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Financial Instruments (Narrative) (Details) - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2023 | Dec. 31, 2022
Unsecured Notes Two | Revolving Credit Facility |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Drawn down amount under credit facility | $ 200 | $ 25
Unsecured debt | Level 2 |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Unsecured notes | 375 | 375
Private Equity Funds |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Unfunded commitments to VIEs | $ 8 | $ 9

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