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Securities - Summary of Amortized Costs and Fair Values of Securities (Detail) - USD ($) $ in Thousands | Mar. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Securities available for sale: |  |  |
Amortized Cost | $ 96,129 | $ 90,594 |
Gross Unrealized Gains | 81 | 153 |
Gross Unrealized (Losses) | (2,511) | (1,492) |
Fair Value | 93,699 | 89,255 |
Securities held to maturity: |  |  |
Amortized Cost | 46,791 | 48,208 |
Gross Unrealized Gains | 18 | 90 |
Gross Unrealized (Losses) | (1,179) | (596) |
Fair Value | 45,630 | 47,702 | [1]
Total securities, Amortized cost | 142,920 | 138,802 |
Total securities, Gross unrealized gains | 99 | 243 |
Total securities, Gross unrealized (losses) | (3,690) | (2,088) |
Total securities, Fair value | 139,329 | 136,957 |
U.S. agency and mortgage-backed securities |  |  |
Securities available for sale: |  |  |
Amortized Cost | 81,309 | 76,074 |
Gross Unrealized Gains | 24 | 67 |
Gross Unrealized (Losses) | (2,225) | (1,337) |
Fair Value | 79,108 | 74,804 |
Securities held to maturity: |  |  |
Amortized Cost | 30,750 | 32,149 |
Gross Unrealized Gains | 0 | 0 |
Gross Unrealized (Losses) | (984) | (551) |
Fair Value | 29,766 | 31,598 |
Obligations of states and political subdivisions |  |  |
Securities available for sale: |  |  |
Amortized Cost | 14,820 | 14,520 |
Gross Unrealized Gains | 57 | 86 |
Gross Unrealized (Losses) | (286) | (155) |
Fair Value | 14,591 | 14,451 |
Securities held to maturity: |  |  |
Amortized Cost | 14,541 | 14,559 |
Gross Unrealized Gains | 18 | 74 |
Gross Unrealized (Losses) | (192) | (45) |
Fair Value | 14,367 | 14,588 |
Corporate debt securities |  |  |
Securities held to maturity: |  |  |
Amortized Cost | 1,500 | 1,500 |
Gross Unrealized Gains | 0 | 16 |
Gross Unrealized (Losses) | (3) | 0 |
Fair Value | $ 1,497 | $ 1,516 |
[1] | Derived from audited consolidated financial statements.

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