Segment Reporting and Significant Expenses- Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($)	Dec. 31, 2025 USD ($)	Dec. 31, 2025 USD ($) operatingSegment	Dec. 31, 2025 USD ($) segment	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Segment Reporting, Asset Reconciling Item [Line Items]
Number of operating segments			2	2
Reportable segments not disclosed	segments
Assets	$ 43,682	$ 43,682	$ 43,682	$ 43,682	$ 42,764	$ 42,200
Rail Operations
Segment Reporting, Asset Reconciling Item [Line Items]
Number of operating segments | operatingSegment			1
Segment, expenditure, addition to long-lived assets		2,900			2,500	2,200
Assets	$ 43,500	43,500	$ 43,500	$ 43,500	42,600	$ 42,000
Rail Operations | Hurricane Helene
Segment Reporting, Asset Reconciling Item [Line Items]
Segment, expenditure, addition to long-lived assets		$ 470			$ 50