

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

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

11

20

11

20

24

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

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

$ 576

$ 2,210

$ 576

$ 2,210

$ 15,666

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

4,785

6,396

4,785

6,396

4,689

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

5,361

8,606

5,361

8,606

20,355

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

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

1

3

1

3

22

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

282

450

282

450

378

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

283

453

283

453

400

Commercial mortgage-backed securities guaranteed by U.S. government agencies

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

2,899,828

2,942,988

2,899,828

2,942,988

3,035,750

Available-for-sale Securities, Gross Unrealized Gain

2,889,346

2,986,495

2,889,346

2,986,495

3,017,933

5,577

^[1]

45,329

^[2]

5,577

^[1]

45,329

^[2]

5,472

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(16,059)

^[1]

(1,822)

^[2]

(16,059)

^[1]

(1,822)

^[2]

(23,289)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

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

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

59,483

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

978,565

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

1,616,383

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

245,397

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

2,899,828

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

2,899,828

2,942,988

2,899,828

2,942,988

3,035,750

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

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

59,402

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

976,466

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

1,610,642

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

242,836

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

2,889,346

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

$ 2,889,346

$ 2,986,495

$ 2,889,346

$ 2,986,495

$ 3,017,933

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

Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield

1.25%

Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield

1.85%

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield

1.92%

Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield

1.92%

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

1.88%

Available-for-sale Securities, Debt Maturities, Weighted Average Maturity

^[7]

6.90

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

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

137

33

137

33

171

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

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

$ 1,154,911

$ 372,805

$ 1,154,911

$ 372,805

$ 1,904,584

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

559,984

60,851

559,984

60,851

38,875

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

1,714,895

433,656

1,714,895

433,656

1,943,459

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

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

7,194

1,656

7,194

1,656

22,987

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

8,865

166

8,865

166

302

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

16,059

1,822

16,059

1,822

23,289

Other debt securities

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

4,400

Available-for-sale Securities, Gross Unrealized Gain

4,153

4,151

4,153

4,151

4,152

0

^[1]

0

^[2]

0

^[1]

0

^[2]

0

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(247)

^[1]

(249)

^[2]

(247)

^[1]

(249)

^[2]

(248)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

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

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

0

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

0

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

0

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

4,400

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

4,400

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

4,400

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

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

0

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

0

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

0

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

4,153

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

4,153

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

$ 4,153

$ 4,151

$ 4,153

$ 4,151

$ 4,152

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

Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield

0.00%

Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield

0.00%

Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield

0.00%

Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield

^[9]

1.71%

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

1.71%

Available-for-sale Securities, Debt Maturities, Weighted Average Maturity

^[7]

29.91

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

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

2

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

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

$ 0

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

4,153

4,151

4,153

4,151

4,152

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

4,153

4,151

4,153

4,151

4,152

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

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

0

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

247

249

247

249

248

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

247

249

247

249

248

Residential Mortgage Backed Securities [Member]

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

5,405,134

5,679,520

5,405,134

5,679,520

5,576,543

Available-for-sale Securities, Gross Unrealized Gain

5,426,378

5,790,275

5,426,378

5,790,275

5,575,921

54,642

^[1]

114,446

^[2]

54,642

^[1]

114,446

^[2]

50,377

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(33,398)

^[1]

(3,487)

^[2]

(33,398)

^[1]

(3,487)

^[2]

(50,781)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

(204)

^[5]

0

^[4]

(204)

^[5]

(218)

^[6]

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

Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis

5,405,134

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

5,405,134

5,679,520

5,405,134

5,679,520

5,576,543

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

Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value

5,426,378

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

$ 5,426,378

$ 5,790,275

$ 5,426,378

$ 5,790,275

$ 5,575,921

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

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

^[10]

1.99%

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

4 years

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

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

141

42

141

42

186

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

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

$ 1,718,517

$ 732,771

$ 1,718,517

$ 732,771

$ 3,308,229

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

803,509

255,013

803,509

255,013

129,716

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

2,522,026

987,784

2,522,026

987,784

3,437,945

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

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

15,594

3,127

15,594

3,127

47,767

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

17,804

564

17,804

564

3,232

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

33,398

3,691

33,398

3,691

50,999

U.S. government agency residential mortgage-backed securities

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

5,324,337

5,571,104

5,324,337

5,571,104

5,475,351

Available-for-sale Securities, Gross Unrealized Gain

5,326,384

5,668,672

5,326,384

5,668,672

5,460,386

35,445

^[1]

101,029

^[2]

35,445

^[1]

101,029

^[2]

35,800

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(33,398)

^[1]

(3,461)

^[2]

(33,398)

^[1]

(3,461)

^[2]

(50,765)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

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

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

5,324,337

5,571,104

5,324,337

5,571,104

5,475,351

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

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

$ 5,326,384

$ 5,668,672

$ 5,326,384

$ 5,668,672

$ 5,460,386

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

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

141

36

141

36

180

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

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

$ 1,718,517

$ 717,957

$ 1,718,517

$ 717,957

$ 3,300,298

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

803,509

247,240

803,509

247,240

116,208

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

2,522,026

965,197

2,522,026

965,197

3,416,506

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

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

15,594

2,960

15,594

2,960

47,593

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

17,804

501

17,804

501

3,172

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

33,398

3,461

33,398

3,461

50,765

U.S. government agency residential mortgage-backed securities | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]

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

3,103,869

3,035,041

3,103,869

3,035,041

3,062,525

Available-for-sale Securities, Gross Unrealized Gain

3,108,822

3,101,136

3,108,822

3,101,136

3,055,676

25,510

^[1]

67,859

^[2]

25,510

^[1]

67,859

^[2]

25,066

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(20,557)

^[1]

(1,764)

^[2]

(20,557)

^[1]

(1,764)

^[2]

(31,915)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

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

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

3,103,869

3,035,041

3,103,869

3,035,041

3,062,525

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

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

$ 3,108,822

$ 3,101,136

$ 3,108,822

$ 3,101,136

$ 3,055,676

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

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

81

14

81

14

91

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

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

$ 1,054,171

$ 365,201

$ 1,054,171

$ 365,201

$ 1,787,644

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

480,994

14,229

480,994

14,229

72,105

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

1,535,165

379,430

1,535,165

379,430

1,859,749

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

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

10,288

1,712

10,288

1,712

30,238

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

10,269

52

10,269

52

1,677

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

20,557

1,764

20,557

1,764

31,915

U.S. government agency residential mortgage-backed securities | Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]

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

1,331,212

1,611,887

1,331,212

1,611,887

1,534,451

Available-for-sale Securities, Gross Unrealized Gain

1,330,159

1,641,178

1,330,159

1,641,178

1,531,116

6,630

^[1]

29,640

^[2]

6,630

^[1]

29,640

^[2]

8,475

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(7,683)

^[1]

(349)

^[2]

(7,683)

^[1]

(349)

^[2]

(11,810)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

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

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

1,331,212

1,611,887

1,331,212

1,611,887

1,534,451

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

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

$ 1,330,159

$ 1,641,178

$ 1,330,159

$ 1,641,178

$ 1,531,116

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

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

42

6

42

6

58

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

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

$ 477,823

$ 122,713

$ 477,823

$ 122,713

$ 964,017

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

198,478

20,306

198,478

20,306

18,307

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

676,301

143,019

676,301

143,019

982,324

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

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

3,546

91

3,546

91

11,210

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

4,137

258

4,137

258

600

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

7,683

349

7,683

349

11,810

U.S. government agency residential mortgage-backed securities | Government National Mortgage Association Certificates and Obligations (GNMA) [Member]

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

864,256

924,176

864,256

924,176

878,375

Available-for-sale Securities, Gross Unrealized Gain

862,394

926,358

862,394

926,358

873,594

3,254

^[1]

3,530

^[2]

3,254

^[1]

3,530

^[2]

2,259

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(5,116)

^[1]

(1,348)

^[2]

(5,116)

^[1]

(1,348)

^[2]

(7,040)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

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

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

864,256

924,176

864,256

924,176

878,375

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

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

$ 862,394

$ 926,358

$ 862,394

$ 926,358

$ 873,594

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

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

17

16

17

16

31

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

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

$ 166,565

$ 230,043

$ 166,565

$ 230,043

$ 548,637

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

124,037

212,705

124,037

212,705

25,796

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

290,602

442,748

290,602

442,748

574,433

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

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

1,718

1,157

1,718

1,157

6,145

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

3,398

191

3,398

191

895

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

5,116

1,348

5,116

1,348

7,040

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

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

25,000

Available-for-sale Securities, Gross Unrealized Gain

25,009

^[1]

51

Available-for-sale Securities, Gross Unrealized Loss

^[1]

(42)

Available-for-Sale Securities, Other Than Temporary Impairments

0

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

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

25,000

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

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

$ 25,009

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

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

1

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

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

$ 19,958

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

0

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

19,958

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

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

42

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

0

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

42

Privately issued residential mortgage-backed securities

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

80,797

108,416

80,797

108,416

101,192

Available-for-sale Securities, Gross Unrealized Gain

99,994

121,603

99,994

121,603

115,535

19,197

^[1]

13,417

^[2]

19,197

^[1]

13,417

^[2]

14,577

^[3]

Available-for-sale Securities, Gross Unrealized Loss

0

^[1]

(26)

^[2]

0

^[1]

(26)

^[2]

(16)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

(204)

^[5]

0

^[4]

(204)

^[5]

(218)

^[6]

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

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

80,797

108,416

80,797

108,416

101,192

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

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

$ 99,994

$ 121,603

$ 99,994

$ 121,603

$ 115,535

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

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

0

6

^[11]

0

6

^[11]

6

^[12]

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

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

$ 0

$ 14,814

^[11]

$ 0

$ 14,814

^[11]

$ 7,931

^[12]

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

0

7,773

^[11]

0

7,773

^[11]

13,508

^[12]

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

0

22,587

^[11]

0

22,587

^[11]

21,439

^[12]

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

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

0

167

^[11]

0

167

^[11]

174

^[12]

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

0

63

^[11]

0

63

^[11]

60

^[12]

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

0

230

^[11]

0

230

^[11]

234

^[12]

Privately issued residential mortgage-backed securities | Alt A loans Member]

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

35,853

47,039

35,853

47,039

44,245

Available-for-sale Securities, Gross Unrealized Gain

46,695

54,065

46,695

54,065

51,512

10,842

^[1]

7,230

^[2]

10,842

^[1]

7,230

^[2]

7,485

^[3]

Available-for-sale Securities, Gross Unrealized Loss

0

^[1]

0

^[2]

0

^[1]

0

^[2]

0

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

(204)

^[5]

0

^[4]

(204)

^[5]

(218)

^[6]

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

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

35,853

47,039

35,853

47,039

44,245

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

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

$ 46,695

$ 54,065

$ 46,695

$ 54,065

$ 51,512

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

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

0

5

^[11]

0

5

^[11]

5

^[12]

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

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

$ 0

$ 8,231

^[11]

$ 0

$ 8,231

^[11]

$ 7,931

^[12]

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

0

7,773

^[11]

0

7,773

^[11]

7,410

^[12]

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

0

16,004

^[11]

0

16,004

^[11]

15,341

^[12]

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

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

0

141

^[11]

0

141

^[11]

174

^[12]

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

0

63

^[11]

0

63

^[11]

44

^[12]

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

0

204

^[11]

0

204

^[11]

218

^[12]

Privately issued residential mortgage-backed securities | Jumbo A loans [Member]

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

44,944

61,377

44,944

61,377

56,947

Available-for-sale Securities, Gross Unrealized Gain

53,299

67,538

53,299

67,538

64,023

8,355

^[1]

6,187

^[2]

8,355

^[1]

6,187

^[2]

7,092

^[3]

Available-for-sale Securities, Gross Unrealized Loss

0

^[1]

(26)

^[2]

0

^[1]

(26)

^[2]

(16)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

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

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

44,944

61,377

44,944

61,377

56,947

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

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

$ 53,299

$ 67,538

$ 53,299

$ 67,538

$ 64,023

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

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

0

1

^[11]

0

1

^[11]

1

^[12]

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

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

$ 0

$ 6,583

^[11]

$ 0

$ 6,583

^[11]

$ 0

^[12]

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

0

^[11]

0

^[11]

6,098

^[12]

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

0

6,583

^[11]

0

6,583

^[11]

6,098

^[12]

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

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

0

26

^[11]

0

26

^[11]

0

^[12]

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

0

^[11]

0

^[11]

16

^[12]

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

0

26

^[11]

0

26

^[11]

16

^[12]

Perpetual Preferred, Equity Securities and Mutual Funds [Member]

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

Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis

30,365

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

Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value

$ 33,955

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

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

0.00%

Perpetual preferred stock

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

$ 12,562

15,562

$ 12,562

15,562

15,561

Available-for-sale Securities, Gross Unrealized Gain

16,245

19,578

16,245

19,578

18,474

3,683

^[1]

4,016

^[2]

3,683

^[1]

4,016

^[2]

2,913

^[3]

Available-for-sale Securities, Gross Unrealized Loss

0

^[1]

0

^[2]

0

^[1]

0

^[2]

0

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

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

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

12,562

15,562

12,562

15,562

15,561

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

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

$ 16,245

$ 19,578

$ 16,245

$ 19,578

$ 18,474

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

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

0

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

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

$ 0

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

0

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

0

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

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

0

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

0

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

0

Equity securities and mutual funds

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

17,803

17,337

17,803

17,337

17,424

Available-for-sale Securities, Gross Unrealized Gain

17,710

18,690

17,710

18,690

18,357

655

^[1]

1,370

^[2]

655

^[1]

1,370

^[2]

1,060

^[3]

Available-for-sale Securities, Gross Unrealized Loss

(748)

^[1]

(17)

^[2]

(748)

^[1]

(17)

^[2]

(127)

^[3]

Available-for-Sale Securities, Other Than Temporary Impairments

0

^[4]

0

^[5]

0

^[4]

0

^[5]

0

^[6]

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

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

17,803

17,337

17,803

17,337

17,424

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

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

$ 17,710

$ 18,690

$ 17,710

$ 18,690

$ 18,357

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

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

91

33

91

33

104

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

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

$ 3,672

$ 86

$ 3,672

$ 86

$ 2,127

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

1,428

886

1,428

886

817

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

5,100

972

5,100

972

2,944

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

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

696

0

696

0

41

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

52

17

52

17

86

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

$ 748

$ 17

$ 748

$ 17

$ 127

[1]	Gross unrealized gain/loss recognized in AOCI in the consolidated balance sheet.
[2]	Gross unrealized gain/loss recognized in AOCI in the consolidated balance sheet.
[3]	Gross unrealized gain/loss recognized in AOCI in the consolidated balance sheet.
[4]	Amounts represent unrealized loss that remains in AOCI after an other-than-temporary credit loss has been recognized in income.
[5]	Amounts represent unrealized loss that remains in AOCI after an other-than-temporary credit loss has been recognized in income.
[6]	Amounts represent unrealized loss that remains in AOCI after an other-than-temporary credit loss has been recognized in income.
[7]	Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty.
[8]	Calculated on a taxable equivalent basis using a 39 percent effective tax rate.
[9]	Nominal yield on municipal and other tax-exempt securities and other debt securities with contractual maturity dates over ten years are based on variable rates which generally are reset within 35 days.
[10]	The nominal yield on mortgage-backed securities is based upon prepayment assumptions at the purchase date. Actual yields earned may differ significantly based upon actual prepayments. See Quarterly Financial Summary –– Unaudited following for current yields on available for sale securities portfolio.
[11]	Includes securities for which an unrealized loss remains in AOCI after an other-than-temporary credit loss has been recognized in income.
[12]	Includes securities for which an unrealized loss remains in AOCI after an other-than-temporary credit loss has been recognized in income.

