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Securities, AFS Securities in Continuous Unrealized Loss Position (Details) $ in Thousands | Sep. 30, 2021 USD ($) Position | Dec. 31, 2020 USD ($) Position
--- | --- | ---
Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 657,563 | $ 213,643
12 months or longer | 154,869 | 800
Total | 812,432 | 214,443
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less than 12 months | (8,405) | (2,170)
12 months or longer | (4,105) | (9)
Total | $ (12,510) | $ (2,179)
Unrealized Loss Position, Number of Positions [Abstract] |  |
Less than 12 months | Position | 94 | 19
12 months or longer | Position | 15 | 4
Total | Position | 109 | 23
AIR on AFS debt securities | $ 3,300 | $ 3,300
Federal Agency [Member] |  |
Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | 101,674 | 148,537
12 months or longer | 141,292 | 0
Total | 242,966 | 148,537
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less than 12 months | (1,799) | (2,052)
12 months or longer | (3,697) | 0
Total | $ (5,496) | $ (2,052)
Unrealized Loss Position, Number of Positions [Abstract] |  |
Less than 12 months | Position | 7 | 10
12 months or longer | Position | 9 | 0
Total | Position | 16 | 10
State & Municipal [Member] |  |
Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 68,492 |
12 months or longer | 0 |
Total | 68,492 |
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less than 12 months | (753) |
12 months or longer | 0 |
Total | $ (753) |
Unrealized Loss Position, Number of Positions [Abstract] |  |
Less than 12 months | Position | 45 |
12 months or longer | Position | 0 |
Total | Position | 45 |
Mortgage-Backed [Member] |  |
Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 239,779 | $ 47,269
12 months or longer | 761 | 800
Total | 240,540 | 48,069
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less than 12 months | (4,060) | (60)
12 months or longer | (8) | (9)
Total | $ (4,068) | $ (69)
Unrealized Loss Position, Number of Positions [Abstract] |  |
Less than 12 months | Position | 18 | 3
12 months or longer | Position | 4 | 4
Total | Position | 22 | 7
Collateralized Mortgage Obligations [Member] |  |
Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 247,618 | $ 17,837
12 months or longer | 12,816 | 0
Total | 260,434 | 17,837
Unrealized Loss Position, Unrealized Losses [Abstract] |  |
Less than 12 months | (1,793) | (58)
12 months or longer | (400) | 0
Total | $ (2,193) | $ (58)
Unrealized Loss Position, Number of Positions [Abstract] |  |
Less than 12 months | Position | 24 | 6
12 months or longer | Position | 2 | 0
Total | Position | 26 | 6

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