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	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	$ 196,901	$ 152,344
Less than 12 Months, Unrealized Loss	(2,419)	(2,466)
12 Months or More, Fair Value	64,882	121,004
12 Months or More, Unrealized Loss	(3,120)	(4,516)
Total, Fair Value	261,783	273,348
Total, Unrealized Loss	(5,539)	(6,982)
U.S. Government Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	90,380	65,675
Less than 12 Months, Unrealized Loss	(579)	(640)
12 Months or More, Fair Value	0	31,923
12 Months or More, Unrealized Loss	0	(488)
Total, Fair Value	90,380	97,598
Total, Unrealized Loss	(579)	(1,128)
States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	32,353	9,103
Less than 12 Months, Unrealized Loss	(448)	(234)
12 Months or More, Fair Value	264	2,478
12 Months or More, Unrealized Loss	(201)	(9)
Total, Fair Value	32,617	11,581
Total, Unrealized Loss	(649)	(243)
Residential and Multi-Family Mortgage [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	65,598	69,631
Less than 12 Months, Unrealized Loss	(1,255)	(1,562)
12 Months or More, Fair Value	34,611	50,351
12 Months or More, Unrealized Loss	(1,127)	(1,832)
Total, Fair Value	100,209	119,982
Total, Unrealized Loss	(2,382)	(3,394)
Corporate Notes and Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	2,089	5,027
Less than 12 Months, Unrealized Loss	(11)	(2)
12 Months or More, Fair Value	8,476	8,144
12 Months or More, Unrealized Loss	(951)	(1,269)
Total, Fair Value	10,565	13,171
Total, Unrealized Loss	(962)	(1,271)
Pooled SBA [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	6,481	2,908
Less than 12 Months, Unrealized Loss	(126)	(28)
12 Months or More, Fair Value	20,560	27,127
12 Months or More, Unrealized Loss	(792)	(879)
Total, Fair Value	27,041	30,035
Total, Unrealized Loss	(918)	(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	971	981
12 Months or More, Unrealized Loss	(49)	(39)
Total, Fair Value	971	981
Total, Unrealized Loss	$ (49)	$ (39)