Expenses Related to Foreclosed Assets (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Real Estate [Line Items]
Net (gains) losses on sales	$ (292)	$ 35
Provision for unrealized losses	1,218	2,654
Operating expenses	592	499
Total	$ 1,518	$ 3,188