Securities - Securities with Unrealized Losses Aggregated by Investment Category and Length of Time that Individual Securities have been in Continuous Unrealized Loss Position (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	$ 60,223	$ 117,835
Less than 12 Months, Unrealized Loss	(251)	(961)
12 Months or More, Fair Value	171,792	240,321
12 Months or More, Unrealized Loss	(3,716)	(7,543)
Total, Fair Value	232,015	358,156
Total, Unrealized Loss	(3,967)	(8,504)
U.S. Government Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	12,509	26,069
Less than 12 Months, Unrealized Loss	(16)	(149)
12 Months or More, Fair Value	65,116	85,016
12 Months or More, Unrealized Loss	(391)	(2,070)
Total, Fair Value	77,625	111,085
Total, Unrealized Loss	(407)	(2,219)
States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	14,513	16,398
Less than 12 Months, Unrealized Loss	(61)	(179)
12 Months or More, Fair Value	5,412	12,363
12 Months or More, Unrealized Loss	(75)	(223)
Total, Fair Value	19,925	28,761
Total, Unrealized Loss	(136)	(402)
Residential and Multi-Family Mortgage [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	33,201	70,360
Less than 12 Months, Unrealized Loss	(174)	(603)
12 Months or More, Fair Value	58,378	99,397
12 Months or More, Unrealized Loss	(812)	(2,202)
Total, Fair Value	91,579	169,757
Total, Unrealized Loss	(986)	(2,805)
Corporate Notes and Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	0	5,008
Less than 12 Months, Unrealized Loss	0	(30)
12 Months or More, Fair Value	7,984	7,935
12 Months or More, Unrealized Loss	(1,423)	(1,470)
Total, Fair Value	7,984	12,943
Total, Unrealized Loss	(1,423)	(1,500)
Pooled SBA [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	0	0
Less than 12 Months, Unrealized Loss	0	0
12 Months or More, Fair Value	32,991	34,608
12 Months or More, Unrealized Loss	(1,000)	(1,560)
Total, Fair Value	32,991	34,608
Total, Unrealized Loss	(1,000)	(1,560)
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	0	0
Less than 12 Months, Unrealized Loss	0	0
12 Months or More, Fair Value	1,005	1,002
12 Months or More, Unrealized Loss	(15)	(18)
Total, Fair Value	1,005	1,002
Total, Unrealized Loss	$ (15)	$ (18)