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Securities - Fair Values and Amortized Costs Securities (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Dec. 31, 2019
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Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | $ 679,473 | $ 768,427
Debt Securities, Available-for-Sale, Gross Unrealized Gains | 35,448 | 11,659
Debt Securities, Available-for-Sale, Gross Unrealized Losses | (1) | (953)
Debt Securities, Available-for-Sale, Fair Value | 714,920 | 779,133
Marketable equity securities | 3,249 | 5,150
Total Securities | 718,169 | 784,283
Interest receivable | 3,000 | 3,400
U.S. Treasury securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 9,977 | 9,969
Debt Securities, Available-for-Sale, Gross Unrealized Gains | 346 | 71
Debt Securities, Available-for-Sale, Gross Unrealized Losses | 0 |
Debt Securities, Available-for-Sale, Fair Value | 10,323 | 10,040
Obligations of U.S. government corporations and agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 88,809 | 155,969
Debt Securities, Available-for-Sale, Gross Unrealized Gains | 4,542 | 1,773
Debt Securities, Available-for-Sale, Gross Unrealized Losses | 0 | (45)
Debt Securities, Available-for-Sale, Fair Value | 93,351 | 157,697
Collateralized mortgage obligations of U.S. government corporations and agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 175,516 | 186,879
Debt Securities, Available-for-Sale, Gross Unrealized Gains | 7,516 | 2,773
Debt Securities, Available-for-Sale, Gross Unrealized Losses | 0 | (304)
Debt Securities, Available-for-Sale, Fair Value | 183,032 | 189,348
Residential mortgage-backed securities of U.S. government corporations and agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 16,578 | 22,120
Debt Securities, Available-for-Sale, Gross Unrealized Gains | 774 | 321
Debt Securities, Available-for-Sale, Gross Unrealized Losses | 0 | (23)
Debt Securities, Available-for-Sale, Fair Value | 17,352 | 22,418
Commercial mortgage-backed securities of U.S. government corporations and agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 265,202 | 273,771
Debt Securities, Available-for-Sale, Gross Unrealized Gains | 15,022 | 2,680
Debt Securities, Available-for-Sale, Gross Unrealized Losses | 0 | (581)
Debt Securities, Available-for-Sale, Fair Value | 280,224 | 275,870
Corporate obligations |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 4,023 | 7,603
Debt Securities, Available-for-Sale, Gross Unrealized Gains | 5 | 24
Debt Securities, Available-for-Sale, Gross Unrealized Losses | (1) | 0
Debt Securities, Available-for-Sale, Fair Value | 4,027 | 7,627
Obligations of states and political subdivisions |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-Sale, Amortized Cost | 119,368 | 112,116
Debt Securities, Available-for-Sale, Gross Unrealized Gains | 7,243 | 4,017
Debt Securities, Available-for-Sale, Gross Unrealized Losses | 0 | 0
Debt Securities, Available-for-Sale, Fair Value | $ 126,611 | $ 116,133

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