Reportable Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting Information [Line Items]
Net interest revenue from external sources	$ 167,156	$ 181,361	$ 337,561	$ 354,930
Net interest revenue (expense) from internal sources	0	0	0	0
Net interest revenue	167,156	181,361	337,561	354,930
Provision for credit losses	0	(8,000)	(8,000)	(8,000)
Net interest revenue after provision for credit losses	167,156	189,361	345,561	362,930
Other operating revenue	150,761	186,260	309,835	323,541
Operating expense	196,606	223,011	397,930	405,148
Net income before taxes	121,311	152,610	257,466	281,323
Federal and state income taxes	41,423	53,149	88,519	98,669
Net income	79,888	99,461	168,947	182,654
Net income attributable to non-controlling interest	(43)	1,833	1,052	1,411
Net income attributable to BOK Financial Corporation shareholders	79,931	97,628	167,895	181,243
Average assets	27,659,324	25,538,517	27,586,781	25,527,550
Average invested capital	3,027,654	2,868,733	3,012,828	2,851,983
Performance measurements: [Abstract]
Return on average assets	1.16%	1.54%	1.23%	1.43%
Return on average invested capital	10.59%	13.69%	11.24%	12.78%
Efficiency ratio	63.11%	61.98%	62.07%	60.42%
Commercial [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	90,505	93,549	181,349	183,041
Net interest revenue (expense) from internal sources	(9,375)	(11,439)	(18,502)	(23,488)
Net interest revenue	81,130	82,110	162,847	159,553
Provision for credit losses	86	748	1,107	7,140
Net interest revenue after provision for credit losses	81,044	81,362	161,740	152,413
Other operating revenue	43,411	52,158	84,843	90,950
Operating expense	59,746	62,625	118,826	118,485
Net income before taxes	64,709	70,895	127,757	124,878
Federal and state income taxes	25,172	27,578	49,697	48,578
Net income	39,537	43,317	78,060	76,300
Net income attributable to non-controlling interest			0	0
Net income attributable to BOK Financial Corporation shareholders	39,537	43,317	78,060	76,300
Average assets	10,359,660	9,865,389	10,486,541	9,939,627
Average invested capital	899,088	862,816	895,749	883,408
Performance measurements: [Abstract]
Return on average assets	1.53%	1.77%	1.50%	1.54%
Return on average invested capital	17.64%	20.19%	17.57%	17.37%
Efficiency ratio	48.00%	52.23%	47.99%	50.19%
Consumer [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	24,830	25,723	48,925	52,310
Net interest revenue (expense) from internal sources	5,167	4,803	10,650	9,683
Net interest revenue	29,997	30,526	59,575	61,993
Provision for credit losses	1,402	4,221	2,332	5,653
Net interest revenue after provision for credit losses	28,595	26,305	57,243	56,340
Other operating revenue	47,993	74,520	105,135	124,760
Operating expense	43,320	75,602	95,690	122,913
Net income before taxes	33,268	25,223	66,688	58,187
Federal and state income taxes	12,941	9,812	25,942	22,635
Net income	20,327	15,411	40,746	35,552
Net income attributable to non-controlling interest			0	0
Net income attributable to BOK Financial Corporation shareholders	20,327	15,411	40,746	35,552
Average assets	5,695,098	5,660,601	5,709,448	5,722,627
Average invested capital	297,675	289,443	297,376	286,420
Performance measurements: [Abstract]
Return on average assets	1.43%	1.09%	1.44%	1.25%
Return on average invested capital	27.39%	21.41%	27.63%	24.96%
Efficiency ratio	63.10%	67.66%	61.19%	65.08%
Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	6,557	7,137	13,073	14,277
Net interest revenue (expense) from internal sources	5,093	5,194	10,371	10,051
Net interest revenue	11,650	12,331	23,444	24,328
Provision for credit losses	931	521	1,449	1,171
Net interest revenue after provision for credit losses	10,719	11,810	21,995	23,157
Other operating revenue	55,164	51,556	107,767	97,949
Operating expense	61,692	53,264	118,701	104,589
Net income before taxes	4,191	10,102	11,061	16,517
Federal and state income taxes	1,630	3,930	4,303	6,425
Net income	2,561	6,172	6,758	10,092
Net income attributable to non-controlling interest			0	0
Net income attributable to BOK Financial Corporation shareholders	2,561	6,172	6,758	10,092
Average assets	4,543,947	4,166,137	4,615,054	4,167,268
Average invested capital	206,216	176,703	204,158	175,376
Performance measurements: [Abstract]
Return on average assets	0.23%	0.59%	0.29%	0.49%
Return on average invested capital	4.99%	14.01%	6.66%	11.60%
Efficiency ratio	92.43%	83.80%	90.87%	85.73%
Funds Management and Other [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	45,264	54,952	94,214	105,302
Net interest revenue (expense) from internal sources	(885)	1,442	(2,519)	3,754
Net interest revenue	44,379	56,394	91,695	109,056
Provision for credit losses	(2,419)	(13,490)	(12,888)	(21,964)
Net interest revenue after provision for credit losses	46,798	69,884	104,583	131,020
Other operating revenue	4,193	8,026	12,090	9,882
Operating expense	31,848	31,520	64,713	59,161
Net income before taxes	19,143	46,390	51,960	81,741
Federal and state income taxes	1,680	11,829	8,577	21,031
Net income	17,463	34,561	43,383	60,710
Net income attributable to non-controlling interest	(43)	1,833	1,052	1,411
Net income attributable to BOK Financial Corporation shareholders	17,506	32,728	42,331	59,299
Average assets	7,060,619	5,846,390	6,775,738	5,698,028
Average invested capital	$ 1,624,675	$ 1,539,771	$ 1,615,545	$ 1,506,779