Gains and Losses Included in Net Income (Loss) from Assets Measured at Fair Value (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Fair value of financial instruments [Abstract]
Total realized and unrealized gains (losses) included in net income, assets	$ (5)	$ (2)	$ 2	$ 7
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest
Total gains (losses) included in net income attributable to assets still held, assets	$ 1	$ (2)	$ 8	$ 4
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest
Net Investment Income
Fair value of financial instruments [Abstract]
Total realized and unrealized gains (losses) included in net income, assets	$ 2	$ 2	$ 8	$ 8
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest
Total gains (losses) included in net income attributable to assets still held, assets	$ 0	$ 2	$ 5	$ 7
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest
Net investment gains (losses)
Fair value of financial instruments [Abstract]
Total realized and unrealized gains (losses) included in net income, assets	$ (7)	$ (4)	$ (6)	$ (1)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest
Total gains (losses) included in net income attributable to assets still held, assets	$ 1	$ (4)	$ 3	$ (3)
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest

Indicates line item in statement of income or comprehensive income that includes unrealized gain (loss) from asset measured at fair value using unobservable input (level 3) and still held.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-3

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
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-Name Accounting Standards Codification
-Section 55
-Paragraph 102
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-102

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-Topic 820
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-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

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Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

+ References

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-Topic 820
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-Section 55
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-URI https://asc.fasb.org/1943274/2147482078/820-10-55-101

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-Topic 820
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Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 101
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-URI https://asc.fasb.org/1943274/2147482078/820-10-55-101

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