Consolidated Statements of Earnings (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Interest revenue [Abstract]
Loans	$ 168,952	$ 141,560	$ 329,847	$ 280,672
Residential mortgage loans held for sale	2,386	3,508	4,222	6,208
Trading securities	3,339	616	8,522	1,140
Investment securities	4,005	4,217	8,176	8,604
Available for sale securities	43,363	43,872	86,735	89,339
Fair value option securities	3,539	2,062	5,919	4,651
Restricted equity securities	4,399	3,863	8,708	8,174
Interest-bearing cash and cash equivalents	5,198	2,569	9,442	5,275
Total interest revenue	235,181	202,267	461,571	404,063
Interest expense [Abstract]
Deposits	12,622	9,997	23,976	20,539
Borrowed funds	15,352	8,780	27,181	16,752
Subordinated debentures	2,003	878	4,028	1,588
Total interest expense	29,977	19,655	55,185	38,879
Net interest revenue	205,204	182,612	406,386	365,184
Provision for credit losses	0	20,000	0	55,000
Net interest revenue after provision for credit losses	205,204	162,612	406,386	310,184
Other operating revenue [Abstract]
Brokerage and trading revenue	31,764	39,530	65,387	71,871
Transaction card revenue	35,296	34,950	67,423	67,304
Fiduciary and asset management revenue	41,808	34,813	80,439	66,869
Deposit service charges and fees	23,354	22,618	46,384	45,160
Mortgage banking revenue	30,276	34,884	55,467	66,984
Other revenue	14,984	13,352	26,736	25,256
Total fees and commissions	177,482	180,147	341,836	343,444
Other gains, net	6,108	1,307	9,735	2,867
Gain (loss) on derivatives, net	3,241	10,766	2,791	17,904
Gain (loss) on fair value option securities, net	1,984	4,279	844	13,722
Change in fair value of mortgage servicing rights	(6,943)	(16,283)	(5,087)	(44,271)
Gain on available for sale securities, net	380	5,326	2,429	9,290
Total other operating revenue	182,252	185,542	352,548	342,956
Other operating expense [Abstract]
Personnel	143,744	139,213	280,169	272,775
Business promotion	7,738	6,703	14,455	12,399
Professional fees and services	12,419	14,158	23,836	25,917
Net occupancy and equipment	21,125	19,677	42,749	38,443
Insurance	689	7,129	7,093	14,394
Data processing and communications	36,330	32,802	71,232	64,819
Printing, postage and supplies	4,140	3,889	7,991	7,796
Net losses (gains) and operating expenses of repossessed assets	2,267	1,588	3,276	2,658
Amortization of intangible assets	1,803	2,624	3,605	3,783
Mortgage banking costs	12,072	15,746	25,075	28,076
Other expense	8,558	7,856	16,115	22,895
Total other operating expense	250,885	251,385	495,596	493,955
Net income before taxes	136,571	96,769	263,338	159,185
Federal and state income taxes	47,705	30,497	85,808	51,925
Net income	88,866	66,272	177,530	107,260
Net income (loss) attributable to non-controlling interests	719	471	1,027	(1,105)
Net income attributable to BOK Financial Corporation shareholders	$ 88,147	$ 65,801	$ 176,503	$ 108,365
Earnings per share: [Abstract]
Basic	$ 1.35	$ 1.00	$ 2.70	$ 1.64
Diluted	$ 1.35	$ 1.00	$ 2.69	$ 1.64
Average shares used in computation: [Abstract]
Basic	64,729,752	65,245,887	64,722,744	65,271,214
Diluted	64,793,134	65,302,926	64,788,322	65,317,177
Dividends declared per share	$ 0.44	$ 0.43	$ 0.88	$ 0.86