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Securities - Summary of Amortized Costs and Fair Values of Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Debt and Equity, Amortized Cost Basis, Total	$ 92,634	$ 96,106
Securities available for sale, Gross Unrealized Gains	394	333
Securities available for sale, Gross Unrealized (Losses)	(1,121)	(1,637)
Securities available for sale, Fair Value	91,907	94,802	[1]
Securities held to maturity, Amortized Cost	51,999	53,398
Securities held to maturity, Gross Unrealized Gains	69	19
Securities held to maturity, Gross Unrealized (Losses)	(460)	(708)
Securities held to maturity, Fair Value	51,608	52,709	[1]
Total securities, Amortized Cost	144,633	149,504
Total securities, Gross Unrealized Gains	463	352
Total securities, Gross Unrealized (Losses)	(1,581)	(2,345)
Total securities, Fair Value	143,515	147,511
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	78,026	81,451
Securities available for sale, Gross Unrealized Gains	186	177
Securities available for sale, Gross Unrealized (Losses)	(985)	(1,457)
Securities available for sale, Fair Value	77,227	80,171
Securities held to maturity, Amortized Cost	35,888	37,269
Securities held to maturity, Gross Unrealized Gains	20	1
Securities held to maturity, Gross Unrealized (Losses)	(351)	(483)
Securities held to maturity, Fair Value	35,557	36,787
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	14,607	14,654
Securities available for sale, Gross Unrealized Gains	198	146
Securities available for sale, Gross Unrealized (Losses)	(136)	(180)
Securities available for sale, Fair Value	14,669	14,620
Securities held to maturity, Amortized Cost	14,611	14,629
Securities held to maturity, Gross Unrealized Gains	49	18
Securities held to maturity, Gross Unrealized (Losses)	(93)	(211)
Securities held to maturity, Fair Value	14,567	14,436
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	10
Securities available for sale, Fair Value	11	11
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)	(16)	(14)
Securities held to maturity, Fair Value	$ 1,484	$ 1,486
[1] Derived from audited consolidated financial statements.

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

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