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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, 2022 | Dec. 31, 2021
--- | --- | ---
AFS Fair Value, Less than 12 Months | $ 3,142,206 | $ 1,376,128
AFS Unrealized Losses, Less than 12 months | (134,038) | (14,849)
AFS Fair Value, 12 months or longer | 155,481 | 85,122
AFS Unrealized Losses, 12 months or longer | (9,441) | (2,505)
AFS Fair Value | 3,297,687 | 1,461,250
AFS Unrealized Losses | (143,479) | (17,354)
U.S. Government and Government Agencies [Member] |  |
AFS Fair Value, Less than 12 Months | 89,044 | 34,857
AFS Unrealized Losses, Less than 12 months | (4,410) | (746)
AFS Fair Value, 12 months or longer | 5,252 | 7,827
AFS Unrealized Losses, 12 months or longer | (973) | (399)
AFS Fair Value | 94,296 | 42,684
AFS Unrealized Losses | (5,383) | (1,145)
Foreign Government [Member] |  |
AFS Fair Value, Less than 12 Months | 5,394 | 2,000
AFS Unrealized Losses, Less than 12 months | (268) | (84)
AFS Fair Value, 12 months or longer | 1,996 | 1,061
AFS Unrealized Losses, 12 months or longer | (184) | (39)
AFS Fair Value | 7,390 | 3,061
AFS Unrealized Losses | (452) | (123)
Obligations of States and Political Subdivisions [Member] |  |
AFS Fair Value, Less than 12 Months | 223,497 | 25,837
AFS Unrealized Losses, Less than 12 months | (9,846) | (235)
AFS Fair Value, 12 months or longer | 2,834 | 0
AFS Unrealized Losses, 12 months or longer | (193) | 0
AFS Fair Value | 226,331 | 25,837
AFS Unrealized Losses | (10,039) | (235)
Corporate Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 1,002,980 | 300,549
AFS Unrealized Losses, Less than 12 months | (59,605) | (4,903)
AFS Fair Value, 12 months or longer | 6,823 | 2,520
AFS Unrealized Losses, 12 months or longer | (715) | (50)
AFS Fair Value | 1,009,803 | 303,069
AFS Unrealized Losses | (60,320) | (4,953)
Collateralized Loan Obligations and Other Asset Backed Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 937,362 | 663,976
AFS Unrealized Losses, Less than 12 months | (28,658) | (4,934)
AFS Fair Value, 12 months or longer | 101,722 | 53,368
AFS Unrealized Losses, 12 months or longer | (4,043) | (1,350)
AFS Fair Value | 1,039,084 | 717,344
AFS Unrealized Losses | (32,701) | (6,284)
Residential Mortgage Backed Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 545,934 | 236,010
AFS Unrealized Losses, Less than 12 months | (21,444) | (2,931)
AFS Fair Value, 12 months or longer | 13,731 | 20
AFS Unrealized Losses, 12 months or longer | (1,147) | (1)
AFS Fair Value | 559,665 | 236,030
AFS Unrealized Losses | (22,591) | (2,932)
Commercial Mortgage Backed Securities [Member] |  |
AFS Fair Value, Less than 12 Months | 337,995 | 112,899
AFS Unrealized Losses, Less than 12 months | (9,807) | (1,016)
AFS Fair Value, 12 months or longer | 23,123 | 20,326
AFS Unrealized Losses, 12 months or longer | (2,186) | (666)
AFS Fair Value | 361,118 | 133,225
AFS Unrealized Losses | $ (11,993) | $ (1,682)

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