Fair Value Disclosures - Other Real Estate Owned (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Summary Of Activity Related To Other Real Estate Owned [Line Items]
Carrying value of other real estate owned prior to re-measurement	$ 5,375	$ 7,064
Write-downs included in gain (loss) on sale of other real estate owned	(704)	(1,522)
Fair value	$ 4,671	$ 5,542