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Fair Value Measurements - Information about Valuation Inputs for Variable Interest Entity Assets and Liabilities Classified as Level 3 (Details) - USD ($) $ in Millions | 3 Months Ended |  |  |
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Mar. 31, 2024 | Mar. 31, 2023 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Variable Interest Entity, Primary Beneficiary [Member] |  |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |  |
Estimated Future Premium Payments Minimum Discounted Rate | 5.40% |  | 5.30% |  |
Estimated Future Premium Payments Maximum Discounted Rate | 8.30% |  | 7.80% |  |
Fair Value, Inputs, Level 3 [Member] |  |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability | $ 3,782 | $ 3,972 |  | $ 3,848 | $ 3,762
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 35 | 196 |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | (38) | 87 |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | (64) | (74) |  |  |
Fair Value, Inputs, Level 3 [Member] | Investments [Member] |  |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability | 87 | 81 |  | 87 | 79
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 0 | 0 |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | 0 | 3 |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | 0 | 0 |  |  |
Loan Origination Commitments [Member] | Fair Value, Inputs, Level 3 [Member] | Loans Receivable [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability | 1,604 | 1,856 |  | 1,663 | 1,829
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 21 | 59 |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | (16) | 42 |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | (64) | (73) |  |  |
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member] |  |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability | 21 | 31 |  | 26 | 26
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | (5) | 5 |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | 0 | 0 |  |  |
Investment Contracts [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability | 2,070 | 2,003 |  | $ 2,072 | $ 1,828
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 19 | 133 |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | $ (21) | $ 43 |  |  |

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- Definition Estimated Future Premium Payments Maximum Discounted Rate + References No definition available. + Details
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- Definition Estimated Future Premium Payments Minimum Discounted Rate + References No definition available. + Details
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- Definition Fair value measurement with unobservable inputs reconciliation recurring basis asset or liability. + References No definition available. + Details
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- Definition Amount of gain or loss included in earnings arising from financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
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- Definition Amount of gain or loss included in other comprehensive income arising from financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
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