Fair Value of Assets and Liabilities - Rollforward of level 3 assets and liabilities held at fair value on a recurring basis during the period (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Assets
Balance at beginning of period	$ 618	$ 565
Total gains (losses) included in: net income	3	38
Total gains (losses) included in: OCI	2	(1)
Transfers into Level 3	0	0
Transfers out of Level 3	0	(28)
Purchases	42	113
Sales	(63)	(7)
Issues	0	0
Settlements	(2)	(2)
Balance at end of period	600	678
Net investment income
Total Level 3 gains (losses) included in net income
Gain (loss) included in earnings	$ (5)	$ 9
Fair Value, Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net investment income	Net investment income
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net investment income	Net investment income
Net gains (losses) on investments and derivatives
Total Level 3 gains (losses) included in net income
Gain (loss) included in earnings	$ 8	$ 29
Fair Value, Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net gains (losses) on investments and derivatives	Net gains (losses) on investments and derivatives
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net gains (losses) on investments and derivatives	Net gains (losses) on investments and derivatives
Municipal
Assets
Balance at beginning of period	$ 21	$ 18
Total gains (losses) included in: net income	0	0
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	0	0
Sales	(3)	0
Issues	0	0
Settlements	(1)	(1)
Balance at end of period	17	17
Corporate - public
Assets
Balance at beginning of period	69	20
Total gains (losses) included in: net income	(1)	0
Total gains (losses) included in: OCI	2	(2)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	0	35
Sales	(41)	(4)
Issues	0	0
Settlements	0	0
Balance at end of period	29	49
Corporate - privately placed
Assets
Balance at beginning of period	55	66
Total gains (losses) included in: net income	(4)	0
Total gains (losses) included in: OCI	0	1
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	0	63
Sales	(2)	0
Issues	0	0
Settlements	0	0
Balance at end of period	49	130
ABS
Assets
Balance at beginning of period	28	40
Total gains (losses) included in: net income	0	1
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	(28)
Purchases	0	7
Sales	0	0
Issues	0	0
Settlements	(1)	(1)
Balance at end of period	27	19
Fixed income securities
Assets
Balance at beginning of period	173	144
Total gains (losses) included in: net income	(5)	1
Total gains (losses) included in: OCI	2	(1)
Transfers into Level 3	0	0
Transfers out of Level 3	0	(28)
Purchases	0	105
Sales	(46)	(4)
Issues	0	0
Settlements	(2)	(2)
Balance at end of period	122	215
Equity securities
Assets
Balance at beginning of period	333	349
Total gains (losses) included in: net income	0	25
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	42	2
Sales	(17)	(3)
Issues	0	0
Settlements	0	0
Balance at end of period	358	373
Short-term investments
Assets
Balance at beginning of period	6	5
Total gains (losses) included in: net income	0	0
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	0	6
Sales	0	0
Issues	0	0
Settlements	0	0
Balance at end of period	6	11
Other investments
Assets
Balance at beginning of period	3	2
Total gains (losses) included in: net income	(1)	0
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	0	0
Sales	0	0
Issues	0	0
Settlements	0	0
Balance at end of period	2	2
Other assets
Assets
Balance at beginning of period	103	65
Total gains (losses) included in: net income	9	12
Total gains (losses) included in: OCI	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Purchases	0	0
Sales	0	0
Issues	0	0
Settlements	0	0
Balance at end of period	$ 112	$ 77

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

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-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 2
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Amount of gain (loss) recognized in income from asset and liability measured at fair value on recurring basis using unobservable input (level 3).

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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).

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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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Amount of issuances 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 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 transfer of financial instrument classified as an asset into 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 net income is reported that includes gain (loss) from asset (liability), measured at fair value using unobservable input (level 3).

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