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Investment Information - Aging of available for sale securities in an unrealized loss position (Details) $ in Millions | Dec. 31, 2024 USD ($) lots | Dec. 31, 2023 USD ($) lots
--- | --- | ---
Estimated Fair Value |  |
Estimated Fair Value - Less than 12 Months | $ 12,494 | $ 3,867
Estimated Fair Value - 12 Months or More | 5,080 | 9,555
Estimated Fair Value - Total | 17,574 | 13,422
Gross Unrealized Losses |  |
Gross Unrealized Losses - Less than 12 Months | (290) | (67)
Gross Unrealized Losses - 12 Months or More | (404) | (760)
Gross Unrealized Losses - Total | $ (694) | $ (827)
Continuous unrealized loss, qualitative disclosures: |  |
Number of positions in an unrealized loss position (lots) | lots | 9,980 | 7,100
Total number of positions (lots) | lots | 20,930 | 15,720
Largest single loss | $ 8 | $ 6
Fixed maturities available for sale, at fair value |  |
Estimated Fair Value |  |
Estimated Fair Value - Less than 12 Months | 12,397 | 3,565
Estimated Fair Value - 12 Months or More | 5,080 | 9,555
Estimated Fair Value - Total | 17,477 | 13,120
Gross Unrealized Losses |  |
Gross Unrealized Losses - Less than 12 Months | (288) | (65)
Gross Unrealized Losses - 12 Months or More | (404) | (760)
Gross Unrealized Losses - Total | (692) | (825)
Corporate bonds |  |
Estimated Fair Value |  |
Estimated Fair Value - Less than 12 Months | 4,582 | 1,559
Estimated Fair Value - 12 Months or More | 2,924 | 4,959
Estimated Fair Value - Total | 7,506 | 6,518
Gross Unrealized Losses |  |
Gross Unrealized Losses - Less than 12 Months | (114) | (45)
Gross Unrealized Losses - 12 Months or More | (232) | (419)
Gross Unrealized Losses - Total | (346) | (464)
US government and government agencies |  |
Estimated Fair Value |  |
Estimated Fair Value - Less than 12 Months | 5,130 | 1,066
Estimated Fair Value - 12 Months or More | 516 | 941
Estimated Fair Value - Total | 5,646 | 2,007
Gross Unrealized Losses |  |
Gross Unrealized Losses - Less than 12 Months | (100) | (10)
Gross Unrealized Losses - 12 Months or More | (49) | (76)
Gross Unrealized Losses - Total | (149) | (86)
Non-US government securities |  |
Estimated Fair Value |  |
Estimated Fair Value - Less than 12 Months | 1,650 | 365
Estimated Fair Value - 12 Months or More | 418 | 897
Estimated Fair Value - Total | 2,068 | 1,262
Gross Unrealized Losses |  |
Gross Unrealized Losses - Less than 12 Months | (58) | (4)
Gross Unrealized Losses - 12 Months or More | (49) | (96)
Gross Unrealized Losses - Total | (107) | (100)
Mortgage backed securities |  |
Estimated Fair Value |  |
Estimated Fair Value - Less than 12 Months | 571 | 221
Estimated Fair Value - 12 Months or More | 186 | 522
Estimated Fair Value - Total | 757 | 743
Gross Unrealized Losses |  |
Gross Unrealized Losses - Less than 12 Months | (6) | (3)
Gross Unrealized Losses - 12 Months or More | (25) | (63)
Gross Unrealized Losses - Total | (31) | (66)
Asset backed securities |  |
Estimated Fair Value |  |
Estimated Fair Value - Less than 12 Months | 236 | 234
Estimated Fair Value - 12 Months or More | 426 | 1,112
Estimated Fair Value - Total | 662 | 1,346
Gross Unrealized Losses |  |
Gross Unrealized Losses - Less than 12 Months | (8) | (1)
Gross Unrealized Losses - 12 Months or More | (24) | (54)
Gross Unrealized Losses - Total | (32) | (55)
Commercial mortgage backed securities |  |
Estimated Fair Value |  |
Estimated Fair Value - Less than 12 Months | 180 | 100
Estimated Fair Value - 12 Months or More | 434 | 909
Estimated Fair Value - Total | 614 | 1,009
Gross Unrealized Losses |  |
Gross Unrealized Losses - Less than 12 Months | (1) | (1)
Gross Unrealized Losses - 12 Months or More | (10) | (33)
Gross Unrealized Losses - Total | (11) | (34)
Municipal bonds |  |
Estimated Fair Value |  |
Estimated Fair Value - Less than 12 Months | 48 | 20
Estimated Fair Value - 12 Months or More | 176 | 215
Estimated Fair Value - Total | 224 | 235
Gross Unrealized Losses |  |
Gross Unrealized Losses - Less than 12 Months | (1) | (1)
Gross Unrealized Losses - 12 Months or More | (15) | (19)
Gross Unrealized Losses - Total | (16) | (20)
Short-term investments |  |
Estimated Fair Value |  |
Estimated Fair Value - Less than 12 Months | 97 | 302
Estimated Fair Value - 12 Months or More | 0 | 0
Estimated Fair Value - Total | 97 | 302
Gross Unrealized Losses |  |
Gross Unrealized Losses - Less than 12 Months | (2) | (2)
Gross Unrealized Losses - 12 Months or More | 0 | 0
Gross Unrealized Losses - Total | $ (2) | $ (2)

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