Operating Assets and Facilities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 19,780.9		$ 15,662.6
Less: allowance for depreciation	(4,328.3)		(4,251.7)
Operating assets and facilities, net	15,452.6		11,410.9
Total depreciation expense	174.6	$ 108.4
Railcars and locomotives
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	17,880.1		13,802.1
Aircraft spare engines
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	1,177.7		1,177.5
Tank containers
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	277.3		278.0
Buildings, leasehold improvements, and other equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	322.8		318.5
Other
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 123.0		$ 86.5