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v3.23.1

Investments in Fixed Maturity Securities (Investments in fixed maturity securities) (Details) - USD ($) $ in Thousands | Mar. 31, 2023 | Dec. 31, 2022 | Mar. 31, 2022 | Dec. 31, 2021
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Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total held to maturity, Amortized Cost | $ 51,873 | $ 51,410 |  |
Held-to-maturity, Allowance for Credit Loss | (107) | (114) | $ (378) | $ (387)
Held to maturity, Gross Unrealized Gains | 3,955 | 4,277 |  |
Held to maturity, Gross Unrealized Losses | 0 | 0 |  |
Total held to maturity, Fair Value | 55,721 | 55,573 |  |
Total held to maturity, Carrying Value | 51,766 | 51,296 |  |
Total available for sale, Amortized Cost | 18,936,586 | 18,664,073 |  |
Available-for-sale, Allowance for Credit Loss | (37,142) | (37,352) | (26,153) | (22,238)
Total available for sale, Gross Unrealized Gains | 56,556 | 32,166 |  |
Total available for sale, Gross Unrealized Losses | (916,653) | (1,122,834) |  |
Total available for sale, Fair Value | 18,039,347 | 17,536,053 |  |
Total available for sale, Carrying Value | 18,039,347 | 17,536,053 |  |
Total investments in fixed maturity securities, Amortized Value | 18,988,459 | 18,715,483 |  |
Fixed maturity securities, allowance for credit loss | (37,249) | (37,466) |  |
Total investments in fixed maturity securities, Gross Unrealized Gains | 60,511 | 36,443 |  |
Total investments in fixed maturity securities, Gross Unrealized Losses | (916,653) | (1,122,834) |  |
Total investments in fixed maturity securities, Fair Value | 18,095,068 | 17,591,626 |  |
Total investments in fixed maturity securities, Carrying Value | 18,091,113 | 17,587,349 |  |
State and municipal |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total held to maturity, Amortized Cost | 48,474 | 47,802 |  |
Held-to-maturity, Allowance for Credit Loss | (107) | (114) |  |
Held to maturity, Gross Unrealized Gains | 3,902 | 4,239 |  |
Held to maturity, Gross Unrealized Losses | 0 | 0 |  |
Total held to maturity, Fair Value | 52,269 | 51,927 |  |
Total held to maturity, Carrying Value | 48,367 | 47,688 |  |
Total available for sale, Amortized Cost | 2,899,206 | 3,046,335 |  |
Available-for-sale, Allowance for Credit Loss | 0 | 0 |  |
Total available for sale, Gross Unrealized Gains | 17,573 | 12,355 |  |
Total available for sale, Gross Unrealized Losses | (127,420) | (168,592) |  |
Total available for sale, Fair Value | 2,789,359 | 2,890,098 |  |
Total available for sale, Carrying Value | 2,789,359 | 2,890,098 |  |
Residential mortgage-backed |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total held to maturity, Amortized Cost | 3,399 | 3,608 |  |
Held-to-maturity, Allowance for Credit Loss | 0 | 0 |  |
Held to maturity, Gross Unrealized Gains | 53 | 38 |  |
Held to maturity, Gross Unrealized Losses | 0 | 0 |  |
Total held to maturity, Fair Value | 3,452 | 3,646 |  |
Total held to maturity, Carrying Value | 3,399 | 3,608 |  |
Total available for sale, Amortized Cost | 1,464,856 | 1,308,019 |  |
Available-for-sale, Allowance for Credit Loss | (23) | (18) |  |
Total available for sale, Gross Unrealized Gains | 2,298 | 395 |  |
Total available for sale, Gross Unrealized Losses | (153,147) | (171,595) |  |
Total available for sale, Fair Value | 1,313,984 | 1,136,801 |  |
Total available for sale, Carrying Value | 1,313,984 | 1,136,801 |  |
U.S. government and government agency |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 1,100,204 | 960,479 |  |
Available-for-sale, Allowance for Credit Loss | 0 | 0 |  |
Total available for sale, Gross Unrealized Gains | 3,728 | 937 |  |
Total available for sale, Gross Unrealized Losses | (54,665) | (69,158) |  |
Total available for sale, Fair Value | 1,049,267 | 892,258 |  |
Total available for sale, Carrying Value | 1,049,267 | 892,258 |  |
Special revenue |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 1,759,098 | 1,837,309 |  |
Available-for-sale, Allowance for Credit Loss | 0 | 0 |  |
Total available for sale, Gross Unrealized Gains | 5,429 | 3,662 |  |
Total available for sale, Gross Unrealized Losses | (90,044) | (119,474) |  |
Total available for sale, Fair Value | 1,674,483 | 1,721,497 |  |
Total available for sale, Carrying Value | 1,674,483 | 1,721,497 |  |
State general obligation |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 386,952 | 387,709 |  |
Available-for-sale, Allowance for Credit Loss | 0 | 0 |  |
Total available for sale, Gross Unrealized Gains | 4,090 | 2,651 |  |
Total available for sale, Gross Unrealized Losses | (16,577) | (21,335) |  |
Total available for sale, Fair Value | 374,465 | 369,025 |  |
Total available for sale, Carrying Value | 374,465 | 369,025 |  |
Pre-refunded |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 105,812 | 156,106 |  |
Available-for-sale, Allowance for Credit Loss | 0 | 0 |  |
Total available for sale, Gross Unrealized Gains | 3,351 | 2,741 |  |
Total available for sale, Gross Unrealized Losses | (248) | (7) |  |
