Segment Reporting and Significant Expenses- Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2025 USD ($) segment	Mar. 31, 2024 USD ($)	Dec. 31, 2024 USD ($)
Segment Reporting, Asset Reconciling Item [Line Items]
Number of operating segments | segment	2
Assets	$ 43,199		$ 42,764
Rail Operations
Segment Reporting, Asset Reconciling Item [Line Items]
Segment, expenditure, addition to long-lived assets	691	$ 498
Assets	$ 43,000		$ 42,600