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	6 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Assets
Beginning balance	$ 2,537	$ 2,552	$ 2,483	$ 2,708
Total realized/unrealized gains (losses), Included in net income	(10)	(11)	(18)	(4)
Total realized/unrealized gains (losses), Included in OCI	4	(115)	30	(186)
Purchases	75	361	223	700
Settlements	(72)	(125)	(141)	(271)
Sales	(7)	(14)	(14)	(22)
Transfers into Level 3	10	24	47	24
Transfers out of Level 3	(115)	(227)	(188)	(504)
Ending balance	2,422	2,445	2,422	2,445
Equity securities, at fair value
Assets
Beginning balance	60	57	61	64
Total realized/unrealized gains (losses), Included in net income	(1)	2	(2)	9
Total realized/unrealized gains (losses), Included in OCI	0	0	0	0
Purchases	0	2	1	2
Settlements	0	(1)	(1)	(15)
Sales	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending balance	59	60	59	60
Short-term investments
Assets
Beginning balance	187	32	193	80
Total realized/unrealized gains (losses), Included in net income	0	0	0	0
Total realized/unrealized gains (losses), Included in OCI	0	0	0	0
Purchases	3	32	4	36
Settlements	(4)	(4)	(11)	(6)
Sales	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	(50)
Ending balance	186	60	186	60
Securities available-for-sale and other \| Total Fixed Maturities, AFS
Assets
Beginning balance	2,118	2,289	2,051	2,404
Total realized/unrealized gains (losses), Included in net income	(4)	0	(3)	(2)
Total realized/unrealized gains (losses), Included in OCI	4	(115)	30	(186)
Purchases	72	292	218	607
Settlements	(64)	(117)	(127)	(239)
Sales	(7)	(14)	(14)	(22)
Transfers into Level 3	10	24	47	24
Transfers out of Level 3	(115)	(227)	(188)	(454)
Ending balance	2,014	2,132	2,014	2,132
Securities available-for-sale and other \| ABS \| Total Fixed Maturities, AFS
Assets
Beginning balance	36	19	30	0
Total realized/unrealized gains (losses), Included in net income	0	0	0	0
Total realized/unrealized gains (losses), Included in OCI	0	0	0	0
Purchases	0	0	36	19
Settlements	0	0	0	0
Sales	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(36)	(19)	(66)	(19)
Ending balance	0	0	0	0
Securities available-for-sale and other \| Collateralized Loan Obligations [Member] \| Total Fixed Maturities, AFS
Assets
Beginning balance	151	214	115	257
Total realized/unrealized gains (losses), Included in net income	0	0	0	0
Total realized/unrealized gains (losses), Included in OCI	0	(1)	0	(2)
Purchases	0	28	40	82
Settlements	(26)	(23)	(30)	(40)
Sales	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(40)	(54)	(40)	(133)
Ending balance	85	164	85	164
Securities available-for-sale and other \| CMBS \| Total Fixed Maturities, AFS
Assets
Beginning balance	231	236	222	196
Total realized/unrealized gains (losses), Included in net income	(2)	0	(2)	0
Total realized/unrealized gains (losses), Included in OCI	7	(10)	2	(15)
Purchases	2	0	6	46
Settlements	(1)	(2)	(1)	(3)
Sales	(5)	0	(5)	0
Transfers into Level 3	6	0	16	0
Transfers out of Level 3	0	0	0	0
Ending balance	238	224	238	224
Securities available-for-sale and other \| Corporate \| Total Fixed Maturities, AFS
Assets
Beginning balance	1,643	1,515	1,589	1,618
Total realized/unrealized gains (losses), Included in net income	(2)	1	(1)	(1)
Total realized/unrealized gains (losses), Included in OCI	(3)	(99)	28	(158)
Purchases	51	264	117	323
Settlements	(30)	(62)	(81)	(132)
Sales	(2)	(14)	(9)	(21)
Transfers into Level 3	4	21	31	21
Transfers out of Level 3	(39)	(17)	(52)	(41)
Ending balance	1,622	1,609	1,622	1,609
Securities available-for-sale and other \| Foreign government/government agencies \| Total Fixed Maturities, AFS
Assets
Beginning balance		4		5
Total realized/unrealized gains (losses), Included in net income		(1)		(1)
Total realized/unrealized gains (losses), Included in OCI		(1)		(1)
Purchases		0		0
Settlements		0		0
Sales		0		(1)
Transfers into Level 3		3		3
Transfers out of Level 3		0		0
Ending balance		5		5
Securities available-for-sale and other \| RMBS \| Total Fixed Maturities, AFS
Assets
Beginning balance	57	301	95	328
Total realized/unrealized gains (losses), Included in net income	0	0	0	0
Total realized/unrealized gains (losses), Included in OCI	0	(4)	0	(10)
Purchases	19	0	19	137
Settlements	(7)	(30)	(15)	(64)
Sales	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	(137)	(30)	(261)
Ending balance	69	130	69	130
Fair Value Option, Other Eligible Items \| Collateralized Loan Obligations [Member] \| Total Fixed Maturities, AFS
Assets
Beginning balance	172	174	178	160
Total realized/unrealized gains (losses), Included in net income	(5)	(13)	(13)	(11)
Total realized/unrealized gains (losses), Included in OCI	0	0	0	0
Purchases	0	35	0	55
Settlements	(4)	(3)	(2)	(11)
Sales	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending balance	$ 163	$ 193	$ 163	$ 193

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
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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-Name Accounting Standards Codification
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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
-Section 50
-Paragraph 2
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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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