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Investments - Additional Information (Details) - USD ($) $ in Millions | Mar. 31, 2023 | Dec. 31, 2022 | Mar. 31, 2022
--- | --- | --- | ---
Schedule of Investments [Line Items] |  |  |
Debt Securities, Available-for-sale, Allowance for Credit Loss | $ 1 | $ 0 | $ 1
Securities fair value | 23 | 23 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | $ 90 | 106 |
Average Percentage of Unrealized Loss Versus Amortized Cost for Below Investment Grade Securities | 6.00% |  |
Average Percentage of Unrealized Loss Versus Amortized Cost for Investment Grade Securities | 8.00% |  |
Investment Portfolio [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Fair Value of Cash and Securities Pledged to Derivative Counterparties | $ 61 | 64 |
Interest Rate Contract [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Other investments | 84 | 80 |
Fixed Income Securities [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Debt Securities, Available-for-sale, Allowance for Credit Loss | 1 | 0 |
Debt Securities, Available-for-sale, Unrealized Loss Position | 1,147 | 1,183 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 90 | 106 |
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 | 630 | 559 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 54 | 63 |
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 | 53 |  |
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 | 1 | 0 |
Debt Securities, Available-for-sale, Unrealized Loss Position | 132 | 132 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 16 | 19 |
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 | 111 | 203 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 5 | 5 |
Reported Value Measurement [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Other investments | 65 | $ 61 |
Commitments [Member] | Partnership Interest [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Other investments | $ 57 |  |

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