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Investments - Equity securities reported at fair value (Details) - USD ($) $ in Millions | Mar. 31, 2026 | Dec. 31, 2025
--- | --- | ---
Debt and Equity Securities, FV-NI [Line Items] |  |
Fair Value | $ 753 | $ 785
Common stocks |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Actual Cost | 341 | 332
Fair Value | 363 | 365
Fair Value Over Cost | 22 | 33
Perpetual preferred stocks |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Actual Cost | 379 | 398
Fair Value | 390 | 420
Fair Value Over Cost | 11 | 22
Equity securities |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Actual Cost | 720 | 730
Fair Value | 753 | 785
Fair Value Over Cost | $ 33 | $ 55

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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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- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482736/825-10-45-1A Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(2)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483467/210-10-45-1 + Details
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