Securities - Available for Sale Securities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 196,069	$ 199,094
Gross Unrealized Gains	5,776	3,549
Gross Unrealized Losses	(954)	(3,030)
Total securities available for sale, Fair Value	200,891	199,613
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	44,857	52,229
Gross Unrealized Gains	104	95
Gross Unrealized Losses	(222)	(764)
Total securities available for sale, Fair Value	44,739	51,560
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	83,044	79,975
Gross Unrealized Gains	4,587	2,327
Gross Unrealized Losses	(378)	(1,677)
Total securities available for sale, Fair Value	87,253	80,625
Mortgage-backed Securities in Government Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	67,687	66,409
Gross Unrealized Gains	1,033	1,127
Gross Unrealized Losses	(354)	(557)
Total securities available for sale, Fair Value	68,366	66,979
Total Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	195,588	198,613
Gross Unrealized Gains	5,724	3,549
Gross Unrealized Losses	(954)	(2,998)
Total securities available for sale, Fair Value	200,358	199,164
Equity Securities in Financial Institutions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	481	481
Gross Unrealized Gains	52
Gross Unrealized Losses		(32)
Total securities available for sale, Fair Value	$ 533	$ 449