Consolidated Statements of Earnings (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest revenue [Abstract]
Loans	$ 197,574	$ 243,218
Residential mortgage loans held for sale	1,380	1,123
Trading securities	35,922	11,760
Investment securities	2,726	3,121
Available for sale securities	58,608	69,720
Fair value option securities	496	11,708
Restricted equity securities	1,359	5,894
Interest-bearing cash and cash equivalents	174	2,393
Total interest revenue	298,239	348,937
Interest expense [Abstract]
Deposits	9,850	46,159
Borrowed funds	4,622	37,785
Subordinated debentures	3,347	3,633
Total interest expense	17,819	87,577
Net interest revenue	280,420	261,360
Provision for credit losses	(25,000)	93,771
Net interest revenue after provision for credit losses	305,420	167,589
Total fees and commissions	162,152	192,724
Other gains (losses), net	(3,036)	(10,741)
Gain (loss) on derivatives, net	(27,650)	18,420
Gain (loss) on fair value option securities, net	(1,910)	68,393
Change in fair value of mortgage servicing rights	33,874	(88,480)
Gain on available for sale securities, net	467	3
Total other operating revenue	163,897	180,319
Other operating expense [Abstract]
Personnel	173,010	156,181
Business promotion	2,154	6,215
Charitable contributions to BOKF Foundation	4,000	0
Professional fees and services	11,980	12,948
Net occupancy and equipment	26,662	26,061
Insurance	4,620	4,980
Data processing and communications	37,467	32,743
Printing, postage and supplies	3,440	4,272
Net losses (gains) and operating expenses of repossessed assets	(6,588)	1,531
Amortization of intangible assets	4,807	5,094
Mortgage banking costs	13,943	10,545
Other expense	7,132	8,054
Total other operating expense	282,627	268,624
Net income before taxes	186,690	79,284
Federal and state income taxes	42,382	17,300
Net income	144,308	61,984
Net loss attributable to non-controlling interests	(1,752)	(95)
Net income attributable to BOK Financial Corporation shareholders	$ 146,060	$ 62,079
Dividends declared per share	$ 0.52	$ 0.51
Earnings Per Share [Abstract]
Basic	2.10	0.88
Diluted	$ 2.10	$ 0.88
Average shares used in computation: [Abstract]
Basic	69,137,375	70,123,685
Diluted	69,141,710	70,130,166
Brokerage and trading revenue [Member]
Total fees and commissions	$ 20,782	$ 50,779
Transaction card revenue [Member]
Total fees and commissions	22,430	21,881
Fiduciary and asset management revenue [Member]
Total fees and commissions	41,322	44,458
Deposit service charges and fees [Member]
Total fees and commissions	24,209	26,130
Mortgage banking revenue [Member]
Total fees and commissions	37,113	37,167
Other revenue [Member]
Total fees and commissions	$ 16,296	$ 12,309