Securities Fair Value Option Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Schedule of Fair Value Option Securities [Line Items]
Fair Value Option Securities, Fair Value	$ 819,531	$ 77,046	$ 222,409
Fair Value Option Securities, Net Unrealized Gain or Loss	1,671	(1,777)	(2,397)
U.S. Treasury
Schedule of Fair Value Option Securities [Line Items]
Fair Value Option Securities, Fair Value	0	0	222,409
Fair Value Option Securities, Net Unrealized Gain or Loss	0	0	(2,397)
U.S. government agency residential mortgage-backed securities
Schedule of Fair Value Option Securities [Line Items]
Fair Value Option Securities, Fair Value	819,531	77,046	0
Fair Value Option Securities, Net Unrealized Gain or Loss	$ 1,671	$ (1,777)	$ 0

Securities Restricted Equity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Restricted Equity Securities [Abstract]
Federal Reserve stock	$ 36,676	$ 36,498	$ 36,283
Federal Home Loan Bank stock	310,622	270,541	296,907
Other	244	201	201
Total	$ 347,542	$ 307,240	$ 333,391

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

Sep. 30, 2017

Dec. 31, 2016

Sep. 30, 2016

Derviative contracts, net of cash collateral, Assets, Fair value

$ 352,559

$ 689,872

$ 655,078

Derivative Liabilities, Fair Value, Net [Abstract]

Derivative Liabilities, Fair Value, Net of Cash Collateral

336,327

664,531

573,987

Not Designated as Hedging Instrument [Member]

28,952,817

^[1]

22,437,314

^[2]

25,136,553

^[3]

26,144,409

^[1]

22,178,359

^[2]

23,988,858

^[3]

402,422

789,791

734,256

Derivative Assets, Net Fair Value Before Cash Collateral

(45,885)

(89,368)

(68,713)

356,537

700,423

665,543

Derviative contracts, net of cash collateral, Assets, Fair value

(3,978)

(10,551)

(10,465)

352,559

689,872

655,078

Derivative Liabilities, Fair Value, Net [Abstract]

400,580

801,809

725,452

Derivative Liabilities, Net Fair Value Before Cash Collateral

(45,885)

(89,368)

(68,713)

354,695

712,441

656,739

Derivative Liabilities, Fair Value, Net of Cash Collateral

(18,368)

(47,910)

(82,752)

336,327

664,531

573,987

Not Designated as Hedging Instrument [Member] | To-be-announced residential mortgage-backed securities

14,244,442

^[1]

16,949,152

^[2]

20,078,974

^[3]

14,244,442

^[1]

16,637,532

^[2]

19,776,883

^[3]

38,875

180,695

90,999

Derivative Assets, Net Fair Value Before Cash Collateral

(9,547)

(60,555)

(38,678)

29,328

120,140

52,321

Derviative contracts, net of cash collateral, Assets, Fair value

0

29,328

120,140

52,321

Derivative Liabilities, Fair Value, Net [Abstract]

34,948

176,928

86,812

Derivative Liabilities, Net Fair Value Before Cash Collateral

(9,547)

(60,555)

(38,678)

25,401

116,373

48,134

Derivative Liabilities, Fair Value, Net of Cash Collateral

(374)

0

(39,042)

25,027

116,373

9,092

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

1,368,210

^[1]

1,403,408

^[2]

1,323,045

^[3]

1,368,230

^[1]

1,403,408

^[2]

1,323,045

^[3]

27,016

34,442

49,279

Derivative Assets, Net Fair Value Before Cash Collateral

0

27,016

34,442

49,279

Derviative contracts, net of cash collateral, Assets, Fair value

(2,820)

(4,567)

(794)

24,196

29,875

48,485

Derivative Liabilities, Fair Value, Net [Abstract]

27,056

34,442

49,518

Derivative Liabilities, Net Fair Value Before Cash Collateral

0

27,056

34,442

49,518

Derivative Liabilities, Fair Value, Net of Cash Collateral

(16,599)

(11,977)

(34,457)

10,457

22,465

15,061

Not Designated as Hedging Instrument [Member] | Energy contracts

983,794

^[1]

835,566

^[2]

729,202

^[3]

939,350

^[1]

820,365

^[2]

695,835

^[3]

45,368

64,140

41,775

Derivative Assets, Net Fair Value Before Cash Collateral

(35,166)

(28,298)

(28,464)

10,202

35,842

13,311

Derviative contracts, net of cash collateral, Assets, Fair value

(238)

(71)

(288)

9,964

35,771

13,023

Derivative Liabilities, Fair Value, Net [Abstract]

42,744

64,306

40,888

Derivative Liabilities, Net Fair Value Before Cash Collateral

(35,166)

(28,298)

(28,464)

7,578

36,008

12,424

Derivative Liabilities, Fair Value, Net of Cash Collateral

0

(31,534)

(3,857)

7,578

4,474

8,567

Not Designated as Hedging Instrument [Member] | Agricultural contracts

60,745

^[1]

53,209

^[2]

53,002

^[3]

60,746

^[1]

53,216

^[2]

52,997

^[3]

1,870

1,382

3,950

Derivative Assets, Net Fair Value Before Cash Collateral

(1,172)

(515)

(1,571)

698

867

2,379

Derviative contracts, net of cash collateral, Assets, Fair value

0

(1,076)

698

867

1,303

Derivative Liabilities, Fair Value, Net [Abstract]

1,846

1,365

3,943

Derivative Liabilities, Net Fair Value Before Cash Collateral

(1,172)

(515)

(1,571)

674

850

2,372

Derivative Liabilities, Fair Value, Net of Cash Collateral

0

(769)

0

674

81

2,372

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

252,525

^[1]

580,886

^[2]

550,828

^[3]

249,269

^[1]

580,712

^[2]

550,943

^[3]

249,788

494,349

536,264

Derivative Assets, Net Fair Value Before Cash Collateral

0

249,788

494,349

536,264

Derviative contracts, net of cash collateral, Assets, Fair value

0

(5,183)

(7,577)

249,788

489,166

528,687

Derivative Liabilities, Fair Value, Net [Abstract]

245,925

494,695

536,660

Derivative Liabilities, Net Fair Value Before Cash Collateral

0

245,925

494,695

536,660

Derivative Liabilities, Fair Value, Net of Cash Collateral

(1,395)

(3,630)

(5,396)

244,530

491,065

531,264

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

101,841

^[1]

100,924

^[2]

103,464

^[3]

101,841

^[1]

100,924

^[2]

103,464

^[3]

4,871

4,357

4,654

Derivative Assets, Net Fair Value Before Cash Collateral

0

4,871

4,357

4,654

Derviative contracts, net of cash collateral, Assets, Fair value

(920)

(730)

3,951

3,627

3,924

Derivative Liabilities, Fair Value, Net [Abstract]

4,871

4,357

4,654

Derivative Liabilities, Net Fair Value Before Cash Collateral

0

4,871

4,357

4,654

Derivative Liabilities, Fair Value, Net of Cash Collateral

0

4,871

4,357

4,654

Not Designated as Hedging Instrument [Member] | Total customer risk management programs

17,011,557

^[1]

19,923,145

^[2]

22,838,515

^[3]

16,963,878

^[1]

19,596,157

^[2]

22,503,167

^[3]

367,788

779,365

726,921

Derivative Assets, Net Fair Value Before Cash Collateral

(45,885)

(89,368)

(68,713)

321,903

689,997

658,208

Derviative contracts, net of cash collateral, Assets, Fair value

(3,978)

(10,551)

(10,465)

317,925

679,446

647,743

Derivative Liabilities, Fair Value, Net [Abstract]

357,390

776,093

722,475

Derivative Liabilities, Net Fair Value Before Cash Collateral

(45,885)

(89,368)

(68,713)

311,505

686,725

653,762

Derivative Liabilities, Fair Value, Net of Cash Collateral

(18,368)

(47,910)

(82,752)

293,137

638,815

571,010

Not Designated as Hedging Instrument [Member] | Internal risk management programs

11,941,260

^[1]

2,514,169

^[2]

2,298,038

^[3]

9,180,531

^[1]

2,582,202

^[2]

1,485,691

^[3]

34,634

10,426

7,335

Derivative Assets, Net Fair Value Before Cash Collateral

0

34,634

10,426

7,335

Derviative contracts, net of cash collateral, Assets, Fair value

0

34,634

10,426

7,335

Derivative Liabilities, Fair Value, Net [Abstract]

43,190

25,716

2,977

Derivative Liabilities, Net Fair Value Before Cash Collateral

0

43,190

25,716

2,977

Derivative Liabilities, Fair Value, Net of Cash Collateral

0

$ 43,190

$ 25,716

$ 2,977

[1]	Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.
[2]	Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.
[3]	Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.

Derivatives, Derivatives Instruments Gain (Loss) in Income Statement (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	$ 9,817	$ 12,151	$ 39,110	$ 34,510
Gain (Loss) on Derivatives, Net	1,033	2,226	3,824	20,130
To-be-announced residential mortgage-backed securities
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	9,181	11,584	26,413	28,886
Gain (Loss) on Derivatives, Net	0	0	0	0
Interest rate swaps
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	767	710	1,891	1,758
Gain (Loss) on Derivatives, Net	0	0	0	0
Energy contracts
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	378	1,222	4,917	4,667
Gain (Loss) on Derivatives, Net	0	0	0	0
Agricultural contracts
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	38	25	58	86
Gain (Loss) on Derivatives, Net	0	0	0	0
Foreign exchange contracts
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	164	218	524	730
Gain (Loss) on Derivatives, Net	0	0	0	0
Equity option contracts
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	0	0	0	0
Gain (Loss) on Derivatives, Net	0	0	0	0
Total customer risk management programs
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	10,528	13,759	33,803	36,127
Gain (Loss) on Derivatives, Net	0	0	0	0
Internal risk management programs
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract]
Brokergage and Trading Revenue	(711)	(1,608)	5,307	(1,617)
Gain (Loss) on Derivatives, Net	$ 1,033	$ 2,226	$ 3,824	$ 20,130

Loans and Allowance for Credit Losses, Loans by Portfolio Type (Details) - USD ($)
$ in Thousands

9 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Sep. 30, 2016

$ 4,532,914

$ 4,753,600

$ 4,233,548

12,448,284

12,005,076

11,994,286

225,636

230,984

236,952

Accruing loans past due (90 days)

17,206,834

16,989,660

16,464,786

^[1]

253

5

3,839

Credit Commitments [Abstract]

Outstanding commitments to extend credit

9,700,000

Outstanding standby letters of credit

666,000

Outstanding commercial letters of credit

2,300

Texas [Member] | Geographic Concentration Risk [Member]

$ 5,900,000

Percentage of loan portfolio attributed to Texas (in hundredths)

34.00%

Oklahoma [Member] | Geographic Concentration Risk [Member]

$ 3,400,000

Percentage of loan portfolio attributed to Oklahoma (in hundredths)

20.00%

Commercial

$ 2,225,470

2,327,085

1,991,423

8,393,564

7,884,786

7,952,276

176,900

178,953

176,464

Commercial | Texas [Member] | Geographic Concentration Risk [Member]

10,795,934

10,390,824

10,120,163

$ 3,700,000

Percentage of loan portfolio attributed to Texas (in hundredths)

34.00%

Commercial | Oklahoma [Member] | Geographic Concentration Risk [Member]

$ 2,100,000

Percentage of loan portfolio attributed to Oklahoma (in hundredths)

19.00%

Commercial | Energy [Member]

Commercial | Energy [Member] | Credit Concentration Risk [Member]

$ 2,867,981

2,497,868

2,520,804

$ 2,900,000

Percentage of loan class to total loans

17.00%

Commercial | Energy Producers [Member] | Credit Concentration Risk [Member]

$ 2,300,000

Percentage of committed energy production loans secured by oil

57.00%

Percentage of committed energy production loans secured by natural gas

43.00%

Commercial | Services [Member]

Commercial | Services [Member] | Credit Concentration Risk [Member]

$ 2,967,513

3,108,990

2,936,599

$ 3,000,000

Percentage of loan class to total loans

17.00%

Amount of loans with individual balances less than $10 million

$ 1,500,000

Maximum loan amount for certain individual loans in category

10,000

Commercial | Healthcare [Member]

Commercial | Healthcare [Member] | Credit Concentration Risk [Member]

2,239,451

2,201,916

2,085,046

$ 2,200,000

Percentage of loan class to total loans

13.00%

Commercial real estate

$ 564,681

624,187

565,429

2,950,486

3,179,338

3,220,819

2,975

5,521

7,350

Commercial real estate | Texas [Member] | Geographic Concentration Risk [Member]

$ 3,518,142

3,809,046

3,793,598

Percentage of loan portfolio secured by property in Texas (in hundredths)

35.00%

Commercial real estate | Oklahoma [Member] | Geographic Concentration Risk [Member]

Percentage of loan portfolio secured by property in Oklahoma (in hundredths)

13.00%

Residential mortgage

$ 1,589,013

1,647,357

1,572,288

311,231

256,255

248,053

45,506

46,220

52,452

Residential mortgage | Permanent mortgage [Member]

1,945,750

1,949,832

1,872,793

$ 1,013,965

1,006,820

969,558

Minimum FICO required for jumbo loan approval

720

Maximum debt-to-income ratio on jumbo loans (in hundredths)

38.00%

Minimum loan-to-value ratio on jumbo loans (in hundredths)

60.00%

Maximum loan-to-value ratio on jumbo loans (in hundredths)

100.00%

Minimum period for fixed rate on variable rate jumbo loans (in years)

3 years

Maximum period for fixed rate on variable rate jumbo loans (in years)

10 years

Residential mortgage | Permanent mortgages guaranteed by US government agencies [Member]

$ 187,370

199,387

190,309

Amount of loans guaranteed by US government and previously sold into GNMA mortgage pools

187,000

Residential mortgage | Home equity [Member]

$ 744,415

743,625

712,926

Percentage of home equity portfolio comprised of first lien loans

64.00%

Percentage of home equity portfolio comprised of junior lien loans

36.00%

Percentage of junior lien home equity loans that are amortizing term loans

47.00%

Percentage of junior lien home equity loans that are revolving lines of credit

53.00%

Home equity loans, description

Home equity loans generally require a minimum FICO score of 700 and a maximum DTI of 40 percent.

