Commitments and Contingencies (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Commitments and Contingencies
Total outstanding loan balances	$ 17,887,349,000	$ 15,849,299,000
Fair value of risk participation guaranteed obligations	1,000,000	400,000
Maximum liability under indemnity in connection with liquidation of an investment acquired	23,000,000
Commitments and Contingencies
Commitments
Off-balance sheet loan commitments
Commitments and Contingencies
Commitments	8,040,000,000	6,480,000,000
Letters of Credit
Commitments and Contingencies
Commitments	733,500,000	765,000,000
Standby letters of credit, included within letters of credit
Commitments and Contingencies
Commitments	617,300,000	659,200,000
Commercial letters of credit, including within letters of credit
Commitments and Contingencies
Commitments	116,200,000	105,800,000
Private equity fund and alternative investment
Commitments and Contingencies
Commitments	70,900,000	68,900,000
Commitments, funded amount	62,200,000	61,300,000
Affordable housing fund
Commitments and Contingencies
Commitments	$ 80,800,000	$ 58,600,000