Investment Securities - Gross Unrealized Losses on Investment (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
12 months or more, Fair Value	$ 10,068
Less than 12 months, Fair Value		10,486
12 months or more, Unrealized Loss	(63)
Less than 12 months, Unrealized Loss		(358)
Total Fair Value	10,068	10,486
Total Unrealized Loss	(63)	(358)
Less than 12 months, Fair Value, held to maturity	3,861	199,403
Less than 12 months, Unrealized Loss, held to maturity	(45)	(6,995)
12 months or more, Fair Value, held to maturity	69,727
12 months or more, Unrealized Loss, held to maturity	(1,485)
Total Fair Value, held to maturity	73,588	199,403
Total Unrealized Loss, held to maturity	(1,530)	(6,995)
Obligations of U.S. government corporations and agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
12 months or more, Fair Value	10,068
Less than 12 months, Fair Value		10,287
12 months or more, Unrealized Loss	(63)
Less than 12 months, Unrealized Loss		(357)
Total Fair Value	10,068	10,287
Total Unrealized Loss	(63)	(357)
Less than 12 months, Fair Value, held to maturity	3,384	188,218
Less than 12 months, Unrealized Loss, held to maturity	(14)	(5,540)
12 months or more, Fair Value, held to maturity	57,938
12 months or more, Unrealized Loss, held to maturity	(1,161)
Total Fair Value, held to maturity	61,322	188,218
Total Unrealized Loss, held to maturity	(1,175)	(5,540)
Obligations of states and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value		199
Less than 12 months, Unrealized Loss		(1)
Total Fair Value		199
Total Unrealized Loss		(1)
Less than 12 months, Fair Value, held to maturity	477	11,185
Less than 12 months, Unrealized Loss, held to maturity	(31)	(1,455)
12 months or more, Fair Value, held to maturity	11,789
12 months or more, Unrealized Loss, held to maturity	(324)
Total Fair Value, held to maturity	12,266	11,185
Total Unrealized Loss, held to maturity	$ (355)	$ (1,455)