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Investment Securities - Amortized Cost and Fair Value (Details) - USD ($) $ in Thousands | Sep. 30, 2017 | Dec. 31, 2016
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Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Held to maturity, Amortized Cost | $ 155,122 | $ 44,438
Held to maturity, Fair Value | 156,149 | 45,097
Held-to-maturity, Gross Unrealized Gains | 1,175 | 820
Held-to-maturity, Gross Unrealized Losses | (148) | (161)
Available-for-sale, Amortized Cost | 257,468 | 378,254
Available-for-sale, at fair value | 258,092 | 372,580
Available-for-sale, Gross Unrealized Gains | 1,477 | 575
Available-for-sale, Gross Unrealized Losses | (853) | (6,249)
Total investment securities, Amortized Cost | 412,590 | 422,692
Total investment securities, Fair Value | 414,241 | 417,677
Total investment securities, Gross Unrealized Gains | 2,652 | 1,395
Total investment securities, Gross Unrealized Losses | (1,001) | (6,410)
MBS pass-through securities issued by FHLMC and FNMA |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available-for-sale, Amortized Cost | 91,404 | 193,998
Available-for-sale, at fair value | 91,716 | 190,566
Available-for-sale, Gross Unrealized Gains | 551 | 145
Available-for-sale, Gross Unrealized Losses | (239) | (3,577)
CMOs issued by FNMA |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available-for-sale, Amortized Cost | 11,504 | 13,790
Available-for-sale, at fair value | 11,529 | 13,772
Available-for-sale, Gross Unrealized Gains | 68 | 91
Available-for-sale, Gross Unrealized Losses | (43) | (109)
CMOs issued by FHLMC |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available-for-sale, Amortized Cost | 35,317 | 43,452
Available-for-sale, at fair value | 35,360 | 42,758
Available-for-sale, Gross Unrealized Gains | 56 | 37
Available-for-sale, Gross Unrealized Losses | (13) | (731)
CMOs issued by GNMA |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available-for-sale, Amortized Cost | 8,754 | 6,844
Available-for-sale, at fair value | 8,765 | 6,945
Available-for-sale, Gross Unrealized Gains | 62 | 102
Available-for-sale, Gross Unrealized Losses | (51) | (1)
Debentures of government- sponsored agencies |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available-for-sale, Amortized Cost | 30,492 | 35,486
Available-for-sale, at fair value | 30,382 | 35,403
Available-for-sale, Gross Unrealized Gains | 0 | 7
Available-for-sale, Gross Unrealized Losses | (110) | (90)
Privately issued CMOs |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available-for-sale, Amortized Cost | 127 | 419
Available-for-sale, at fair value | 128 | 419
Available-for-sale, Gross Unrealized Gains | 1 | 1
Available-for-sale, Gross Unrealized Losses | 0 | (1)
Obligations of state and political subdivisions |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available-for-sale, Amortized Cost | 74,903 | 79,306
Available-for-sale, at fair value | 75,181 | 77,701
Available-for-sale, Gross Unrealized Gains | 675 | 135
Available-for-sale, Gross Unrealized Losses | (397) | (1,740)
Corporate bonds |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available-for-sale, Amortized Cost | 4,967 | 4,959
Available-for-sale, at fair value | 5,031 | 5,016
Available-for-sale, Gross Unrealized Gains | 64 | 57
Available-for-sale, Gross Unrealized Losses | 0 | 0
Obligations of state and political subdivisions |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Held to maturity, Amortized Cost | 20,213 | 30,856
Held to maturity, Fair Value | 20,790 | 31,544
Held-to-maturity, Gross Unrealized Gains | 577 | 694
Held-to-maturity, Gross Unrealized Losses | 0 | (6)
Corporate bonds |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Held to maturity, Amortized Cost | 0 | 3,519
Held to maturity, Fair Value | 0 | 3,518
Held-to-maturity, Gross Unrealized Gains | 0 | 0
Held-to-maturity, Gross Unrealized Losses | 0 | (1)
MBS pass-through securities issued by FHLMC and FNMA |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Held to maturity, Amortized Cost | 103,624 | 10,063
Held to maturity, Fair Value | 103,904 | 10,035
Held-to-maturity, Gross Unrealized Gains | 425 | 126
Held-to-maturity, Gross Unrealized Losses | (145) | (154)
CMOs issued by FHLMC |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Held to maturity, Amortized Cost | 31,285 | 0
Held to maturity, Fair Value | 31,455 | 0
Held-to-maturity, Gross Unrealized Gains | 173 | 0
Held-to-maturity, Gross Unrealized Losses | $ (3) | $ 0

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