Consolidated Statements of Earnings (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Interest revenue [Abstract]
Loans	$ 132,985	$ 126,559	$ 392,878	$ 374,523
Residential mortgage loans held for sale	3,793	2,929	10,634	7,042
Trading securities	669	414	1,618	1,233
Taxable securities	3,211	3,238	9,788	9,715
Tax-exempt securities	1,274	1,373	3,933	4,348
Total investment securities	4,485	4,611	13,721	14,063
Taxable securities	43,473	45,257	128,933	138,970
Tax-exempt securities	535	451	1,718	1,576
Total available for sale securities	44,008	45,708	130,651	140,546
Fair value option securities	2,480	913	6,803	2,558
Restricted equity securities	3,802	2,133	9,627	4,405
Interest-bearing cash and cash equivalents	1,442	601	4,114	1,249
Total interest revenue	193,664	183,868	570,046	545,619
Interest expense [Abstract]
Deposits	10,731	12,719	34,102	38,482
Borrowed funds	3,701	2,204	9,395	5,106
Subordinated debentures	596	2,154	4,456	6,501
Total interest expense	15,028	17,077	47,953	50,089
Net interest revenue	178,636	166,791	522,093	495,530
Provision for credit losses	7,500	0	11,500	0
Net interest revenue after provision for credit losses	171,136	166,791	510,593	495,530
Other operating revenue [Abstract]
Brokerage and trading revenue	31,582	35,263	99,301	103,835
Transaction card revenue	32,514	31,578	96,302	92,222
Fiduciary and asset management revenue	30,807	29,738	94,988	85,003
Deposit service charges and fees	23,606	22,508	67,618	68,330
Mortgage banking revenue	33,170	26,814	109,336	78,988
Bank-owned life insurance	2,360	2,326	6,956	6,706
Other revenue	10,618	10,320	28,694	28,380
Total fees and commissions	164,657	158,547	503,195	463,464
Gain on other assets, net	1,161	1,422	3,373	2,615
Gain (loss) on derivatives, net	1,283	(93)	1,162	1,706
Gain (loss) on fair value option securities, net	5,926	(332)	443	6,504
Change in fair value of mortgage servicing rights	(11,757)	5,281	(12,269)	(5,624)
Gain on available for sale securities, net	2,166	146	9,926	1,390
Total other-than-temporary impairment losses	0	0	(781)	0
Portion of loss recognized in (reclassified from) other comprehensive income	0	0	689	0
Net impairment losses recognized in earnings	0	0	(92)	0
Total other operating revenue	163,436	164,971	505,738	470,055
Other operating expense [Abstract]
Personnel	129,062	123,043	390,305	351,190
Business promotion	5,922	6,160	19,435	19,151
Charitable contributions to BOKF Foundation	796	0	796	2,420
Professional fees and services	10,147	14,763	29,766	33,382
Net occupancy and equipment	18,689	18,892	56,660	54,577
Insurance	4,864	4,793	14,960	13,801
Data processing and communications	31,228	29,971	93,311	86,177
Printing, postage and supplies	3,376	3,380	10,390	10,350
Net losses and operating expenses of repossessed assets	267	4,966	1,103	7,516
Amortization of intangible assets	1,089	1,100	3,269	2,865
Mortgage banking costs	8,587	7,734	25,325	19,328
Other expense	10,601	7,032	26,686	20,888
Total other operating expense	224,628	221,834	672,006	621,645
Net income before taxes	109,944	109,928	344,325	343,940
Federal and state income taxes	34,128	33,802	113,142	114,042
Net income	75,816	76,126	231,183	229,898
Net income attributable to non-controlling interests	925	494	2,219	1,781
Net income attributable to BOK Financial Corporation shareholders	$ 74,891	$ 75,632	$ 228,964	$ 228,117
Earnings per share: [Abstract]
Basic (in dollars per share)	$ 1.09	$ 1.09	$ 3.33	$ 3.30
Diluted (in dollars per share)	$ 1.09	$ 1.09	$ 3.32	$ 3.29
Average shares used in computation: [Abstract]
Basic (in shares)	67,668,076	68,455,866	68,004,508	68,364,549
Diluted (in shares)	67,762,483	68,609,765	68,104,017	68,520,591
Dividends declared per share (in dollars per share)	$ 0.42	$ 0.40	$ 1.26	$ 1.20