Commitments, Contingencies, and Guarantees (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Credit Commitments
Total Credit Commitments	$ 2,160,057,000	$ 2,075,456,000
Current Residential Mortgage Loans Serviced for Third Parties as Percentage of Total	99.00%
Unfunded Commitments to Extend Credit
Credit Commitments
Total Credit Commitments	2,081,364,000	1,999,542,000
Standby Letters of Credit
Credit Commitments
Total Credit Commitments	62,711,000	62,043,000
Commercial Letters of Credit
Credit Commitments
Total Credit Commitments	15,982,000	13,871,000
Residential Mortgage
Credit Commitments
Sold Financing Receivable, Unpaid Principal Balance	2,900,000,000
Number of Mortgage Loans Repurchased	2
Repurchased Financing Receivable, Unpaid Principal Balance	$ 700,000