Fair Value Measurements (Estimated Fair Values of Financial Instruments) (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Cash and cash equivalents	$ 3,420,561	$ 2,820,977	$ 2,648,813
Loans, net	7,945,471	7,990,704	7,940,237
Deposits	15,104,131	14,479,342	13,952,160
Federal funds purchased and repurchase agreements	574,132	475,673	438,496
Junior subordinated deferrable interest debentures	123,712	123,712	136,084
Subordinated notes payable and other borrowings	250,036	250,045	250,054
Carrying Amount [Member]
Cash and cash equivalents	3,420,561	2,820,977
Securities	5,796,868	5,456,200
Loans, net	7,945,471	7,990,704
Cash surrender value of life insurance policies	131,883	129,922
Non-hedging commercial loan/lease interest rate swaps, caps and floors	44,496	44,723
Commodity and foreign exchange derivatives	19,418	14,177
Accrued interest receivable	74,010	72,328
Deposits	15,104,131	14,479,342
Federal funds purchased and repurchase agreements	574,132	475,673
Junior subordinated deferrable interest debentures	123,712	123,712
Subordinated notes payable and other borrowings	250,036	250,045
Commercial loan/lease interest rate swaps designated as hedges of fair value	7,496	8,350
Interest rate swap on junior subordinated deferrable interest debentures designated as a hedge of cash flows	9,353	9,895
Non-hedging commercial loan/lease interest rate swaps, caps and floors	44,700	45,054
Commodity and foreign exchange derivatives	19,216	14,101
Accrued interest payable	9,152	9,991
Estimated Fair Value [Member]
Cash and cash equivalents	3,420,561	2,820,977
Securities	5,817,846	5,468,799
Loans, net	7,973,858	8,038,760
Cash surrender value of life insurance policies	131,883	129,922
Non-hedging commercial loan/lease interest rate swaps, caps and floors	44,496	44,723
Commodity and foreign exchange derivatives	19,418	14,177
Accrued interest receivable	74,010	72,328
Deposits	15,105,135	14,480,725
Federal funds purchased and repurchase agreements	574,132	475,673
Junior subordinated deferrable interest debentures	123,712	123,712
Subordinated notes payable and other borrowings	252,831	256,172
Commercial loan/lease interest rate swaps designated as hedges of fair value	7,496	8,350
Interest rate swap on junior subordinated deferrable interest debentures designated as a hedge of cash flows	9,353	9,895
Non-hedging commercial loan/lease interest rate swaps, caps and floors	44,700	45,054
Commodity and foreign exchange derivatives	19,216	14,101
Accrued interest payable	$ 9,152	$ 9,991

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Commodity and foreign exchange derivatives, assets

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Commodity and foreign exchange derivatives, liabilities

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Interest rate swap on junior subordinated deferrable interest debentures designated as a hedge of cash flows

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Non-hedging commercial loan/lease interest rate swaps, caps and floors, assets

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Non-hedging commercial loan/lease interest rate swaps, caps and floors, liabilities

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The sum of cash and cash equivalents plus Federal Funds Sold. Cash and cash equivalents consist of short term, highly liquid investments that are readily convertible to known amounts of cash and are so near their maturity that they present negligible risk of changes in value due to changes in interest rates -- usually with an original maturity less than 90 days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
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-Paragraph 8, 9, 10

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Carrying amount as of the balance sheet date of amounts which could be received based on the terms of the insurance contract upon surrendering life policies owned by the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
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-Paragraph 17
-Article 5

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-Name FASB Technical Bulletin (FTB)
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The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

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-Publisher SEC
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-Paragraph 12
-Article 9

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-Name Audit and Accounting Guide (AAG)
-Number AAG-DEP
-Chapter 13
-Paragraph 37, 38, 39
-IssueDate 2006-05-01

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The amount shown on the books that a bank with insufficient reserves borrows, at the federal funds rate, from another bank to meet its reserve requirements and the amount of securities that an institution sells and agrees to repurchase at a specified date for a specified price, net of any reductions or offsets.

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-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 13
-Subparagraph 1
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Carrying value as of the balance sheet date of [accrued] interest payable on all forms of debt, including trade payables, that has been incurred and is unpaid.

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-Publisher SEC
-Name Regulation S-X (SX)
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-Paragraph 15
-Subparagraph 5
-Article 9

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Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

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-Publisher SEC
-Name Regulation S-X (SX)
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Including the current and noncurrent portions, carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Junior Subordinated Notes, which have a lower priority than senior instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
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-Paragraph 20, 22
-Article 5

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Reflects the aggregate carrying amount of all categories of loans and leases held in portfolio, net of unearned income and the allowance for losses on loans and leases.

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-Publisher AICPA
-Name Statement of Position (SOP)
-Number 01-6
-Paragraph 13
-Subparagraph e

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Total debt and equity financial instruments including: (1) securities held-to-maturity, (2) trading securities, and (3) securities available-for-sale.

+ References

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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 19

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Including both current and noncurrent portions, carrying amount as of the balance-sheet date of other forms of debt not elsewhere specified in the taxonomy with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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-Name Regulation S-X (SX)
-Number 210
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-Article 5

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