Securities - Securities Available for Sale (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 508,976	$ 540,614
Unrealized Gains	14,605	12,411
Unrealized Losses	(2,580)	(6,982)
Fair Value	521,001	546,043
U.S. Government Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	139,061	141,300
Unrealized Gains	2,732	1,579
Unrealized Losses	(4)	(1,128)
Fair Value	141,789	141,751
States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	156,731	165,828
Unrealized Gains	8,108	6,234
Unrealized Losses	(194)	(243)
Fair Value	164,645	171,819
Residential and Multi-Family Mortgage [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	145,782	160,316
Unrealized Gains	1,792	1,060
Unrealized Losses	(716)	(3,394)
Fair Value	146,858	157,982
Corporate Notes and Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	18,188	19,794
Unrealized Gains	199	165
Unrealized Losses	(1,463)	(1,271)
Fair Value	16,924	18,688
Pooled Trust Preferred [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	800	800
Unrealized Gains	902	2,613
Unrealized Losses	0	0
Fair Value	1,702	3,413
Pooled SBA [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	47,394	51,556
Unrealized Gains	872	760
Unrealized Losses	(179)	(907)
Fair Value	48,087	51,409
Other Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,020	1,020
Unrealized Gains	0	0
Unrealized Losses	(24)	(39)
Fair Value	$ 996	$ 981