Contingencies and Guarantees (Schedule of Remaining Contractual Loan Commitments by Class) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loan Commitments	$ 3,892,865	$ 3,608,939	$ 3,549,253
Commercial [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loan Commitments	2,227,184	2,023,284	1,933,575
Consumer Loan [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loan Commitments	$ 1,665,681	$ 1,585,655	$ 1,615,678