Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2024

Stockholders' Equity Note [Abstract]

Summary of Regulatory Capital Levels [Table Text Block]

A summary of regulatory capital minimum requirements and levels follows (dollars in thousands):

	Minimum Capital Requirement	Capital Conservation Buffer	Minimum Capital Requirement Including Capital Conservation Buffer	Well Capitalized Bank Requirement	December 31, 2024				December 31, 2023
Common Equity Tier 1 Capital (to Risk Weighted Assets):
Consolidated	4.50%	2.50%	7.00%	N/A	$	4,992,810	13.03	%	$	4,683,510	12.06	%
BOKF, NA	4.50%	N/A	4.50%	6.50%	4,615,811		12.23	%	4,370,891		11.37	%
Tier 1 Capital (to Risk Weighted Assets):
Consolidated	6.00%	2.50%	8.50%	N/A	$	4,995,414	13.04	%	$	4,686,487	12.07	%
BOKF, NA	6.00%	N/A	6.00%	8.00%	4,615,811		12.23	%	4,370,891		11.37	%
Total Capital (to Risk Weighted Assets):
Consolidated	8.00%	2.50%	10.50%	N/A	$	5,445,399	14.21	%	$	5,110,471	13.16	%
BOKF, NA	8.00%	N/A	8.00%	10.00%	4,999,728		13.25	%	4,728,876		12.30	%
Leverage (Tier 1 Capital to Average Assets):
Consolidated	4.00%	N/A	4.00%	N/A	$	4,995,414	9.97	%	$	4,686,487	9.45	%
BOKF, NA	4.00%	N/A	4.00%	5.00%	4,615,811		9.26	%	4,370,891		8.86	%

Accumulated Other Comprehensive Income (Loss) [Table Text Block]

A rollforward of the components of accumulated other comprehensive income (loss) is included as follows (in thousands):

	Unrealized Gain (Loss) on
	Available for Sale Securities		Investment Securities Transferred from AFS		Employee Benefit Plans		Total
Balance, December 31, 2021	$	69,775	$	—	$	2,596	$	72,371
Net change in unrealized gain (loss)	(1,227,414)		—		—		(1,227,414)
Transfer of net unrealized loss from AFS to investment securities	267,509		(267,509)		—		—
Reclassification adjustments included in earnings:
Interest revenue, Investment securities	—		42,514		—		42,514
Operating expense, Personnel	—		—		(3,483)		(3,483)
Loss on available for sale securities, net	971		—		—		971
Other comprehensive income (loss), before income taxes	(958,934)		(224,995)		(3,483)		(1,187,412)
Federal and state income tax	(224,541)		(52,658)		(887)		(278,086)
Other comprehensive income (loss), net of income taxes	(734,393)		(172,337)		(2,596)		(909,326)
Balance, December 31, 2022	(664,618)		(172,337)		—		(836,955)
Net change in unrealized gain (loss)	218,293		—		—		218,293
Reclassification adjustments included in earnings:
Interest revenue, Investment securities	—		60,394		—		60,394
Loss on available for sale securities, net	30,636		—		—		30,636
Other comprehensive income (loss), before income taxes	248,929		60,394		—		309,323
Federal and state income tax	57,523		13,945		—		71,468
Other comprehensive income (loss), net of income taxes	191,406		46,449		—		237,855
Balance, December 31, 2023	(473,212)		(125,888)		—		(599,100)
Net change in unrealized gain (loss)	33,461		—		—		33,461
Reclassification adjustments included in earnings:
Interest revenue, Investment securities	—		46,020		—		46,020
Loss on available for sale securities, net	45,828		—		—		45,828
Other comprehensive income (loss), before income taxes	79,289		46,020		—		125,309
Federal and state income tax	18,425		10,824		—		29,249
Other comprehensive income (loss), net of income taxes	60,864		35,196		—		96,060
Balance, December 31, 2024	$	(412,348)	$	(90,692)	$	—	$	(503,040)