Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator: [Abstract]
Net income attributable to BOK Financial Corp. shareholders	$ 64,693	$ 137,563	$ 126,772	$ 248,175
Less: Earnings allocated to participating securities	397	850	740	1,678
Numerator for basic earnings per share – income available to common shareholders	64,296	136,713	126,032	246,497
Effect of reallocating undistributed earnings of participating securities	0	0	0	0
Numerator for diluted earnings per share – income available to common shareholders	$ 64,296	$ 136,713	$ 126,032	$ 246,497
Denominator: [Abstract]
Weighted average shares outstanding (in shares)	70,307,606	71,327,928	70,410,707	71,625,332
Less: Participating securities included in weighted average shares (in shares)	431,563	440,865	410,842	489,918
Denominator for basic earnings per common share (in shares)	69,876,043	70,887,063	69,999,865	71,135,414
Dilutive effect of employee stock compensation plans (in shares)	1,424	14,970	3,952	16,144
Denominator for diluted earnings per common share (in shares)	69,877,467	70,902,033	70,003,817	71,151,558
Basic	$ 0.92	$ 1.93	$ 1.80	$ 3.47
Diluted	$ 0.92	$ 1.93	$ 1.80	$ 3.46
Excludes employee stock options with exercise prices greater than current market price.	22,238	0	0	0
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Diluted	$ 0.92	$ 1.93	$ 1.80	$ 3.46