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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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