Commitments and Contingent Liabilities (Details) (USD $)	Mar. 31, 2015
Parent Company [Member] | Visa Membership [Member]
Loss Contingencies [Line Items]
Number of Visa Class B Shares Owned by Entity (in shares)	251,837
Number of Visa Class A Shares Visa Class B Shares Are Convertible To	415,103
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	5,200,000
Cavanal Hill Funds [Member]
Loss Contingencies [Line Items]
Mutual Fund Investment in US Treasury Securities	1,000,000,000
Mutual Fund Investment in Cash Management	1,400,000,000
Mutual Fund Investment in Tax-Free Money Market Funds	262,000,000
The Net Asset Value of Units in Mutual Funds (per unit)	1.00