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Fair Value of Assets and Liabilities - Schedule of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Millions | Mar. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Assets |  |
Fixed income securities, at fair value | $ 51,993 | $ 52,747
Equity securities | 4,465 | 4,463
Short-term investments | 6,541 | 4,537
Other investments | 901 | 824
Assets held for sale | 3,786 | 3,092
Total assets at fair value | 64,946 | 63,521
Counterparty and cash collateral netting | (1) | (19)
Total | 65,958 | 64,617
Liabilities |  |
Preferred stock measured at cost | 150 | 150
U.S. government and agencies |  |
Assets |  |
Fixed income securities, at fair value | 10,705 | 11,108
Municipal |  |
Assets |  |
Fixed income securities, at fair value | 7,474 | 8,842
Foreign government |  |
Assets |  |
Fixed income securities, at fair value | 1,334 | 1,364
ABS |  |
Assets |  |
Fixed income securities, at fair value | 1,713 | 1,241
Quoted prices in active markets for identical assets (Level 1) |  |
Assets |  |
Total assets at fair value | 15,540 | 16,956
Significant other observable inputs (Level 2) |  |
Assets |  |
Total assets at fair value | 48,560 | 45,779
Significant unobservable inputs (Level 3) |  |
Assets |  |
Total assets at fair value | 847 | 805
Reported to NAV |  |
Assets |  |
Investments reported at NAV | 1,012 | 1,096
Recurring basis |  |
Assets |  |
Fixed income securities, at fair value | 51,993 | 52,747
Equity securities | 4,315 | 4,313
Short-term investments | 6,541 | 4,537
Other investments | 2 | 3
Other investments | (1) | (19)
Other assets | 135 | 134
Assets held for sale | 1,958 | 1,784
Total assets at fair value | 64,944 | 63,518
Counterparty and cash collateral netting | (1) | (19)
Liabilities |  |
Other liabilities | (1) | (1)
Other liabilities | 7 | 1
Counterparty and cash collateral netting | 7 | 1
Total recurring basis liabilities | (1) | (1)
Recurring basis | U.S. government and agencies |  |
Assets |  |
Fixed income securities, at fair value | 10,705 | 11,108
Recurring basis | Municipal |  |
Assets |  |
Fixed income securities, at fair value | 7,474 | 8,842
Recurring basis | Corporate - public |  |
Assets |  |
Fixed income securities, at fair value | 21,440 | 21,233
Recurring basis | Corporate - privately placed |  |
Assets |  |
Fixed income securities, at fair value | 9,327 | 8,959
Recurring basis | Foreign government |  |
Assets |  |
Fixed income securities, at fair value | 1,334 | 1,364
Recurring basis | ABS |  |
Assets |  |
Fixed income securities, at fair value | 1,713 | 1,241
Recurring basis | Quoted prices in active markets for identical assets (Level 1) |  |
Assets |  |
Fixed income securities, at fair value | 10,697 | 11,099
Equity securities | 3,586 | 3,600
Short-term investments | 992 | 2,016
Other investments | 0 | 0
Other assets | 1 | 0
Assets held for sale | 264 | 241
Total assets at fair value | 15,540 | 16,956
Liabilities |  |
Other liabilities | 0 | (1)
Total recurring basis liabilities | 0 | (1)
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | U.S. government and agencies |  |
Assets |  |
Fixed income securities, at fair value | 10,697 | 11,099
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Municipal |  |
Assets |  |
Fixed income securities, at fair value | 0 | 0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Corporate - public |  |
Assets |  |
Fixed income securities, at fair value | 0 | 0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Corporate - privately placed |  |
Assets |  |
Fixed income securities, at fair value | 0 | 0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Foreign government |  |
Assets |  |
Fixed income securities, at fair value | 0 | 0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | ABS |  |
Assets |  |
Fixed income securities, at fair value | 0 | 0
Recurring basis | Significant other observable inputs (Level 2) |  |
Assets |  |
Fixed income securities, at fair value | 41,011 | 41,400
Equity securities | 313 | 306
Short-term investments | 5,547 | 2,516
Other investments | 2 | 21
Other assets | 0 | 0
Assets held for sale | 1,687 | 1,536
Total assets at fair value | 48,560 | 45,779
Liabilities |  |
Other liabilities | (7) | (1)
Total recurring basis liabilities | (7) | (1)
Recurring basis | Significant other observable inputs (Level 2) | U.S. government and agencies |  |
Assets |  |
Fixed income securities, at fair value | 8 | 9
Recurring basis | Significant other observable inputs (Level 2) | Municipal |  |
Assets |  |
Fixed income securities, at fair value | 7,472 | 8,840
Recurring basis | Significant other observable inputs (Level 2) | Corporate - public |  |
Assets |  |
Fixed income securities, at fair value | 21,405 | 21,211
Recurring basis | Significant other observable inputs (Level 2) | Corporate - privately placed |  |
Assets |  |
Fixed income securities, at fair value | 9,218 | 8,849
Recurring basis | Significant other observable inputs (Level 2) | Foreign government |  |
Assets |  |
Fixed income securities, at fair value | 1,334 | 1,364
Recurring basis | Significant other observable inputs (Level 2) | ABS |  |
Assets |  |
Fixed income securities, at fair value | 1,574 | 1,127
Recurring basis | Significant unobservable inputs (Level 3) |  |
Assets |  |
Fixed income securities, at fair value | 285 | 248
Equity securities | 416 | 407
Short-term investments | 2 | 5
Other investments | 1 | 1
Other assets | 134 | 134
Assets held for sale | 7 | 7
Total assets at fair value | 845 | 802
Liabilities |  |
Other liabilities | (1) | 0
Total recurring basis liabilities | (1) | 0
Recurring basis | Significant unobservable inputs (Level 3) | U.S. government and agencies |  |
Assets |  |
Fixed income securities, at fair value | 0 | 0
Recurring basis | Significant unobservable inputs (Level 3) | Municipal |  |
Assets |  |
Fixed income securities, at fair value | 2 | 2
Recurring basis | Significant unobservable inputs (Level 3) | Corporate - public |  |
Assets |  |
Fixed income securities, at fair value | 35 | 22
Recurring basis | Significant unobservable inputs (Level 3) | Corporate - privately placed |  |
Assets |  |
Fixed income securities, at fair value | 109 | 110
Recurring basis | Significant unobservable inputs (Level 3) | Foreign government |  |
Assets |  |
Fixed income securities, at fair value | 0 | 0
Recurring basis | Significant unobservable inputs (Level 3) | ABS |  |
Assets |  |
Fixed income securities, at fair value | 139 | 114
Non-recurring basis |  |
Assets |  |
Total assets at fair value | 2 | 3
Non-recurring basis | Quoted prices in active markets for identical assets (Level 1) |  |
Assets |  |
Total assets at fair value | 0 | 0
Non-recurring basis | Significant other observable inputs (Level 2) |  |
Assets |  |
Total assets at fair value | 0 | 0
Non-recurring basis | Significant unobservable inputs (Level 3) |  |
Assets |  |
Total assets at fair value | $ 2 | $ 3

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