Fair Value - Schedule of Financial Assets Measured at Fair Value on Nonrecurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Collateral-dependent impaired loans	$ 27,981	$ 72,694
Other real estate owned	21,148	43,803
Total nonrecurring fair value measurements	49,129	116,497
Level 2 [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Collateral-dependent impaired loans	27,981	72,694
Total nonrecurring fair value measurements	27,981	72,694
Level 3 [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Other real estate owned	21,148	43,803
Total nonrecurring fair value measurements	$ 21,148	$ 43,803