Home equity loans, maximum

$ 400

Home equity loans, revolving period

5 years

Home equity loans, amortization period following revolving period

15 years

Home equity loans, discretionary additional revolving period

5 years

Personal

$ 153,750

154,971

104,408

793,003

684,697

573,138

255

290

686

$ 947,008

$ 839,958

$ 678,232

[1]	Excludes residential mortgage loans guaranteed by agencies of the U.S. government

Loans and Allowances for Credit Losses, Activity in Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Allowance for loan losses [Roll Forward]
Beginning balance	$ 250,061	$ 243,259	$ 246,159	$ 225,524
Provision for loan losses	1,030	7,907	5,843	55,573
Loans charged off	(5,825)	(8,101)	(10,850)	(40,937)
Recoveries	2,437	2,038	6,551	4,943
Ending balance	247,703	245,103	247,703	245,103
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	6,431	9,045	11,244	1,711
Provision for off-balance sheet credit losses	(1,030)	2,093	(5,843)	9,427
Ending balance	5,401	11,138	5,401	11,138
Total provision for credit losses	0	10,000	0	65,000
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					$ 16,981,198	$ 16,758,676	$ 16,227,834
Individually measured for impairment, recorded investment					225,636	230,984	236,952
Total					17,206,834	16,989,660	16,464,786
Related allowance [Abstract]
Collectively measured for impairment, related allowance					206,341	217,116	210,353
Individually measured for impairment, related allowance					13,284	843	6,564
Total	250,061	243,259	246,159	225,524	247,703	246,159	245,103
Commercial
Allowance for loan losses [Roll Forward]
Beginning balance	137,742	145,139	140,213	130,334
Provision for loan losses	2,474	2,420	665	45,995
Loans charged off	(4,429)	(6,266)	(6,556)	(35,747)
Recoveries	1,014	177	2,479	888
Ending balance	136,801	141,470	136,801	141,470
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	6,301	8,752	11,063	1,506
Provision for off-balance sheet credit losses	(976)	2,170	(5,738)	9,416
Ending balance	5,325	10,922	5,325	10,922
Total provision for credit losses	1,498	4,590	(5,073)	55,411
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					10,619,034	10,211,871	9,943,699
Individually measured for impairment, recorded investment					176,900	178,953	176,464
Total					10,795,934	10,390,824	10,120,163
Related allowance [Abstract]
Collectively measured for impairment, related allowance					123,517	139,416	134,968
Individually measured for impairment, related allowance					13,284	797	6,502
Total	137,742	145,139	140,213	130,334	136,801	140,213	141,470
Commercial real estate
Allowance for loan losses [Roll Forward]
Beginning balance	58,580	46,745	50,749	41,391
Provision for loan losses	(2,914)	2,551	4,050	7,538
Loans charged off	0	0	(76)	0
Recoveries	739	521	1,682	888
Ending balance	56,405	49,817	56,405	49,817
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	84	203	123	153
Provision for off-balance sheet credit losses	(49)	(53)	(88)	(3)
Ending balance	35	150	35	150
Total provision for credit losses	(2,963)	2,498	3,962	7,535
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					3,515,167	3,803,525	3,786,248
Individually measured for impairment, recorded investment					2,975	5,521	7,350
Total					3,518,142	3,809,046	3,793,598
Related allowance [Abstract]
Collectively measured for impairment, related allowance					56,405	50,749	49,817
Individually measured for impairment, related allowance					0	0	0
Total	58,580	46,745	50,749	41,391	56,405	50,749	49,817
Residential mortgage
Allowance for loan losses [Roll Forward]
Beginning balance	18,259	18,690	18,224	19,509
Provision for loan losses	168	(466)	82	(829)
Loans charged off	(168)	(285)	(444)	(1,104)
Recoveries	134	650	531	1,013
Ending balance	18,393	18,589	18,393	18,589
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	38	62	50	30
Provision for off-balance sheet credit losses	1	(7)	(11)	25
Ending balance	39	55	39	55
Total provision for credit losses	169	(473)	71	(804)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					1,900,244	1,903,612	1,820,341
Individually measured for impairment, recorded investment					45,506	46,220	52,452
Total					1,945,750	1,949,832	1,872,793
Related allowance [Abstract]
Collectively measured for impairment, related allowance					18,393	18,178	18,527
Individually measured for impairment, related allowance					0	46	62
Total	18,259	18,690	18,224	19,509	18,393	18,224	18,589
Personal
Allowance for loan losses [Roll Forward]
Beginning balance	8,106	6,001	8,773	4,164
Provision for loan losses	598	1,900	1,168	4,809
Loans charged off	(1,228)	(1,550)	(3,774)	(4,086)
Recoveries	550	690	1,859	2,154
Ending balance	8,026	7,041	8,026	7,041
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	8	28	8	22
Provision for off-balance sheet credit losses	(6)	(17)	(6)	(11)
Ending balance	2	11	2	11
Total provision for credit losses	592	1,883	1,162	4,798
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					946,753	839,668	677,546
Individually measured for impairment, recorded investment					255	290	686
Total					947,008	839,958	678,232
Related allowance [Abstract]
Collectively measured for impairment, related allowance					8,026	8,773	7,041
Individually measured for impairment, related allowance					0	0	0
Total	8,106	6,001	8,773	4,164	8,026	8,773	7,041
Specific Allowance [Member]
Allowance for loan losses [Roll Forward]
Beginning balance			217,959
Ending balance	219,625	216,917	219,625	216,917
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					16,981,198	16,758,676	16,227,834
Individually measured for impairment, recorded investment					225,636	230,984	236,952
Total					17,206,834	16,989,660	16,464,786
Related allowance [Abstract]
Collectively measured for impairment, related allowance					206,341	217,116	210,353
Individually measured for impairment, related allowance					13,284	843	6,564
Total	219,625	216,917	217,959	216,917	219,625	217,959	216,917
Nonspecific Allowance [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	27,374	26,684	28,200	30,126
Provision for loan losses	704	1,502	(122)	(1,940)
Loans charged off	0	0	0	0
Recoveries	0	0	0	0
Ending balance	28,078	28,186	28,078	28,186
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	0	0	0	0
Provision for off-balance sheet credit losses	0	0	0	0
Ending balance	0	0	0	0
Total provision for credit losses	704	1,502	(122)	(1,940)
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment					0	0	0
Individually measured for impairment, recorded investment					0	0	0
Total					0	0	0
Related allowance [Abstract]
Collectively measured for impairment, related allowance					0	0	0
Individually measured for impairment, related allowance					0	0	0
Total	$ 27,374	$ 26,684	$ 28,200	$ 30,126	$ 28,078	$ 28,200	$ 28,186

Loans and Allowances for Credit Losses, Credit Quality Indicators (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	$ 15,351,135		$ 15,158,076	$ 14,680,781
Non-Graded, Recorded Investment	1,855,699		1,831,584	1,784,005
Total	17,206,834		16,989,660	16,464,786
Related Allowance [Abstract]
Internally Risk Graded, Allowance	201,362		197,970	197,579
Non-Graded, Allowance	18,263		19,989	19,338
Total	247,703	$ 250,061	246,159	245,103	$ 243,259	$ 225,524
Commercial
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	10,750,657		10,360,725	10,093,884
Non-Graded, Recorded Investment	45,277		30,099	26,279
Total	10,795,934		10,390,824	10,120,163
Related Allowance [Abstract]
Internally Risk Graded, Allowance	135,846		139,293	140,552
Non-Graded, Allowance	955		920	918
Total	136,801	137,742	140,213	141,470	145,139	130,334
Commercial \| Energy [Member]
Recorded Investment [Abstract]
Total	2,867,981		2,497,868	2,520,804
Commercial \| Services [Member]
Recorded Investment [Abstract]
Total	2,967,513		3,108,990	2,936,599
Commercial \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Total	1,658,098		1,576,818	1,602,030
Commercial \| Manufacturing [Member]
Recorded Investment [Abstract]
Total	519,446		514,975	499,486
Commercial \| Healthcare [Member]
Recorded Investment [Abstract]
Total	2,239,451		2,201,916	2,085,046
Commercial \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Total	543,445		490,257	476,198
Commercial real estate
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	3,518,142		3,809,046	3,793,598
Non-Graded, Recorded Investment	0		0	0
Total	3,518,142		3,809,046	3,793,598
Related Allowance [Abstract]
Internally Risk Graded, Allowance	56,405		50,749	49,817
Non-Graded, Allowance	0		0	0
Total	56,405	58,580	50,749	49,817	46,745	41,391
Commercial real estate \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Total	112,102		135,533	159,946
Commercial real estate \| Retail [Member]
Recorded Investment [Abstract]
Total	725,865		761,888	801,377
Commercial real estate \| Office [Member]
Recorded Investment [Abstract]
Total	797,089		798,888	752,705
Commercial real estate \| Multifamily [Member]
Recorded Investment [Abstract]
Total	999,009		903,272	873,773
Commercial real estate \| Industrial [Member]
Recorded Investment [Abstract]
Total	591,080		871,749	838,021
Commercial real estate \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Total	292,997		337,716	367,776
Residential mortgage
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	226,306		243,703	206,430
Non-Graded, Recorded Investment	1,719,444		1,706,129	1,666,363
Total	1,945,750		1,949,832	1,872,793
Related Allowance [Abstract]
Internally Risk Graded, Allowance	3,068		2,893	3,028
Non-Graded, Allowance	15,325		15,331	15,561
Total	18,393	18,259	18,224	18,589	18,690	19,509
Residential mortgage \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Total	1,013,965		1,006,820	969,558
Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Recorded Investment [Abstract]
Total	187,370		199,387	190,309
Residential mortgage \| Home equity [Member]
Recorded Investment [Abstract]
Total	744,415		743,625	712,926
Personal
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	856,030		744,602	586,869
Non-Graded, Recorded Investment	90,978		95,356	91,363
Total	947,008		839,958	678,232
Related Allowance [Abstract]
Internally Risk Graded, Allowance	6,043		5,035	4,182
Non-Graded, Allowance	1,983		3,738	2,859
Total	8,026	8,106	8,773	7,041	6,001	4,164
Specific Allowance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	15,351,135		15,158,076	14,680,781
Non-Graded, Recorded Investment	1,855,699		1,831,584	1,784,005
Total	17,206,834		16,989,660	16,464,786
Related Allowance [Abstract]
Internally Risk Graded, Allowance	201,362		197,970	197,579
Non-Graded, Allowance	18,263		19,989	19,338
Total	219,625		217,959	216,917
Nonspecific Allowance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Non-Graded, Recorded Investment	0		0	0
Total	0		0	0
Related Allowance [Abstract]
Internally Risk Graded, Allowance	0		0	0
Non-Graded, Allowance	0		0	0
Total	28,078	$ 27,374	28,200	28,186	$ 26,684	$ 30,126
Performing [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	1,811,095		1,786,530	1,733,743
Performing [Member] \| Commercial
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	45,132		30,041	26,210
Performing [Member] \| Commercial \| Energy [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial \| Services [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial \| Manufacturing [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial \| Healthcare [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	45,132		30,041	26,210
Performing [Member] \| Commercial real estate
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial real estate \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial real estate \| Retail [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial real estate \| Office [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial real estate \| Multifamily [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial real estate \| Industrial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Commercial real estate \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	0		0	0
Performing [Member] \| Residential mortgage
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	1,675,154		1,661,326	1,616,425
Performing [Member] \| Residential mortgage \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	764,252		741,679	739,686
Performing [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	178,000		188,000	175,000
Performing [Member] \| Residential mortgage \| Home equity [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	732,423		732,106	701,862
Performing [Member] \| Personal
Recorded Investment [Abstract]
Non-Graded, Recorded Investment	90,809		95,163	91,108
Performing [Member] \| Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	14,687,428		14,343,507	13,778,278
Performing [Member] \| Pass [Member] \| Commercial
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	10,102,018		9,567,816	9,217,958
Performing [Member] \| Pass [Member] \| Commercial \| Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,436,465		1,937,790	1,869,598
Performing [Member] \| Pass [Member] \| Commercial \| Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,932,577		3,052,002	2,882,065
Performing [Member] \| Pass [Member] \| Commercial \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,637,698		1,535,463	1,557,067
Performing [Member] \| Pass [Member] \| Commercial \| Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	486,383		468,314	470,702
Performing [Member] \| Pass [Member] \| Commercial \| Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,150,099		2,140,458	2,022,757
Performing [Member] \| Pass [Member] \| Commercial \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	458,796		433,789	415,769
Performing [Member] \| Pass [Member] \| Commercial real estate
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	3,505,318		3,793,471	3,774,443
Performing [Member] \| Pass [Member] \| Commercial real estate \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	110,178		131,630	155,737
Performing [Member] \| Pass [Member] \| Commercial real estate \| Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	724,887		756,418	794,920
Performing [Member] \| Pass [Member] \| Commercial real estate \| Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	788,539		798,462	750,924
Performing [Member] \| Pass [Member] \| Commercial real estate \| Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	998,125		898,800	868,501
Performing [Member] \| Pass [Member] \| Commercial real estate \| Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	591,080		871,673	837,945
Performing [Member] \| Pass [Member] \| Commercial real estate \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	292,509		336,488	366,416
Performing [Member] \| Pass [Member] \| Residential mortgage
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	224,235		238,769	200,590
Performing [Member] \| Pass [Member] \| Residential mortgage \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	224,235		238,769	200,590
Performing [Member] \| Pass [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Pass [Member] \| Residential mortgage \| Home equity [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Pass [Member] \| Personal
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	855,857		743,451	585,287
Performing [Member] \| Other Loans Especially Mentioned [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	197,952		229,673	237,948
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	188,546		223,742	230,827
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial \| Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	114,065		119,583	147,153
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial \| Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	26,372		10,960	14,861
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	9,021		16,886	15,337
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial \| Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	7,181		26,532	8,774
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial \| Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	31,855		44,472	42,224
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	52		5,309	2,478
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial real estate
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	8,964		4,745	5,701
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial real estate \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial real estate \| Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	689		4,745	4,802
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial real estate \| Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	8,275		0	899
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial real estate \| Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial real estate \| Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Commercial real estate \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Residential mortgage
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	393		1,186	1,192
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Residential mortgage \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	393		1,186	1,192
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Residential mortgage \| Home equity [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Other Loans Especially Mentioned [Member] \| Personal
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	49		0	228
Performing [Member] \| Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	284,723		398,966	477,865
Performing [Member] \| Substandard [Member] \| Commercial
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	283,338		390,272	468,704
Performing [Member] \| Substandard [Member] \| Commercial \| Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	206,768		307,996	361,087
Performing [Member] \| Substandard [Member] \| Commercial \| Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	7,390		37,855	31,196
Performing [Member] \| Substandard [Member] \| Commercial \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	9,486		13,062	27,173
Performing [Member] \| Substandard [Member] \| Commercial \| Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	16,823		15,198	19,736
Performing [Member] \| Substandard [Member] \| Commercial \| Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	33,051		16,161	19,210
Performing [Member] \| Substandard [Member] \| Commercial \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	9,820		0	10,302
Performing [Member] \| Substandard [Member] \| Commercial real estate
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	885		5,309	6,104
Performing [Member] \| Substandard [Member] \| Commercial real estate \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		470	470
Performing [Member] \| Substandard [Member] \| Commercial real estate \| Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		399	406
Performing [Member] \| Substandard [Member] \| Commercial real estate \| Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Substandard [Member] \| Commercial real estate \| Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	884		4,434	5,221
Performing [Member] \| Substandard [Member] \| Commercial real estate \| Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Substandard [Member] \| Commercial real estate \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1		6	7
Performing [Member] \| Substandard [Member] \| Residential mortgage
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	462		2,331	2,134
Performing [Member] \| Substandard [Member] \| Residential mortgage \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	462		2,331	2,134
Performing [Member] \| Substandard [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Substandard [Member] \| Residential mortgage \| Home equity [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Performing [Member] \| Substandard [Member] \| Personal
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	38		1,054	923
Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	181,032		185,930	186,690
Non-Graded, Recorded Investment	44,604		45,054	50,262
Nonaccrual [Member] \| Commercial
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	176,755		178,895	176,395
Non-Graded, Recorded Investment	145		58	69
Nonaccrual [Member] \| Commercial \| Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	110,683		132,499	142,966
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial \| Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,174		8,173	8,477
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial \| Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,893		11,407	2,453
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial \| Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	9,059		4,931	274
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial \| Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	24,446		825	855
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial \| Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	29,500		21,060	21,370
Non-Graded, Recorded Investment	145		58	69
Nonaccrual [Member] \| Commercial real estate
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,975		5,521	7,350
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial real estate \| Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,924		3,433	3,739
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial real estate \| Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	289		326	1,249
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial real estate \| Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	275		426	882
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial real estate \| Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		38	51
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial real estate \| Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		76	76
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Commercial real estate \| Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	487		1,222	1,353
Non-Graded, Recorded Investment	0		0	0
Nonaccrual [Member] \| Residential mortgage
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,216		1,417	2,514
Non-Graded, Recorded Investment	44,290		44,803	49,938
Nonaccrual [Member] \| Residential mortgage \| Permanent mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,216		1,417	2,514
Non-Graded, Recorded Investment	23,407		21,438	23,442
Nonaccrual [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Non-Graded, Recorded Investment	8,900		12,000	15,000
Nonaccrual [Member] \| Residential mortgage \| Home equity [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Non-Graded, Recorded Investment	11,992		11,519	11,064
Nonaccrual [Member] \| Personal
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	86		97	431
Non-Graded, Recorded Investment	$ 169		$ 193	$ 255

