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Fair Value Measurements - Information about Valuation Inputs for Fixed Income Securities Classified as Level 3 (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Mar. 31, 2024 | Mar. 31, 2023 | Dec. 31, 2023 | Dec. 31, 2022
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |
Fair Value Inputs Yield Rate | 14.40% |  | 11.20% |
Asset-backed Securities [Member] |  |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |
Coupon rate | 5.98% |  | 5.97% |
Fair Value Inputs Maturity | 12 years 7 months 20 days |  | 12 years 9 months 18 days |
Yield | 12.00% |  | 12.00% |
Fair Value, Inputs, Level 3 [Member] |  |  |  |
Fair Value Inputs, Assets, 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 Settlements | (64) | (74) |  |
Fair Value, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss) | 35 | 196 |  |
Fair Value, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss), OCI | (38) | 87 |  |
Fair Value, Inputs, Level 3 [Member] | Investments [Member] |  |  |  |
Fair Value Inputs, Assets, 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 Settlements | 0 | 0 |  |
Fair Value, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss), OCI |  | $ 3 |  |
Corporate Obligations [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] |  |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |
Fair Value Inputs Maturity |  | 8 months 15 days | 10 months 20 days |
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member] |  |  |  |
Fair Value Inputs, Assets, 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 Settlements | 0 | 0 |  |
Fair Value, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss) | (5) | 5 |  |
Fair Value, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss), OCI | 0 | 0 |  |
Variable Interest Entity, Primary Beneficiary [Member] | Investment Contracts [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Obligations [Member] |  |  |  |
Fair Value Inputs, Assets, 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, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss) | 19 | 133 |  |
Fair Value, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss), OCI | (21) | 43 |  |
Variable Interest Entity, Primary Beneficiary [Member] | Loan Origination Commitments [Member] | Fair Value, Inputs, Level 3 [Member] | Loans Receivable [Member] |  |  |  |
Fair Value Inputs, Assets, 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 Settlements | (64) | (73) |  |
Fair Value, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss) | 21 | 59 |  |
Fair Value, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss), OCI | $ (16) | $ 42 |  |

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- Definition Fair value inputs coupon rate. + References No definition available. + Details
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- Definition Fair value inputs maturity. + References No definition available. + Details
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- Definition Fair value inputs yield. + References No definition available. + Details
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- Definition Fair Value Inputs Yield 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 settlements related to financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
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- Definition Amount of unrealized gain (loss) recognized in income from asset (liability) measured at fair value on recurring basis using unobservable input (level 3) and still held. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 + Details
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- Definition Amount of unrealized gain (loss) recognized in other comprehensive income (OCI) from asset (liability) measured at fair value on recurring basis using unobservable input (level 3) and still held. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 + Details
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