Investment Securities - Schedule of Gross Unrealized Losses and Fair Value of Securities (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months Fair Value	$ 118,634	$ 44,540	$ 42,022
12 Months or More Fair Value	5,755	8,682	11,602
Total Fair Value	124,389	53,222	53,624
Less Than 12 Months Unrealized Losses	(3,371)	(386)	(241)
12 Months or More Unrealized Losses	(780)	(581)	(545)
Total Unrealized Losses	(4,151)	(967)	(786)
U.S. Government Agencies [Member]
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months Fair Value	14,335	4,994
12 Months or More Fair Value
Total Fair Value	14,335	4,994
Less Than 12 Months Unrealized Losses	(609)	(6)
12 Months or More Unrealized Losses
Total Unrealized Losses	(609)	(6)
State, County and Municipal Securities [Member]
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months Fair Value	36,268	15,595	10,342
12 Months or More Fair Value	497	505
Total Fair Value	36,765	16,100	10,342
Less Than 12 Months Unrealized Losses	(726)	(199)	(74)
12 Months or More Unrealized Losses	(16)	(11)
Total Unrealized Losses	(742)	(210)	(74)
Corporate Debt Securities [Member]
Schedule of Available-for-Sale Securities [Line Items]
12 Months or More Fair Value	4,333	4,560	6,562
Total Fair Value	4,333	4,560	6,562
12 Months or More Unrealized Losses	(764)	(547)	(517)
Total Unrealized Losses	(764)	(547)	(517)
Mortgage-Backed Securities [Member]
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months Fair Value	68,031	23,951	31,680
12 Months or More Fair Value	925	3,617	5,040
Total Fair Value	68,956	27,568	36,720
Less Than 12 Months Unrealized Losses	(2,036)	(181)	(167)
12 Months or More Unrealized Losses		(23)	(28)
Total Unrealized Losses	$ (2,036)	$ (204)	$ (195)