Fair Value Measurements Details of Book Value and Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, FinancialStatement Captions[Line Items]
Cash and Cash Equivalents	$ 219,944		$ 256,300
Interest-Rate Deposits with Other Banks	130,065		173,257
Loans Held-for-sale	60,909	[1]	67,899	[1]
Securities Held-to-maturity	227		292
Securities Available-for-sale	2,915,652	[1]	2,793,725	[1]
Loans, net of unearned income	12,645,418	[1]	12,146,971	[1]
Accrued Interest Receivable	45,713		45,786
Other Financial Assets	151,485	[1]	201,069	[1]
Demand and Savings Deposit Liabilities, Fair Value Disclosure	9,155,883		9,100,825
Time Deposit Liabilities, Fair Value Disclosure	3,101,926		3,383,338
Short-term borrowings	1,620,318		868,399
Accrued interest payable	17,708		19,330
Other Financial Liabilities	79,569	[1]	58,255	[1]
Federal Home Loan Bank Advances And Debt Long Term, Fair Value Disclosre	889,167		894,253
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, FinancialStatement Captions[Line Items]
Cash and Cash Equivalents	219,944		256,300
Interest-Rate Deposits with Other Banks	130,065		173,257
Loans Held-for-sale	60,909	[1]	67,899	[1]
Securities Held-to-maturity	246		319
Securities Available-for-sale	2,915,652	[1]	2,793,725	[1]
Loans, net of unearned income	12,606,477	[1]	12,129,971	[1]
Accrued Interest Receivable	45,713		45,786
Other Financial Assets	151,485	[1]	201,069	[1]
Demand and Savings Deposit Liabilities, Fair Value Disclosure	9,155,883		9,100,825
Time Deposit Liabilities, Fair Value Disclosure	3,120,950		3,413,060
Short-term borrowings	1,620,318		868,399
Accrued interest payable	17,708		19,330
Other Financial Liabilities	79,569	[1]	58,255	[1]
Federal Home Loan Bank Advances And Debt Long Term, Fair Value Disclosre	$ 890,359		$ 853,547

[1] Description of fair value determinations for these financial instruments, or certain financial instruments within these categories, measured at fair value on the Corporation’s consolidated balance sheets, are disclosed above.