Related Parties Related Parties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Loans and Leases Receivable, Related Parties [Roll Forward]
Lease payments on office space in facilities owned by related party afffiliates	$ 25,800	$ 25,200	$ 25,000
Directors and Senior Management [Member]
Loans and Leases Receivable, Related Parties [Roll Forward]
Beginning balance	594,225	103,395
Advances	884,511	3,582,384
Payments	(1,123,747)	(3,104,004)
Adjustments	(218,044)	12,450
Ending balance	136,945	594,225	103,395
Board of Directors Chairman [Member]
Loans and Leases Receivable, Related Parties [Roll Forward]
Lease payments on office space in facilities owned by related party afffiliates	$ 1,100	975	$ 1,100
Executive Officer [Member]
Loans and Leases Receivable, Related Parties [Roll Forward]
Percentage of investment funds' assets held by clients	94.00%
Assets Held in Cavanal Hill Funds	$ 3,800,000
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	$ 287,000
Maximum loan commitments and equity investments to all affiliates	573,000
Largest loan commitment and equity investment to a single affiliate	220,000
Aggregate loan commitment and equity investment to all affiliates	337,000	330,000
Outstanding amounts to all affiliates	39,000	$ 244,000
Largest amount outstanding to a single affiliate	$ 24,000