Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Numerator: [Abstract]
Net income attributable to BOK Financial Corp. shareholders	$ 88,356	$ 42,564
Less: Earnings allocated to participating securities	1,003	538
Numerator for basic earnings per share – income available to common shareholders	87,353	42,026
Effect of reallocating undistributed earnings of participating securities	0	0
Numerator for diluted earnings per share – income available to common shareholders	$ 87,353	$ 42,026
Denominator: [Abstract]
Weighted average shares outstanding (in shares)	65,457,772	66,131,166
Less: Participating securities included in weighted average shares (in shares)	741,808	834,625
Denominator for basic earnings per common share (in shares)	64,715,964	65,296,541
Dilutive effect of employee stock compensation plans (in shares)	67,773	34,887
Denominator for diluted earnings per common share (in shares)	64,783,737	65,331,428
Basic earnings per share (per share)	$ 1.35	$ 0.64
Diluted earnings per share (per share)	$ 1.35	$ 0.64
Excludes employee stock options with exercise prices greater than current market price.	0	244,019