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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, 2021 | Dec. 31, 2020
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Other Investments | $ 690 | $ 595
Debt Securities, Available-for-sale | $ 2,265 |
Fair Value Inputs Yield Rate | 11.60% |
Asset-backed Securities [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Coupon rate | 5.97% | 5.97%
Fair Value Inputs Maturity | 14 years 1 month 20 days | 14 years 9 months 29 days
Yield | 10.20% | 10.50%
Variable Interest Entity, Primary Beneficiary [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Debt Securities, Available-for-sale | $ 3,455 | $ 3,354
Real Estate [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Other Investments | 33 | 16
Hedge Funds, Multi-strategy [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Other Investments | 216 | 196
Interest Rate Contract [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Other Investments | 78 | 78
Illiquid Investments [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |
Other Investments | 88 | 65
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 | 3,320 | 3,215
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 | 3,320 | 3,215
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 | 252 | 302
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 | 613 | 1,077
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 | 0
Fair Value Inputs Maturity | 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 | $ 3,320 | $ 3,215

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- Definition Fair value inputs yield. + References No definition available. + Details
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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 http://asc.fasb.org/extlink&oid=120398452&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 http://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 http://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 http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
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