Federal and State Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Amount [Abstract]
Federal statutory tax	$ 39,886	$ 42,459	$ 79,976	$ 90,113
Tax exempt revenue	(2,099)	(1,803)	(4,090)	(3,545)
Effect of state income taxes, net of federal benefit	2,457	3,122	5,327	6,500
Utilization of tax credits	(2,836)	(1,826)	(5,466)	(3,548)
Bank-owned life insurance	(784)	(993)	(1,552)	(1,878)
Charitable contributions to BOKF Foundation	0	0	(427)	0
Other, net	606	464	963	877
Total	$ 37,230	$ 41,423	$ 74,731	$ 88,519
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory tax (in hundredths)	35.00%	35.00%	35.00%	35.00%
Tax exempt revenue (in hundredths)	(2.00%)	(1.00%)	(2.00%)	(1.00%)
Effect of state income taxes, net of federal benefit (in hundredths)	3.00%	3.00%	3.00%	2.00%
Utilization of tax credits (in hundredths)	(2.00%)	(2.00%)	(2.00%)	(1.00%)
Bank-owned life insurance (in hundredths)	(1.00%)	(1.00%)	(1.00%)	(1.00%)
Charitable contribution to BOKF Foundation (in hundredths)	0.00%	0.00%	0.00%	0.00%
Other, net (in hundredths)	0.00%	0.00%	0.00%	0.00%
Total (in hundredths)	33.00%	34.00%	33.00%	34.00%