Financial instruments with off-Balance Sheet credit risk, whose contract amounts represent potential credit risk (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Commitments To Extend Credit Member | Credit Card [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure Offbalance Sheet Risks Face Amount Asset	$ 4,361,641	$ 4,297,755	$ 3,864,026
Commitments To Extend Credit Member | Commercial Line Of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure Offbalance Sheet Risks Face Amount Asset	2,092,520	2,039,629	2,471,756
Commitments To Extend Credit Member | Other Loan Commitments [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure Offbalance Sheet Risks Face Amount Asset	367,672	358,572	373,832
Commercial Letters Of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure Offbalance Sheet Risks Face Amount Asset	11,700	11,632	13,297
Standby Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure Offbalance Sheet Risks Face Amount Asset	131,785	124,709	133,178
Mortgage Loan Commitments [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure Offbalance Sheet Risks Face Amount Asset	$ 66,908	$ 53,323	$ 40,002