Fair Value Measurements (Financial Assets And Financial Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010
Securities available for sale	$ 5,339,812	$ 5,157,470	$ 5,255,006
Trading account securities	15,823	15,101	14,934
U.S. Treasury [Member] \| Level 1 Inputs
Securities available for sale	799,915	987,031
Trading account securities	14,035	14,986
Level 1 Inputs \| Commodity And Foreign Exchange Derivatives [Member]
Derivative assets	13
Derivative liabilities		19
Residential Mortgage-Backed Securities [Member] \| Level 2 Inputs
Securities available for sale	2,394,338	2,091,330
States And Political Subdivisions [Member] \| Level 2 Inputs
Securities available for sale	2,107,567	2,040,300
Trading account securities	1,788	115
Other [Member] \| Level 2 Inputs
Securities available for sale	37,992	38,809
Level 2 Inputs \| Interest Rate Swaps, Caps And Floors [Member]
Derivative assets	60,475	43,633
Derivative liabilities	79,418	63,299
Level 2 Inputs \| Commodity And Foreign Exchange Derivatives [Member]
Derivative assets	32,917	14,177
Derivative liabilities	32,707	14,082
Level 3 Inputs \| Interest Rate Swaps, Caps And Floors [Member]
Derivative assets	718	1,090
U.S. Treasury [Member]
Securities available for sale	799,915	987,031
Trading account securities	14,035	14,986
Residential Mortgage-Backed Securities [Member]
Securities available for sale	2,394,338	2,091,330
Other [Member]
Securities available for sale	37,992	38,809
Interest Rate Swaps, Caps And Floors [Member]
Derivative assets	61,193	44,723
Derivative liabilities	79,418	63,299
Commodity And Foreign Exchange Derivatives [Member]
Derivative assets	32,930	14,177
Derivative liabilities	32,707	14,101
States And Political Subdivisions [Member]
Securities available for sale	2,107,567	2,040,300
Trading account securities	$ 1,788	$ 115

For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading.

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+ Details

- Definition

Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References+ Details

- Definition

Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References+ Details

- Definition

The total of financial instruments that are bought and held principally for the purpose of selling them in the near term (thus held for only a short period of time) or for debt and equity securities formerly categorized as available-for-sale or held-to-maturity which the entity held as of the date it opted to account for such securities at fair value. An enterprise may also categorize such a security as trading without the intent to sell it in the near term assuming the decision to categorize the security as trading occurred at acquisition.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Glossary Trading Securities

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