Debt and Equity Securities - Summary of Debt and Equity Securities (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Summary Of Debt And Equity Securities [Line Items]
Available-for-sale, amortized cost	$ 353,067	$ 336,335
Available-for-sale, Gross Unrealized Gains	1,104	889
Available-for-sale, Gross Unrealized Losses	3,817	7,851
Available-for-sale, Estimated Market Value	350,354	329,373
Held-To-Maturity Securities, Amortized Cost	29,247	26,823
Held-To-Maturity Securities, Gross Unrealized Gains	463	497
Held-To-Maturity Securities, Gross Unrealized Losses	424	759
Held-To-Maturity Securities, Estimated Market Value	29,286	26,561
Government- sponsored enterprises (GSEs) residential Mortgage Backed [Member]
Summary Of Debt And Equity Securities [Line Items]
Available-for-sale, amortized cost	159,871	175,855
Available-for-sale, Gross Unrealized Gains	863	808
Available-for-sale, Gross Unrealized Losses	795	1,481
Available-for-sale, Estimated Market Value	159,939	175,182
Held-To-Maturity Securities, Amortized Cost	8,221	8,649
Held-To-Maturity Securities, Gross Unrealized Gains	79	73
Held-To-Maturity Securities, Gross Unrealized Losses	290	520
Held-To-Maturity Securities, Estimated Market Value	8,010	8,202
Obligations of States and Political Subdivisions [Member]
Summary Of Debt And Equity Securities [Line Items]
Available-for-sale, amortized cost	14,360	13,711
Available-for-sale, Gross Unrealized Gains	73	71
Available-for-sale, Gross Unrealized Losses	233	409
Available-for-sale, Estimated Market Value	14,200	13,373
Held-To-Maturity Securities, Amortized Cost	21,026	18,174
Held-To-Maturity Securities, Gross Unrealized Gains	384	424
Held-To-Maturity Securities, Gross Unrealized Losses	134	239
Held-To-Maturity Securities, Estimated Market Value	21,276	18,359
US Government-Sponsored Enterprises (GSEs) and agency-backed securities [Member]
Summary Of Debt And Equity Securities [Line Items]
Available-for-sale, amortized cost	178,836	146,769
Available-for-sale, Gross Unrealized Gains	168	10
Available-for-sale, Gross Unrealized Losses	2,789	5,961
Available-for-sale, Estimated Market Value	$ 176,215	$ 140,818