Reportable Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting Information [Line Items]
Net interest revenue from external sources	$ 166,791	$ 167,889	$ 495,530	$ 508,233
Net interest revenue (expense) from internal sources	0	0	0	0
Net interest revenue	166,791	167,889	495,530	508,233
Provision for credit losses	0	(8,500)	0	(16,500)
Net interest revenue after provision for credit losses	166,791	176,389	495,530	524,733
Other operating revenue	163,048	143,432	462,623	467,457
Other operating expense	221,834	210,298	621,645	625,201
Net direct contribution	108,005	109,523	336,508	366,989
Corporate expense allocations	0	0	0	0
Net income before taxes	108,005	109,523	336,508	366,989
Federal and state income taxes	31,879	33,461	106,610	121,980
Net income	76,126	76,062	229,898	245,009
Net income attributable to non-controlling interest	494	324	1,781	1,376
Net income attributable to BOK Financial Corporation shareholders	75,632	75,738	228,117	243,633
Average assets	28,115,557	27,254,732	27,616,927	27,474,882
Average invested capital	3,248,429	2,964,923	3,177,268	2,996,685
Performance measurements: [Abstract]
Return on average assets	1.07%	1.10%	1.10%	1.19%
Return on average invested capital	9.24%	10.13%	9.60%	10.87%
Efficiency ratio	66.79%	66.03%	63.45%	63.35%
Operating Segments [Member] | Commercial [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	95,423	91,418	281,064	272,565
Net interest revenue (expense) from internal sources	(9,794)	(13,070)	(33,415)	(38,838)
Net interest revenue	85,629	78,348	247,649	233,727
Provision for credit losses	(994)	45	(8,978)	98
Net interest revenue after provision for credit losses	86,623	78,303	256,627	233,629
Other operating revenue	45,121	40,268	126,527	120,911
Other operating expense	54,961	47,385	153,707	139,743
Net direct contribution	76,783	71,186	229,447	214,797
Corporate expense allocations	9,447	11,650	30,246	36,291
Net income before taxes	67,336	59,536	199,201	178,506
Federal and state income taxes	26,194	23,160	77,489	69,439
Net income	41,142	36,376	121,712	109,067
Net income attributable to non-controlling interest	0	0	0	0
Net income attributable to BOK Financial Corporation shareholders	41,142	36,376	121,712	109,067
Average assets	11,508,375	10,440,231	11,222,552	10,362,166
Average invested capital	940,091	911,228	937,281	900,788
Performance measurements: [Abstract]
Return on average assets	1.42%	1.38%	1.45%	1.41%
Return on average invested capital	17.38%	15.84%	17.40%	16.19%
Efficiency ratio	41.95%	39.87%	40.85%	39.34%
Operating Segments [Member] | Consumer [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	23,187	25,302	72,410	74,513
Net interest revenue (expense) from internal sources	8,058	8,714	23,825	26,598
Net interest revenue	31,245	34,016	96,235	101,111
Provision for credit losses	1,207	889	4,248	4,189
Net interest revenue after provision for credit losses	30,038	33,127	91,987	96,922
Other operating revenue	55,243	48,798	154,030	175,041
Other operating expense	49,172	46,781	141,670	140,585
Net direct contribution	36,109	35,144	104,347	131,378
Corporate expense allocations	15,783	13,491	50,793	40,957
Net income before taxes	20,326	21,653	53,554	90,421
Federal and state income taxes	7,907	8,423	20,833	35,174
Net income	12,419	13,230	32,721	55,247
Net income attributable to non-controlling interest	0	0	0	0
Net income attributable to BOK Financial Corporation shareholders	12,419	13,230	32,721	55,247
Average assets	6,575,217	6,488,471	6,528,629	6,493,883
Average invested capital	271,705	293,716	278,396	295,394
Performance measurements: [Abstract]
Return on average assets	0.75%	0.81%	0.67%	1.14%
Return on average invested capital	18.13%	17.87%	15.71%	25.01%
Efficiency ratio	57.69%	54.67%	54.98%	49.61%
Operating Segments [Member] | Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	5,956	6,251	17,574	19,242
Net interest revenue (expense) from internal sources	5,191	4,848	14,593	15,251
Net interest revenue	11,147	11,099	32,167	34,493
Provision for credit losses	0	(555)	448	898
Net interest revenue after provision for credit losses	11,147	11,654	31,719	33,595
Other operating revenue	61,001	55,308	180,790	162,086
Other operating expense	56,234	50,016	160,638	148,578
Net direct contribution	15,914	16,946	51,871	47,103
Corporate expense allocations	8,065	7,650	24,096	22,777
Net income before taxes	7,849	9,296	27,775	24,326
Federal and state income taxes	3,053	3,616	10,804	9,463
Net income	4,796	5,680	16,971	14,863
Net income attributable to non-controlling interest	0	0	0	0
Net income attributable to BOK Financial Corporation shareholders	4,796	5,680	16,971	14,863
Average assets	4,324,204	4,385,932	4,499,858	4,537,917
Average invested capital	194,104	206,872	199,537	204,592
Performance measurements: [Abstract]
Return on average assets	0.49%	0.54%	0.55%	0.47%
Return on average invested capital	10.94%	11.46%	12.31%	10.32%
Efficiency ratio	77.60%	74.87%	75.03%	75.12%
Corporate, Non-Segment [Member] | Funds Management and Other [Member]
Segment Reporting Information [Line Items]
Net interest revenue from external sources	42,225	44,918	124,482	141,913
Net interest revenue (expense) from internal sources	(3,455)	(492)	(5,003)	(3,011)
Net interest revenue	38,770	44,426	119,479	138,902
Provision for credit losses	(213)	(8,879)	4,282	(21,685)
Net interest revenue after provision for credit losses	38,983	53,305	115,197	160,587
Other operating revenue	1,683	(942)	1,276	9,419
Other operating expense	61,467	66,116	165,630	196,295
Net direct contribution	(20,801)	(13,753)	(49,157)	(26,289)
Corporate expense allocations	(33,295)	(32,791)	(105,135)	(100,025)
Net income before taxes	12,494	19,038	55,978	73,736
Federal and state income taxes	(5,275)	(1,738)	(2,516)	7,904
Net income	17,769	20,776	58,494	65,832
Net income attributable to non-controlling interest	494	324	1,781	1,376
Net income attributable to BOK Financial Corporation shareholders	17,275	20,452	56,713	64,456
Average assets	5,707,761	5,940,098	5,365,888	6,080,916
Average invested capital	$ 1,842,529	$ 1,553,107	$ 1,762,054	$ 1,595,911