Loans and Allowance for Credit Losses, Impaired Loans (Details) - USD ($)
$ in Thousands

3 Months Ended

9 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Sep. 30, 2017

Sep. 30, 2016

Dec. 31, 2016

$ 460,466

$ 489,949

$ 460,466

$ 489,949

$ 473,526

Impaired loans, recorded investment with no related allowance

404,115

411,829

404,115

411,829

418,525

314,610

369,054

314,610

369,054

407,363

Impaired loans, recorded investment with related allowance

89,505

42,775

89,505

42,775

11,162

13,284

6,564

13,284

6,564

843

415,027

415,029

417,476

350,511

2,199

2,390

6,721

6,816

Commercial

218,386

230,950

218,386

230,950

211,762

Impaired loans, recorded investment with no related allowance

176,900

176,464

176,900

176,464

178,953

87,395

133,798

87,395

133,798

167,837

Impaired loans, recorded investment with related allowance

89,505

42,666

89,505

42,666

11,116

13,284

6,502

13,284

6,502

797

187,029

179,227

177,927

109,701

Commercial | Energy [Member]

0

133,643

179,578

133,643

179,578

146,897

Impaired loans, recorded investment with no related allowance

110,683

142,966

110,683

142,966

132,499

45,169

100,300

45,169

100,300

121,418

Impaired loans, recorded investment with related allowance

65,514

42,666

65,514

42,666

11,081

4,944

6,502

4,944

6,502

762

117,338

155,555

121,591

85,333

Commercial | Services [Member]

0

3,838

11,858

3,838

11,858

11,723

Impaired loans, recorded investment with no related allowance

1,174

8,477

1,174

8,477

8,173

1,174

8,477

1,174

8,477

8,173

Impaired loans, recorded investment with related allowance

0

0

4,464

8,932

4,674

9,384

Commercial | Wholesale/retail [Member]

0

8,418

8,528

8,418

8,528

17,669

Impaired loans, recorded investment with no related allowance

1,893

2,453

1,893

2,453

11,407

1,893

2,453

1,893

2,453

11,407

Impaired loans, recorded investment with related allowance

0

0

6,256

2,613

6,650

2,686

Commercial | Manufacturing [Member]

0

9,674

642

9,674

642

5,320

Impaired loans, recorded investment with no related allowance

9,059

274

9,059

274

4,931

9,059

274

9,059

274

4,931

Impaired loans, recorded investment with related allowance

0

0

9,357

284

6,995

303

Commercial | Healthcare [Member]

0

24,591

1,168

24,591

1,168

1,147

Impaired loans, recorded investment with no related allowance

24,446

855

24,446

855

825

474

855

474

855

825

Impaired loans, recorded investment with related allowance

23,972

0

23,972

0

8,323

0

8,323

0

24,476

865

12,635

964

Commercial | Other commercial and industrial [Member]

0

38,222

29,176

38,222

29,176

29,006

Impaired loans, recorded investment with no related allowance

29,645

21,439

29,645

21,439

21,118

29,626

21,439

29,626

21,439

21,083

Impaired loans, recorded investment with related allowance

19

0

19

0

35

17

0

17

0

35

25,138

10,978

25,382

11,031

0

Commercial real estate

5,003

17,642

5,003

17,642

14,427

Impaired loans, recorded investment with no related allowance

2,975

7,350

2,975

7,350

5,521

2,975

7,350

2,975

7,350

5,521

Impaired loans, recorded investment with related allowance

0

0

3,375

7,565

4,250

8,176

Commercial real estate | Residential construction and land development [Member]

0

3,532

6,090

3,532

6,090

4,951

Impaired loans, recorded investment with no related allowance

1,924

3,739

1,924

3,739

3,433

1,924

3,739

1,924

3,739

3,433

Impaired loans, recorded investment with related allowance

0

0

1,988

4,000

2,679

4,074

Commercial real estate | Retail [Member]

0

513

1,914

513

1,914

530

Impaired loans, recorded investment with no related allowance

289

1,249

289

1,249

326

289

1,249

289

1,249

326

Impaired loans, recorded investment with related allowance

0

0

295

1,257

308

1,284

Commercial real estate | Office [Member]

0

287

1,187

287

1,187

521

Impaired loans, recorded investment with no related allowance

275

882

275

882

426

275

882

275

882

426

Impaired loans, recorded investment with related allowance

0

0

335

744

351

766

Commercial real estate | Multifamily [Member]

0

0

1,000

0

1,000

Impaired loans, recorded investment with no related allowance

0

51

0

51

38

0

51

0

51

38

Impaired loans, recorded investment with related allowance

0

0

5

58

19

163

Commercial real estate | Industrial [Member]

0

0

76

0

76

Impaired loans, recorded investment with no related allowance

0

76

0

76

0

76

0

76

Impaired loans, recorded investment with related allowance

0

0

0

76

38

76

Commercial real estate | Other commercial real estate [Member]

0

671

7,375

671

7,375

7,349

Impaired loans, recorded investment with no related allowance

487

1,353

487

1,353

1,222

487

1,353

487

1,353

1,222

Impaired loans, recorded investment with related allowance

0

0

752

1,430

855

1,813

0

Residential mortgage

236,787

240,633

236,787

240,633

247,005

Impaired loans, recorded investment with no related allowance

223,985

227,329

223,985

227,329

233,761

223,985

227,220

223,985

227,220

233,715

Impaired loans, recorded investment with related allowance

0

109

0

109

46

0

62

0

62

46

224,360

227,717

235,026

232,059

Residential mortgage | Permanent mortgage [Member]

2,199

2,390

6,721

6,816

29,861

32,372

29,861

32,372

28,830

Impaired loans, recorded investment with no related allowance

24,623

25,956

24,623

25,956

22,855

24,623

25,847

24,623

25,847

22,809

Impaired loans, recorded investment with related allowance

0

109

0

109

46

0

62

0

62

46

24,019

26,592

23,739

27,470

Residential mortgage | Permanent mortgages guaranteed by US government agencies [Member]

315

292

912

923

193,594

^[1]

196,162

^[2]

193,594

^[1]

196,162

^[2]

205,564

^[3]

Impaired loans, recorded investment with no related allowance

187,370

^[1]

190,309

^[2]

187,370

^[1]

190,309

^[2]

199,387

^[3]

187,370

^[1]

190,309

^[2]

187,370

^[1]

190,309

^[2]

199,387

^[3]

Impaired loans, recorded investment with related allowance

0

^[1]

0

^[2]

0

^[1]

0

^[2]

0

^[3]

0

^[1]

0

^[2]

0

^[1]

0

^[2]

0

^[3]

188,461

^[1]

190,547

^[2]

199,532

^[1]

193,879

^[2]

Residential mortgage | Home equity [Member]

1,884

^[1]

2,098

^[2]

5,809

^[1]

5,893

^[2]

13,332

12,099

13,332

12,099

12,611

Impaired loans, recorded investment with no related allowance

11,992

11,064

11,992

11,064

11,519

11,992

11,064

11,992

11,064

11,519

Impaired loans, recorded investment with related allowance

0

0

11,880

10,578

11,755

10,710

0

Personal

290

724

290

724

332

Impaired loans, recorded investment with no related allowance

255

686

255

686

290

255

686

255

686

290

Impaired loans, recorded investment with related allowance

0

0

$ 0

263

520

273

575

Dividends declared (in dollars per share)

$ 0

[1]	All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At September 30, 2017, $8.9 million of these loans were nonaccruing and $178 million were accruing based on the guarantee by U.S. government agencies.
[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 September 30, 2016, $15 million of these loans were nonaccruing and $175 million were accruing based on the guarantee by U.S. government agencies.
[3]	All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2016, $12 million of these loans were nonaccruing and $188 million were accruing based on the guarantee by U.S. government agencies.

