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	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	$ 14,621	$ 152,344
Less than 12 Months, Unrealized Loss	(103)	(2,466)
12 Months or More, Fair Value	75,239	121,004
12 Months or More, Unrealized Loss	(1,949)	(4,516)
Total, Fair Value	89,860	273,348
Total, Unrealized Loss	(2,052)	(6,982)
U.S. Government Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	0	65,675
Less than 12 Months, Unrealized Loss	0	(640)
12 Months or More, Fair Value	3,001	31,923
12 Months or More, Unrealized Loss	(1)	(488)
Total, Fair Value	3,001	97,598
Total, Unrealized Loss	(1)	(1,128)
States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	1,669	9,103
Less than 12 Months, Unrealized Loss	(2)	(234)
12 Months or More, Fair Value	272	2,478
12 Months or More, Unrealized Loss	(193)	(9)
Total, Fair Value	1,941	11,581
Total, Unrealized Loss	(195)	(243)
Residential and Multi-Family Mortgage [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	10,975	69,631
Less than 12 Months, Unrealized Loss	(78)	(1,562)
12 Months or More, Fair Value	40,280	50,351
12 Months or More, Unrealized Loss	(433)	(1,832)
Total, Fair Value	51,255	119,982
Total, Unrealized Loss	(511)	(3,394)
Corporate Notes and Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	1,977	5,027
Less than 12 Months, Unrealized Loss	(23)	(2)
12 Months or More, Fair Value	8,251	8,144
12 Months or More, Unrealized Loss	(1,174)	(1,269)
Total, Fair Value	10,228	13,171
Total, Unrealized Loss	(1,197)	(1,271)
Pooled SBA [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	0	2,908
Less than 12 Months, Unrealized Loss	0	(28)
12 Months or More, Fair Value	22,441	27,127
12 Months or More, Unrealized Loss	(122)	(879)
Total, Fair Value	22,441	30,035
Total, Unrealized Loss	(122)	(907)
Other Equity 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	994	981
12 Months or More, Unrealized Loss	(26)	(39)
Total, Fair Value	994	981
Total, Unrealized Loss	$ (26)	$ (39)