Investment Securities - Schedule of Gross Unrealized Losses and Fair Value of Securities (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	$ 103,393	$ 156,316	$ 74,592
12 Months or More, Estimated Fair Value	44,459	32,008	6,131
Total Estimated Fair Value	147,852	188,324	80,723
Less Than 12 Months, Unrealized Losses	(3,052)	(5,396)	(792)
12 Months or More, Unrealized Losses	(2,290)	(2,098)	(604)
Total Unrealized Losses	(5,342)	(7,494)	(1,396)
US Government Agencies [Member]
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	9,353	13,926
12 Months or More, Estimated Fair Value	4,792
Total Estimated Fair Value	14,145	13,926
Less Than 12 Months, Unrealized Losses	(595)	(1,021)
12 Months or More, Unrealized Losses	(208)
Total Unrealized Losses	(803)	(1,021)
State, County and Municipal Securities [Member]
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	38,937	47,401	19,159
12 Months or More, Estimated Fair Value	3,612	3,794	505
Total Estimated Fair Value	42,549	51,195	19,664
Less Than 12 Months, Unrealized Losses	(1,238)	(1,882)	(138)
12 Months or More, Unrealized Losses	(243)	(292)	(9)
Total Unrealized Losses	(1,481)	(2,174)	(147)
Corporate Debt Securities [Member]
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value			244
12 Months or More, Estimated Fair Value	4,871	4,826	4,506
Total Estimated Fair Value	4,871	4,826	4,750
Less Than 12 Months, Unrealized Losses			(6)
12 Months or More, Unrealized Losses	(209)	(261)	(594)
Total Unrealized Losses	(209)	(261)	(600)
Mortgage-Backed Securities [Member]
Schedule of Available-for-Sale Securities [Line Items]
Less Than 12 Months, Estimated Fair Value	55,103	94,989	55,189
12 Months or More, Estimated Fair Value	31,184	23,388	1,120
Total Estimated Fair Value	86,287	118,377	56,309
Less Than 12 Months, Unrealized Losses	(1,219)	(2,493)	(648)
12 Months or More, Unrealized Losses	(1,630)	(1,545)	(1)
Total Unrealized Losses	(2,849)	(4,038)	(649)
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