Commitments, Credit Risk and Contingencies - Summary of Off-Balance Sheet Credit Risk Information (Detail) (USD $)
In Thousands, unless otherwise specified |
Sep. 30, 2013
|
Dec. 31, 2012
|
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Commitments to Extend Credit [Member]
|
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Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | ||
Extended credit and standby letters of credit | $ 2,822,545 | $ 2,600,355 |
Standby Letters of Credit [Member]
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Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | ||
Extended credit and standby letters of credit | $ 122,713 | $ 130,912 |