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Pending Acquisition - Schedule of Acquisition-Related Expense Associated with the Merger Agreement (Details) - Norfolk Southern - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2025
Business Combination [Line Items] |  |
Total acquisition-related expense | $ 41 | $ 42
Purchased services and materials |  |
Business Combination [Line Items] |  |
Total acquisition-related expense | 40 | 41
Other |  |
Business Combination [Line Items] |  |
Total acquisition-related expense | $ 1 | $ 1

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