Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Numerator: [Abstract]
Net income attributable to BOK Financial Corp. shareholders	$ 74,891	$ 75,632	$ 228,964	$ 228,117
Less: Earnings allocated to participating securities	894	898	2,652	2,479
Numerator for basic earnings per share - income available to common shareholders	73,997	74,734	226,312	225,638
Effect of reallocating undistributed earnings of participating securities	1	1	2	3
Numerator for diluted earnings per share - income available to common shareholders	$ 73,998	$ 74,735	$ 226,314	$ 225,641
Denominator: [Abstract]
Weighted average shares outstanding (in shares)	68,486,376	69,275,121	68,800,419	69,113,914
Less: Participating securities included in weighted average shares (in shares)	818,300	819,255	795,911	749,365
Denominator for basic earnings per common share (in shares)	67,668,076	68,455,866	68,004,508	68,364,549
Dilutive effect of employee stock compensation plans (in shares)	94,407	153,899	99,509	156,042
Denominator for diluted earnings per common share (in shares)	67,762,483	68,609,765	68,104,017	68,520,591
Basic earnings per share (per share)	$ 1.09	$ 1.09	$ 3.33	$ 3.30
Diluted earnings per share (per share)	$ 1.09	$ 1.09	$ 3.32	$ 3.29
Excludes employee stock options with exercise prices greater than current market price.	0	0	0	0