Securities - Amortized Cost and Fair Value of Securities Available for Sale and Held to Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized cost within one year	$ 4,738	$ 3,643
Amortized cost one to five years	45,331	49,198
Amortized cost for five to ten years	28,584	106,225
Amortized cost for after ten years	5,513	62,120
Total amortized cost	84,166	221,186
Total available for sale investment securities, Amortized Cost	359,468	508,427
Within one year, amortized cost	5,951	9,910
One to five years, amortized cost	383
Five to ten years, amortized cost	89,024
After ten years, amortized cost	50,537
Total amortized cost	145,895	9,910
Total held to maturity investment securities, amortized cost	173,200	9,910
Fair value within one year	4,778	3,663
Fair value for one to five years	45,937	49,627
Fair value for five to ten years	29,278	107,424
Fair value for after ten years	5,676	61,051
Total fair value	85,669	221,765
Investment securities, available for sale	364,418	508,591
Within one year, fair value	5,951	9,910
One to five years, fair value	384
five to ten years, fair value	90,139
After ten years, fair value	51,297
Total fair value	147,771	9,910
Held-to-maturity, fair value	175,494	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
Total held to maturity investment securities, amortized cost	4,360
Investment securities, available for sale	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
Total held to maturity investment securities, amortized cost	22,945
Investment securities, available for sale	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
Investment securities, available for sale	$ 920	$ 1,226