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Securities - Amortized Cost and Fair Value of Debt Securities (Details) - USD ($) $ in Thousands | Jun. 30, 2023 | Dec. 31, 2022
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | $ 1,071,876 | $ 1,104,105
Gross Unrealized Gains | 14 | 261
Gross Unrealized Losses | (102,465) | (102,582)
Fair Value | 969,425 | 1,001,784
Interest receivable | 3,300 | 3,700
U.S. Treasury securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 144,858 | 145,416
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (13,623) | (13,721)
Fair Value | 131,235 | 131,695
Obligations of U.S. government corporations and agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 43,411 | 43,479
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (1,546) | (1,668)
Fair Value | 41,865 | 41,811
Collateralized mortgage obligations of U.S. government corporations and agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 485,131 | 482,039
Gross Unrealized Gains | 0 | 203
Gross Unrealized Losses | (56,242) | (53,835)
Fair Value | 428,889 | 428,407
Residential mortgage-backed securities of U.S. government corporations and agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 46,958 | 49,418
Gross Unrealized Gains | 2 | 3
Gross Unrealized Losses | (7,180) | (7,834)
Fair Value | 39,780 | 41,587
Commercial mortgage-backed securities of U.S. government corporations and agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 320,993 | 352,465
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (23,715) | (25,152)
Fair Value | 297,278 | 327,313
Corporate obligations |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 0 | 500
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | 0 | 0
Fair Value | 0 | 500
Obligations of states and political subdivisions |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 30,525 | 30,788
Gross Unrealized Gains | 12 | 55
Gross Unrealized Losses | (159) | (372)
Fair Value | $ 30,378 | $ 30,471

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