Reportable Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Segment Reporting Information [Line Items]
Net interest revenue from external sources	$ 170,405	$ 173,569
Net interest revenue (expense) from internal sources	0	0
Net interest revenue	170,405	173,569
Provision for credit losses	(8,000)	0
Net interest revenue after provision for credit losses	178,405	173,569
Other operating revenue	159,074	137,281
Operating expense	201,324	182,137
Income before taxes	136,155	128,713
Federal and state income tax	47,096	45,520
Net income	89,059	83,193
Net income attributable to non-controlling interest	1,095	(422)
Net income attributable to BOK Financial Corporation	87,964	83,615
Average assets	27,513,431	25,516,583
Average invested capital	2,997,839	2,835,233
Performance measurements: [Abstract]
Return on average assets	1.30%	1.32%
Return on average invested capital	11.90%	11.86%
Efficiency ratio	61.04%	58.76%
Commercial [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	90,818	89,492
Net interest revenue (expense) from internal sources	(9,128)	(12,049)
Net interest revenue	81,690	77,443
Provision for credit losses	1,021	6,392
Net interest revenue after provision for credit losses	80,669	71,051
Other operating revenue	41,432	38,792
Operating expense	59,080	55,860
Income before taxes	63,021	53,983
Federal and state income tax	24,515	20,999
Net income	38,506	32,984
Net income attributable to non-controlling interest	0	0
Net income attributable to BOK Financial Corporation	38,506	32,984
Average assets	10,629,339	10,013,866
Average invested capital	890,844	896,552
Performance measurements: [Abstract]
Return on average assets	1.47%	1.32%
Return on average invested capital	17.53%	14.80%
Efficiency ratio	47.98%	48.08%
Consumer [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	24,095	26,587
Net interest revenue (expense) from internal sources	5,483	4,879
Net interest revenue	29,578	31,466
Provision for credit losses	930	1,432
Net interest revenue after provision for credit losses	28,648	30,034
Other operating revenue	57,141	50,240
Operating expense	52,371	47,310
Income before taxes	33,418	32,964
Federal and state income tax	13,000	12,823
Net income	20,418	20,141
Net income attributable to non-controlling interest	0	0
Net income attributable to BOK Financial Corporation	20,418	20,141
Average assets	5,723,958	5,784,654
Average invested capital	297,074	283,496
Performance measurements: [Abstract]
Return on average assets	1.45%	1.40%
Return on average invested capital	27.87%	28.57%
Efficiency ratio	59.31%	62.28%
Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	6,516	7,140
Net interest revenue (expense) from internal sources	5,278	4,857
Net interest revenue	11,794	11,997
Provision for credit losses	519	650
Net interest revenue after provision for credit losses	11,275	11,347
Other operating revenue	52,603	46,393
Operating expense	57,007	51,324
Income before taxes	6,871	6,416
Federal and state income tax	2,673	2,496
Net income	4,198	3,920
Net income attributable to non-controlling interest	0	0
Net income attributable to BOK Financial Corporation	4,198	3,920
Average assets	4,686,952	4,168,398
Average invested capital	202,310	173,853
Performance measurements: [Abstract]
Return on average assets	0.36%	0.38%
Return on average invested capital	8.35%	9.14%
Efficiency ratio	89.23%	87.82%
Funds Management and Other [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	48,976	50,350
Net interest revenue (expense) from internal sources	(1,633)	2,313
Net interest revenue	47,343	52,663
Provision for credit losses	(10,470)	(8,474)
Net interest revenue after provision for credit losses	57,813	61,137
Other operating revenue	7,898	1,856
Operating expense	32,866	27,643
Income before taxes	32,845	35,350
Federal and state income tax	6,908	9,202
Net income	25,937	26,148
Net income attributable to non-controlling interest	1,095	(422)
Net income attributable to BOK Financial Corporation	24,842	26,570
Average assets	6,473,182	5,549,665
Average invested capital	$ 1,607,611	$ 1,481,332