Property, Plant, and Equipment - Components of property, plant, and equipment (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,919.8 and $1,917.6	$ 9,415.8	$ 9,272.6
Less: accumulated depreciation	(2,439.3)	(2,385.8)
Property, Plant and Equipment, Net	6,976.5	6,886.8
Intersegment Eliminations [Member]
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,919.8 and $1,917.6	(1,055.6)	(1,050.7)
Property, Plant and Equipment, Net	(763.4)	(763.3)
Negative Accumulated Depreciation PP&E- Deferred Profit	292.2	287.4
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member]
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Net	7,398.0	7,309.4
Manufacturing and Corporate [Member]
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,919.8 and $1,917.6	832.2	823.9
Less: accumulated depreciation	(490.3)	(483.2)
Property, Plant and Equipment, Net	341.9	340.7
Manufacturing and Corporate [Member] | Land
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,919.8 and $1,917.6	17.1	15.7
Manufacturing and Corporate [Member] | Buildings and improvements
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,919.8 and $1,917.6	386.9	384.6
Manufacturing and Corporate [Member] | Machinery and other
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,919.8 and $1,917.6	405.9	405.5
Manufacturing and Corporate [Member] | Construction in progress
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,919.8 and $1,917.6	22.3	18.1
Wholly-owned subsidiaries | Railcar Leasing and Management Services Group [Member] | Operating Segments [Member]
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,919.8 and $1,917.6	7,406.1	7,269.0
Less: accumulated depreciation	(1,518.0)	(1,480.9)
Property, Plant and Equipment, Net	5,888.1	5,788.1
Wholly-owned subsidiaries | Railcar Leasing and Management Services Group [Member] | Machinery and other | Operating Segments [Member]
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,919.8 and $1,917.6	27.1	21.7
Wholly-owned subsidiaries | Railcar Leasing and Management Services Group [Member] | Equipment on lease | Operating Segments [Member]
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,919.8 and $1,917.6	7,379.0	7,247.3
Partially-owned subsidiaries
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,919.8 and $1,917.6	1,919.8	1,917.6
Less: accumulated depreciation	(610.9)	(599.0)
Partially-owned subsidiaries | Railcar Leasing and Management Services Group [Member] | Operating Segments [Member]
Property, Plant and Equipment, Net [Abstract]
Less: accumulated depreciation	(723.2)	(709.1)
Property, Plant and Equipment, Net	1,509.9	1,521.3
Partially-owned subsidiaries | Railcar Leasing and Management Services Group [Member] | Equipment on lease | Operating Segments [Member]
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,919.8 and $1,917.6	$ 2,233.1	$ 2,230.4