Investments - Internally Managed Investment Portfolio (Details) - USD ($) $ in Millions |
Sep. 30, 2026 |
Dec. 31, 2025 |
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| Debt and Equity Securities, FV-NI [Line Items] | ||
| Estimated fair value | $ 6,506 | $ 6,369 |
| Fixed-maturity securities, trading | 85 | 124 |
| Short-term investments, at fair value | 950 | 903 |
| Other invested assets | 189 | 12 |
| Total investments | 8,792 | 8,487 |
| Sound Point Capital Management, LP | ||
| Debt and Equity Securities, FV-NI [Line Items] | ||
| Equity method investments | 399 | 415 |
| Total investments | 534 | 628 |
| Equity method investments | ||
| Debt and Equity Securities, FV-NI [Line Items] | ||
| Equity method investments | $ 663 | $ 664 |
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- Definition Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Sum of the carrying amounts as of the balance sheet date of all investments. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of long-term investments classified as other. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Amount of short-term investments classified as other. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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