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Investment Information - Investments in operating affiliates (Details) € / shares in Units, $ / shares in Units, € in Millions, $ in Millions | 12 Months Ended |
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Dec. 31, 2025 USD ($) | Dec. 31, 2024 USD ($) | Dec. 31, 2023 USD ($) | Dec. 31, 2021 USD ($) $ / shares | Dec. 31, 2021 EUR (€) € / shares
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Investment in operating affiliates | $ 1,313 | $ 1,240 |  |  |
Income (loss) from operating affiliates | $ 180 | 200 | $ 184 |  |
Coface |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Percentage ownership | 29.90% |  |  | 29.50% | 29.50%
Investment in affiliate, price per share | € / shares |  |  |  |  | € 9.95
Equity method investment, aggregate cost |  |  |  | $ 546 | € 453
Investment in operating affiliates | $ 707 | $ 592 |  |  |
Coface | Issued Shares Excluding Treasury Stock |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Percentage ownership | 30.00% |  |  |  |
Greysbridge Holdings Ltd |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Percentage ownership | 30.00% | 40.00% |  |  |
Investment in affiliate, price per share | $ / shares |  |  |  | $ 35.00 |
Investment in operating affiliates | $ 486 | $ 523 |  |  |

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