Reportable Segments (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Net interest revenue from external sources	$ 704,326	$ 691,494	$ 709,052
Net interest revenue (expense) from internal sources	0	0	0
Net interest revenue	704,326	691,494	709,052
Provision for credit losses	(22,000)	(6,050)	105,139
Net interest revenue after provision for credit losses	726,326	697,544	603,913
Other operating revenue	666,111	570,535	518,058
Operating expense	849,573	819,744	750,320
Income before taxes	542,864	448,335	371,651
Federal and state income tax	188,740	158,511	123,357
Net income	354,124	289,824	248,294
Net income attributable to non-controlling interest	2,933	3,949	1,540
Net income attributable to BOK Financial Corp. shareholders	351,191	285,875	246,754
Average assets	26,289,151	24,494,861	23,805,799
Average invested capital	2,905,955	2,681,865	2,424,643
Performance measurements: [Abstract]
Return on average assets	1.34%	1.17%	1.04%
Return on average invested capital	12.09%	10.66%	10.18%
Efficiency ratio	62.03%	63.13%	60.83%
Commercial [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	367,412	342,833	338,391
Net interest revenue (expense) from internal sources	(46,414)	(30,676)	(45,317)
Net interest revenue	320,998	312,157	293,074
Provision for credit losses	10,852	20,760	70,489
Net interest revenue after provision for credit losses	310,146	291,397	222,585
Other operating revenue	171,131	147,545	138,992
Operating expense	246,888	230,451	230,116
Income before taxes	234,389	208,491	131,461
Federal and state income tax	91,177	81,103	51,138
Net income	143,212	127,388	80,323
Net income attributable to non-controlling interest	0	0	0
Net income attributable to BOK Financial Corp. shareholders	143,212	127,388	80,323
Average assets	9,949,735	9,383,528	8,893,868
Average invested capital	882,288	884,169	899,005
Performance measurements: [Abstract]
Return on average assets	1.44%	1.36%	0.90%
Return on average invested capital	16.23%	14.41%	8.93%
Efficiency ratio	51.68%	50.22%	52.94%
Consumer [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	90,036	89,745	86,292
Net interest revenue (expense) from internal sources	25,120	33,109	47,624
Net interest revenue	115,156	122,854	133,916
Provision for credit losses	9,345	13,451	24,705
Net interest revenue after provision for credit losses	105,811	109,403	109,211
Other operating revenue	272,118	223,322	215,057
Operating expense	256,315	277,891	242,065
Income before taxes	121,614	54,834	82,203
Federal and state income tax	47,308	21,330	31,977
Net income	74,306	33,504	50,226
Net income attributable to non-controlling interest	0	0	0
Net income attributable to BOK Financial Corp. shareholders	74,306	33,504	50,226
Average assets	5,727,267	5,937,585	6,243,746
Average invested capital	287,972	273,906	277,837
Performance measurements: [Abstract]
Return on average assets	1.30%	0.56%	0.80%
Return on average invested capital	25.73%	12.23%	18.08%
Efficiency ratio	64.73%	74.17%	72.69%
Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	27,754	30,813	36,012
Net interest revenue (expense) from internal sources	21,432	16,540	12,546
Net interest revenue	49,186	47,353	48,558
Provision for credit losses	2,284	2,960	10,831
Net interest revenue after provision for credit losses	46,902	44,393	37,727
Other operating revenue	200,007	171,873	165,528
Operating expense	214,385	190,706	179,825
Income before taxes	32,524	25,560	23,430
Federal and state income tax	12,652	9,943	9,114
Net income	19,872	15,617	14,316
Net income attributable to non-controlling interest	0	0	0
Net income attributable to BOK Financial Corp. shareholders	19,872	15,617	14,316
Average assets	4,357,523	4,073,623	3,686,133
Average invested capital	184,622	174,877	169,775
Performance measurements: [Abstract]
Return on average assets	0.46%	0.38%	0.39%
Return on average invested capital	10.76%	8.93%	8.43%
Efficiency ratio	86.24%	87.21%	84.29%
Funds Management and Other [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	219,124	228,103	248,357
Net interest revenue (expense) from internal sources	(138)	(18,973)	(14,853)
Net interest revenue	218,986	209,130	233,504
Provision for credit losses	(44,481)	(43,221)	(886)
Net interest revenue after provision for credit losses	263,467	252,351	234,390
Other operating revenue	22,855	27,795	(1,519)
Operating expense	131,985	120,696	98,314
Income before taxes	154,337	159,450	134,557
Federal and state income tax	37,603	46,135	31,128
Net income	116,734	113,315	103,429
Net income attributable to non-controlling interest	2,933	3,949	1,540
Net income attributable to BOK Financial Corp. shareholders	113,801	109,366	101,889
Average assets	6,254,626	5,100,125	4,982,052
Average invested capital	$ 1,551,073	$ 1,348,913	$ 1,078,026