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Investments - Additional Information (Details) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2024 USD ($) security fund manager | Mar. 31, 2023 USD ($) | Dec. 31, 2023 USD ($) security
Schedule of Investments [Line Items] |  |  |
Number of outside managers managing investment portfolio | manager | 3 |  |
Accrued investment income | $ 72 |  | $ 71
Number of securities with unrealized losses greater than 10% of book value for 12 months or more | security | 458 |  | 409
Total unrealized losses for securities having losses greater than 10% of book value for 12 months or more | $ 224 |  | $ 200
Assets held-in-trust | 143 |  | 234
Securities purchased with credit deterioration | 0 | $ 0 |
Disposal Group, Held-for-sale, Not Discontinued Operations | Sound Point Agreement |  |  |
Schedule of Investments [Line Items] |  |  |
Transaction commitment, new and transitioned investments | 1,000 |  |
AGL Subsidiaries |  |  |
Schedule of Investments [Line Items] |  |  |
Assets held-in-trust | $ 1,144 |  | $ 1,154
AGAS |  |  |
Schedule of Investments [Line Items] |  |  |
Funds accounted for as CIVs | fund | 3 |  |
Total number of investments | fund | 8 |  |
Future Equity Investments |  |  |
Schedule of Investments [Line Items] |  |  |
Investments, authorized amount to invest | $ 1,500 |  |
Investments, fair value disclosure | 803 |  |
Unfunded commitment | 743 |  |
Unfunded commitment, committed for specific funds | 324 |  |
Investments, including distributed gains, authorized amount to invest | 162 |  |
Future Equity Investments | AGL Subsidiaries |  |  |
Schedule of Investments [Line Items] |  |  |
Investments, authorized amount to invest | 912 |  |
Authorized amount to invest, excluding distributed gains | 750 |  |
Equity in Earnings (Losses) of Investees | AGAS |  |  |
Schedule of Investments [Line Items] |  |  |
Investments, fair value disclosure | 632 |  |
Long-term purchase commitment, amount | 772 |  |
Funded amount | $ 574 |  |

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