Note Commitments and Contingencies (Financial instruments with off-Balance Sheet credit risk) (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Commitments To Extend Credit | Credit card
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial Instruments with Off-Balance Sheet Credit Risk	$ 4,562,439	$ 4,552,331
Commitments To Extend Credit | Commercial and construction lines of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial Instruments with Off-Balance Sheet Credit Risk	2,711,061	2,619,092
Commitments To Extend Credit | Other consumer unused credit commitments
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial Instruments with Off-Balance Sheet Credit Risk	259,134	262,685
Commercial Letters of Credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial Instruments with Off-Balance Sheet Credit Risk	1,560	2,040
Standby Letters of Credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial Instruments with Off-Balance Sheet Credit Risk	36,252	49,670
Commitments to originate or fund mortgage loans
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial Instruments with Off-Balance Sheet Credit Risk	$ 25,079	$ 21,311