Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator: [Abstract]
Net income attributable to BOK Financial Corp. shareholders	$ 88,147	$ 65,801	$ 176,503	$ 108,365
Less: Earnings allocated to participating securities	926	821	1,929	1,359
Numerator for basic earnings per share – income available to common shareholders	87,221	64,980	174,574	107,006
Effect of reallocating undistributed earnings of participating securities	1	0	1	0
Numerator for diluted earnings per share – income available to common shareholders	$ 87,222	$ 64,980	$ 174,575	$ 107,006
Denominator: [Abstract]
Weighted average shares outstanding (in shares)	65,416,274	66,069,392	65,436,909	66,100,279
Less: Participating securities included in weighted average shares (in shares)	686,522	823,505	714,165	829,065
Denominator for basic earnings per common share (in shares)	64,729,752	65,245,887	64,722,744	65,271,214
Dilutive effect of employee stock compensation plans (in shares)	63,382	57,039	65,578	45,963
Denominator for diluted earnings per common share (in shares)	64,793,134	65,302,926	64,788,322	65,317,177
Basic earnings per share (per share)	$ 1.35	$ 1.00	$ 2.70	$ 1.64
Diluted earnings per share (per share)	$ 1.35	$ 1.00	$ 2.69	$ 1.64
Excludes employee stock options with exercise prices greater than current market price.	0	0	0	145,247,000