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Investments - Summary of Fair Value, Including Financial Guarantee, and Weighted-Average Underlying Rating, Excluding Financial Guarantee, of Insured Securities (Phantom) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Investment [Line Items]
Net Realized and Unrealized Gain (Loss) on Trading Securities	$ 7	$ (13)
Investment expense	(2)	(1)
Interest and Dividend Income, Securities, Operating, Available-for-Sale	21	14
Net investment income	34	5
Gains (losses) on securities held as of reporting date [Member]
Investment [Line Items]
Other Investments Income	5	(10)
Fixed Income Investments [Member]
Investment [Line Items]
Gross Investment Income, Operating	17	15
Short-Term [Member]
Investment [Line Items]
Gross Investment Income, Operating	6	0
Other Investments [Member]
Investment [Line Items]
Gross Investment Income, Operating	$ 13	$ 0

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Other Investments Income

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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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Amount, after 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://www.xbrl.org/2003/role/disclosureRef
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