Consolidated Statements of Earnings (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Interest revenue [Abstract]
Loans	$ 126,696	$ 122,471
Residential mortgage loans held for sale	2,949	1,590
Trading securities	507	411
Taxable securities	3,326	3,282
Tax-exempt securities	1,344	1,504
Total investment securities	4,670	4,786
Taxable securities	43,105	47,255
Tax-exempt securities	620	494
Total available for sale securities	43,725	47,749
Fair value option securities	2,003	851
Restricted equity securities	2,597	997
Interest-bearing cash and cash equivalents	1,422	265
Total interest revenue	184,569	179,120
Interest expense [Abstract]
Deposits	12,105	12,986
Borrowed funds	2,573	1,334
Subordinated debentures	2,165	2,158
Total interest expense	16,843	16,478
Net interest revenue	167,726	162,642
Provision for credit losses	0	0
Net interest revenue after provision for credit losses	167,726	162,642
Other operating revenue [Abstract]
Brokerage and trading revenue	31,707	29,516
Transaction card revenue	31,010	29,134
Fiduciary and asset management revenue	31,469	25,722
Deposit service charges and fees	21,684	22,689
Mortgage banking revenue	39,320	22,844
Bank-owned life insurance	2,198	2,106
Other revenue	8,603	8,852
Total fees and commissions	165,991	140,863
Gain (loss) on other assets, net	755	(2,328)
Gain on derivatives, net	911	968
Gain on fair value option securities, net	2,647	2,660
Change in fair value of mortgage servicing rights	(8,522)	(4,461)
Gain on available for sale securities, net	4,327	1,240
Total other-than-temporary impairment losses	(781)	0
Portion of loss recognized in (reclassified from) other comprehensive income	689	0
Net impairment losses recognized in earnings	(92)	0
Total other operating revenue	166,017	138,942
Other operating expense [Abstract]
Personnel	128,548	104,433
Business promotion	5,748	5,841
Charitable contributions to BOKF Foundation	0	2,420
Professional fees and services	10,059	7,565
Net occupancy and equipment	19,044	16,896
Insurance	4,980	4,541
Data processing and communications	30,620	27,135
Printing, postage and supplies	3,461	3,541
Net losses and operating expenses of repossessed assets	613	1,432
Amortization of intangible assets	1,090	816
Mortgage banking costs	9,319	3,634
Other expense	6,783	6,850
Total other operating expense	220,265	185,104
Net income before taxes	113,478	116,480
Federal and state income taxes	38,384	39,437
Net income	75,094	77,043
Net income attributable to non-controlling interests	251	453
Net income attributable to BOK Financial Corporation shareholders	$ 74,843	$ 76,590
Earnings per share: [Abstract]
Basic (in dollars per share)	$ 1.08	$ 1.11
Diluted (in dollars per share)	$ 1.08	$ 1.11
Average shares used in computation: [Abstract]
Basic (in shares)	68,254,780	68,273,685
Diluted (in shares)	68,344,886	68,436,478
Dividends declared per share (in dollars per share)	$ 0.42	$ 0.40