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Investments (Fair Value and Gross Pre-Tax Net Unrealized Loss of Securities By Length of Time) (Details) - Available-for-sale Securities - USD ($) $ in Thousands | Mar. 31, 2021 | Dec. 31, 2020
--- | --- | ---
AFS Fair Value, Less than 12 Months | $ 812,132 | $ 415,506
AFS Unrealized Losses, Less than 12 months | (16,207) | (6,108)
AFS Fair Value, 12 months or longer | 143,129 | 185,335
AFS Unrealized Losses, 12 months or longer | (3,922) | (5,434)
AFS Fair Value | 955,261 | 600,841
AFS Unrealized Losses | (20,129) | (11,542)
U.S. Government and Government Agencies [Member] |  |
AFS Fair Value, Less than 12 Months | 53,796 | 11,519
AFS Unrealized Losses, Less than 12 months | (2,104) | (137)
AFS Fair Value, 12 months or longer | 0 | 0
AFS Unrealized Losses, 12 months or longer | 0 | 0
AFS Fair Value | 53,796 | 11,519
AFS Unrealized Losses | (2,104) | (137)
Foreign Government [Member] |  |
AFS Fair Value, Less than 12 Months | 3,313 | 1,122
AFS Unrealized Losses, Less than 12 months | (136) | (3)
AFS Fair Value, 12 months or longer | 0 | 0
AFS Unrealized Losses, 12 months or longer | 0 | 0
AFS Fair Value | 3,313 | 1,122
AFS Unrealized Losses | (136) | (3)
Obligations of States and Political Subdivisions [Member] |  |
AFS Fair Value, Less than 12 Months | 18,838 | 2,223
AFS Unrealized Losses, Less than 12 months | (352) | (11)
AFS Fair Value, 12 months or longer | 369 | 0
AFS Unrealized Losses, 12 months or longer | (8) | 0
AFS Fair Value | 19,207 | 2,223
AFS Unrealized Losses | (360) | (11)
Corporate Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 306,052 | 65,187
AFS Unrealized Losses, Less than 12 months | (8,560) | (2,152)
AFS Fair Value, 12 months or longer | 14,025 | 2,400
AFS Unrealized Losses, 12 months or longer | (1,310) | (188)
AFS Fair Value | 320,077 | 67,587
AFS Unrealized Losses | (9,870) | (2,340)
Collateralized Loan Obligations and Other Asset Backed Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 282,939 | 261,746
AFS Unrealized Losses, Less than 12 months | (1,737) | (2,995)
AFS Fair Value, 12 months or longer | 105,261 | 165,661
AFS Unrealized Losses, 12 months or longer | (2,315) | (4,848)
AFS Fair Value | 388,200 | 427,407
AFS Unrealized Losses | (4,052) | (7,843)
Residential Mortgage Backed Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 76,684 | 18,227
AFS Unrealized Losses, Less than 12 months | (1,229) | (194)
AFS Fair Value, 12 months or longer | 0 | 1,181
AFS Unrealized Losses, 12 months or longer | 0 | (7)
AFS Fair Value | 76,684 | 19,408
AFS Unrealized Losses | (1,229) | (201)
Commercial Mortgage Backed Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 70,510 | 55,482
AFS Unrealized Losses, Less than 12 months | (2,089) | (616)
AFS Fair Value, 12 months or longer | 23,474 | 16,093
AFS Unrealized Losses, 12 months or longer | (289) | (391)
AFS Fair Value | 93,984 | 71,575
AFS Unrealized Losses | $ (2,378) | $ (1,007)

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