Securities - Securities Available for Sale (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 692,949	$ 697,738
Unrealized Gains	11,016	9,827
Unrealized Losses	(16,103)	(21,574)
Fair Value	687,862	685,991
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	0	0
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	0	0
U.S. Government Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	184,938	185,205
Unrealized Gains	2,899	2,894
Unrealized Losses	(5,110)	(6,474)
Fair Value	182,727	181,625
States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	172,586	176,490
Unrealized Gains	4,964	3,770
Unrealized Losses	(1,282)	(2,317)
Fair Value	176,268	177,943
Residential and Multi-Family Mortgage [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	248,878	248,017
Unrealized Gains	2,263	2,410
Unrealized Losses	(5,313)	(7,820)
Fair Value	245,828	242,607
Commercial Mortgage [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	232	385
Unrealized Gains	0	0
Unrealized Losses	(7)	(11)
Fair Value	225	374
Corporate Notes and Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	15,746	15,744
Unrealized Gains	93	65
Unrealized Losses	(1,637)	(1,734)
Fair Value	14,202	14,075
Pooled Trust Preferred [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	800	800
Unrealized Gains	0	0
Unrealized Losses	(2)	(139)
Fair Value	798	661
Pooled SBA [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	68,749	70,077
Unrealized Gains	797	688
Unrealized Losses	(2,722)	(3,044)
Fair Value	66,824	67,721
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,020	1,020
Unrealized Gains	0	0
Unrealized Losses	(30)	(35)
Fair Value	$ 990	$ 985