Loans and Other Repossessed Assets Acquired (Detail) - Components of other real estate expenses, net (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Gain on sale of other real estate, net	$ (214)	$ (643)
Fair value writedown	805	989
Expenses, net	674	527
Rental income	(75)	(59)
Covered OREO expense reimbursement	(266)	(284)
Total other real estate expenses, net	$ 924	$ 530