Total available for sale, Fair Value | 108,915 | 158,840 |  |
Total available for sale, Carrying Value | 108,915 | 158,840 |  |
Corporate backed |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 204,773 | 210,228 |  |
Available-for-sale, Allowance for Credit Loss | 0 | 0 |  |
Total available for sale, Gross Unrealized Gains | 491 | 334 |  |
Total available for sale, Gross Unrealized Losses | (8,447) | (10,923) |  |
Total available for sale, Fair Value | 196,817 | 199,639 |  |
Total available for sale, Carrying Value | 196,817 | 199,639 |  |
Local general obligation |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 442,571 | 454,983 |  |
Available-for-sale, Allowance for Credit Loss | 0 | 0 |  |
Total available for sale, Gross Unrealized Gains | 4,212 | 2,967 |  |
Total available for sale, Gross Unrealized Losses | (12,104) | (16,853) |  |
Total available for sale, Fair Value | 434,679 | 441,097 |  |
Total available for sale, Carrying Value | 434,679 | 441,097 |  |
Commercial |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 595,818 | 547,757 |  |
Available-for-sale, Allowance for Credit Loss | 0 | 0 |  |
Total available for sale, Gross Unrealized Gains | 1,220 | 215 |  |
Total available for sale, Gross Unrealized Losses | (13,293) | (19,363) |  |
Total available for sale, Fair Value | 583,745 | 528,609 |  |
Total available for sale, Carrying Value | 583,745 | 528,609 |  |
Mortgage-backed |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 2,060,674 | 1,855,776 |  |
Available-for-sale, Allowance for Credit Loss | (23) | (18) |  |
Total available for sale, Gross Unrealized Gains | 3,518 | 610 |  |
Total available for sale, Gross Unrealized Losses | (166,440) | (190,958) |  |
Total available for sale, Fair Value | 1,897,729 | 1,665,410 |  |
Total available for sale, Carrying Value | 1,897,729 | 1,665,428 |  |
Asset-backed |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 3,960,140 | 4,132,365 |  |
Available-for-sale, Allowance for Credit Loss | 0 | 0 |  |
Total available for sale, Gross Unrealized Gains | 3,166 | 2,730 |  |
Total available for sale, Gross Unrealized Losses | (117,853) | (152,322) |  |
Total available for sale, Fair Value | 3,845,453 | 3,982,773 |  |
Total available for sale, Carrying Value | 3,845,453 | 3,982,773 |  |
Industrial |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 3,563,744 | 3,491,645 |  |
Available-for-sale, Allowance for Credit Loss | (66) | (1,704) |  |
Total available for sale, Gross Unrealized Gains | 9,599 | 4,439 |  |
Total available for sale, Gross Unrealized Losses | (187,833) | (241,381) |  |
Total available for sale, Fair Value | 3,385,444 | 3,252,999 |  |
Total available for sale, Carrying Value | 3,385,444 | 3,252,999 |  |
Financial |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 2,737,880 | 2,585,247 |  |
Available-for-sale, Allowance for Credit Loss | (3,729) | (2,997) |  |
Total available for sale, Gross Unrealized Gains | 7,421 | 5,505 |  |
Total available for sale, Gross Unrealized Losses | (115,268) | (117,383) |  |
Total available for sale, Fair Value | 2,626,304 | 2,470,372 |  |
Total available for sale, Carrying Value | 2,626,304 | 2,470,372 |  |
Utilities |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 650,151 | 586,066 |  |
Available-for-sale, Allowance for Credit Loss | 0 | 0 |  |
Total available for sale, Gross Unrealized Gains | 5,117 | 1,307 |  |
Total available for sale, Gross Unrealized Losses | (27,941) | (36,325) |  |
Total available for sale, Fair Value | 627,327 | 551,048 |  |
Total available for sale, Carrying Value | 627,327 | 551,048 |  |
Other |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 495,850 | 441,230 |  |
Available-for-sale, Allowance for Credit Loss | 0 | 0 |  |
Total available for sale, Gross Unrealized Gains | 122 | 0 |  |
Total available for sale, Gross Unrealized Losses | (9,398) | (11,657) |  |
Total available for sale, Fair Value | 486,574 | 429,573 |  |
Total available for sale, Carrying Value | 486,574 | 429,573 |  |
Corporate |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 7,447,625 | 7,104,188 |  |
Available-for-sale, Allowance for Credit Loss | (3,795) | (4,701) | 0 | (16)
Total available for sale, Gross Unrealized Gains | 22,259 | 11,251 |  |
Total available for sale, Gross Unrealized Losses | (340,440) | (406,746) |  |
Total available for sale, Fair Value | 7,125,649 | 6,703,992 |  |
Total available for sale, Carrying Value | 7,125,649 | 6,703,992 |  |
Foreign government |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Total available for sale, Amortized Cost | 1,468,737 | 1,564,930 |  |
Available-for-sale, Allowance for Credit Loss | (33,324) | (32,633) | $ (26,153) | $ (22,222)
Total available for sale, Gross Unrealized Gains | 6,312 | 4,283 |  |
Total available for sale, Gross Unrealized Losses | (109,835) | (135,058) |  |
Total available for sale, Fair Value | 1,331,890 | 1,401,522 |  |
Total available for sale, Carrying Value | $ 1,331,890 | $ 1,401,522 |  |

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