Fair Value of Financial Instruments - Schedule of Financial Assets Measured at Fair Value on Nonrecurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Collateral dependent impaired loans	$ 76,413	$ 55,252
Other real estate owned	105,835	144,367
Total nonrecurring fair value measurements	182,248	199,619
Level 1 [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Collateral dependent impaired loans
Other real estate owned
Total nonrecurring fair value measurements
Level 2 [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Collateral dependent impaired loans	76,413	55,252
Other real estate owned	105,835	144,367
Total nonrecurring fair value measurements	$ 182,248	$ 199,619