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	6 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Assets
Balance at beginning of period	$ 600	$ 678	$ 618	$ 565
Total gains (losses) included in: net income	(5)	54	(2)	92
Total gains (losses) included in: OCI	0	(3)	2	(4)
Transfers into Level 3	16	0	16	0
Transfers out of Level 3	0	(86)	0	(28)
Purchases	36	91	78	118
Sales	(21)	(34)	(84)	(41)
Issues	0	0	0	0
Settlements	(1)	(24)	(3)	(26)
Balance at end of period	625	676	625	676
Net investment income
Total Level 3 gains (losses) included in net income
Gain (loss) included in earnings	$ 3	$ 4	$ (2)	$ 13
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	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 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)	$ 50	$ 0	$ 79
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	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	Net gains (losses) on investments and derivatives	Net gains (losses) on investments and derivatives
Municipal
Assets
Balance at beginning of period	$ 17	$ 17	$ 21	$ 18
Total gains (losses) included in: net income	3	0	3	0
Total gains (losses) included in: OCI	(1)	1	(1)	1
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Purchases	0	1	0	1
Sales	(6)	0	(9)	0
Issues	0	0	0	0
Settlements	(1)	(1)	(2)	(2)
Balance at end of period	12	18	12	18
Corporate - public
Assets
Balance at beginning of period	29	49	69	20
Total gains (losses) included in: net income	0	0	(1)	0
Total gains (losses) included in: OCI	0	(1)	2	(3)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	(35)	0	0
Purchases	0	71	0	71
Sales	(3)	(5)	(44)	(9)
Issues	0	0	0	0
Settlements	0	(2)	0	(2)
Balance at end of period	26	77	26	77
Corporate - privately placed
Assets
Balance at beginning of period	49	130	55	66
Total gains (losses) included in: net income	(7)	19	(11)	19
Total gains (losses) included in: OCI	1	(3)	1	(2)
Transfers into Level 3	16	0	16	0
Transfers out of Level 3	0	(51)	0	0
Purchases	1	2	1	14
Sales	0	(24)	(2)	(24)
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	60	73	60	73
ABS
Assets
Balance at beginning of period	27	19	28	40
Total gains (losses) included in: net income	0	0	0	1
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	(28)
Purchases	7	0	7	7
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	0	(1)	(1)	(2)
Balance at end of period	34	18	34	18
Fixed income securities
Assets
Balance at beginning of period	122	215	173	144
Total gains (losses) included in: net income	(4)	19	(9)	20
Total gains (losses) included in: OCI	0	(3)	2	(4)
Transfers into Level 3	16	0	16	0
Transfers out of Level 3	0	(86)	0	(28)
Purchases	8	74	8	93
Sales	(9)	(29)	(55)	(33)
Issues	0	0	0	0
Settlements	(1)	(4)	(3)	(6)
Balance at end of period	132	186	132	186
Equity securities
Assets
Balance at beginning of period	358	373	333	349
Total gains (losses) included in: net income	7	4	7	29
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Purchases	28	0	70	2
Sales	(12)	(5)	(29)	(8)
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	381	372	381	372
Short-term investments
Assets
Balance at beginning of period	6	11	6	5
Total gains (losses) included in: net income	0	0	0	0
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Purchases	0	17	0	23
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	0	(20)	0	(20)
Balance at end of period	6	8	6	8
Other investments
Assets
Balance at beginning of period	2	2	3	2
Total gains (losses) included in: net income	0	0	(1)	0
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	2	2	2	2
Other assets
Assets
Balance at beginning of period	112	77	103	65
Total gains (losses) included in: net income	(8)	31	1	43
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	$ 104	$ 108	$ 104	$ 108

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

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