Segment Reporting and Significant Expenses- Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($)	Dec. 31, 2024 USD ($) operatingSegment	Dec. 31, 2024 USD ($) segment	Dec. 31, 2023 USD ($)		Dec. 31, 2022 USD ($)	Mar. 31, 2024 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)
Segment Reporting, Asset Reconciling Item [Line Items]
Number of operating segments		2	2
Assets	$ 42,764	$ 42,764	$ 42,764	$ 42,212	[1]	$ 41,682	$ 42,482	$ 41,589	$ 40,979	$ 41,256
Rail Operations
Segment Reporting, Asset Reconciling Item [Line Items]
Segment, expenditure, addition to long-lived assets	2,450			2,170		2,020
Assets	$ 42,600	$ 42,600	$ 42,600	$ 42,000		$ 41,500

[1] See Note 20, Revision of Prior Period Financial Statements.