Reportable Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Segment Reporting Information [Line Items]
Net interest revenue from external sources	$ 181,361	$ 174,001	$ 354,930	$ 344,640
Net interest revenue (expense) from internal sources	0	0	0	0
Net interest revenue	181,361	174,001	354,930	344,640
Provision for credit losses	(8,000)	2,700	(8,000)	8,950
Net interest revenue after provision for credit losses	189,361	171,301	362,930	335,690
Other operating revenue	187,035	142,960	327,416	260,538
Operating expense	223,786	203,209	409,023	381,658
Income before taxes	152,610	111,052	281,323	214,570
Federal and state income tax	53,149	39,357	98,669	78,109
Net income	99,461	71,695	182,654	136,461
Net income attributable to non-controlling interest	1,833	2,688	1,411	2,680
Net income attributable to BOK Financial Corporation	97,628	69,007	181,243	133,781
Average assets	25,538,517	23,979,235	25,527,550	23,849,611
Average invested capital	2,868,733	2,650,889	2,851,983	2,608,081
Performance measurements: [Abstract]
Return on average assets	1.54%	1.15%	1.43%	1.13%
Return on average invested capital	13.69%	10.44%	12.78%	10.34%
Efficiency ratio	62.45%	62.23%	61.14%	61.70%
Commercial [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	93,360	85,325	182,698	168,583
Net interest revenue (expense) from internal sources	(11,164)	(7,444)	(22,920)	(16,718)
Net interest revenue	82,196	77,881	159,778	151,865
Provision for credit losses	748	4,829	7,140	11,605
Net interest revenue after provision for credit losses	81,448	73,052	152,638	140,260
Other operating revenue	52,158	36,014	90,950	71,430
Operating expense	62,625	57,447	118,485	113,198
Income before taxes	70,981	51,619	125,103	98,492
Federal and state income tax	27,612	20,080	48,665	38,313
Net income	43,369	31,539	76,438	60,179
Net income attributable to non-controlling interest	0	0	0	0
Net income attributable to BOK Financial Corporation	43,369	31,539	76,438	60,179
Average assets	9,934,469	9,174,216	10,008,708	9,068,308
Average invested capital	862,816	867,491	864,167	865,439
Performance measurements: [Abstract]
Return on average assets	1.76%	1.38%	1.54%	1.34%
Return on average invested capital	20.22%	14.58%	17.79%	14.02%
Efficiency ratio	52.19%	50.44%	50.14%	50.70%
Consumer [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	23,125	21,358	46,939	40,022
Net interest revenue (expense) from internal sources	5,885	7,675	12,005	17,080
Net interest revenue	29,010	29,033	58,944	57,102
Provision for credit losses	4,221	3,049	5,653	5,731
Net interest revenue after provision for credit losses	24,789	25,984	53,291	51,371
Other operating revenue	75,200	57,486	126,297	94,968
Operating expense	75,888	71,852	123,640	124,054
Income before taxes	24,101	11,618	55,948	22,285
Federal and state income tax	9,375	4,519	21,764	8,669
Net income	14,726	7,099	34,184	13,616
Net income attributable to non-controlling interest	0	0	0	0
Net income attributable to BOK Financial Corporation	14,726	7,099	34,184	13,616
Average assets	5,695,019	5,864,942	5,757,046	5,992,191
Average invested capital	289,443	271,353	288,351	272,301
Performance measurements: [Abstract]
Return on average assets	1.04%	0.49%	1.19%	0.46%
Return on average invested capital	20.46%	10.49%	23.91%	10.08%
Efficiency ratio	69.07%	77.47%	66.60%	77.44%
Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	7,137	7,926	14,277	16,150
Net interest revenue (expense) from internal sources	5,306	3,696	10,279	6,667
Net interest revenue	12,443	11,622	24,556	22,817
Provision for credit losses	521	623	1,171	1,061
Net interest revenue after provision for credit losses	11,922	10,999	23,385	21,756
Other operating revenue	51,556	42,788	97,949	82,756
Operating expense	53,209	47,397	104,484	91,102
Income before taxes	10,269	6,390	16,850	13,410
Federal and state income tax	3,995	2,486	6,555	5,216
Net income	6,274	3,904	10,295	8,194
Net income attributable to non-controlling interest	0	0	0	0
Net income attributable to BOK Financial Corporation	6,274	3,904	10,295	8,194
Average assets	4,194,153	3,883,815	4,195,283	3,862,949
Average invested capital	176,704	176,070	176,149	175,506
Performance measurements: [Abstract]
Return on average assets	0.60%	0.40%	0.49%	0.43%
Return on average invested capital	14.28%	8.89%	11.75%	9.41%
Efficiency ratio	83.57%	87.95%	85.48%	86.76%
Funds Management and Other [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	57,739	59,392	111,016	119,885
Net interest revenue (expense) from internal sources	(27)	(3,927)	636	(7,029)
Net interest revenue	57,712	55,465	111,652	112,856
Provision for credit losses	(13,490)	(5,801)	(21,964)	(9,447)
Net interest revenue after provision for credit losses	71,202	61,266	133,616	122,303
Other operating revenue	8,121	6,672	12,220	11,384
Operating expense	32,064	26,513	62,414	53,304
Income before taxes	47,259	41,425	83,422	80,383
Federal and state income tax	12,167	12,272	21,685	25,911
Net income	35,092	29,153	61,737	54,472
Net income attributable to non-controlling interest	1,833	2,688	1,411	2,680
Net income attributable to BOK Financial Corporation	33,259	26,465	60,326	51,792
Average assets	5,714,876	5,056,262	5,566,513	4,926,163
Average invested capital	$ 1,539,770	$ 1,335,975	$ 1,523,316	$ 1,294,835