Fair Value - Reconciliations of Assets and Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Corporate bonds and other
Reconciliations for All Assets and Liabilities [Roll Forward]
Balance at beginning of period	$ 912	$ 915	$ 810	$ 937
Included in Net Income		(1)		(2)
Included in OCI	(15)	(82)	9	(153)
Purchases	68	51	149	118
Sales				(5)
Settlements	(5)	(37)	(8)	(59)
Transfers into Level 3	11		11	10
Transfers out of Level 3
Balance at end of period	971	846	971	846
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities Held at June 30
Unrealized Gains (Losses) Recognized in Other Comprehensive Income (Loss) on Level 3 Assets and Liabilities Held at June 30	(15)	(81)	9	(153)
States, municipalities and political subdivisions
Reconciliations for All Assets and Liabilities [Roll Forward]
Balance at beginning of period	44	51	43	56
Included in Net Income
Included in OCI	(1)	(5)		(10)
Purchases
Sales
Settlements
Transfers into Level 3
Transfers out of Level 3
Balance at end of period	43	46	43	46
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities Held at June 30
Unrealized Gains (Losses) Recognized in Other Comprehensive Income (Loss) on Level 3 Assets and Liabilities Held at June 30	(1)	(5)		(10)
Asset-backed
Reconciliations for All Assets and Liabilities [Roll Forward]
Balance at beginning of period	859	604	788	556
Included in Net Income	4	8	9	11
Included in OCI	(7)	(52)		(84)
Purchases	87	92	142	232
Sales		(2)		(2)
Settlements	(17)	(23)	(26)	(40)
Transfers into Level 3		14	23	19
Transfers out of Level 3	(43)		(53)	(51)
Balance at end of period	883	641	883	641
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities Held at June 30
Unrealized Gains (Losses) Recognized in Other Comprehensive Income (Loss) on Level 3 Assets and Liabilities Held at June 30	(7)	(52)	(1)	(83)
Fixed maturities available-for-sale
Reconciliations for All Assets and Liabilities [Roll Forward]
Balance at beginning of period	1,815	1,570	1,641	1,549
Included in Net Income	4	7	9	9
Included in OCI	(23)	(139)	9	(247)
Purchases	155	143	291	350
Sales	0	(2)	0	(7)
Settlements	(22)	(60)	(34)	(99)
Transfers into Level 3	11	14	34	29
Transfers out of Level 3	(43)	0	(53)	(51)
Balance at end of period	1,897	1,533	1,897	1,533
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities Held at June 30	0	0	0	0
Unrealized Gains (Losses) Recognized in Other Comprehensive Income (Loss) on Level 3 Assets and Liabilities Held at June 30	(23)	(138)	8	(246)
Equity securities
Reconciliations for All Assets and Liabilities [Roll Forward]
Balance at beginning of period	29	44	35	29
Included in Net Income	(1)	(3)	(7)
Included in OCI
Purchases				12
Sales	(2)	(3)	(2)	(3)
Settlements		9		9
Transfers into Level 3
Transfers out of Level 3
Balance at end of period	26	47	26	47
Unrealized Gains (Losses) Recognized in Net Income (Loss) on Level 3 Assets and Liabilities Held at June 30	(1)	(3)	(7)	(1)
Unrealized Gains (Losses) Recognized in Other Comprehensive Income (Loss) on Level 3 Assets and Liabilities Held at June 30

Amount of unrealized gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis 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 2
-Subparagraph (d)
-Publisher FASB
-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.

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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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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
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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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
-SubTopic 10
-Name Accounting Standards Codification
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-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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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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-Name Accounting Standards Codification
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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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Amount of settlement 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 transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

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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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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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