Commitments and Contingent Liabilities (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended
	Oct. 11, 2011	Sep. 30, 2012
BOKF, NA [Member] | Putative Class Actions [Member]
Loss Contingencies [Line Items]
Number of Putative Class Actions Named as a Defendant		3
Settlement Agreement, Amount		$ 19.0
BOKF, NA [Member] | Invalidated Settlement by Oklahoma Supreme Court [Member]
Loss Contingencies [Line Items]
Settlement Agreement, Counterparty's Name	City of Tulsa
Settlement Agreement, Amount		7.1
Parent Company [Member] | Visa Membership [Member]
Loss Contingencies [Line Items]
Number of Visa Class B Shares Owned by Entity (in shares)		251,837
Amount Deposited by Visa in Escrow for Covered Litigation		150
Current Exchange Rate For Class A shares For Each Class B Share		0.4206
Cavanal Hill Funds [Member]
Loss Contingencies [Line Items]
Mutual Fund Investment in US Treasury Securities		917
Mutual Fund Investment in Cash Management		955
Mutual Fund Investment in Tax-Free Money Market Funds		379
The Net Asset Value of Units in Mutual Funds (per unit)		1
BOKF Equity, LLC [Member]
Loss Contingencies [Line Items]
Number of Private Equity Funds of which the Entity is a General Partner		2
Contingent Obligations For Additional Investments in Private Equity Funds		$ 8.1