Reportable Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	$ 747,228	$ 703,354	$ 665,194
Net interest revenue (expense) from internal sources	0	0	0
Net interest and dividend revenue	747,228	703,354	665,194
Provision for credit losses	65,000	34,000	0
Net interest and dividend revenue after provision for credit losses	682,228	669,354	665,194
Other operating revenue	674,020	658,480	621,958
Other operating expense	1,017,590	896,191	847,522
Net direct contribution	338,658	431,643	439,630
Gain (loss) on financial instruments, net	0	0	0
Change in fair value of mortgage servicing rights	0	0	0
Gain (loss) on repossessed assets, net	0	0	0
Corporate expense allocations	0	0	0
Net income before taxes	338,658	431,643	439,630
Federal and state income taxes	106,377	139,384	144,151
Net income	232,281	292,259	295,479
Net income (loss) attributable to non-controlling interests	(387)	3,694	3,044
Net income attributable to BOK Financial Corp. shareholders	232,668	288,565	292,435
Average assets	32,278,402	30,574,755	27,998,858
Operating Segments [Member] | Commercial [Member]
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	492,967	439,751	382,331
Net interest revenue (expense) from internal sources	(58,781)	(52,313)	(40,083)
Net interest and dividend revenue	434,186	387,438	342,248
Provision for credit losses	32,959	(6,748)	(7,447)
Net interest and dividend revenue after provision for credit losses	401,227	394,186	349,695
Other operating revenue	195,521	177,729	171,390
Other operating expense	216,451	202,804	195,706
Net direct contribution	380,297	369,111	325,379
Gain (loss) on financial instruments, net	10	0	0
Change in fair value of mortgage servicing rights	0	0	0
Gain (loss) on repossessed assets, net	669	708	(3,187)
Corporate expense allocations	35,760	43,279	45,502
Net income before taxes	345,216	326,540	276,690
Federal and state income taxes	134,289	127,024	107,632
Net income	210,927	199,516	169,058
Net income (loss) attributable to non-controlling interests	0	0	0
Net income attributable to BOK Financial Corp. shareholders	210,927	199,516	169,058
Average assets	16,998,626	16,284,527	15,394,957
Operating Segments [Member] | Consumer [Member]
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	85,998	84,848	81,852
Net interest revenue (expense) from internal sources	37,777	28,503	26,813
Net interest and dividend revenue	123,775	113,351	108,665
Provision for credit losses	4,927	6,934	5,477
Net interest and dividend revenue after provision for credit losses	118,848	106,417	103,188
Other operating revenue	224,802	218,095	214,657
Other operating expense	249,744	203,070	207,131
Net direct contribution	93,906	121,442	110,714
Gain (loss) on financial instruments, net	(26,252)	(4,712)	12,406
Change in fair value of mortgage servicing rights	(2,193)	(4,853)	(16,445)
Gain (loss) on repossessed assets, net	979	916	1,418
Corporate expense allocations	66,411	74,936	64,531
Net income before taxes	29	37,857	43,562
Federal and state income taxes	11	14,726	16,946
Net income	18	23,131	26,616
Net income (loss) attributable to non-controlling interests	0	0	0
Net income attributable to BOK Financial Corp. shareholders	18	23,131	26,616
Average assets	8,722,372	8,836,327	8,373,317
Operating Segments [Member] | Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	33,006	24,744	23,817
Net interest revenue (expense) from internal sources	29,043	24,043	20,959
Net interest and dividend revenue	62,049	48,787	44,776
Provision for credit losses	(801)	(1,083)	213
Net interest and dividend revenue after provision for credit losses	62,850	49,870	44,563
Other operating revenue	283,222	267,523	242,268
Other operating expense	250,994	228,664	218,000
Net direct contribution	95,078	88,729	68,831
Gain (loss) on financial instruments, net	(42)	(204)	(235)
Change in fair value of mortgage servicing rights	0	0	0
Gain (loss) on repossessed assets, net	0	0	0
Corporate expense allocations	42,378	40,357	38,731
Net income before taxes	52,658	48,168	29,865
Federal and state income taxes	20,484	18,737	11,617
Net income	32,174	29,431	18,248
Net income (loss) attributable to non-controlling interests	0	0	0
Net income attributable to BOK Financial Corp. shareholders	32,174	29,431	18,248
Average assets	6,281,127	5,444,483	5,002,515
Corporate, Non-Segment [Member] | Funds Management and Other [Member]
Segment Reporting Information [Line Items]
Net interest and dividend revenue from external sources	135,257	154,011	177,194
Net interest revenue (expense) from internal sources	(8,039)	(233)	(7,689)
Net interest and dividend revenue	127,218	153,778	169,505
Provision for credit losses	27,915	34,897	1,757
Net interest and dividend revenue after provision for credit losses	99,303	118,881	167,748
Other operating revenue	(29,525)	(4,867)	(6,357)
Other operating expense	300,401	261,653	226,685
Net direct contribution	(230,623)	(147,639)	(65,294)
Gain (loss) on financial instruments, net	26,284	4,916	(12,171)
Change in fair value of mortgage servicing rights	2,193	4,853	16,445
Gain (loss) on repossessed assets, net	(1,648)	(1,624)	1,769
Corporate expense allocations	(144,549)	(158,572)	(148,764)
Net income before taxes	(59,245)	19,078	89,513
Federal and state income taxes	(48,407)	(21,103)	7,956
Net income	(10,838)	40,181	81,557
Net income (loss) attributable to non-controlling interests	(387)	3,694	3,044
Net income attributable to BOK Financial Corp. shareholders	(10,451)	36,487	78,513
Average assets	$ 276,277	$ 9,418	$ (771,931)