Loans and Allowances for Credit Losses, Troubled Debt Restructurings (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	$ 128,986	$ 126,126	$ 128,986	$ 126,126	$ 147,117
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	60,479	59,919	60,479	59,919	74,738
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	68,507	66,207	68,507	66,207	72,379
Troubled Debt Restructuring, Specific allowance	0	62	0	62	46
Troubled Debt Restructuring, Charge-offs	4,370	543	4,412	1,230
Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	59,546	45,820	59,546	45,820	65,747
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	45,531	30,899	45,531	30,899	47,449
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	14,015	14,921	14,015	14,921	18,298
Troubled Debt Restructuring, Specific allowance	0	62	0	62	46
Troubled Debt Restructuring, Charge-offs	4,370	543	4,412	1,230
Nonaccrual [Member] \| Commercial
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	32,381	13,192	32,381	13,192	36,879
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	29,679	9,620	29,679	9,620	29,225
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	2,702	3,572	2,702	3,572	7,654
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	4,329	500	4,332	1,057
Nonaccrual [Member] \| Commercial \| Energy [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	9,582	1,746	9,582	1,746	16,893
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	9,506	0	9,506	0	10,867
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	76	1,746	76	1,746	6,026
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	4,322	500	4,322	1,000
Nonaccrual [Member] \| Commercial \| Services [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	720	7,761	720	7,761	7,527
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	103	7,034	103	7,034	6,830
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	617	727	617	727	697
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	7	0	10	0
Nonaccrual [Member] \| Commercial \| Wholesale/retail [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	1,802	2,327	1,802	2,327	11,291
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	0	2,287	0	2,287	11,251
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	1,802	40	1,802	40	40
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial \| Manufacturing [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	180	238	180	238	224
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	180	238	180	238	224
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial \| Healthcare [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	0	623	0	623	607
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	623	0	623	607
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial \| Other commercial and industrial [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	20,097	497	20,097	497	337
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	19,890	61	19,890	61	53
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	207	436	207	436	284
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	57
Nonaccrual [Member] \| Commercial real estate
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	969	2,858	969	2,858	1,707
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	733	2,066	733	2,066	1,114
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	236	792	236	792	593
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Residential construction and land development [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	327	794	327	794	690
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	91	359	91	359	97
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	236	435	236	435	593
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Retail [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	289	1,249	289	1,249	326
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	289	892	289	892	326
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	357	0	357	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Office [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	0	149	0	149	143
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	0	149	0	149	143
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Multifamily [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	0	0	0	0	0
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Industrial [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	0	0	0	0	0
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Other commercial real estate [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	353	666	353	666	548
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	353	666	353	666	548
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Residential mortgage
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	25,991	29,497	25,991	29,497	26,924
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	14,924	18,942	14,924	18,942	16,874
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	11,067	10,555	11,067	10,555	10,050
Troubled Debt Restructuring, Specific allowance	0	62	0	62	46
Troubled Debt Restructuring, Charge-offs	39	34	70	155
Nonaccrual [Member] \| Residential mortgage \| Permanent mortgage [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	14,765	16,109	14,765	16,109	14,876
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	10,188	11,944	10,188	11,944	10,175
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	4,577	4,165	4,577	4,165	4,701
Troubled Debt Restructuring, Specific allowance	0	62	0	62	46
Troubled Debt Restructuring, Charge-offs	0	0	0	2
Nonaccrual [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	5,601	8,220	5,601	8,220	6,702
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	523	2,331	523	2,331	2,241
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	5,078	5,889	5,078	5,889	4,461
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	0	0	0	0
Nonaccrual [Member] \| Residential mortgage \| Home equity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	5,625	5,168	5,625	5,168	5,346
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	4,213	4,667	4,213	4,667	4,458
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	1,412	501	1,412	501	888
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	39	34	70	153
Nonaccrual [Member] \| Personal
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	205	273	205	273	237
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	195	271	195	271	236
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	10	2	10	2	1
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Troubled Debt Restructuring, Charge-offs	2	9	10	18
Accruing [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	69,440	80,306	69,440	80,306	81,370
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	14,948	29,020	14,948	29,020	27,289
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	54,492	51,286	54,492	51,286	54,081
Troubled Debt Restructuring, Specific allowance	0	0	0	0	$ 0
Troubled Debt Restructuring, Charge-offs	$ 0	$ 0	$ 0	$ 0

Loans and Allowances for Credit Losses, Troubled Debt Restructurings, Modifications (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	$ 11,148	$ 9,115	$ 52,853	$ 24,368
Troubled Debt Restructurings, Recorded Balance With Payment Default	34,906	20,899	57,294	23,030
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	60	0	27,666	501
Troubled Debt Restructurings, Recorded Balance With Payment Default	7,857	1,746	29,407	1,746
Commercial \| Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	7,781	501
Troubled Debt Restructurings, Recorded Balance With Payment Default	7,857	1,746	9,582	1,746
Commercial \| Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial \| Wholesale/retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial \| Manufacturing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial \| Healthcare [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial \| Other commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	60	0	19,885	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	19,825	0
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial real estate \| Residential construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial real estate \| Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial real estate \| Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial real estate \| Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial real estate \| Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Commercial real estate \| Other commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	11,084	9,096	25,139	23,785
Troubled Debt Restructurings, Recorded Balance With Payment Default	27,039	19,142	27,877	21,273
Residential mortgage \| Permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	1,475	151	1,712	2,088
Troubled Debt Restructurings, Recorded Balance With Payment Default	1,511	298	1,511	542
Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	9,140	8,025	21,855	20,019
Troubled Debt Restructurings, Recorded Balance With Payment Default	24,498	18,586	25,227	20,473
Residential mortgage \| Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	469	920	1,572	1,678
Troubled Debt Restructurings, Recorded Balance With Payment Default	1,030	258	1,139	258
Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	4	19	48	82
Troubled Debt Restructurings, Recorded Balance With Payment Default	10	11	10	11
Accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	8,825	7,738	21,327	19,037
Troubled Debt Restructurings, Recorded Balance With Payment Default	23,620	17,491	24,349	19,352
Accruing [Member] \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial \| Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial \| Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial \| Wholesale/retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial \| Manufacturing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial \| Healthcare [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial \| Other commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial real estate \| Residential construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial real estate \| Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial real estate \| Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial real estate \| Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial real estate \| Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Commercial real estate \| Other commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	8,825	7,738	21,327	19,037
Troubled Debt Restructurings, Recorded Balance With Payment Default	23,620	17,491	24,349	19,352
Accruing [Member] \| Residential mortgage \| Permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	8,825	7,738	21,327	19,037
Troubled Debt Restructurings, Recorded Balance With Payment Default	23,620	17,491	24,349	19,352
Accruing [Member] \| Residential mortgage \| Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Accruing [Member] \| Payment Stream [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	8,205	3,527	18,678	9,687
Accruing [Member] \| Payment Stream [Member] \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial \| Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial \| Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial \| Wholesale/retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial \| Manufacturing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial \| Healthcare [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial \| Other commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial real estate \| Residential construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial real estate \| Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial real estate \| Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial real estate \| Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial real estate \| Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Commercial real estate \| Other commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	8,205	3,527	18,678	9,687
Accruing [Member] \| Payment Stream [Member] \| Residential mortgage \| Permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	8,205	3,527	18,678	9,687
Accruing [Member] \| Payment Stream [Member] \| Residential mortgage \| Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Payment Stream [Member] \| Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	620	4,211	2,649	9,350
Accruing [Member] \| Combination & Other [Member] \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial \| Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial \| Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial \| Wholesale/retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial \| Manufacturing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial \| Healthcare [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial \| Other commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial real estate \| Residential construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial real estate \| Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial real estate \| Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial real estate \| Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial real estate \| Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Commercial real estate \| Other commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	620	4,211	2,649	9,350
Accruing [Member] \| Combination & Other [Member] \| Residential mortgage \| Permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	620	4,211	2,649	9,350
Accruing [Member] \| Combination & Other [Member] \| Residential mortgage \| Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Accruing [Member] \| Combination & Other [Member] \| Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	2,323	1,377	31,526	5,331
Troubled Debt Restructurings, Recorded Balance With Payment Default	11,286	3,408	32,945	3,678
Nonaccrual [Member] \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	60	0	27,666	501
Troubled Debt Restructurings, Recorded Balance With Payment Default	7,857	1,746	29,407	1,746
Nonaccrual [Member] \| Commercial \| Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	7,781	501
Troubled Debt Restructurings, Recorded Balance With Payment Default	7,857	1,746	9,582	1,746
Nonaccrual [Member] \| Commercial \| Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial \| Wholesale/retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial \| Manufacturing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial \| Healthcare [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial \| Other commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	60	0	19,885	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	19,825	0
Nonaccrual [Member] \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Residential construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Commercial real estate \| Other commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Troubled Debt Restructurings, Recorded Balance With Payment Default	0	0	0	0
Nonaccrual [Member] \| Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	2,259	1,358	3,812	4,748
Troubled Debt Restructurings, Recorded Balance With Payment Default	3,419	1,651	3,528	1,921
Nonaccrual [Member] \| Residential mortgage \| Permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	1,475	151	1,712	2,088
Troubled Debt Restructurings, Recorded Balance With Payment Default	1,511	298	1,511	542
Nonaccrual [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	315	287	528	982
Troubled Debt Restructurings, Recorded Balance With Payment Default	878	1,095	878	1,121
Nonaccrual [Member] \| Residential mortgage \| Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	469	920	1,572	1,678
Troubled Debt Restructurings, Recorded Balance With Payment Default	1,030	258	1,139	258
Nonaccrual [Member] \| Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	4	19	48	82
Troubled Debt Restructurings, Recorded Balance With Payment Default	10	11	10	11
Nonaccrual [Member] \| Payment Stream [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	1,284	0	28,306	1,586
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	27,606	501
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial \| Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	7,781	501
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial \| Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial \| Wholesale/retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial \| Manufacturing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial \| Healthcare [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial \| Other commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	19,825	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial real estate \| Residential construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial real estate \| Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial real estate \| Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial real estate \| Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial real estate \| Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Commercial real estate \| Other commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Payment Stream [Member] \| Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	1,284	0	700	1,085
Nonaccrual [Member] \| Payment Stream [Member] \| Residential mortgage \| Permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	969	0	153	1,037
Nonaccrual [Member] \| Payment Stream [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	315	0	443	0
Nonaccrual [Member] \| Payment Stream [Member] \| Residential mortgage \| Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	104	48
Nonaccrual [Member] \| Payment Stream [Member] \| Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	1,039	1,377	3,220	3,745
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	60	0	60	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial \| Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial \| Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial \| Wholesale/retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial \| Manufacturing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial \| Healthcare [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial \| Other commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	60	0	60	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial real estate \| Residential construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial real estate \| Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial real estate \| Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial real estate \| Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial real estate \| Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Commercial real estate \| Other commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	0	0	0
Nonaccrual [Member] \| Combination & Other [Member] \| Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	975	1,358	3,112	3,663
Nonaccrual [Member] \| Combination & Other [Member] \| Residential mortgage \| Permanent mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	506	151	1,559	1,051
Nonaccrual [Member] \| Combination & Other [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	0	287	85	982
Nonaccrual [Member] \| Combination & Other [Member] \| Residential mortgage \| Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	469	920	1,468	1,630
Nonaccrual [Member] \| Combination & Other [Member] \| Personal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled Debt Restructurings, Recorded Balance Modified During The Period	$ 4	$ 19	$ 48	$ 82

