Investment Securities - Schedule of Gross Unrealized Losses and Fair Value of Securities (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	$ 29,195	$ 156,316	$ 118,634
12 Months or More, Estimated Fair Value	99,632	32,008	5,755
Total Estimated Fair Value	128,827	188,324	124,389
Less Than 12 Months, Unrealized Losses	(100)	(5,396)	(3,371)
12 Months or More, Unrealized Losses	(3,581)	(2,098)	(780)
Total Unrealized Losses	(3,681)	(7,494)	(4,151)
US Government Agencies [Member]
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value		13,926	14,335
12 Months or More, Estimated Fair Value	14,445
Total Estimated Fair Value	14,445	13,926	14,335
Less Than 12 Months, Unrealized Losses		(1,021)	(609)
12 Months or More, Unrealized Losses	(505)
Total Unrealized Losses	(505)	(1,021)	(609)
State, County and Municipal Securities [Member]
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	4,088	47,401	36,268
12 Months or More, Estimated Fair Value	29,203	3,794	497
Total Estimated Fair Value	33,291	51,195	36,765
Less Than 12 Months, Unrealized Losses	(35)	(1,882)	(726)
12 Months or More, Unrealized Losses	(828)	(292)	(16)
Total Unrealized Losses	(863)	(2,174)	(742)
Corporate Debt Securities [Member]
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value
12 Months or More, Estimated Fair Value	4,945	4,826	4,333
Total Estimated Fair Value	4,945	4,826	4,333
Less Than 12 Months, Unrealized Losses
12 Months or More, Unrealized Losses	(131)	(261)	(764)
Total Unrealized Losses	(131)	(261)	(764)
Mortgage-Backed Securities [Member]
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	25,107	94,989	68,031
12 Months or More, Estimated Fair Value	51,039	23,388	925
Total Estimated Fair Value	76,146	118,377	68,956
Less Than 12 Months, Unrealized Losses	(65)	(2,493)	(2,036)
12 Months or More, Unrealized Losses	(2,117)	(1,545)
Total Unrealized Losses	(2,182)	(4,038)	(2,036)
Collateralized Debt Obligations [Member]
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value
12 Months or More, Estimated Fair Value
Total Estimated Fair Value
Less Than 12 Months, Unrealized Losses
12 Months or More, Unrealized Losses
Total Unrealized Losses