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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 | Jun. 30, 2022 | Dec. 31, 2021
--- | --- | ---
AFS Fair Value, Less than 12 Months | $ 4,657,248 | $ 1,376,128
AFS Unrealized Losses, Less than 12 months | (335,523) | (14,849)
AFS Fair Value, 12 months or longer | 225,652 | 85,122
AFS Unrealized Losses, 12 months or longer | (22,174) | (2,505)
AFS Fair Value | 4,882,900 | 1,461,250
AFS Unrealized Losses | (357,697) | (17,354)
U.S. Government and Government Agencies [Member] |  |
AFS Fair Value, Less than 12 Months | 89,797 | 34,857
AFS Unrealized Losses, Less than 12 months | (9,864) | (746)
AFS Fair Value, 12 months or longer | 4,522 | 7,827
AFS Unrealized Losses, 12 months or longer | (1,532) | (399)
AFS Fair Value | 94,319 | 42,684
AFS Unrealized Losses | (11,396) | (1,145)
Foreign Government [Member] |  |
AFS Fair Value, Less than 12 Months | 11,027 | 2,000
AFS Unrealized Losses, Less than 12 months | (962) | (84)
AFS Fair Value, 12 months or longer | 1,799 | 1,061
AFS Unrealized Losses, 12 months or longer | (376) | (39)
AFS Fair Value | 12,826 | 3,061
AFS Unrealized Losses | (1,338) | (123)
Obligations of States and Political Subdivisions [Member] |  |
AFS Fair Value, Less than 12 Months | 466,743 | 25,837
AFS Unrealized Losses, Less than 12 months | (31,280) | (235)
AFS Fair Value, 12 months or longer | 2,875 | 0
AFS Unrealized Losses, 12 months or longer | (278) | 0
AFS Fair Value | 469,618 | 25,837
AFS Unrealized Losses | (31,558) | (235)
Corporate Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 1,649,434 | 300,549
AFS Unrealized Losses, Less than 12 months | (152,902) | (4,903)
AFS Fair Value, 12 months or longer | 6,839 | 2,520
AFS Unrealized Losses, 12 months or longer | (1,302) | (50)
AFS Fair Value | 1,656,273 | 303,069
AFS Unrealized Losses | (154,204) | (4,953)
Collateralized Loan Obligations and Other Asset Backed Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 1,114,978 | 663,976
AFS Unrealized Losses, Less than 12 months | (68,918) | (4,934)
AFS Fair Value, 12 months or longer | 158,322 | 53,368
AFS Unrealized Losses, 12 months or longer | (11,581) | (1,350)
AFS Fair Value | 1,273,300 | 717,344
AFS Unrealized Losses | (80,499) | (6,284)
Residential Mortgage Backed Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 813,811 | 236,010
AFS Unrealized Losses, Less than 12 months | (47,346) | (2,931)
AFS Fair Value, 12 months or longer | 17,605 | 20
AFS Unrealized Losses, 12 months or longer | (2,839) | (1)
AFS Fair Value | 831,416 | 236,030
AFS Unrealized Losses | (50,185) | (2,932)
Commercial Mortgage Backed Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 511,458 | 112,899
AFS Unrealized Losses, Less than 12 months | (24,251) | (1,016)
AFS Fair Value, 12 months or longer | 33,690 | 20,326
AFS Unrealized Losses, 12 months or longer | (4,266) | (666)
AFS Fair Value | 545,148 | 133,225
AFS Unrealized Losses | $ (28,517) | $ (1,682)

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