Investments - Summary of Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Investment [Line Items]
Equity Securities, FV-NI, Realized Gain (Loss)	$ 6	$ (14)
Interest and Dividend Income, Securities, Operating, Available-for-Sale	22	13	$ 43	$ 27
Short-term Investments [Member]
Investment [Line Items]
Gross Investment Income, Operating	5	1	10	1
Fixed Income Investments [Member]
Investment [Line Items]
Gross Investment Income, Operating	19	13	35	28
Fixed Income Securities, Trading
Investment [Line Items]
Gross Investment Income, Operating	$ 4	$ (11)	$ 5	$ (21)

Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 4
-URI https://asc.fasb.org/extlink&oid=126980263&loc=SL75117546-209714

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(3)(d))
-URI https://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

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Amount, before investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.2)
-URI https://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

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