Assets Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	$ 180,408	$ 169,214
Securities Investment
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	125,302	128,014
Securities Investment | Government Sponsored Enterprises
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	121,055	123,679
Securities Investment | Trust Preferred Securities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	4,247	4,335
Mortgage-Backed Securities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	55,106	41,200
Level 1
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	121,055	123,679
Level 1 | Securities Investment
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	121,055	123,679
Level 1 | Securities Investment | Government Sponsored Enterprises
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	121,055	123,679
Level 2
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	57,660	43,988
Level 2 | Securities Investment
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	2,554	2,788
Level 2 | Securities Investment | Trust Preferred Securities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	2,554	2,788
Level 2 | Mortgage-Backed Securities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	55,106	41,200
Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	1,693	1,547
Level 3 | Securities Investment
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	1,693	1,547
Level 3 | Securities Investment | Trust Preferred Securities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset Fair Value disclosure	$ 1,693	$ 1,547