Loans and Allowances for Credit Losses, By Aging Category (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Financing receivable, recorded investment, aging [Abstract]
Current	$ 16,803,397	$ 16,597,641	$ 16,061,958
Nonaccrual	225,636	230,984	236,952
Total	17,206,834	16,989,660	16,464,786
Commercial
Financing receivable, recorded investment, aging [Abstract]
Current	10,606,851	10,205,838	9,926,386
Nonaccrual	176,900	178,953	176,464
Total	10,795,934	10,390,824	10,120,163
Commercial \| Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	2,752,259	2,364,890	2,365,850
Nonaccrual	110,683	132,499	142,966
Total	2,867,981	2,497,868	2,520,804
Commercial \| Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	2,963,746	3,099,605	2,923,874
Nonaccrual	1,174	8,173	8,477
Total	2,967,513	3,108,990	2,936,599
Commercial \| Wholesale/retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,654,018	1,561,650	1,599,356
Nonaccrual	1,893	11,407	2,453
Total	1,658,098	1,576,818	1,602,030
Commercial \| Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	508,231	509,662	499,212
Nonaccrual	9,059	4,931	274
Total	519,446	514,975	499,486
Commercial \| Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	2,214,849	2,201,050	2,083,556
Nonaccrual	24,446	825	855
Total	2,239,451	2,201,916	2,085,046
Commercial \| Other commercial and industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	513,748	468,981	454,538
Nonaccrual	29,645	21,118	21,439
Total	543,445	490,257	476,198
Commercial real estate
Financing receivable, recorded investment, aging [Abstract]
Current	3,513,942	3,803,519	3,777,344
Nonaccrual	2,975	5,521	7,350
Total	3,518,142	3,809,046	3,793,598
Commercial real estate \| Residential construction and land development [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	109,994	132,100	156,207
Nonaccrual	1,924	3,433	3,739
Total	112,102	135,533	159,946
Commercial real estate \| Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	724,850	761,562	796,362
Nonaccrual	289	326	1,249
Total	725,865	761,888	801,377
Commercial real estate \| Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	796,687	798,462	751,823
Nonaccrual	275	426	882
Total	797,089	798,888	752,705
Commercial real estate \| Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	999,009	903,234	868,591
Nonaccrual	0	38	51
Total	999,009	903,272	873,773
Commercial real estate \| Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	591,080	871,673	837,945
Nonaccrual	0	76	76
Total	591,080	871,749	838,021
Commercial real estate \| Other commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	292,322	336,488	366,416
Nonaccrual	487	1,222	1,353
Total	292,997	337,716	367,776
Residential mortgage
Financing receivable, recorded investment, aging [Abstract]
Current	1,739,236	1,749,473	1,681,034
Nonaccrual	45,506	46,220	52,452
Total	1,945,750	1,949,832	1,872,793
Residential mortgage \| Permanent mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	985,183	979,386	939,853
Nonaccrual	24,623	22,855	25,956
Total	1,013,965	1,006,820	969,558
Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	25,169	40,594	41,150
Nonaccrual	8,891	11,846	15,432
Total	187,370	199,387	190,309
Residential mortgage \| Home equity [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	728,884	729,493	700,031
Nonaccrual	11,992	11,519	11,064
Total	744,415	743,625	712,926
Personal
Financing receivable, recorded investment, aging [Abstract]
Current	943,368	838,811	677,194
Nonaccrual	255	290	686
Total	947,008	839,958	678,232
30 to 59 Days [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	32,750	28,603	39,781
30 to 59 Days [Member] \| Commercial
Financing receivable, recorded investment, aging [Abstract]
Past Due	4,299	4,968	13,380
30 to 59 Days [Member] \| Commercial \| Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	479	11,988
30 to 59 Days [Member] \| Commercial \| Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	2,343	191	502
30 to 59 Days [Member] \| Commercial \| Wholesale/retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	1,748	3,761	221
30 to 59 Days [Member] \| Commercial \| Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	382	0
30 to 59 Days [Member] \| Commercial \| Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	156	0	635
30 to 59 Days [Member] \| Commercial \| Other commercial and industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	52	155	34
30 to 59 Days [Member] \| Commercial real estate
Financing receivable, recorded investment, aging [Abstract]
Past Due	1,038	6	3,773
30 to 59 Days [Member] \| Commercial real estate \| Residential construction and land development [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	184	0	0
30 to 59 Days [Member] \| Commercial real estate \| Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	726	0	3,766
30 to 59 Days [Member] \| Commercial real estate \| Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	127	0	0
30 to 59 Days [Member] \| Commercial real estate \| Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
30 to 59 Days [Member] \| Commercial real estate \| Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
30 to 59 Days [Member] \| Commercial real estate \| Other commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	1	6	7
30 to 59 Days [Member] \| Residential mortgage
Financing receivable, recorded investment, aging [Abstract]
Past Due	24,117	23,040	22,437
30 to 59 Days [Member] \| Residential mortgage \| Permanent mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	3,705	3,299	3,547
30 to 59 Days [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	17,346	17,465	17,364
30 to 59 Days [Member] \| Residential mortgage \| Home equity [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	3,066	2,276	1,526
30 to 59 Days [Member] \| Personal
Financing receivable, recorded investment, aging [Abstract]
Past Due	3,296	589	191
60 to 89 Days [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	22,177	16,748	18,856
60 to 89 Days [Member] \| Commercial
Financing receivable, recorded investment, aging [Abstract]
Past Due	7,854	1,065	107
60 to 89 Days [Member] \| Commercial \| Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	5,039	0	0
60 to 89 Days [Member] \| Commercial \| Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	250	1,021	39
60 to 89 Days [Member] \| Commercial \| Wholesale/retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	409	0	0
60 to 89 Days [Member] \| Commercial \| Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	2,156	0	0
60 to 89 Days [Member] \| Commercial \| Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	41	0
60 to 89 Days [Member] \| Commercial \| Other commercial and industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	3	68
60 to 89 Days [Member] \| Commercial real estate
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	5,131
60 to 89 Days [Member] \| Commercial real estate \| Residential construction and land development [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Commercial real estate \| Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Commercial real estate \| Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Commercial real estate \| Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	5,131
60 to 89 Days [Member] \| Commercial real estate \| Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Commercial real estate \| Other commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
60 to 89 Days [Member] \| Residential mortgage
Financing receivable, recorded investment, aging [Abstract]
Past Due	14,242	15,420	13,470
60 to 89 Days [Member] \| Residential mortgage \| Permanent mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	454	1,280	202
60 to 89 Days [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	13,343	13,803	12,963
60 to 89 Days [Member] \| Residential mortgage \| Home equity [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	445	337	305
60 to 89 Days [Member] \| Personal
Financing receivable, recorded investment, aging [Abstract]
Past Due	81	263	148
90 Days or More [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	122,874	115,684	107,239
90 Days or More [Member] \| Commercial
Financing receivable, recorded investment, aging [Abstract]
Past Due	30	0	3,826
90 Days or More [Member] \| Commercial \| Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial \| Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	3,707
90 Days or More [Member] \| Commercial \| Wholesale/retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	30	0	0
90 Days or More [Member] \| Commercial \| Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial \| Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial \| Other commercial and industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	119
90 Days or More [Member] \| Commercial real estate
Financing receivable, recorded investment, aging [Abstract]
Past Due	187	0	0
90 Days or More [Member] \| Commercial real estate \| Residential construction and land development [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial real estate \| Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial real estate \| Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial real estate \| Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial real estate \| Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Commercial real estate \| Other commercial real estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	187	0	0
90 Days or More [Member] \| Residential mortgage
Financing receivable, recorded investment, aging [Abstract]
Past Due	122,649	115,679	103,400
90 Days or More [Member] \| Residential mortgage \| Permanent mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	0	0	0
90 Days or More [Member] \| Residential mortgage \| Permanent mortgages guaranteed by US government agencies [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	122,621	115,679	103,400
90 Days or More [Member] \| Residential mortgage \| Home equity [Member]
Financing receivable, recorded investment, aging [Abstract]
Past Due	28	0	0
90 Days or More [Member] \| Personal
Financing receivable, recorded investment, aging [Abstract]
Past Due	$ 8	$ 5	$ 13

Acquisitions (Details) - MBT Bancshares [Member] - USD ($) $ in Thousands		9 Months Ended
	Dec. 01, 2016	Sep. 30, 2017
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Dec. 01, 2016
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	$ 102,500
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles		$ 2,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment		1,500
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Goodwill		$ 526

Mortgage Banking Activities, Components of Loans Held For Sale (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Schedule of Residential Mortgage Loans Held For Sale [Line Items]
Number of days for past due for loan to be considered nonperforming (in days)	90 days	90 days	90 days
Residential mortgage loans held for sale, nonperforming	$ 0	$ 0	$ 0
Credit losses recognized on residential mortgage loans held for sale	0	0	0
Components of Residential Mortgage Loans Held for Sale [Abstract]
Unpaid principal balance	261,868	422,523	286,414
Residential mortgage loans held for sale, Fair value	265,783	433,040	286,971
Total residential mortgage loans held for sale and mortgage loan commitments, net of forward sales contracts	$ 275,643	$ 447,592	$ 301,897
Residential Mortgage Loan Commitments [Member] \| Not Designated as Hedging Instrument [Member]
Schedule of Residential Mortgage Loans Held For Sale [Line Items]
General number of days outstanding for residential mortgage commitments, minimum (in days)	60 days	60 days	60 days
General number of days outstanding for residential mortgage commitments, maximum (in days)	90 days	90 days	90 days
Components of Residential Mortgage Loans Held for Sale [Abstract]
Notional	$ 334,337	$ 630,804	$ 318,359
Derivative, Net fair value	$ 9,066	$ 18,598	$ 9,733
Forward sales contracts [Member] \| Not Designated as Hedging Instrument [Member]
Schedule of Residential Mortgage Loans Held For Sale [Line Items]
General number of days for delivery of loans, for which the price is set by forward sales contracts, minimum (in days)	60 days	60 days	60 days
General number of days for delivery for loans, for which the price is set by forward sales contracts, maximum (in days)	90 days	90 days	90 days
Components of Residential Mortgage Loans Held for Sale [Abstract]
Notional	$ 524,878	$ 929,907	$ 569,543
Derivative, Net fair value	$ 794	$ (4,046)	$ 5,193

Mortgage Banking Activities Mortgage Banking Activities, Mortgage Banking Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Mortgage Banking Revenue [Abstract]
Net realized gains on sale of mortgage loans	$ 12,041	$ 23,110	$ 32,443	$ 47,424
Net change in unrealized gain on mortgage loans held for sale	(1,492)	(2,518)	3,335	4,649
Net change in the fair value of mortgage loan commitments	(1,927)	(6,901)	(667)	10,464
Net change in the fair value of forward sales contracts	(293)	8,267	(4,399)	(4,846)
Total production revenue	8,329	21,958	30,712	57,691
Servicing revenue	16,561	16,558	49,645	47,809
Total mortgage banking revenue	$ 24,890	$ 38,516	$ 80,357	$ 105,500

Mortgage Banking Activities, Mortgage Servicing Rights (Details)	3 Months Ended			9 Months Ended
	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Summary of Mortgage Servicing Rights [Abstract]
Number of residential mortgage loans serviced for others	137,359	139,340	139,587	137,359	139,587
Outstanding principal balance of residential mortgage loans serviced for others	$ 22,063,121,000	$ 21,997,568,000	$ 21,851,536,000	$ 22,063,121,000	$ 21,851,536,000
Weighted average interest rate	3.95%	3.97%	4.01%	3.95%	4.01%
Remaining term (in months)	298	301	302
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance	$ 245,239,000	$ 203,621,000	$ 190,747,000	$ 247,073,000	$ 218,605,000
Additions, net	9,925,000		21,990,000	29,439,000	56,345,000
Change in fair value due to principal payments	(8,667,000)		(11,443,000)	(24,928,000)	(29,385,000)
Change in fair value due to market assumption changes	(639,000)		2,327,000	(5,726,000)	(41,944,000)
Ending balance	$ 245,858,000	$ 247,073,000	$ 203,621,000	$ 245,858,000	$ 203,621,000
Servicing Assets at Fair Value, Assumptions Used to Estimate Fair Value [Abstract]
Discount rate - risk-free rate plus a market premium (in hundredths)	9.84%	10.08%	10.08%
Prepayment rate - based upon loan interest rate, original term and loan type, minimum	8.71%	8.98%	9.16%
Prepayment rate - based upon loan interest rate, original term and loan type, maximum	15.43%	16.91%	47.15%
Loan servicing costs - annually per loan based upon loan type, performing, minimum (in dollars per loan)	$ 65	$ 63	$ 63
Loan servicing costs - annually per loan based upon loan type, performing, maximum (in dollars per loan)	120	120	120
Loan servicing costs - annually per loan based upon loan type, delinquent, minimum (in dollars per loan)	150	150	150
Loan servicing costs - annually per loan based upon loan type, delinquent, maximum (in dollars per loan)	500	500	500
Loan servicing costs - annually per loan based upon loan type, foreclosure, minimum (in dollars per loan)	1,000	650	650
Loan servicing costs - annually per loan based upon loan type, foreclosure, maximum (in dollars per loan)	$ 4,250	$ 4,250	$ 4,250
Escrow earnings rate - indexed to rates paid on deposit accounts with comparable average life (in hundredths)	2.00%	1.98%	1.18%
Primary secondary mortgage rate spread (in basis points)	105	105	115	105	115
Purchased [Member]
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance	$ 7,995,000	$ 3,565,000	$ 4,067,000	$ 8,909,000	$ 9,911,000
Additions, net	0		0	0	0
Change in fair value due to principal payments	(470,000)		(753,000)	(1,443,000)	(2,109,000)
Change in fair value due to market assumption changes	303,000		251,000	362,000	(4,237,000)
Ending balance	7,828,000	8,909,000	3,565,000	7,828,000	3,565,000
Originated [Member]
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance	237,244,000	200,056,000	186,680,000	238,164,000	208,694,000
Additions, net	9,925,000		21,990,000	29,439,000	56,345,000
Change in fair value due to principal payments	(8,197,000)		(10,690,000)	(23,485,000)	(27,276,000)
Change in fair value due to market assumption changes	(942,000)		2,076,000	(6,088,000)	(37,707,000)
Ending balance	$ 238,030,000	$ 238,164,000	$ 200,056,000	$ 238,030,000	$ 200,056,000

Mortgage Banking Activities Mortgage Banking Activities, Loans Serviced for Others (Details) $ in Thousands	Sep. 30, 2017 USD ($)
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	$ 21,535,339
30 to 59 Days Past Due	373,605
60 to 89 Days Past Due	84,324
90 Days or More Past Due	69,853
Total	22,063,121
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	8,021,016
30 to 59 Days Past Due	78,542
60 to 89 Days Past Due	13,100
90 Days or More Past Due	26,171
Total	8,138,829
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	6,635,428
30 to 59 Days Past Due	76,065
60 to 89 Days Past Due	10,398
90 Days or More Past Due	20,596
Total	6,742,487
Government National Mortgage Association Certificates and Obligations (GNMA) [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	6,376,127
30 to 59 Days Past Due	215,506
60 to 89 Days Past Due	59,659
90 Days or More Past Due	20,925
Total	6,672,217
Other Investor Loans [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
Current	502,768
30 to 59 Days Past Due	3,492
60 to 89 Days Past Due	1,167
90 Days or More Past Due	2,161
Total	$ 509,588

Commitments and Contingent Liabilities (Details)	9 Months Ended
Commitments and Contingent Liabilities (Details)	Sep. 30, 2017 USD ($) shares
BOKF Equity, LLC [Member]
Litigation Settlement [Abstract]
Number of Private Equity Funds of which the Entity is a General Partner	2
Contingent Obligations For Additional Investments in Private Equity Funds	$ 3,400,000
Cavanal Hill Funds [Member]
Litigation Settlement [Abstract]
The Net Asset Value of Units in Mutual Funds (per unit)	1.00
Judicial Ruling [Member] \| Misuse of Revenues Pledged to Municipal Bonds [Member]
Litigation Settlement [Abstract]
Outstanding principal, accrued interest and other amounts required by bond documents	$ 48,000,000
Disgorged fees	1,067,721
Litigation Settlement, Amount Awarded to Other Party	$ 600,000
Pending Litigation [Member] \| Misuse of Revenues Pledged to Municipal Bonds [Member]
Litigation Settlement [Abstract]
Loss Contingency, Number of Plaintiffs	2
Pending Litigation [Member] \| Bank Participation in Fraudulent Sale of Securities by Principals [Member]
Litigation Settlement [Abstract]
Loss Contingency, Number of Plaintiffs	19
Pending Litigation [Member] \| Purchase of facilities from principals subject to SEC New Jersey proceedings [Member]
Litigation Settlement [Abstract]
Outstanding principal, accrued interest and other amounts required by bond documents	$ 60,000,000
Number of individuals who purchased facilities from the principals subject to SEC New Jersey proceedings	2
Number of principals in SEC New Jersey proceedings	2
Pending Litigation [Member] \| Ownership of deposit accounts [Member]
Litigation Settlement [Abstract]
Loss Contingency, Number of Plaintiffs	2
Amount paid by the bank from creditor accounts to judgment creditor	$ 4,200,000
Loss Contingency, Damages Sought, Value	7,000,000
Settled Litigation [Member] \| County of Bernalillo [Member] [Domain]
Litigation Settlement [Abstract]
Loss Contingency, Damages Sought, Value	$ 5,600,000
Visa Membership [Member]
Loss Contingencies [Line Items]
Number of Visa Class B Shares Owned by Entity (in shares) \| shares	252,233
Number of Visa Class A Shares Visa Class B Shares Are Convertible To (in shares) \| shares	415,755

