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Business Segments (Revenues by Line of Business) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Total revenues | $ 14,270 | $ 13,299 | $ 11,879
Total operating revenues | 14,351 | 13,398 | 12,078
Net investment gains (losses) | (81) | (99) | (199)
Operating Segments | Specialty |  |  |
Total revenues | 5,598 | 5,490 | 5,209
Operating Segments | Commercial |  |  |
Total revenues | 5,920 | 5,221 | 4,441
Operating Segments | International |  |  |
Total revenues | 1,387 | 1,279 | 1,134
Operating Segments | Life & Group |  |  |
Total revenues | 1,377 | 1,346 | 1,276
Operating Segments | Corporate & Other |  |  |
Total revenues | 80 | 73 | 24
Eliminations |  |  |
Total revenues | (11) | (11) | (6)
Management & Professional Liability | Operating Segments | Specialty |  |  |
Total revenues | 2,998 | 2,931 | 2,771
Surety | Operating Segments | Specialty |  |  |
Total revenues | 785 | 731 | 652
Warranty & Alternative Risks | Operating Segments | Specialty |  |  |
Total revenues | 1,815 | 1,828 | 1,786
Middle Market | Operating Segments | Commercial |  |  |
Total revenues | 1,775 | 1,696 | 1,532
Construction | Operating Segments | Commercial |  |  |
Total revenues | 1,991 | 1,678 | 1,421
Small Business | Operating Segments | Commercial |  |  |
Total revenues | 637 | 631 | 581
Other Commercial | Operating Segments | Commercial |  |  |
Total revenues | 1,517 | 1,216 | 907
Canada | Operating Segments | International |  |  |
Total revenues | 401 | 383 | 366
Europe | Operating Segments | International |  |  |
Total revenues | 593 | 532 | 466
Hardy | Operating Segments | International |  |  |
Total revenues | $ 393 | $ 364 | $ 302

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