Fair Value Measurements - Fair Value Recurring Basis, Unobservable Input (Details) - Fair Value, Measurements, Recurring - Significant Unobservable Inputs (Level 3) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Assets
Beginning balance	$ 2,708	$ 1,805
Total realized/unrealized gains (losses), Included in net income	7	5
Total realized/unrealized gains (losses), Included in OCI	(71)	(14)
Purchases	339	371
Settlements	(146)	(84)
Sales	(8)	(17)
Transfers into Level 3	0	48
Transfers out of Level 3	(277)	(110)
Ending balance	2,552	2,004
Equity securities, at fair value
Assets
Beginning balance	64	70
Total realized/unrealized gains (losses), Included in net income	7	0
Total realized/unrealized gains (losses), Included in OCI	0	0
Purchases	0	0
Settlements	(14)	0
Sales	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance	57	70
Short-term investments
Assets
Beginning balance	80	30
Total realized/unrealized gains (losses), Included in net income	0	0
Total realized/unrealized gains (losses), Included in OCI	0	0
Purchases	4	0
Settlements	(2)	(14)
Sales	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	(50)	0
Ending balance	32	16
Securities available-for-sale and other \| Total Fixed Maturities, AFS
Assets
Beginning balance	2,404	1,705
Total realized/unrealized gains (losses), Included in net income	(2)	5
Total realized/unrealized gains (losses), Included in OCI	(71)	(14)
Purchases	315	371
Settlements	(122)	(70)
Sales	(8)	(17)
Transfers into Level 3	0	48
Transfers out of Level 3	(227)	(110)
Ending balance	2,289	1,918
Securities available-for-sale and other \| ABS \| Total Fixed Maturities, AFS
Assets
Beginning balance	0	0
Total realized/unrealized gains (losses), Included in net income	0	0
Total realized/unrealized gains (losses), Included in OCI	0	0
Purchases	19	6
Settlements	0	0
Sales	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance	19	6
Securities available-for-sale and other \| Collateralized Loan Obligations [Member] \| Total Fixed Maturities, AFS
Assets
Beginning balance	257	360
Total realized/unrealized gains (losses), Included in net income	0	0
Total realized/unrealized gains (losses), Included in OCI	(1)	0
Purchases	54	140
Settlements	(17)	(15)
Sales	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	(79)	(59)
Ending balance	214	426
Securities available-for-sale and other \| CMBS \| Total Fixed Maturities, AFS
Assets
Beginning balance	196	77
Total realized/unrealized gains (losses), Included in net income	0	0
Total realized/unrealized gains (losses), Included in OCI	(5)	0
Purchases	46	1
Settlements	(1)	(2)
Sales	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	(15)
Ending balance	236	61
Securities available-for-sale and other \| Corporate \| Total Fixed Maturities, AFS
Assets
Beginning balance	1,618	881
Total realized/unrealized gains (losses), Included in net income	(2)	5
Total realized/unrealized gains (losses), Included in OCI	(59)	(13)
Purchases	59	73
Settlements	(70)	(7)
Sales	(7)	(7)
Transfers into Level 3	0	48
Transfers out of Level 3	(24)	(36)
Ending balance	1,515	944
Securities available-for-sale and other \| Foreign government/government agencies \| Total Fixed Maturities, AFS
Assets
Beginning balance	5	6
Total realized/unrealized gains (losses), Included in net income	0	0
Total realized/unrealized gains (losses), Included in OCI	0	0
Purchases	0	0
Settlements	0	0
Sales	(1)	(6)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance	4	0
Securities available-for-sale and other \| RMBS \| Total Fixed Maturities, AFS
Assets
Beginning balance	328	381
Total realized/unrealized gains (losses), Included in net income	0	0
Total realized/unrealized gains (losses), Included in OCI	(6)	(1)
Purchases	137	151
Settlements	(34)	(46)
Sales	0	(4)
Transfers into Level 3	0	0
Transfers out of Level 3	(124)	0
Ending balance	301	$ 481
Fair Value Option, Other Eligible Items \| Collateralized Loan Obligations [Member] \| Total Fixed Maturities, AFS
Assets
Beginning balance	160
Total realized/unrealized gains (losses), Included in net income	2
Total realized/unrealized gains (losses), Included in OCI	0
Purchases	20
Settlements	(8)
Sales	0
Transfers into Level 3	0
Transfers out of Level 3	0
Ending balance	$ 174

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).

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- Definition

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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- 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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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.

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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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