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Investment Securities - Amortized Cost and Fair Value (Details) - USD ($) $ in Thousands | Dec. 31, 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 | $ 151,032 | $ 44,438
Held-to-maturity, Fair Value | 151,032 | 45,097
Held-to-maturity, Gross Unrealized Gains | 619 | 820
Held-to-maturity, Gross Unrealized (Losses) | (619) | (161)
Available for sale, Amortized Cost | 334,285 | 378,254
Available-for-sale, at fair value | 332,467 | 372,580
Available-for-sale, Gross Unrealized Gains | 574 | 575
Available-for-sale, Gross Unrealized (Losses) | (2,392) | (6,249)
Total investment securities, Amortized Cost | 485,317 | 422,692
Total investment securities, Fair Value | 483,499 | 417,677
Total investment securities, Gross Unrealized Gains | 1,193 | 1,395
Total investment securities, Gross Unrealized (Losses) | (3,011) | (6,410)
MBS pass-through securities |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available for sale, Amortized Cost | 65,559 | 193,384
Available-for-sale, at fair value | 65,262 | 189,959
Available-for-sale, Gross Unrealized Gains | 126 | 145
Available-for-sale, Gross Unrealized (Losses) | (423) | (3,570)
SBA-backed securities |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available for sale, Amortized Cost | 25,979 | 614
Available-for-sale, at fair value | 25,982 | 607
Available-for-sale, Gross Unrealized Gains | 58 | 0
Available-for-sale, Gross Unrealized (Losses) | (55) | (7)
CMOs issued by FNMA |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available for sale, Amortized Cost | 35,340 | 13,790
Available-for-sale, at fair value | 35,125 | 13,772
Available-for-sale, Gross Unrealized Gains | 33 | 91
Available-for-sale, Gross Unrealized (Losses) | (248) | (109)
CMOs issued by FHLMC |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available for sale, Amortized Cost | 70,514 | 43,452
Available-for-sale, at fair value | 69,889 | 42,758
Available-for-sale, Gross Unrealized Gains | 3 | 37
Available-for-sale, Gross Unrealized (Losses) | (628) | (731)
CMOs issued by GNMA |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available for sale, Amortized Cost | 17,953 | 6,844
Available-for-sale, at fair value | 17,785 | 6,945
Available-for-sale, Gross Unrealized Gains | 26 | 102
Available-for-sale, Gross Unrealized (Losses) | (194) | (1)
Debentures of government- sponsored agencies |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available for sale, Amortized Cost | 12,940 | 35,486
Available-for-sale, at fair value | 12,938 | 35,403
Available-for-sale, Gross Unrealized Gains | 3 | 7
Available-for-sale, Gross Unrealized (Losses) | (5) | (90)
Privately issued CMOs |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Available for sale, Amortized Cost | 1,432 | 419
Available-for-sale, at fair value | 1,431 | 419
Available-for-sale, Gross Unrealized Gains | 1 | 1
Available-for-sale, Gross Unrealized (Losses) | (2) | (1)
Obligations of state and political subdivisions |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Held to maturity, Amortized Cost | 19,646 | 30,856
Held-to-maturity, Fair Value | 19,998 | 31,544
Held-to-maturity, Gross Unrealized Gains | 383 | 694
Held-to-maturity, Gross Unrealized (Losses) | (31) | (6)
Available for sale, Amortized Cost | 98,027 | 79,306
Available-for-sale, at fair value | 97,491 | 77,701
Available-for-sale, Gross Unrealized Gains | 298 | 135
Available-for-sale, Gross Unrealized (Losses) | (834) | (1,740)
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)
Available for sale, Amortized Cost | 6,541 | 4,959
Available-for-sale, at fair value | 6,564 | 5,016
Available-for-sale, Gross Unrealized Gains | 26 | 57
Available-for-sale, Gross Unrealized (Losses) | (3) | 0
MBS pass-through securities |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Held to maturity, Amortized Cost | 100,376 | 10,063
Held-to-maturity, Fair Value | 100,096 | 10,035
Held-to-maturity, Gross Unrealized Gains | 234 | 126
Held-to-maturity, Gross Unrealized (Losses) | (514) | (154)
CMOs issued by FHLMC |  |
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Held to maturity, Amortized Cost | 31,010 | 0
Held-to-maturity, Fair Value | 30,938 | 0
Held-to-maturity, Gross Unrealized Gains | 2 | 0
Held-to-maturity, Gross Unrealized (Losses) | $ (74) | $ 0

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