Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator: [Abstract]
Net income attributable to BOK Financial Corp. shareholders	$ 188,322	$ 154,034	$ 500,803	$ 280,806
Less: Earnings allocated to participating securities	1,351	938	3,458	1,678
Numerator for basic earnings per share – income available to common shareholders	186,971	153,096	497,345	279,128
Effect of reallocating undistributed earnings of participating securities	0	0	0	0
Numerator for diluted earnings per share – income available to common shareholders	$ 186,971	$ 153,096	$ 497,345	$ 279,128
Denominator: [Abstract]
Weighted average shares outstanding (in shares)	68,852,688	70,306,233	69,243,562	70,375,628
Less: Participating securities included in weighted average shares (in shares)	493,563	428,367	475,518	416,684
Denominator for basic earnings per common share (in shares)	68,359,125	69,877,866	68,768,044	69,958,944
Dilutive effect of employee stock compensation plans (in shares)	1,746	1,424	2,619	3,109
Denominator for diluted earnings per common share (in shares)	68,360,871	69,879,290	68,770,663	69,962,053
Basic earnings per share	$ 2.74	$ 2.19	$ 7.23	$ 3.99
Diluted earnings per share	$ 2.74	$ 2.19	$ 7.23	$ 3.99
Excludes employee stock options with exercise prices greater than current market price.	0	19,227	0	0