Noninterest Income and Expense - Components of Noninterest Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended							9 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Base salaries, net of deferred loan origination costs	$ 9,066				$ 8,716			$ 26,940	$ 25,572
Incentive compensation	1,265				1,166			3,593	3,751
Benefits and other compensation costs	3,038				2,979			9,456	9,389
Total salaries and benefits expense	13,369				12,861			39,989	38,712
Occupancy	1,971				1,925			5,735	5,337
Equipment	995				1,089			3,091	3,036
Data processing and software	1,637				1,184			4,165	3,542
ATM network charges	657				626			2,010	1,801
Telecommunications	648				629			1,941	1,741
Postage	179				269			627	633
Courier service	269				217			727	639
Advertising	581				492			1,264	1,232
Assessments	493				572			1,495	1,721
Operational losses	138				137			465	376
Professional fees	1,468				776			3,825	1,982
Foreclosed assets expense	94				48			403	310
Provision for foreclosed asset losses	98				47			137	620
Reserve for unfunded commitments	175				(335)			(195)	(740)
Intangible amortization	53				53			157	157
Other	2,555				3,026			7,976	7,627
Total other noninterest expense	12,011				10,755			33,824	30,014
Total noninterest expense	$ 25,380	$ 25,116	$ 23,317	$ 24,878	$ 23,616	$ 23,509	$ 21,601	$ 73,813	$ 68,726