Fair Value Measurements Narrative (Details) (USD $)	Sep. 30, 2011	Dec. 31, 2010
Short Term Borrowings, Reprice Period, In Days	90
Corporate debt securities	$ 2,649,457,000
Other real estate owned (OREO)	37,399,000	32,959,000
Short Term Investments Maximum Borrowing Term In Days	greater than 90 days
Equity Securities Financial Institution [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale Securities, Equity Securities	27,900,000	33,100,000
Single-issuer Trust Preferred Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Corporate debt securities	71,300,000	73,200,000
Single-issuer Trust Preferred Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Corporate debt securities	6,600,000	8,600,000
Single-issuer Trust Preferred Securities [Member] | Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Corporate debt securities	77,900,000	81,800,000
Pooled Trust Preferred Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Corporate debt securities	5,300,000	4,500,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Restricted equity securities issued by the Federal Home Loan Bank and Federal Reserve Bank	85,400,000	96,400,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities, Other [Member]
Available-for-sale Securities, Equity Securities	7,100,000	7,100,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Financial Institutions Subordinated Debt [Member]
Corporate debt securities	36,700,000	35,900,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other Corporate Debt [Member]
Corporate debt securities	2,500,000	2,600,000
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other Assets [Member]
Other real estate owned (OREO)	37,400,000	33,000,000
Servicing Asset at Amortized Value, Fair Value	32,100,000	29,100,000
Equity Securities [Member]
Restricted equity securities issued by the Federal Home Loan Bank and Federal Reserve Bank	85,400,000	96,400,000
Corporate Debt Securities [Member]
Corporate debt securities	122,435,000	124,786,000
Single-issuer Trust Preferred Securities [Member]
Corporate debt securities	77,861,000	81,789,000
Pooled Trust Preferred Securities [Member]
Corporate debt securities	$ 5,275,000	$ 4,528,000