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Investment Securities - Unrealized Loss Positions (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Dec. 31, 2019
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Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, fair value | $ 2,014 | $ 81,958
Available-for-sale, greater than 12 continuous months, fair value | 1,900 | 10,552
Available-for-sale, total securities in a loss position, fair value | 3,914 | 92,510
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, unrealized loss | (1) | (328)
Available-for-sale, greater than 12 continuous months, unrealized loss | (57) | (83)
Available-for-sale, total securities in a loss position, unrealized loss | (58) | (411)
Marketable Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Marketable securities, less than 12 continuous months, fair value | 2,014 | 96,161
Marketable securities, greater than 12 continuous months, fair value | 1,900 | 18,350
Marketable securities, total securities in a loss position, fair value | 3,914 | 114,511
Marketable Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Marketable securities, less than 12 continuous months, unrealized loss | (1) | (388)
Marketable securities, greater than 12 continuous months, unrealized loss | (57) | (172)
Marketable securities, total securities in a loss position, unrealized loss | (58) | (560)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 continuous months |  | 14,203
Greater than or equal to 12 continuous months |  | 7,798
Total Securities in a loss position |  | 22,001
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Less than 12 continuous months |  | (60)
Greater than or equal to 12 continuous months |  | (89)
Held-to-maturity, gross unrealized losses |  | (149)
MBS pass-through securities issued by FHLMC and FNMA |  |
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, fair value |  | 4,367
Available-for-sale, greater than 12 continuous months, fair value |  | 4,464
Available-for-sale, total securities in a loss position, fair value |  | 8,831
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, unrealized loss |  | (34)
Available-for-sale, greater than 12 continuous months, unrealized loss |  | (14)
Available-for-sale, total securities in a loss position, unrealized loss |  | (48)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 continuous months |  | 14,203
Greater than or equal to 12 continuous months |  | 6,073
Total Securities in a loss position |  | 20,276
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Less than 12 continuous months |  | (60)
Greater than or equal to 12 continuous months |  | (84)
Held-to-maturity, gross unrealized losses |  | (144)
SBA-backed securities |  |
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, fair value | 0 | 9,227
Available-for-sale, greater than 12 continuous months, fair value | 1,900 | 2,448
Available-for-sale, total securities in a loss position, fair value | 1,900 | 11,675
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, unrealized loss | 0 | (14)
Available-for-sale, greater than 12 continuous months, unrealized loss | (57) | (62)
Available-for-sale, total securities in a loss position, unrealized loss | (57) | (76)
CMOs issued by FHLMC |  |
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, fair value | 2,014 | 14,918
Available-for-sale, greater than 12 continuous months, fair value | 0 | 2,981
Available-for-sale, total securities in a loss position, fair value | 2,014 | 17,899
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, unrealized loss | (1) | (58)
Available-for-sale, greater than 12 continuous months, unrealized loss | 0 | (6)
Available-for-sale, total securities in a loss position, unrealized loss | $ (1) | (64)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 continuous months |  | 0
Greater than or equal to 12 continuous months |  | 1,725
Total Securities in a loss position |  | 1,725
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Less than 12 continuous months |  | 0
Greater than or equal to 12 continuous months |  | (5)
Held-to-maturity, gross unrealized losses |  | (5)
CMOs issued by GNMA |  |
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, fair value |  | 7,139
Available-for-sale, greater than 12 continuous months, fair value |  | 0
Available-for-sale, total securities in a loss position, fair value |  | 7,139
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, unrealized loss |  | (6)
Available-for-sale, greater than 12 continuous months, unrealized loss |  | 0
Available-for-sale, total securities in a loss position, unrealized loss |  | (6)
Debentures of government- sponsored agencies |  |
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, fair value |  | 25,228
Available-for-sale, greater than 12 continuous months, fair value |  | 0
Available-for-sale, total securities in a loss position, fair value |  | 25,228
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, unrealized loss |  | (70)
Available-for-sale, greater than 12 continuous months, unrealized loss |  | 0
Available-for-sale, total securities in a loss position, unrealized loss |  | (70)
Obligations of state and political subdivisions |  |
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, fair value |  | 20,579
Available-for-sale, greater than 12 continuous months, fair value |  | 659
Available-for-sale, total securities in a loss position, fair value |  | 21,238
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, unrealized loss |  | (145)
Available-for-sale, greater than 12 continuous months, unrealized loss |  | (1)
Available-for-sale, total securities in a loss position, unrealized loss |  | (146)
Corporate bonds |  |
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, fair value |  | 500
Available-for-sale, greater than 12 continuous months, fair value |  | 0
Available-for-sale, total securities in a loss position, fair value |  | 500
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, unrealized loss |  | (1)
Available-for-sale, greater than 12 continuous months, unrealized loss |  | 0
Available-for-sale, total securities in a loss position, unrealized loss |  | $ (1)

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