Securities - Summary of Amortized Costs and Fair Values of Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Debt and Equity, Amortized Cost Basis, Total	$ 96,106	$ 105,851
Securities available for sale, Gross Unrealized Gains	333	601
Securities available for sale, Gross Unrealized (Losses)	(1,637)	(893)
Securities available for sale, Fair Value	94,802	105,559
Securities held to maturity, Amortized Cost	53,398	66,519
Securities held to maturity, Gross Unrealized Gains	19	264
Securities held to maturity, Gross Unrealized (Losses)	(708)	(345)
Securities held to maturity, Fair Value	52,709	66,438
Total securities, Amortized Cost	149,504	172,370
Total securities, Gross Unrealized Gains	352	865
Total securities, Gross Unrealized (Losses)	(2,345)	(1,238)
Total securities, Fair Value	147,511	171,997
U.S. Agency and Mortgage-Backed Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Debt and Equity, Amortized Cost Basis, Total	81,451	89,919
Securities available for sale, Gross Unrealized Gains	177	261
Securities available for sale, Gross Unrealized (Losses)	(1,457)	(843)
Securities available for sale, Fair Value	80,171	89,337
Securities held to maturity, Amortized Cost	37,269	49,662
Securities held to maturity, Gross Unrealized Gains	1	36
Securities held to maturity, Gross Unrealized (Losses)	(483)	(326)
Securities held to maturity, Fair Value	36,787	49,372
Obligations of States and Political Subdivisions [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Debt and Equity, Amortized Cost Basis, Total	14,654	15,931
Securities available for sale, Gross Unrealized Gains	146	333
Securities available for sale, Gross Unrealized (Losses)	(180)	(50)
Securities available for sale, Fair Value	14,620	16,214
Securities held to maturity, Amortized Cost	14,629	15,357
Securities held to maturity, Gross Unrealized Gains	18	228
Securities held to maturity, Gross Unrealized (Losses)	(211)	(19)
Securities held to maturity, Fair Value	14,436	15,566
Corporate Equity Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Debt and Equity, Amortized Cost Basis, Total	1	1
Securities available for sale, Gross Unrealized Gains	10	7
Securities available for sale, Fair Value	11	8
Corporate Debt Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Securities held to maturity, Amortized Cost	1,500	1,500
Securities held to maturity, Gross Unrealized (Losses)	(14)
Securities held to maturity, Fair Value	$ 1,486	$ 1,500

Available for sale and held to maturity securities accumulated gross unrealized loss.

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Available for sale securities and held to maturity securities accumulated gross unrealized gain.

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

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Amount of accumulated unrealized gain on investments in debt securities classified as held-to-maturity.

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