Reportable Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Segment Reporting Information [Line Items]
Net interest revenue from external sources	$ 176,027	$ 175,384	$ 530,957	$ 520,024
Net interest revenue (expense) from internal sources	0	0	0	0
Net interest revenue	176,027	175,384	530,957	520,024
Provision for credit losses	0	0	(8,000)	8,950
Net interest revenue after provision for credit losses	176,027	175,384	538,957	511,074
Other operating revenue	179,944	173,616	503,485	433,001
Operating expense	222,340	220,535	627,487	601,040
Income before taxes	133,631	128,465	414,955	343,035
Federal and state income tax	45,778	43,006	144,447	121,115
Net income	87,853	85,459	270,508	221,920
Net income attributable to non-controlling interest	471	358	1,882	3,038
Net income attributable to BOK Financial Corporation	87,382	85,101	268,626	218,882
Average assets	26,588,172	24,621,738	25,883,672	24,109,816
Average invested capital	2,946,653	2,738,406	2,883,771	2,652,001
Performance measurements: [Abstract]
Return on average assets	1.31%	1.37%	1.39%	1.21%
Return on average invested capital	11.80%	12.33%	12.44%	11.03%
Efficiency ratio	61.12%	60.02%	60.75%	60.99%
Commercial [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	91,378	85,560	274,411	254,143
Net interest revenue (expense) from internal sources	(10,747)	(6,702)	(33,667)	(23,420)
Net interest revenue	80,631	78,858	240,744	230,723
Provision for credit losses	3,253	5,041	10,393	16,646
Net interest revenue after provision for credit losses	77,378	73,817	230,351	214,077
Other operating revenue	40,091	37,924	131,042	109,354
Operating expense	62,633	57,509	181,117	170,708
Income before taxes	54,836	54,232	180,276	152,723
Federal and state income tax	21,331	21,096	70,127	59,409
Net income	33,505	33,136	110,149	93,314
Net income attributable to non-controlling interest	0	0	0	0
Net income attributable to BOK Financial Corporation	33,505	33,136	110,149	93,314
Average assets	10,134,288	9,526,993	10,050,873	9,222,883
Average invested capital	865,157	886,538	866,346	874,259
Performance measurements: [Abstract]
Return on average assets	1.32%	1.38%	1.46%	1.35%
Return on average invested capital	15.41%	14.83%	16.98%	14.27%
Efficiency ratio	51.88%	49.24%	50.68%	50.20%
Consumer [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	22,195	24,553	69,154	64,574
Net interest revenue (expense) from internal sources	6,457	8,108	18,462	25,188
Net interest revenue	28,652	32,661	87,616	89,762
Provision for credit losses	485	3,837	6,137	9,568
Net interest revenue after provision for credit losses	28,167	28,824	81,479	80,194
Other operating revenue	80,640	79,766	205,400	174,241
Operating expense	74,067	84,520	196,174	208,082
Income before taxes	34,740	24,070	90,705	46,353
Federal and state income tax	13,514	9,363	35,284	18,031
Net income	21,226	14,707	55,421	28,322
Net income attributable to non-controlling interest	0	0	0	0
Net income attributable to BOK Financial Corporation	21,226	14,707	55,421	28,322
Average assets	5,705,781	5,914,337	5,739,833	5,965,955
Average invested capital	292,281	273,143	289,337	272,167
Performance measurements: [Abstract]
Return on average assets	1.48%	0.99%	1.29%	0.63%
Return on average invested capital	28.89%	21.36%	25.61%	13.91%
Efficiency ratio	61.66%	65.41%	64.23%	72.62%
Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	7,064	7,113	21,340	23,263
Net interest revenue (expense) from internal sources	5,554	4,682	15,834	11,348
Net interest revenue	12,618	11,795	37,174	34,611
Provision for credit losses	509	1,247	1,680	2,308
Net interest revenue after provision for credit losses	12,109	10,548	35,494	32,303
Other operating revenue	50,157	46,112	148,105	128,868
Operating expense	53,867	49,982	158,351	141,084
Income before taxes	8,399	6,678	25,248	20,087
Federal and state income tax	3,267	2,598	9,821	7,814
Net income	5,132	4,080	15,427	12,273
Net income attributable to non-controlling interest	0	0	0	0
Net income attributable to BOK Financial Corporation	5,132	4,080	15,427	12,273
Average assets	4,301,283	4,254,954	4,230,874	3,995,054
Average invested capital	188,638	175,478	180,234	175,478
Performance measurements: [Abstract]
Return on average assets	0.47%	0.38%	0.49%	0.41%
Return on average invested capital	10.82%	9.22%	11.43%	9.35%
Efficiency ratio	86.05%	86.48%	85.68%	86.66%
Funds Management and Other [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	55,390	58,158	166,052	178,044
Net interest revenue (expense) from internal sources	(1,264)	(6,088)	(629)	(13,116)
Net interest revenue	54,126	52,070	165,423	164,928
Provision for credit losses	(4,247)	(10,125)	(26,210)	(19,572)
Net interest revenue after provision for credit losses	58,373	62,195	191,633	184,500
Other operating revenue	9,056	9,814	18,938	20,538
Operating expense	31,773	28,524	91,845	81,166
Income before taxes	35,656	43,485	118,726	123,872
Federal and state income tax	7,666	9,949	29,215	35,861
Net income	27,990	33,536	89,511	88,011
Net income attributable to non-controlling interest	471	358	1,882	3,038
Net income attributable to BOK Financial Corporation	27,519	33,178	87,629	84,973
Average assets	6,446,820	4,925,454	5,862,092	4,925,924
Average invested capital	$ 1,600,577	$ 1,403,247	$ 1,547,854	$ 1,330,097