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Fair Value Measurements - Information about Valuation Inputs for Fixed Income Securities Classified as Level 3 (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2022 | Dec. 31, 2021
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Other Investments | $ 568 | $ 690
Debt Securities, Available-for-sale | $ 1,966 |
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 | 13 years 5 months 15 days | 14 years 1 month 20 days
Yield | 12.60% | 10.20%
Variable Interest Entity, Primary Beneficiary [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | $ 1,967 | $ 3,455
Real Estate [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Other Investments | 22 | 33
Hedge Funds, Multi-strategy [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Other Investments | 186 | 216
Interest Rate Contract [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Other Investments | 80 | 78
Illiquid Investments [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Other Investments | 84 | 88
Corporate Obligations [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | 1,828 | 3,320
Corporate Obligations [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | 1,828 | 3,320
Fair Value, Recurring [Member] | Residential Mortgage-Backed Securities [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | 238 | 252
Fair Value, Recurring [Member] | Residential Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | 0 | 0
Fair Value, Recurring [Member] | Corporate Obligations [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | 598 | 613
Fair Value, Recurring [Member] | Corporate Obligations [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | $ 12 | $ 12
Fair Value Inputs Maturity | 1 year 9 months | 2 years 9 months
Fair Value, Recurring [Member] | Corporate Obligations [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | $ 1,828 | $ 3,320

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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563 + Details
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