Securities - Fair Value of Securities (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Total available for sale investment securities, Amortized Cost	$ 359,468	$ 508,427
Held-to-maturity, Amortized Cost	173,200	9,910
Gross Unrealized Gains	7,487	9,015
Held-to-maturity, Gross Unrealized Gains	2,314
Gross Unrealized Losses	(2,537)	(8,851)
Held-to-maturity, Gross Unrealized Losses	(20)
Available-for-sale Securities, Fair Value	364,418	508,591
Held-to-maturity, fair value	175,494	9,910
U.S. Treasury and federal agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available for sale investment securities, Amortized Cost	35,737	43,808
Held-to-maturity, Amortized Cost	9,764
Gross Unrealized Gains	137	133
Held-to-maturity, Gross Unrealized Gains	79
Gross Unrealized Losses	(342)	(807)
Held-to-maturity, Gross Unrealized Losses
Available-for-sale Securities, Fair Value	35,532	43,134
Held-to-maturity, fair value	9,843
State and municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available for sale investment securities, Amortized Cost	47,691	176,670
Held-to-maturity, Amortized Cost	136,131	9,910
Gross Unrealized Gains	1,778	4,405
Held-to-maturity, Gross Unrealized Gains	1,816
Gross Unrealized Losses	(88)	(3,177)
Held-to-maturity, Gross Unrealized Losses	(19)
Available-for-sale Securities, Fair Value	49,381	177,898
Held-to-maturity, fair value	137,928	9,910
Federal agency collateralized mortgage obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available for sale investment securities, Amortized Cost	115,503	116,047
Held-to-maturity, Amortized Cost	4,360
Gross Unrealized Gains	1,159	1,242
Held-to-maturity, Gross Unrealized Gains	5
Gross Unrealized Losses	(1,420)	(2,583)
Held-to-maturity, Gross Unrealized Losses	(1)
Available-for-sale Securities, Fair Value	115,242	114,706
Held-to-maturity, fair value	4,364
Federal agency mortgage-backed pools [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available for sale investment securities, Amortized Cost	158,907	170,006
Held-to-maturity, Amortized Cost	22,945
Gross Unrealized Gains	4,367	3,172
Held-to-maturity, Gross Unrealized Gains	414
Gross Unrealized Losses	(687)	(2,284)
Held-to-maturity, Gross Unrealized Losses
Available-for-sale Securities, Fair Value	162,587	170,894
Held-to-maturity, fair value	23,359
Private labeled mortgage-backed pools [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available for sale investment securities, Amortized Cost	892	1,188
Gross Unrealized Gains	28	38
Gross Unrealized Losses
Available-for-sale Securities, Fair Value	920	1,226
Corporate notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available for sale investment securities, Amortized Cost	738	708
Gross Unrealized Gains	18	25
Gross Unrealized Losses
Available-for-sale Securities, Fair Value	$ 756	$ 733