Parent Company Only Financial Statements Parent Company Only Financial Statements (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Assets [Abstract]
Cash and cash equivalents	$ 1,087,213	$ 1,286,239	$ 986,365
Available for sale securities	10,147,162	11,287,221
Other assets	359,894	324,153
Total assets	27,015,432	28,148,631
Liabilities and Shareholders' Equity [Abstract]
Other liabilities	133,647	164,316
Total liabilities	23,960,459	25,154,950
Shareholders' equity: [Abstract]
Common stock	4	4
Capital surplus	898,586	859,278
Retained earnings	2,349,428	2,137,541
Treasury stock	(202,346)	(188,883)
Accumulated other comprehensive income (loss)	(25,623)	149,920	128,979	107,839
Total shareholders' equity	3,020,049	2,957,860
Total liabilities and equity	27,015,432	28,148,631
Income Statement [Abstract]
Other revenue	38,262	34,604	34,070
Net impairment losses recognized in earnings	(2,308)	(7,351)	(23,507)
Interest expense	70,894	87,322	120,101
Professional fees and services	32,552	34,015	28,798
Other operating expense	840,620	840,363	779,298
Federal and state income tax	157,298	188,740	158,511
Net income attributable to BOK Financial Corp. shareholders	316,609	351,191	285,875
Cash Flows From Operating Activities:
Net income	318,931	354,124	289,824
Adjustments to net income to cash provided by operating activities [Abstract]
Tax benefit (expense) on exercise of stock options	(2,210)	(120)	(659)
Change in other assets	(76,257)	(10,999)	(16,469)
Change in other liabilities	(13,735)	(3,729)	(50,198)
Net cash provided by operating activities	736,320	591,550	327,788
Cash Flows From Investing Activities:
Purchases of available for sale securities	(4,287,146)	(7,334,843)	(7,504,261)
Proceeds from sales of available for sale securities	2,436,093	1,744,662	2,725,760
Acquisitions, net of cash acquired	(7,500)	(23,615)	0
Net cash provided by (used in) investing activities	437,029	(2,368,347)	(1,564,144)
Net Cash Used in Financing Activities [Abstract]
Issuance of common and treasury stock, net	16,566	14,650	14,541
Tax benefit on exercise of stock options	2,210	120	659
Dividends paid	(104,722)	(166,982)	(76,423)
Repurchase of common stock	0	(20,558)	(26,446)
Net cash used in financing activities	(1,372,375)	2,076,671	953,317
Net increase in cash and cash equivalents	(199,026)	299,874	(283,039)
Cash and cash equivalents at beginning of period	1,286,239	986,365	1,269,404
Cash and cash equivalents at end of period	1,087,213	1,286,239	986,365
Cash paid for interest	69,830	90,137	122,166
Parent Company [Member]
Assets [Abstract]
Cash and cash equivalents	561,297	457,514	386,695
Available for sale securities	27,526	44,881
Investments in subsidiaries	2,426,495	2,464,729
Other assets	12,872	4,324
Total assets	3,028,190	2,971,448
Liabilities and Shareholders' Equity [Abstract]
Other liabilities	8,141	13,588
Total liabilities	8,141	13,588
Shareholders' equity: [Abstract]
Common stock	4	4
Capital surplus	898,586	859,278
Retained earnings	2,349,428	2,137,541
Treasury stock	(202,346)	(188,883)
Accumulated other comprehensive income (loss)	(25,623)	149,920
Total shareholders' equity	3,020,049	2,957,860
Total liabilities and equity	3,028,190	2,971,448
Income Statement [Abstract]
Dividends, interest and fees received from subsidiaries	225,340	275,330	270,474
Other revenue	3,341	2,295	2,128
Net impairment losses recognized in earnings	0	(1,099)	(2,098)
Total revenue	228,681	276,526	270,504
Interest expense	292	269	354
Professional fees and services	811	765	538
Other operating expense	3,272	3,099	7,688
Total expenses	4,375	4,133	8,580
Income before taxes and equity in undistributed income of subsidiaries	224,306	272,393	261,924
Federal and state income tax	(1,578)	(1,706)	(3,169)
Income before equity in undistributed earnings of subsidiaries	225,884	274,099	265,093
Equity in undistributed income of subsidiaries	90,725	77,092	20,782
Net income attributable to BOK Financial Corp. shareholders	316,609	351,191	285,875
Cash Flows From Operating Activities:
Net income	316,609	351,191	285,875
Adjustments to net income to cash provided by operating activities [Abstract]
Equity in undistributed income of subsidiaries	(90,725)	(77,092)	(20,782)
Tax benefit (expense) on exercise of stock options	(2,210)	(120)	(659)
Change in other assets	(8,308)	4,237	15,249
Change in other liabilities	4,263	(4,965)	(18,225)
Net cash provided by operating activities	219,629	273,251	261,458
Cash Flows From Investing Activities:
Purchases of available for sale securities	0	(5,343)	(3,797)
Proceeds from sales of available for sale securities	13,600	4,781	16,500
Investment in subsidiaries	(36,000)	(9,100)	(7,250)
Acquisitions, net of cash acquired	(7,500)	(20,000)	0
Net cash provided by (used in) investing activities	(29,900)	(29,662)	5,453
Net Cash Used in Financing Activities [Abstract]
Issuance of common and treasury stock, net	16,566	14,650	14,541
Tax benefit on exercise of stock options	2,210	120	659
Dividends paid	(104,722)	(166,982)	(76,423)
Repurchase of common stock	0	(20,558)	(26,446)
Net cash used in financing activities	(85,946)	(172,770)	(87,669)
Net increase in cash and cash equivalents	103,783	70,819	179,242
Cash and cash equivalents at beginning of period	457,514	386,695	207,453
Cash and cash equivalents at end of period	561,297	457,514	386,695
Cash paid for interest	$ 292	$ 269	$ 354