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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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- Definition 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 + Details
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