Commitments and Contingent Liabilities Variable Interest Entities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Loans Receivable [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	$ 10,000	$ 10,000	$ 10,000
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	65,247	44,488	39,849
Loans Receivable [Member] \| Private equity funds [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Loans Receivable [Member] \| Tax credit entities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	10,000	10,000	10,000
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	65,247	44,488	39,849
Loans Receivable [Member] \| Other [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Other Assets [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	42,358	58,725	61,138
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	177,941	175,390	159,987
Other Assets [Member] \| Private equity funds [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	15,621	17,357	18,420
Other Assets [Member] \| Tax credit entities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	11,119	11,585	11,740
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	145,479	143,715	129,715
Other Assets [Member] \| Other [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	15,618	29,783	30,978
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	32,462	31,675	30,272
Other Liabilities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	1,588	3,189	2,346
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	75,021	78,357	70,679
Other Liabilities [Member] \| Private equity funds [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Other Liabilities [Member] \| Tax credit entities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	61,364	63,329	57,026
Other Liabilities [Member] \| Other [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	1,588	3,189	2,346
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	13,657	15,028	13,653
Other borrowings [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	14,067	12,056	12,027
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Other borrowings [Member] \| Private equity funds [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Other borrowings [Member] \| Tax credit entities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	10,963	10,964	10,964
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Other borrowings [Member] \| Other [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	3,104	1,092	1,063
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Non-Controlling Interests [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	25,625	31,503	34,100
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Non-Controlling Interests [Member] \| Private equity funds [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	12,806	13,237	15,946
Non-Controlling Interests [Member] \| Tax credit entities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	10,000	10,000	10,000
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	0	0
Non-Controlling Interests [Member] \| Other [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net	2,819	8,266	8,154
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	$ 0	$ 0	$ 0

Shareholders' Equity (Details) - USD ($)
$ / shares in Units, $ in Thousands

3 Months Ended

9 Months Ended

Oct. 31, 2017

Sep. 30, 2017

Sep. 30, 2016

Sep. 30, 2017

Sep. 30, 2016

$ 0.44

$ 0.43

$ 1.32

$ 1.29

Schedule of Accumulated Other Income (Loss) [Abstract]

$ (10,967)

$ 21,587

Reclassification adjustments included in earnings:

$ 512

$ (33,458)

33,881

133,108

Interest revenue, Investment securities, Taxable securities

0

(112)

Other comprehensive income (loss), before income taxes

(2,487)

(2,394)

(4,916)

(11,684)

(1,975)

(35,852)

28,965

121,312

Other comprehensive income (loss), net of income taxes

(768)

(13,947)

11,241

^[1]

47,172

^[1]

(1,207)

(21,905)

17,724

74,140

Accumulated Net Unrealized Gain (Loss) on Available for Sale Securities [Member]

6,757

95,727

6,757

95,727

Schedule of Accumulated Other Income (Loss) [Abstract]

(9,087)

23,284

Reclassification adjustments included in earnings:

33,876

133,108

Interest revenue, Investment securities, Taxable securities

0

Other comprehensive income (loss), before income taxes

(4,916)

(11,684)

28,960

121,424

Other comprehensive income (loss), net of income taxes

^[1]

11,239

47,216

17,721

74,208

Accumulated Unrealized Gain on Investment Securities Transferred from AFS [Member]

8,634

97,492

8,634

97,492

Schedule of Accumulated Other Income (Loss) [Abstract]

0

68

Reclassification adjustments included in earnings:

0

Interest revenue, Investment securities, Taxable securities

(112)

Other comprehensive income (loss), before income taxes

0

0

(112)

Other comprehensive income (loss), net of income taxes

^[1]

(44)

0

(68)

Accumulated Unrealized Gain (Loss) on Employee Benefit Plans [Member]

0

Schedule of Accumulated Other Income (Loss) [Abstract]

(1,880)

(1,765)

Reclassification adjustments included in earnings:

5

0

Interest revenue, Investment securities, Taxable securities

0

Other comprehensive income (loss), before income taxes

0

5

0

Other comprehensive income (loss), net of income taxes

^[1]

2

0

3

0

Subsequent Event [Member]

(1,877)

$ (1,765)

(1,877)

$ (1,765)

Dividends Payable, Date Declared

Oct. 31, 2017

Dividends declared (in dollars per share)

$ 0.45

Dividends Payable, Date to be Paid

Nov. 27, 2017

Dividends Payable, Date of Record

Nov. 13, 2017

Perpetual Preferred, Equity Securities and Mutual Funds [Member] | Accumulated Net Unrealized Gain (Loss) on Available for Sale Securities [Member]

Reclassification adjustments included in earnings:

$ 2,200

[1]	Calculated using a 39 percent effective tax rate.

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator: [Abstract]
Net income attributable to BOK Financial Corp. shareholders	$ 85,649	$ 74,277	$ 262,152	$ 182,642
Less: Earnings allocated to participating securities	888	916	2,817	2,275
Numerator for basic earnings per share – income available to common shareholders	84,761	73,361	259,335	180,367
Effect of reallocating undistributed earnings of participating securities	1	1	2	1
Numerator for diluted earnings per share – income available to common shareholders	$ 84,762	$ 73,362	$ 259,337	$ 180,368
Denominator: [Abstract]
Weighted average shares outstanding (in shares)	65,423,258	65,895,430	65,432,313	66,031,497
Less: Participating securities included in weighted average shares (in shares)	680,436	810,038	702,922	822,723
Denominator for basic earnings per common share (in shares)	64,742,822	65,085,392	64,729,391	65,208,774
Dilutive effect of employee stock compensation plans (in shares)	62,350	72,449	64,502	54,792
Denominator for diluted earnings per common share (in shares)	64,805,172	65,157,841	64,793,893	65,263,566
Basic earnings per share (per share)	$ 1.31	$ 1.13	$ 4.01	$ 2.77
Diluted earnings per share (per share)	$ 1.31	$ 1.13	$ 4.00	$ 2.76
Excludes employee stock options with exercise prices greater than current market price.	0	0	0	0

Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Reportable Segments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
NIR (expense) from external sources	$ 218,452	$ 187,846	$ 624,838	$ 553,030
NIR (expense) from internal sources	0	0	0	0
Net interest revenue	218,452	187,846	624,838	553,030
Provision for credit losses	0	10,000	0	65,000
Net interest revenue after provision for credit losses	218,452	177,846	624,838	488,030
Other operating revenue	175,710	187,310	528,258	530,266
Other operating expense	265,934	258,088	761,530	752,043
Net direct contribution	128,228	107,068	391,566	266,253
Gain (loss) on financial instruments, net	0	0	0	0
Change in fair value of mortgage servicing rights	0	0	0	0
Gain (loss) on repossessed assets, net	0	0	0	0
Corporate expense allocations	0	0	0	0
Net income before taxes	128,228	107,068	391,566	266,253
Federal and state income taxes	42,438	31,956	128,246	83,881
Net income	85,790	75,112	263,320	182,372
Net income (loss) attributable to non-controlling interests	141	835	1,168	(270)
Net income attributable to BOK Financial Corp. shareholders	85,649	74,277	262,152	182,642
Average assets	33,008,170	32,646,473	32,777,438	32,049,183
Operating Segments [Member] \| Commercial [Member]
Segment Reporting Information [Line Items]
NIR (expense) from external sources	157,080	123,599	435,946	358,713
NIR (expense) from internal sources	(24,173)	(15,052)	(61,803)	(44,259)
Net interest revenue	132,907	108,547	374,143	314,454
Provision for credit losses	3,217	5,601	2,983	34,024
Net interest revenue after provision for credit losses	129,690	102,946	371,160	280,430
Other operating revenue	54,091	49,642	156,139	146,248
Other operating expense	56,952	53,375	168,517	162,039
Net direct contribution	126,829	99,213	358,782	264,639
Gain (loss) on financial instruments, net	4	0	46	0
Change in fair value of mortgage servicing rights	0	0	0	0
Gain (loss) on repossessed assets, net	(4,126)	1,486	(2,728)	806
Corporate expense allocations	8,650	9,054	26,144	26,681
Net income before taxes	114,057	91,645	329,956	238,764
Federal and state income taxes	44,368	35,650	128,353	92,879
Net income	69,689	55,995	201,603	145,885
Net income (loss) attributable to non-controlling interests	0	0	0	0
Net income attributable to BOK Financial Corp. shareholders	69,689	55,995	201,603	145,885
Average assets	17,558,390	16,934,587	17,525,658	16,958,999
Operating Segments [Member] \| Consumer [Member]
Segment Reporting Information [Line Items]
NIR (expense) from external sources	25,576	22,098	70,208	65,897
NIR (expense) from internal sources	12,213	9,263	35,002	27,492
Net interest revenue	37,789	31,361	105,210	93,389
Provision for credit losses	1,315	1,157	3,512	4,177
Net interest revenue after provision for credit losses	36,474	30,204	101,698	89,212
Other operating revenue	47,033	60,603	146,440	172,072
Other operating expense	56,785	60,964	166,027	179,487
Net direct contribution	26,722	29,843	82,111	81,797
Gain (loss) on financial instruments, net	1,686	(1,087)	5,242	30,539
Change in fair value of mortgage servicing rights	(639)	2,327	(5,726)	(41,944)
Gain (loss) on repossessed assets, net	292	161	253	566
Corporate expense allocations	17,039	16,905	50,947	49,513
Net income before taxes	11,022	14,339	30,933	21,445
Federal and state income taxes	4,288	5,578	12,033	8,342
Net income	6,734	8,761	18,900	13,103
Net income (loss) attributable to non-controlling interests	0	0	0	0
Net income attributable to BOK Financial Corp. shareholders	6,734	8,761	18,900	13,103
Average assets	9,115,319	8,827,816	8,871,470	8,763,564
Operating Segments [Member] \| Wealth Management [Member]
Segment Reporting Information [Line Items]
NIR (expense) from external sources	11,169	9,274	33,130	21,620
NIR (expense) from internal sources	9,604	7,401	28,784	22,258
Net interest revenue	20,773	16,675	61,914	43,878
Provision for credit losses	(623)	(89)	(676)	(479)
Net interest revenue after provision for credit losses	21,396	16,764	62,590	44,357
Other operating revenue	75,707	73,523	225,434	218,042
Other operating expense	61,791	64,426	182,816	186,524
Net direct contribution	35,312	25,861	105,208	75,875
Gain (loss) on financial instruments, net	0	(42)	0	(42)
Change in fair value of mortgage servicing rights	0	0	0	0
Gain (loss) on repossessed assets, net	0	0	0	0
Corporate expense allocations	9,819	10,912	30,438	31,864
Net income before taxes	25,493	14,907	74,770	43,969
Federal and state income taxes	9,917	5,799	29,086	17,104
Net income	15,576	9,108	45,684	26,865
Net income (loss) attributable to non-controlling interests	0	0	0	0
Net income attributable to BOK Financial Corp. shareholders	15,576	9,108	45,684	26,865
Average assets	6,992,021	6,413,735	6,971,369	5,916,545
Funds Management and Other [Member]
Segment Reporting Information [Line Items]
NIR (expense) from external sources	24,627	32,875	85,554	106,800
NIR (expense) from internal sources	2,356	(1,612)	(1,983)	(5,491)
Net interest revenue	26,983	31,263	83,571	101,309
Provision for credit losses	(3,909)	3,331	(5,819)	27,278
Net interest revenue after provision for credit losses	30,892	27,932	89,390	74,031
Other operating revenue	(1,121)	3,542	245	(6,096)
Other operating expense	90,406	79,323	244,170	223,993
Net direct contribution	(60,635)	(47,849)	(154,535)	(156,058)
Gain (loss) on financial instruments, net	(1,690)	1,129	(5,288)	(30,497)
Change in fair value of mortgage servicing rights	639	(2,327)	5,726	41,944
Gain (loss) on repossessed assets, net	3,834	(1,647)	2,475	(1,372)
Corporate expense allocations	(35,508)	(36,871)	(107,529)	(108,058)
Net income before taxes	(22,344)	(13,823)	(44,093)	(37,925)
Federal and state income taxes	(16,135)	(15,071)	(41,226)	(34,444)
Net income	(6,209)	1,248	(2,867)	(3,481)
Net income (loss) attributable to non-controlling interests	141	835	1,168	(270)
Net income attributable to BOK Financial Corp. shareholders	(6,350)	413	(4,035)	(3,211)
Average assets	$ (657,560)	$ 470,335	$ (591,059)	$ 410,075

Fair Value Measurements, Fair Value Of Financial Instruments as Measured On a Recurring Basis (Details) - USD ($)
$ in Thousands

Sep. 30, 2017

Jun. 30, 2017

Dec. 31, 2016

Sep. 30, 2016

Jun. 30, 2016

Dec. 31, 2015

$ 614,117

$ 337,628

$ 546,615

8,383,199

8,676,829

8,862,283

819,531

77,046

222,409

Derviative contracts, net of cash collateral, Assets, Fair value

245,858

$ 245,239

247,073

203,621

$ 190,747

$ 218,605

352,559

689,872

655,078

Derivative contracts, net of cash collateral, Liabilities, Fair Value

336,327

664,531

573,987

U.S. government agency debentures

U.S. government agency residential mortgage-backed securities

30,162

6,234

15,705

516,760

310,067

464,749

5,326,384

5,460,386

5,668,672

Municipal and other tax-exempt securities

819,531

77,046

0

56,148

14,427

54,856

28,368

40,993

42,092

Other trading securities

11,047

6,900

11,305

U.S. Treasury

999

1,002

Privately issued residential mortgage-backed securities

0

222,409

Commercial mortgage-backed securities guaranteed by U.S. government agencies

99,994

115,535

121,603

2,889,346

3,017,933

2,986,495

Other debt securities

Perpetual preferred stock

4,153

4,152

4,151

Equity securities and mutual funds

16,245

18,474

19,578

Fair Value, Measurements, Recurring [Member]

