Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Net interest revenue from external sources	$ 182,572	$ 167,726
Net interest revenue (expense) from internal sources	0	0
Net interest revenue	182,572	167,726
Provision for credit losses	35,000	0
Net interest revenue after provision for credit losses	147,572	167,726
Other operating revenue	159,744	166,017
Other operating expense	244,900	220,265
Net direct contribution	62,416	113,478
Gain (loss) on financial instruments, net	0	0
Change in fair value of mortgage servicing rights	0	0
Gain on repossessed assets, net	0	0
Corporate expense allocations	0	0
Net income before taxes	62,416	113,478
Federal and state income taxes	21,428	38,384
Net income	40,988	75,094
Net income (loss) attributable to non-controlling interests	(1,576)	251
Net income attributable to BOK Financial Corp. shareholders	42,564	74,843
Average assets	31,508,471	29,970,704
Average invested capital	3,288,347	3,318,262
Operating Segments [Member] | Commercial [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	116,637	101,175
Net interest revenue (expense) from internal sources	(14,534)	(12,635)
Net interest revenue	102,103	88,540
Provision for credit losses	21,572	(8,902)
Net interest revenue after provision for credit losses	80,531	97,442
Other operating revenue	45,108	42,446
Other operating expense	56,069	49,145
Net direct contribution	69,570	90,743
Gain (loss) on financial instruments, net	0	0
Change in fair value of mortgage servicing rights	0	0
Gain on repossessed assets, net	(82)	45
Corporate expense allocations	8,744	11,241
Net income before taxes	60,744	79,547
Federal and state income taxes	23,629	30,944
Net income	37,115	48,603
Net income (loss) attributable to non-controlling interests	0	0
Net income attributable to BOK Financial Corp. shareholders	37,115	48,603
Average assets	16,969,015	16,270,266
Average invested capital	1,155,572	994,596
Operating Segments [Member] | Consumer [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	21,465	20,719
Net interest revenue (expense) from internal sources	9,353	6,819
Net interest revenue	30,818	27,538
Provision for credit losses	1,702	1,422
Net interest revenue after provision for credit losses	29,116	26,116
Other operating revenue	56,359	61,195
Other operating expense	58,048	52,306
Net direct contribution	27,427	35,005
Gain (loss) on financial instruments, net	16,581	3,558
Change in fair value of mortgage servicing rights	(27,988)	(8,522)
Gain on repossessed assets, net	153	78
Corporate expense allocations	15,978	18,202
Net income before taxes	195	11,917
Federal and state income taxes	76	4,636
Net income	119	7,281
Net income (loss) attributable to non-controlling interests	0	0
Net income attributable to BOK Financial Corp. shareholders	119	7,281
Average assets	8,687,289	8,798,913
Average invested capital	258,888	272,315
Operating Segments [Member] | Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	6,078	5,376
Net interest revenue (expense) from internal sources	7,663	6,079
Net interest revenue	13,741	11,455
Provision for credit losses	(150)	0
Net interest revenue after provision for credit losses	13,891	11,455
Other operating revenue	68,747	66,961
Other operating expense	60,684	54,480
Net direct contribution	21,954	23,936
Gain (loss) on financial instruments, net	0	0
Change in fair value of mortgage servicing rights	0	0
Gain on repossessed assets, net	0	0
Corporate expense allocations	10,535	9,982
Net income before taxes	11,419	13,954
Federal and state income taxes	4,442	5,428
Net income	6,977	8,526
Net income (loss) attributable to non-controlling interests	0	0
Net income attributable to BOK Financial Corp. shareholders	6,977	8,526
Average assets	5,565,047	5,451,695
Average invested capital	233,079	223,967
Corporate, Non-Segment [Member] | Funds Management and Other [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	38,392	40,456
Net interest revenue (expense) from internal sources	(2,482)	(263)
Net interest revenue	35,910	40,193
Provision for credit losses	11,876	7,480
Net interest revenue after provision for credit losses	24,034	32,713
Other operating revenue	(10,470)	(4,585)
Other operating expense	70,099	64,334
Net direct contribution	(56,535)	(36,206)
Gain (loss) on financial instruments, net	(16,581)	(3,558)
Change in fair value of mortgage servicing rights	27,988	8,522
Gain on repossessed assets, net	(71)	(123)
Corporate expense allocations	(35,257)	(39,425)
Net income before taxes	(9,942)	8,060
Federal and state income taxes	(6,719)	(2,624)
Net income	(3,223)	10,684
Net income (loss) attributable to non-controlling interests	(1,576)	251
Net income attributable to BOK Financial Corp. shareholders	(1,647)	10,433
Average assets	287,120	(550,170)
Average invested capital	$ 1,640,808	$ 1,827,384