Property, Plant, and Equipment - Components of property, plant, and equipment (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,926.6 and $1,927.7	$ 9,106.8	$ 9,105.6
Less: accumulated depreciation	(2,303.2)	(2,258.7)
Property, Plant and Equipment, Net	6,803.6	6,846.9
Intersegment Eliminations [Member]
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,926.6 and $1,927.7	(1,052.1)	(1,047.3)
NegativeAccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	275.2	268.2
Property, Plant and Equipment, Net	(776.9)	(779.1)
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member]
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Net	7,234.2	7,276.7
Manufacturing and Corporate [Member]
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,926.6 and $1,927.7	828.8	828.0
Less: accumulated depreciation	(482.5)	(478.7)
Property, Plant and Equipment, Net	346.3	349.3
Manufacturing and Corporate [Member] | Land
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,926.6 and $1,927.7	16.3	17.4
Manufacturing and Corporate [Member] | Buildings and improvements
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,926.6 and $1,927.7	376.9	377.4
Manufacturing and Corporate [Member] | Machinery and other
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,926.6 and $1,927.7	413.3	415.1
Manufacturing and Corporate [Member] | Construction in progress
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,926.6 and $1,927.7	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 $1,926.6 and $1,927.7	7,088.3	7,082.0
Less: accumulated depreciation	(1,409.6)	(1,375.9)
Property, Plant and Equipment, Net	5,678.7	5,706.1
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 $1,926.6 and $1,927.7	21.5	20.7
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 $1,926.6 and $1,927.7	7,066.8	7,061.3
Partially-owned subsidiaries
Property, Plant and Equipment, Net [Abstract]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,926.6 and $1,927.7	1,926.6	1,927.7
Less: accumulated depreciation	(580.1)	(568.4)
Partially-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 $1,926.6 and $1,927.7	2,241.8	2,242.9
Less: accumulated depreciation	(686.3)	(672.3)
Property, Plant and Equipment, Net	$ 1,555.5	$ 1,570.6