Assets and Liabilities Measured at Fair Value on Non-Recurring Basis (Detail) (Fair Value, Measurements, Nonrecurring, USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Certain impaired loans	$ 14,887		$ 76,704
Other assets	24,391	[1]	22,664	[1]
Total	39,278		99,368
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	24,391	[1]	22,664	[1]
Total	24,391		22,664
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Certain impaired loans	14,887		76,704
Total	$ 14,887		$ 76,704

[1] Represents the fair value of OREO, based on the appraised value of the collateral subsequent to its initial classification as OREO.