Commitments and Contingent Liabilities (Details) (USD $)	12 Months Ended								0 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Corporate Headquarters [Member]	Dec. 31, 2011 Corporate Headquarters [Member]	Dec. 31, 2010 Corporate Headquarters [Member]	Dec. 31, 2011 BOKF, NA [Member] Putative Class Actions [Member]	Dec. 31, 2010 BOKF, NA [Member] Putative Class Actions [Member]	Oct. 11, 2011 BOKF, NA [Member] Invalidated Settlement by Oklahoma Supreme Court [Member]	Dec. 31, 2012 BOKF, NA [Member] Invalidated Settlement by Oklahoma Supreme Court [Member]	Dec. 31, 2012 Parent Company [Member] Visa Membership [Member]	Dec. 31, 2012 Cavanal Hill Funds [Member]	Dec. 31, 2012 BOKF Equity, LLC [Member]
Loss Contingencies [Line Items]
Number of Putative Class Actions Named As Defendant								3
Settlement Agreement, Counterparty's Name									City of Tulsa
Settlement Agreement, Amount							$ 19,000,000			$ 7,100,000
Amount of contingent liability recognized from Visa Membership	7,300,000
Receivable for proportionate interest in escrow account related to Visa membership	7,300,000
Number of Visa Class B Shares Owned by Entity (in shares)											251,837
Amount Deposited by Visa in Escrow for Covered Litigation											150,000,000
Current Exchange Rate For Class A shares For Each Class B Share											0.4206
Number of Private Equity Funds of which the Entity is a General Partner	2												2
Contingent Obligations For Additional Investments in Private Equity Funds													7,100,000
Mutual Fund Investment in US Treasury Securities												903,000,000
Mutual Fund Investment in Cash Management												1,000,000,000
Mutual Fund Investment in Tax-Free Money Market Funds												403,000,000
The Net Asset Value of Units in Mutual Funds (per unit)												1
Operating Leases, Rent Expense, Net	21,700,000	20,600,000	21,200,000	3,100,000	3,200,000	3,000,000
Operating Leases, Future Minimum Payments Due, Next Twelve Months	19,600,000
Operating Leases, Future Minimum Payments, Due in Two Years	18,900,000
Operating Leases, Future Minimum Payments, Due in Three Years	18,200,000
Operating Leases, Future Minimum Payments, Due in Four Years	16,300,000
Operating Leases, Future Minimum Payments, Due in Five Years	12,600,000
Operating Leases, Future Minimum Payments, Due Thereafter	74,800,000
Minimum Average Cash Balance Required to be Maintained at Federal Reserve by Subsidiary Bank	$ 733,000,000	$ 968,000,000