Commitments and Contingent Liabilities (Details) (USD $)	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2011
BOSC, INC [Member] \| SemGroup Energy Partners, LP Class Action [Member]
Loss Contingencies [Line Items]
Dollar amount of units underwritten in IPO by BOSC, a broker dealer subsidiary of entity	$ 6,250,000
Bank of Oklahoma, National Association [Member] \| Putative Class Actions [Member]
Loss Contingencies [Line Items]
Number of Putative Class Actions Named as a Defendant	3	3
Number of Actions Pending in District Court of Tulsa County	2	2
Parent Company [Member] \| Visa Membership [Member]
Loss Contingencies [Line Items]
Amount of Contingent Liability Recognized from Visa Membership	774,000	774,000
Amount of Proportionate Receivable Recognized From Visa Membership	774,000	774,000
Number of Visa Class B Shares Owned by Entity (in shares)	251,837	251,837
Optional Period After Which Class B Shares Can be Converted to Class A Shares (in years)	3 Y
Current Exchange Rate For Class A shares For Each Class B Share		0.4881
Cavanal Hill Funds [Member]
Loss Contingencies [Line Items]
Mutual Fund Investment in US Treasury Securities	1,000,000,000	1,000,000,000
Mutual Fund Investment in Cash Management	863,000,000	863,000,000
Mutual Fund Investment in Tax-Free Money Market Funds	337,000,000	337,000,000
The Net Asset Value of Units in Mutual Funds (per unit)		$ 1.00
BOKF Equity, LLC [Member]
Loss Contingencies [Line Items]
Number of Private Equity Funds of which the Entity is a General Partner	2	2
Consolidated Private Funds Assets Which are Included in Other assets on the Consolidated Balance Sheets	28,000,000	28,000,000
Contingent Obligations For Additional Investments in Private Equity Funds	14,000,000	14,000,000
Property Lease Guarantee [Member]
Guarantor Obligations [Line Items]
Contingent Obligation For Guaranteed Rents	18,600,000	18,600,000
Guaranteed Percentage To Be Received (in hundredths)	80.00%
Maximum Amount To Be Received Under Rent Agreement With City Of Tulsa	4,500,000	4,500,000
City of Tulsa Property Lease Guarantee [Member]
Guarantor Obligations [Line Items]
Contingent Obligation For Guaranteed Rents	$ 28,700,000	$ 28,700,000

Investments held in private equity funds that primarily invest in domestic companies.

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Number of common stock class B owned by the entity

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Contingent obligation to make additional investments if limited partners are unable to perform.

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The current Exchange Rate For Visa Class A shares For Each Class B Share

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Dollar amount of units underwritten in IPO by BOSC, in the Initial Public Offering of SemGroup Energy Partners LP.

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Guaranteed percentage of cash flow to be received by company as per agreement.

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Maximum potential amount of future recourse payments the guarantor may receive under the guarantee or each group of similar guarantees as potential recoveries under recourse provisions.

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Carrying amount of assets an investment adviser manages on behalf of investors

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Mutual Fund Assets Managed investment in US Treasury Securities

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Amount of Mutual Fund Managed Assets in Tax-Free Money Market Funds

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Managed Net Asset Value of Units in Mutual Funds

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The number of actions pending in the district Court of Tulsa County at the balance sheet date.

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The number of consolidated private equity mutual funds that The Entity is a general partner of.

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The number of putative class actions brought against the bank alleging that the manner it posted charges to customer deposit accounts breached an implied obligation of good faith.

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Term in years over which Visa Optional Class B Shares Can be Converted to Class A Shares.

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Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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The portion of the carrying amount as of the balance sheet date of the combined total of loss contingency liabilities which is expected to be resolved within one year or the normal operating cycle, if longer.

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The carrying amount as of the balance sheet date of a recorded receivable related to a loss contingency accrual. For example, an insurance recovery receivable to the extent that the insurance recovery is probable and does not exceed the amount of the loss previously recognized in the financial statements.

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