Securities - Available for Sale Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 192,915	$ 192,252
Gross Unrealized Gains	5,970	6,262
Gross Unrealized Losses	(230)	(609)
Total securities available for sale, Fair Value	198,655	197,905
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	39,271	42,910
Gross Unrealized Gains	234	115
Gross Unrealized Losses	(13)	(123)
Total securities available for sale, Fair Value	39,492	42,902
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	87,971	83,215
Gross Unrealized Gains	4,551	5,112
Gross Unrealized Losses	(143)	(306)
Total securities available for sale, Fair Value	92,379	88,021
Mortgage-backed Securities in Government Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	65,192	65,646
Gross Unrealized Gains	1,079	976
Gross Unrealized Losses	(74)	(180)
Total securities available for sale, Fair Value	66,197	66,442
Total Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	192,434	191,771
Gross Unrealized Gains	5,864	6,203
Gross Unrealized Losses	(230)	(609)
Total securities available for sale, Fair Value	198,068	197,365
Equity Securities in Financial Institutions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	481	481
Gross Unrealized Gains	106	59
Total securities available for sale, Fair Value	$ 587	$ 540

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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