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Investments (Fair Value and Gross Pre-Tax Net Unrealized Loss of Securities By Length of Time) (Details) - AFS Fixed Income Securities [Member] - USD ($) $ in Thousands | Mar. 31, 2020 | Dec. 31, 2019
--- | --- | ---
AFS Fair Value, Less than 12 Months | $ 1,290,052 | $ 516,259
AFS Unrealized Losses, Less than 12 months | (96,447) | (3,379)
AFS Fair Value, 12 months or longer | 157,945 | 230,770
AFS Unrealized Losses, 12 months or longer | (20,464) | (4,359)
AFS Fair Value | 1,447,997 | 747,029
AFS Unrealized Losses | (116,911) | (7,738)
Foreign Government [Member] |  |
AFS Fair Value, Less than 12 Months | 4,376 | 1,416
AFS Unrealized Losses, Less than 12 months | (252) | (2)
AFS Fair Value, 12 months or longer | 0 | 0
AFS Unrealized Losses, 12 months or longer | 0 | 0
AFS Fair Value | 4,376 | 1,416
AFS Unrealized Losses | (252) | (2)
Obligations of States and Political Subdivisions [Member] |  |
AFS Fair Value, Less than 12 Months | 70,830 | 35,838
AFS Unrealized Losses, Less than 12 months | (1,434) | (270)
AFS Fair Value, 12 months or longer | 0 | 0
AFS Unrealized Losses, 12 months or longer | 0 | 0
AFS Fair Value | 70,830 | 35,838
AFS Unrealized Losses | (1,434) | (270)
Corporate Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 553,419 | 84,832
AFS Unrealized Losses, Less than 12 months | (31,677) | (480)
AFS Fair Value, 12 months or longer | 8,185 | 20,182
AFS Unrealized Losses, 12 months or longer | (1,181) | (830)
AFS Fair Value | 561,604 | 105,014
AFS Unrealized Losses | (32,858) | (1,310)
Collateralized Loan Obligations and Other Asset Backed Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 445,676 | 205,191
AFS Unrealized Losses, Less than 12 months | (49,404) | (1,938)
AFS Fair Value, 12 months or longer | 136,413 | 204,385
AFS Unrealized Losses, 12 months or longer | (18,094) | (3,496)
AFS Fair Value | 582,089 | 409,576
AFS Unrealized Losses | (67,498) | (5,434)
Commercial Mortgage Backed Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 144,010 | 62,893
AFS Unrealized Losses, Less than 12 months | (11,119) | (264)
AFS Fair Value, 12 months or longer | 11,373 | 828
AFS Unrealized Losses, 12 months or longer | (1,023) | (3)
AFS Fair Value | 155,383 | 63,721
AFS Unrealized Losses | (12,142) | (267)
Residential Mortgage Backed Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 71,741 | 126,089
AFS Unrealized Losses, Less than 12 months | (2,561) | (425)
AFS Fair Value, 12 months or longer | 1,974 | 5,375
AFS Unrealized Losses, 12 months or longer | (166) | (30)
AFS Fair Value | 73,715 | 131,464
AFS Unrealized Losses | $ (2,727) | $ (455)

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