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Securities - Summary of Amortized Costs and Fair Values of Securities (Detail) - USD ($) $ in Thousands | Dec. 31, 2016 | Dec. 31, 2015
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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

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