Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator: [Abstract]
Net income attributable to BOK Financial Corp. shareholders	$ 146,060	$ 62,079
Less: Earnings allocated to participating securities	937	343
Numerator for basic earnings per share – income available to common shareholders	145,123	61,736
Effect of reallocating undistributed earnings of participating securities	0	0
Numerator for diluted earnings per share – income available to common shareholders	$ 145,123	$ 61,736
Denominator: [Abstract]
Weighted average shares outstanding (in shares)	69,583,788	70,513,807
Less: Participating securities included in weighted average shares (in shares)	446,413	390,122
Denominator for basic earnings per common share (in shares)	69,137,375	70,123,685
Dilutive effect of employee stock compensation plans (in shares)	4,335	6,481
Denominator for diluted earnings per common share (in shares)	69,141,710	70,130,166
Basic earnings per share	$ 2.10	$ 0.88
Diluted earnings per share	$ 2.10	$ 0.88