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Investments - Additional Information (Details) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023 | Mar. 31, 2023
--- | --- | --- | ---
Schedule of Investments [Line Items] |  |  |
Debt Securities, Available-for-sale, Allowance for Credit Loss | $ 2 | $ 3 | $ 1
Securities fair value | 23 | 24 |
Debt Securities, Available-for-sale, Unrealized Loss Position | 1,145 | 1,032 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 75 | 71 |
Debt Securities, Available for sale, Unrealized Loss Position, Accumulated Loss, Including Pledged Securities | $ 1,172 |  |
Average Percentage of Unrealized Loss Versus Amortized Cost for Below Investment Grade Securities | 5.00% |  |
Average Percentage of Unrealized Loss Versus Amortized Cost for Investment Grade Securities | 7.00% |  |
Fiduciary Funds Held by Insurance Distribution Subsidiaries | $ 2 | 2 |
Investment Portfolio [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Fair Value of Cash and Securities Pledged to Derivative Counterparties | 26 | 27 |
Fixed Income Securities [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Debt Securities, Available-for-sale, Allowance for Credit Loss | 2 | 3 |
Debt Securities, Available-for-sale, Unrealized Loss Position | 1,101 | 1,028 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 74 | 71 |
Fixed Income Securities [Member] | Corporate Debt Securities [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Debt Securities, Available-for-sale, Allowance for Credit Loss | 0 | 0 |
Debt Securities, Available-for-sale, Unrealized Loss Position | 596 | 584 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 45 | 44 |
Fixed Income Securities [Member] | Corporate Debt Securities [Member] | External Credit Rating, Investment Grade |  |  |
Schedule of Investments [Line Items] |  |  |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 45 |  |
Fixed Income Securities [Member] | Corporate Debt Securities [Member] | External Credit Rating, Non Investment Grade [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 1 |  |
Fixed Income Securities [Member] | Residential Mortgage-Backed Securities [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Debt Securities, Available-for-sale, Allowance for Credit Loss | 2 | 3 |
Debt Securities, Available-for-sale, Unrealized Loss Position | 153 | 104 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 12 | 14 |
Fixed Income Securities [Member] | Asset-backed Securities [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Debt Securities, Available-for-sale, Allowance for Credit Loss | 0 | 0 |
Debt Securities, Available-for-sale, Unrealized Loss Position | 132 | 92 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 5 | 1 |
Reported Value Measurement [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Other investments | 152 | 77 |
Reported Value Measurement [Member] | Interest Rate Contract [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Other investments | $ 95 | $ 39 |

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