Other Income (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Real estate income	$ 263	$ 414	$ 381
Net periodic pension benefit/(costs)	55	52	84
Interest income	52	52	23
Non-operating property environmental remediation and restoration	(37)	(37)	(47)
Interest from IRS refund claims	24	0	0
Other	(7)	10	(15)
Total	$ 350	491	426
Illinois State Toll Highway Authority \| Land
Property, Plant and Equipment [Line Items]
Gain from land sale			79
Colorado Department of Transportation \| Land
Property, Plant and Equipment [Line Items]
Gain from land sale			$ 35
Real Estate Transaction
Property, Plant and Equipment [Line Items]
Real estate income		$ 107

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