Fair Value Measurements - Fair Value Recurring Basis, Unobservable Input (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023
Assets
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Asset, Gain (Loss), Statement of Other Comprehensive Income or Comprehensive Income [Extensible Enumeration]	Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3)
Assets
Beginning balance	$ 2,487	$ 2,483
Total realized/unrealized gains (losses), Included in net income	3	(8)
Total realized/unrealized gains (losses), Included in OCI	(5)	26
Purchases	291	148
Settlements	(49)	(69)
Sales	(2)	(7)
Transfers into Level 3	6	37
Transfers out of Level 3	(47)	(73)
Ending balance	2,684	2,537
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Equity securities, at fair value
Assets
Beginning balance	58	61
Total realized/unrealized gains (losses), Included in net income	0	(1)
Total realized/unrealized gains (losses), Included in OCI	0	0
Purchases	0	1
Settlements	0	(1)
Sales	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance	58	60
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Short-term investments
Assets
Beginning balance	25	193
Total realized/unrealized gains (losses), Included in net income	0	0
Total realized/unrealized gains (losses), Included in OCI	0	0
Purchases	1	1
Settlements	0	(7)
Sales	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance	26	187
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Securities available-for-sale and other \| Total Fixed Maturities, AFS
Assets
Beginning balance	2,237	2,051
Total realized/unrealized gains (losses), Included in net income	0	1
Total realized/unrealized gains (losses), Included in OCI	(5)	26
Purchases	290	146
Settlements	(46)	(63)
Sales	(2)	(7)
Transfers into Level 3	6	37
Transfers out of Level 3	(47)	(73)
Ending balance	2,433	2,118
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Securities available-for-sale and other \| ABS \| Total Fixed Maturities, AFS
Assets
Beginning balance	0	30
Total realized/unrealized gains (losses), Included in net income	0	0
Total realized/unrealized gains (losses), Included in OCI	0	0
Purchases	16	36
Settlements	0	0
Sales	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	(30)
Ending balance	16	36
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Securities available-for-sale and other \| Collateralized Loan Obligations [Member] \| Total Fixed Maturities, AFS
Assets
Beginning balance	113	115
Total realized/unrealized gains (losses), Included in net income	0	0
Total realized/unrealized gains (losses), Included in OCI	0	0
Purchases	130	40
Settlements	(12)	(4)
Sales	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	(47)	0
Ending balance	184	151
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Securities available-for-sale and other \| CMBS \| Total Fixed Maturities, AFS
Assets
Beginning balance	227	222
Total realized/unrealized gains (losses), Included in net income	0	0
Total realized/unrealized gains (losses), Included in OCI	10	(5)
Purchases	0	4
Settlements	(2)	0
Sales	0	0
Transfers into Level 3	6	10
Transfers out of Level 3	0	0
Ending balance	241	231
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Securities available-for-sale and other \| Corporate \| Total Fixed Maturities, AFS
Assets
Beginning balance	1,861	1,589
Total realized/unrealized gains (losses), Included in net income	0	1
Total realized/unrealized gains (losses), Included in OCI	(15)	31
Purchases	106	66
Settlements	(27)	(51)
Sales	(2)	(7)
Transfers into Level 3	0	27
Transfers out of Level 3	0	(13)
Ending balance	1,923	1,643
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Securities available-for-sale and other \| RMBS \| Total Fixed Maturities, AFS
Assets
Beginning balance	36	95
Total realized/unrealized gains (losses), Included in net income	0	0
Total realized/unrealized gains (losses), Included in OCI	0	0
Purchases	38	0
Settlements	(5)	(8)
Sales	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	(30)
Ending balance	69	57
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Fair Value Option, Other Eligible Items \| Collateralized Loan Obligations [Member] \| Total Fixed Maturities, AFS
Assets
Beginning balance	167	178
Total realized/unrealized gains (losses), Included in net income	3	(8)
Total realized/unrealized gains (losses), Included in OCI	0	0
Purchases	0	0
Settlements	(3)	2
Sales	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance	$ 167	$ 172

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

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/disclosureRef
-Topic 820
-SubTopic 10
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Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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- Definition

Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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- Definition

Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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- Definition

Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
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- Definition

Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Indicates line item in statement in which other comprehensive income (OCI) is reported that includes gain (loss) from asset measured at fair value using unobservable input (level 3).

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