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Securities - Summary of Investments in an Unrealized Loss Position that were Temporarily Impaired (Detail) - USD ($) $ in Thousands | Sep. 30, 2015 | Dec. 31, 2014
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Schedule of Available-for-sale Securities [Line Items] |  |
Securities available for sale, Less than 12 months - Fair Value | $ 27,260 | $ 9,392
Securities available for sale, 12 months or more - Fair Value | 19,172 | 35,368
Securities available for sale, Total - Fair Value | 46,432 | 44,760
Securities available for sale, Less than 12 months - Unrealized (Loss) | (140) | (61)
Securities available for sale, 12 months or more - Unrealized (Loss) | (373) | (845)
Total Unrealized (Loss) | (513) | (906)
Securities held to maturity, Less than 12 months - Fair Value | 19,612 |
Securities held to maturity, 12 months or more - Fair Value | 0 |
Securities held to maturity, Total - Fair Value | 19,612 |
Securities held to maturity, Less than 12 months - Unrealized (Loss) | (165) |
Securities held to maturity, 12 months or more - Unrealized (Loss) | 0 |
Total Unrealized (Loss) | (165) |
Total securities, Less than 12 months - Fair Value | 46,872 |
Total securities, 12 months or more - Fair Value | 19,172 |
Total securities, Total - Fair Value | 66,044 |
Total securities, Less than 12 months - Unrealized (Loss) | (305) |
Total securities, 12 months or more - Unrealized (Loss) | (373) |
Total Unrealized (Loss) | (678) |
U.S. Agency and Mortgage-Backed Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Securities available for sale, Less than 12 months - Fair Value | 24,974 | 8,677
Securities available for sale, 12 months or more - Fair Value | 18,114 | 32,527
Securities available for sale, Total - Fair Value | 43,088 | 41,204
Securities available for sale, Less than 12 months - Unrealized (Loss) | (125) | (60)
Securities available for sale, 12 months or more - Unrealized (Loss) | (338) | (747)
Total Unrealized (Loss) | (463) | (807)
Securities held to maturity, Less than 12 months - Fair Value | 14,612 |
Securities held to maturity, 12 months or more - Fair Value | 0 |
Securities held to maturity, Total - Fair Value | 14,612 |
Securities held to maturity, Less than 12 months - Unrealized (Loss) | (124) |
Securities held to maturity, 12 months or more - Unrealized (Loss) | 0 |
Total Unrealized (Loss) | (124) |
Obligations of States and Political Subdivisions [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Securities available for sale, Less than 12 months - Fair Value | 2,286 | 715
Securities available for sale, 12 months or more - Fair Value | 1,058 | 2,841
Securities available for sale, Total - Fair Value | 3,344 | 3,556
Securities available for sale, Less than 12 months - Unrealized (Loss) | (15) | (1)
Securities available for sale, 12 months or more - Unrealized (Loss) | (35) | (98)
Total Unrealized (Loss) | (50) | $ (99)
Securities held to maturity, Less than 12 months - Fair Value | 5,000 |
Securities held to maturity, 12 months or more - Fair Value | 0 |
Securities held to maturity, Total - Fair Value | 5,000 |
Securities held to maturity, Less than 12 months - Unrealized (Loss) | (41) |
Securities held to maturity, 12 months or more - Unrealized (Loss) | 0 |
Total Unrealized (Loss) | $ (41) |

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