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Investments (Fair Value and Gross Pre-Tax Net Unrealized Loss of Securities By Length of Time) (Details) - USD ($) $ in Thousands | 9 Months Ended |
--- | --- | ---
Sep. 30, 2019 | Dec. 31, 2018
Percent Of Securities of Amortized Cost In An Unrealized Unrecognized Loss Position |  | 1.00% | 2.00%
AFS Fixed Income Securities [Member] |  |  |
AFS Fair Value, Less than 12 Months |  | $ 416,634 | $ 2,142,433
AFS Unrealized Losses, Less than 12 months | [1] | (4,964) | (36,948)
AFS Fair Value, 12 months or longer |  | 214,441 | 275,174
AFS Unrealized Losses, 12 months or longer | [1] | (2,783) | (8,119)
AFS Fair Value |  | 631,075 | 2,417,607
AFS Unrealized Losses | [1] | (7,747) | (45,067)
AFS Fixed Income Securities [Member] | U.S. Government and Government Agencies [Member] |  |  |
AFS Fair Value, Less than 12 Months |  | 5,014 | 6,693
AFS Unrealized Losses, Less than 12 months | [1] | (11) | (174)
AFS Fair Value, 12 months or longer |  | 498 | 23,163
AFS Unrealized Losses, 12 months or longer | [1] | (1) | (418)
AFS Fair Value |  | 5,512 | 29,856
AFS Unrealized Losses | [1] | (12) | (592)
AFS Fixed Income Securities [Member] | Foreign Government [Member] |  |  |
AFS Fair Value, Less than 12 Months |  |  | 12,208
AFS Unrealized Losses, Less than 12 months | [1] |  | (93)
AFS Fair Value, 12 months or longer |  |  | 1,482
AFS Unrealized Losses, 12 months or longer | [1] |  | (14)
AFS Fair Value |  |  | 13,690
AFS Unrealized Losses | [1] |  | (107)
AFS Fixed Income Securities [Member] | Obligations of States and Political Subdivisions [Member] |  |  |
AFS Fair Value, Less than 12 Months |  | 437 | 196,798
AFS Unrealized Losses, Less than 12 months | [1] | (4) | (2,074)
AFS Fair Value, 12 months or longer |  | 0 | 42,821
AFS Unrealized Losses, 12 months or longer | [1] | 0 | (557)
AFS Fair Value |  | 437 | 239,619
AFS Unrealized Losses | [1] | (4) | (2,631)
AFS Fixed Income Securities [Member] | Corporate Securities [Member] |  |  |
AFS Fair Value, Less than 12 Months |  | 89,919 | 1,041,952
AFS Unrealized Losses, Less than 12 months | [1] | (1,862) | (23,649)
AFS Fair Value, 12 months or longer |  | 15,867 | 78,953
AFS Unrealized Losses, 12 months or longer | [1] | (537) | (4,316)
AFS Fair Value |  | 105,786 | 1,120,905
AFS Unrealized Losses | [1] | (2,399) | (27,965)
AFS Fixed Income Securities [Member] | Collateralized Loan Obligations and Other Asset Backed Securities [Member] |  |  |
AFS Fair Value, Less than 12 Months |  | 176,999 | 516,106
AFS Unrealized Losses, Less than 12 months | [1] | (2,458) | (6,750)
AFS Fair Value, 12 months or longer |  | 180,898 | 16,800
AFS Unrealized Losses, 12 months or longer | [1] | (2,195) | (193)
AFS Fair Value |  | 357,897 | 532,906
AFS Unrealized Losses | [1] | (4,653) | (6,943)
AFS Fixed Income Securities [Member] | Commercial Mortgage Backed Securities [Member] |  |  |
AFS Fair Value, Less than 12 Months |  | 59,857 | 229,338
AFS Unrealized Losses, Less than 12 months | [1] | (126) | (2,548)
AFS Fair Value, 12 months or longer |  | 7,665 | 66,294
AFS Unrealized Losses, 12 months or longer | [1] | (19) | (1,200)
AFS Fair Value |  | 67,522 | 295,632
AFS Unrealized Losses | [1] | (145) | (3,748)
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member] |  |  |
AFS Fair Value, Less than 12 Months |  | 84,408 | 139,338
AFS Unrealized Losses, Less than 12 months | [1] | (503) | (1,660)
AFS Fair Value, 12 months or longer |  | 9,513 | 45,661
AFS Unrealized Losses, 12 months or longer | [1] | (31) | (1,421)
AFS Fair Value |  | 93,921 | 184,999
AFS Unrealized Losses | [1] | (534) | $ (3,081)
Available-for-sale Securities [Member] | AFS Fixed Income Securities [Member] |  |  |
AFS Unrealized Losses 9/30/2019 compared to 12/31/2018 | [1] | $ (37,300) |
[1] | Gross unrealized losses include non-OTTI unrealized amounts and OTTI losses recognized in AOCI.

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