Related Parties Related Parties (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Directors and Senior Management [Member]
Loans and Leases Receivable, Related Parties [Roll Forward]
Beginning balance		$ 54,479	$ 95,219
Advances		1,424,041	731,664
Payments		(1,281,323)	(770,808)
Adjustments	[1]	7,212	(1,596)
Ending balance		204,409	54,479	$ 95,219
Director [Member]
Loan Commitments and Equity Investments [Abstract]
Operating Costs and Expenses		$ 11,400	10,700	$ 10,400
Executive Officer [Member]
Loan Commitments and Equity Investments [Abstract]
Percentage of investment funds' assets held by clients		82.00%
Assets Held in Cavanal Hill Funds		$ 5,000,000
Subsidiaries [Member] | BOKF, NA [Member] | Affiliated Entity [Member]
Loan Commitments and Equity Investments [Abstract]
Maximum percentage of unimpaired capital on loan commitments and equity investments to a single affiliate (in hundredths)		10.00%
Maximum percentage of unimpaired capital on loan commitments and equity investments to all affiliates (in hundredths)		20.00%
Maximum loan commitments and equity investments to a single affiliate		$ 473,000
Maximum loan commitments and equity investments to all affiliates		946,000
Largest loan commitment and equity investment to a single affiliate		255,000
Aggregate loan commitment and equity investment to all affiliates		315,000	344,000
Largest amount outstanding to a single affiliate		1,100
Outstanding Receivables to all Affiliates		$ 1,100	$ 3,900

[1] Adjustments generally consist of changes in status as a related party.