Securities - Securities Available for Sale (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 528,036	$ 540,614
Unrealized Gains	14,828	12,411
Unrealized Losses	(4,143)	(6,982)
Fair Value	538,721	546,043
U.S. Government Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	139,178	141,300
Unrealized Gains	2,372	1,579
Unrealized Losses	(48)	(1,128)
Fair Value	141,502	141,751
States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	163,663	165,828
Unrealized Gains	7,572	6,234
Unrealized Losses	(194)	(243)
Fair Value	171,041	171,819
Residential and Multi-Family Mortgage [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	153,587	160,316
Unrealized Gains	1,463	1,060
Unrealized Losses	(1,523)	(3,394)
Fair Value	153,527	157,982
Corporate Notes and Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	19,788	19,794
Unrealized Gains	199	165
Unrealized Losses	(1,886)	(1,271)
Fair Value	18,101	18,688
Pooled Trust Preferred [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	800	800
Unrealized Gains	2,309	2,613
Unrealized Losses	0	0
Fair Value	3,109	3,413
Pooled SBA [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	50,000	51,556
Unrealized Gains	913	760
Unrealized Losses	(465)	(907)
Fair Value	50,448	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	(27)	(39)
Fair Value	$ 993	$ 981