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Investments - Equity securities reported at fair value (Details) - USD ($) $ in Millions | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Debt and Equity Securities, FV-NI [Line Items] |  |
Equity securities | $ 800 | $ 751
Common stocks |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Equity securities, at cost | 323 | 304
Equity securities | 384 | 336
Equity securities, fair value in excess of cost | 61 | 32
Perpetual preferred stocks |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Equity securities, at cost | 391 | 380
Equity securities | 416 | 415
Equity securities, fair value in excess of cost | 25 | 35
Equity securities |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Equity securities, at cost | 714 | 684
Equity securities | 800 | 751
Equity securities, fair value in excess of cost | $ 86 | $ 67

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- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI) in excess of the cost of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Excludes equity method investment and investment in equity security without readily determinable fair value. + References No definition available. + Details
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