Contingencies and Guarantees (Schedule of Remaining Contractual Loan Commitments by Class) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Commercial [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loan Commitments	$ 2,406,226	$ 2,023,284	$ 2,047,840
Consumer Loan [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loan Commitments	1,687,955	1,585,655	1,610,924
Commitments to Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loan Commitments	$ 4,094,181	$ 3,608,939	$ 3,658,764