Selected Components of Other Non-Interest Income And Other Non-Interest Expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Selected Components Of Other Non-Interest Income and Other Non-Interest Expense [Line Items]
Letter of credit fees	$ 992	$ 1,123	$ 1,019
Extension fees	590	406	594
Other income	3,140	2,515	2,816
Total other non-interest income	4,722	4,044	4,429
Professional fees	6,309	4,942	5,586
Other real estate owned	905	2,412	976
Postage and delivery	1,255	1,257	1,328
Communications	1,596	1,433	1,433
Other expenses	8,348	7,598	7,027
Total other non-interest expense	$ 18,413	$ 17,642	$ 16,350