Other Borrowings (Details) - USD ($) $ in Thousands			12 Months Ended
		Jun. 01, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Borrowings [Line Items]
Balance			$ 6,277,866	$ 3,726,277	$ 3,069,690
Average Balance			$ 5,880,647	$ 3,699,621	$ 3,719,768
Rate			0.36%	0.43%	0.40%
US Agency Securities [Member]
Repurchase Agreements, Security Sold/Maturity [Abstract]
Amortized Cost			$ 685,458	$ 1,185,345
Fair Value			688,485	1,192,361
Repurchase Liability	[1]		$ 722,444	$ 1,187,445
Average Rate (in hundredths)			0.02%	0.04%
US Agency Securities [Member] | Overnight [Member]
Repurchase Agreements, Security Sold/Maturity [Abstract]
Amortized Cost			$ 685,458	$ 1,185,345
Fair Value			688,485	1,192,361
Repurchase Liability	[1]		$ 722,444	$ 1,187,445
Average Rate (in hundredths)			0.02%	0.04%
US Agency Securities [Member] | Long-term [Member]
Repurchase Agreements, Security Sold/Maturity [Abstract]
Amortized Cost			$ 0	$ 0
Fair Value			0	0
Repurchase Liability	[1]		$ 0	$ 0
Average Rate (in hundredths)			0.00%	0.00%
Parent Company and other non-bank subsidiaries [Member]
Other Borrowings [Line Items]
Balance			$ 0	$ 0	$ 0
Average Balance			$ 0	$ 0	$ 326
Rate			0.00%	0.00%	0.00%
Other borrowings, Maturities [Abstract]
2016			$ 0
2017			0
2018			0
2019			0
2020			0
Thereafter			0
Parent Company and other non-bank subsidiaries [Member] | Senior unsecured revolving credit facility [Member]
Other Borrowings [Line Items]
Balance				$ 0
Senior Unsecured Revolving Credit Facility [Abstract]
Senior unsecured revolving credit facility, borrowing capacity			$ 100,000
Senior unsecured revolving credit facility, revolving period			364
Parent Company and other non-bank subsidiaries [Member] | Other Borrowings [Member]
Other Borrowings [Line Items]
Balance			$ 0	0	$ 0
Average Balance			$ 0	$ 0	$ 326
Rate			0.00%	0.00%	0.00%
Maximum Outstanding At Any Month End			$ 0	$ 0	$ 0
Subsidiary Bank [Member]
Other Borrowings [Line Items]
Balance			6,277,866	3,726,277	3,069,690
Average Balance			$ 5,880,647	$ 3,699,621	$ 3,719,442
Rate			0.36%	0.43%	0.40%
Other borrowings, Maturities [Abstract]
2016			$ 6,033,638
2017			226,925
2018			711
2019			956
2020			961
Thereafter			14,675
Subsidiary Bank [Member] | Funds purchased [Member]
Other Borrowings [Line Items]
Balance			$ 491,192	$ 57,031	$ 868,081
Rate			0.15%	0.05%	0.04%
Average Balance			$ 73,219	$ 494,220	$ 866,062
Rate			0.09%	0.07%	0.10%
Maximum Outstanding At Any Month End			$ 491,192	$ 1,548,676	$ 997,536
Other borrowings, Other Disclosures [Abstract]
Number of days to maturity, minimum			1 day
Number of days to maturity, maximum			90 days
Subsidiary Bank [Member] | Repurchase agreements [Member]
Other Borrowings [Line Items]
Balance			$ 722,444	$ 1,187,489	$ 813,454
Rate			0.02%	0.04%	0.05%
Average Balance			$ 623,921	$ 928,767	$ 811,996
Rate			0.04%	0.06%	0.06%
Maximum Outstanding At Any Month End			$ 1,008,144	$ 1,187,489	$ 881,033
Other borrowings, Other Disclosures [Abstract]
Number of days to maturity, maximum			90 days
Accrued interest payable			$ 0	0
Subsidiary Bank [Member] | Other Borrowings [Member]
Other Borrowings [Line Items]
Balance			4,837,880	2,133,774	1,040,353
Average Balance			$ 4,957,175	$ 1,928,742	$ 1,693,667
Rate			0.33%	0.35%	0.31%
Subsidiary Bank [Member] | Federal Home Loan Bank advances [Member]
Other Borrowings [Line Items]
Balance			$ 4,800,000	$ 2,103,400	$ 1,005,650
Rate			0.48%	0.25%	0.19%
Average Balance			$ 4,921,739	$ 1,894,966	$ 1,661,424
Rate			0.28%	0.24%	0.20%
Maximum Outstanding At Any Month End			$ 5,000,000	$ 3,453,400	$ 2,451,197
Other borrowings, Other Disclosures [Abstract]
Federal Home Loan Banks, Letters of credit issued to secure public funds			340,000
Unused credit available pursuant to the FHLB's collateral policies			491,000
Subsidiary Bank [Member] | GNMA repurchase liability [Member]
Other Borrowings [Line Items]
Balance			$ 19,478	$ 14,298	$ 18,113
Rate			4.75%	5.05%	5.50%
Average Balance			$ 16,668	$ 17,343	$ 15,741
Rate			4.95%	5.20%	5.43%
Maximum Outstanding At Any Month End			$ 19,478	$ 24,980	$ 21,055
Subsidiary Bank [Member] | Other [Member]
Other Borrowings [Line Items]
Balance			$ 18,402	$ 16,076	$ 16,590
Rate			2.70%	2.73%	2.73%
Average Balance			$ 18,768	$ 16,433	$ 16,502
Rate			2.35%	2.32%	2.54%
Maximum Outstanding At Any Month End			$ 26,058	$ 16,582	$ 17,092
Subsidiary Bank [Member] | Subordinated debentures [Member]
Other Borrowings [Line Items]
Balance			$ 226,350	$ 347,983	$ 347,802
Rate			1.05%	2.35%	2.35%
Average Balance			$ 226,332	$ 347,892	$ 347,717
Rate			1.84%	2.50%	2.51%
Maximum Outstanding At Any Month End			$ 348,076	$ 347,983	$ 347,802
Subsidiary Bank [Member] | Subordinated Debentures, 2007 Issuance [Member]
Other Borrowings [Line Items]
Balance			226,000
Other borrowings, Other Disclosures [Abstract]
Amount of debt issuance			$ 250,000
Maturity date			May 15, 2017
Interest rate description			fixed rate of 5.75% through May 14, 2012 and is based on a floating rate of three-month LIBOR plus 0.69% thereafter
Subsidiary Bank [Member] | Subordinated Debentures, 2005 Issuance [Member]
Other Borrowings [Line Items]
Balance			$ 122,000
Rate			5.56%
Other borrowings, Other Disclosures [Abstract]
Amount of debt issuance			$ 150,000
Maturity date		Jun. 01, 2015

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