17,710

18,357

18,690

614,117

337,628

546,615

8,383,199

8,676,829

8,862,283

222,409

275,643

301,897

447,592

Derviative contracts, net of cash collateral, Assets, Fair value

245,858

^[1]

247,073

^[2]

203,621

^[3]

352,559

^[4]

689,872

^[5]

655,078

^[6]

Derivative contracts, net of cash collateral, Liabilities, Fair Value

336,327

^[4]

664,531

^[5]

573,987

^[6]

Fair Value, Measurements, Recurring [Member] | U.S. government agency debentures

Fair Value, Measurements, Recurring [Member] | U.S. government agency residential mortgage-backed securities

30,162

6,234

15,705

516,760

310,067

464,749

5,326,384

5,460,386

5,668,672

Fair Value, Measurements, Recurring [Member] | Municipal and other tax-exempt securities

819,531

77,046

0

56,148

14,427

54,856

Fair Value, Measurements, Recurring [Member] | Other trading securities

28,368

40,993

42,092

Fair Value, Measurements, Recurring [Member] | U.S. Treasury

11,047

6,900

11,305

999

1,002

Fair Value, Measurements, Recurring [Member] | Privately issued residential mortgage-backed securities

222,409

Fair Value, Measurements, Recurring [Member] | Commercial mortgage-backed securities guaranteed by U.S. government agencies

99,994

115,535

121,603

Fair Value, Measurements, Recurring [Member] | Other debt securities

2,889,346

3,017,933

2,986,495

Fair Value, Measurements, Recurring [Member] | Perpetual preferred stock

4,153

4,152

4,151

Fair Value, Measurements, Recurring [Member] | Equity securities and mutual funds

16,245

18,474

19,578

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]

17,710

18,357

18,690

0

3,577

4,494

4,546

222,409

0

Derviative contracts, net of cash collateral, Assets, Fair value

0

^[1]

0

^[2]

0

^[3]

8,498

^[4]

7,541

^[5]

5,575

^[6]

Derivative contracts, net of cash collateral, Liabilities, Fair Value

6,903

^[4]

6,972

^[5]

1,308

^[6]

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. government agency debentures

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. government agency residential mortgage-backed securities

0

0

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Municipal and other tax-exempt securities

0

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other trading securities

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Treasury

0

999

1,002

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Privately issued residential mortgage-backed securities

222,409

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial mortgage-backed securities guaranteed by U.S. government agencies

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other debt securities

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Perpetual preferred stock

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Equity securities and mutual funds

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]

2,578

3,495

3,544

614,117

337,628

546,615

8,370,684

8,662,394

8,847,873

0

263,543

290,280

438,291

Derviative contracts, net of cash collateral, Assets, Fair value

0

^[1]

0

^[2]

0

^[3]

344,061

^[4]

682,331

^[5]

649,503

^[6]

Derivative contracts, net of cash collateral, Liabilities, Fair Value

329,424

^[4]

657,559

^[5]

572,679

^[6]

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. government agency debentures

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. government agency residential mortgage-backed securities

30,162

6,234

15,705

516,760

310,067

464,749

5,326,384

5,460,386

5,668,672

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Municipal and other tax-exempt securities

819,531

77,046

0

56,148

14,427

54,856

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other trading securities

23,583

35,204

36,379

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Treasury

11,047

6,900

11,305

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Privately issued residential mortgage-backed securities

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial mortgage-backed securities guaranteed by U.S. government agencies

99,994

115,535

121,603

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other debt securities

2,889,346

3,017,933

2,986,495

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Perpetual preferred stock

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Equity securities and mutual funds

16,245

18,474

19,578

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]

15,132

14,862

15,146

0

8,938

9,941

9,864

0

12,100

11,617

9,301

Derviative contracts, net of cash collateral, Assets, Fair value

245,858

^[1]

247,073

^[2]

203,621

^[3]

0

^[4]

0

^[5]

0

^[6]

Derivative contracts, net of cash collateral, Liabilities, Fair Value

0

^[4]

0

^[5]

0

^[6]

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. government agency debentures

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. government agency residential mortgage-backed securities

0

0

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Municipal and other tax-exempt securities

0

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other trading securities

4,785

5,789

5,713

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Treasury

0

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Privately issued residential mortgage-backed securities

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial mortgage-backed securities guaranteed by U.S. government agencies

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other debt securities

0

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Perpetual preferred stock

4,153

4,152

4,151

Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Equity securities and mutual funds

0

Available-for-sale securities [Member] | Municipal and other tax-exempt securities

$ 0

[1]	A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 6, Mortgage Banking Activities.
[2]	A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 6, Mortgage Banking Activities.
[3]	A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 6, Mortgage Banking Activities.
[4]	See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts in asset positions that were valued based on quoted prices in active markets for identical instruments (Level 1) are primarily exchange-traded interest rate, energy and agricultural derivative contacts. Derivative contacts in liability positions that were valued using quoted prices in active markets for identical instruments are exchange-traded interest rate derivative contracts, net of cash margin.
[5]	See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts based on quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest-rate and energy derivative contacts, net of cash margin. Derivative contracts in liability positions that were valued using quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate, energy and agricultural derivative contracts, net of cash margin.
[6]	See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts based on quoted prices in active markets for identical instruments (Level 1) are exchange-traded energy and agricultural derivative contacts, net of cash margin. Derivative contracts in liability positions that were valued using quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate and energy derivative contracts, net cash margin.

Fair Value Measurements, Measured On Recurring Basis Significant Unobservable Inputs (Details) - Fair Value, Measurements, Recurring [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($)
$ in Thousands

3 Months Ended

9 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Sep. 30, 2017

Sep. 30, 2016

Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]

Balance, beginning of period

$ 4,655

$ 9,600

$ 5,789

$ 9,610

Transfer to Level 3 from Level 2

0

^[1]

0

^[2]

0

^[1]

0

^[2]

Purchases

0

Proceeds from sales

0

Redemptions and distributions

0

(3,975)

(1,100)

(3,975)

Other comprehensive income (loss)

130

88

96

78

Balance, end of period

4,785

5,713

4,785

5,713

Available-for-sale securities [Member] | Municipal and other tax-exempt securities | Mortgage banking revenue [Member]

Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]

Gain (loss) recognized in earnings

0

Available-for-sale securities [Member] | Other debt securities

Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]

Balance, beginning of period

4,152

4,151

4,152

4,151

Transfer to Level 3 from Level 2

0

^[1]

0

^[2]

0

^[1]

0

^[2]

Purchases

0

Proceeds from sales

0

Redemptions and distributions

0

Other comprehensive income (loss)

1

0

1

0

Balance, end of period

4,153

4,151

4,153

4,151

Available-for-sale securities [Member] | Other debt securities | Mortgage banking revenue [Member]

Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]

Gain (loss) recognized in earnings

0

Residential mortgage loans held for sale [Member]

Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward]

Balance, beginning of period

12,735

9,749

11,617

7,874

Transfer to Level 3 from Level 2

176

^[1]

442

^[2]

2,916

^[1]

3,982

^[2]

Purchases

0

Proceeds from sales

(847)

(1,003)

(2,549)

(2,365)

Redemptions and distributions

0

Other comprehensive income (loss)

0

Balance, end of period

12,100

9,301

12,100

9,301

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

$ 36

$ 113

$ 116

$ (190)

[1]	1 Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.
[2]	1 Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.

Fair Value Measurements Fair Value Measurements, Financial Instruments Measured On a Recurring Basis, Quantitative Information (Details) - Fair Value, Measurements, Recurring [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($)
$ in Thousands

9 Months Ended

12 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Dec. 31, 2016

Available-for-sale securities [Member] | Municipal and other tax-exempt securities

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Fair Value Inputs, Asset, Par Value

$ 5,095

$ 6,195

Fair Value Inputs, Asset, Amortized Cost/Unpaid Principal Balance

5,067

6,162

6,163

Fair Value Inputs, Asset, Fair Value

$ 4,785

$ 5,713

$ 5,789

Fair Value Measurements, Significant Unobservable Input

Discounted cash flows

^[1]

Discounted cash flows

^[2]

Discounted cash flows

^[3]

Interest rate spread

Fair Value Inputs, Assets, Discount Rate, Minimum

6.05%

^[4]

5.60%

^[5]

5.91%

^[6]

Fair Value Inputs, Assets, Discount Rate, Maximum

6.05%

^[4]

5.90%

^[5]

6.21%

^[6]

Fair Value Inputs, Assets, Discount Rate, Weighted Average

6.05%

^[4]

5.85%

^[5]

6.16%

^[6]

Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Minimum

92.25%

^[7]

90.00%

^[8]

90.00%

^[9]

Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Maximum

95.02%

^[7]

93.79%

^[8]

93.40%

^[9]

Fair Value Inputs, Fair Value As Percentage of Par Value, Weighted Average

93.91%

^[7]

92.22%

^[8]

92.20%

^[9]

Investment Grade Tax Exempt Securities Yield Spread Over Comparable Securities Minimum

352

437

467

Investment Grade Tax Exempt Securities Yield Spread Over Comparable Securities Maximum

467

484

525

Available-for-sale securities [Member] | Other debt securities

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Fair Value Inputs, Asset, Par Value

$ 4,400

Fair Value Inputs, Asset, Amortized Cost/Unpaid Principal Balance

4,400

Fair Value Inputs, Asset, Fair Value

$ 4,153

$ 4,151

$ 4,152

Fair Value Measurements, Significant Unobservable Input

Discounted cash flows

^[1]

Discounted cash flows

^[2]

Discounted cash flows

^[3]

Interest rate spread

Fair Value Inputs, Assets, Discount Rate, Minimum

6.65%

^[10]

5.98%

^[11]

6.01%

^[12]

Fair Value Inputs, Assets, Discount Rate, Maximum

6.73%

^[10]

6.03%

^[11]

6.26%

^[12]

Fair Value Inputs, Assets, Discount Rate, Weighted Average

6.72%

^[10]

6.02%

^[11]

6.23%

^[12]

Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Minimum

94.38%

^[7]

94.34%

^[8]

94.34%

^[9]

Fair Value Inputs, Assets, Fair Value As Percentage of Par Value, Maximum

94.38%

^[7]

94.34%

^[8]

94.36%

^[9]

Fair Value Inputs, Fair Value As Percentage of Par Value, Weighted Average

94.38%

^[7]

94.34%

^[8]

94.36%

^[9]

Average Yields On Comparable Short-term Taxable Securities, Maximum

3.00%

1.00%

Residential mortgage loans held for sale [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Fair Value Inputs, Asset, Amortized Cost/Unpaid Principal Balance

$ 12,612

$ 9,957

$ 12,431

Fair Value Inputs, Asset, Fair Value

$ 12,100

$ 9,301

$ 11,617

Fair Value Measurements, Significant Unobservable Input

Quoted prices of loans sold in securitization transactions, with a liquidity discount applied

Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies.

Liquidity Discount on Mortgage Loans Qualifying for Sale to US Govt Agencies

95.94%

93.41%

93.45%

[1]	Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume
[2]	Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume
[3]	Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume
[4]	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 352 to 467 basis points over average yields for comparable tax-exempt securities.
[5]	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 437 to 484 basis points over average yields for comparable tax-exempt securities.
[6]	Interest rate yields used to value investment grade tax-exempt securities represent a spread of 467 to 525 basis points over average yields for comparable tax-exempt securities.
[7]	Represents fair value as a percentage of par value.
[8]	Represents fair value as a percentage of par value.
[9]	Represents fair value as a percentage of par value.
[10]	Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 3 percent.
[11]	Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 1 percent.
[12]	Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 1 percent.

Fair Value Measurements, Fair Value Measured On a Nonrecurring Basis (Details) - Fair Value, Measurements, Nonrecurring [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross charge-offs against allowance for loan losses	$ 4,397	$ 6,334	$ 5,058	$ 30,200
Net losses and expenses of repossessed assets, net	0	0	0	0
Real estate and other repossessed assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross charge-offs against allowance for loan losses	0	0	0	0
Net losses and expenses of repossessed assets, net	4,683	480	4,915	1,260
Fair Value, Inputs, Level 1 [Member] \| Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	0	0	0	0
Fair Value, Inputs, Level 1 [Member] \| Real estate and other repossessed assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	0	0	0	0
Fair Value, Inputs, Level 2 [Member] \| Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	423	436	423	436
Fair Value, Inputs, Level 2 [Member] \| Real estate and other repossessed assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	4,392	6,048	4,392	6,048
Fair Value, Inputs, Level 3 [Member] \| Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	10,960	23,089	10,960	23,089
Fair Value, Inputs, Level 3 [Member] \| Real estate and other repossessed assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	$ 6,845	$ 1,927	$ 6,845	$ 1,927

Fair Value Measurements Fair Value Measurement, Measured On Non-Recurring Basis, Signfiicant Unobservable Inputs, Quantitative Information (Details) - Fair Value, Measurements, Nonrecurring [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($)
$ in Thousands

3 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Impaired Loans [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Carrying Value

$ 10,960

$ 23,089

Fair Value Measurements, Significant Unobservable Input

Discounted cash flows

Recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs

Fair Value of Impaired Loans as a Percentage of Unpaid Principal Balance [Abstract]

Fair Value Measurements, Fair Value of Impaired Loans as a Percentage of Unpaid Principal Balance, Minimum

^[1]

64.00%

23.00%

Fair Value Measurements, Fair Value of Impaired Loans as a Percentage of Unpaid Principal Balance, Maximum

^[1]

88.00%

59.00%

Fair Value of Impaired Loans as a Percentage of Unpaid Principal Balance, Weighted Average

^[1]

68.00%

43.00%

Real estate and other repossessed assets [Member]

Fair Value Inputs, Assets, Quantitative Information [Line Items]

Carrying Value

$ 6,845

$ 1,927