Railcar Leasing and Management Services Group - Selected consolidating financial information for the Leasing Group (Details) - USD ($) $ in Millions		Mar. 31, 2021		Dec. 31, 2020
Segment Reporting Information [Line Items]
Cash and cash equivalents		$ 178.1		$ 132.0
Receivables, net of allowance		197.3		199.0
Property, Plant and Equipment, Net		7,026.8		7,003.4
Restricted cash		107.4		96.4
Other assets		288.8		295.2
Total assets		8,775.5		8,701.8
Total debt		5,165.1		5,017.0
Deferred income taxes		1,051.5		1,047.5
Other liabilities		155.5		150.2
Total liabilities		6,807.6		6,685.8
Noncontrolling interest		275.5		277.2
Total Equity		1,692.4		1,738.8
Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Segment Reporting Information [Line Items]
Cash and cash equivalents		5.1		3.5
Receivables, net of allowance		91.8		90.4
Property, Plant and Equipment, Net		7,442.2		7,422.2
Restricted cash		107.3		96.3
Other assets		49.6		39.7
Total assets		7,696.0		7,652.1
Accounts payable and accrued liabilities		146.5		172.3
Total debt		4,766.9		4,568.8
Deferred income taxes		1,068.9		1,063.4
Other liabilities		33.2		25.7
Total liabilities		6,015.5		5,830.2
Noncontrolling interest		275.5		277.2
Total Equity		1,405.0		1,544.7
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net		(813.0)		(820.3)
Railcar Leasing and Management Services Group [Member]
Segment Reporting Information [Line Items]
Cash and cash equivalents		5.1		3.5
Receivables, net of allowance		91.8		90.4
Property, Plant and Equipment, Net		6,629.2		6,601.9
Restricted cash		107.3		96.3
Other assets		49.6		39.7
Total assets		6,883.0		6,831.8
Accounts payable and accrued liabilities		146.5		172.3
Total debt		4,766.9		4,568.8
Deferred income taxes		880.3		877.2
Other liabilities		33.2		25.7
Total liabilities		5,826.9		5,644.0
Noncontrolling interest		275.5		277.2
Total Equity		780.6		910.6
Wholly-owned subsidiaries | Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Segment Reporting Information [Line Items]
Cash and cash equivalents		5.1		3.5
Receivables, net of allowance		81.2		82.0
Property, Plant and Equipment, Net		5,830.3		5,795.9
Restricted cash		74.4		65.2
Other assets		48.6		38.1
Total assets		6,039.6		5,984.7
Accounts payable and accrued liabilities		112.5		141.4
Total debt		3,550.5		3,340.5
Deferred income taxes		1,067.8		1,062.3
Other liabilities		33.2		25.7
Total liabilities		4,764.0		4,569.9
Noncontrolling interest		0.0		0.0
Total Equity		1,275.6		1,414.8
Partially-owned subsidiaries | Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Segment Reporting Information [Line Items]
Cash and cash equivalents		0.0		0.0
Receivables, net of allowance		10.6		8.4
Property, Plant and Equipment, Net		1,611.9		1,626.3
Restricted cash		32.9		31.1
Other assets		1.0		1.6
Total assets		1,656.4		1,667.4
Accounts payable and accrued liabilities		34.0		30.9
Total debt		1,216.4		1,228.3
Deferred income taxes		1.1		1.1
Other liabilities		0.0		0.0
Total liabilities		1,251.5		1,260.3
Noncontrolling interest		275.5		277.2
Total Equity		129.4		129.9
Consolidated Subsidiaries, Leasing [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Cash and cash equivalents		0.0		0.0
Receivables, net of allowance		0.0		0.0
Property, Plant and Equipment, Net	[1]	(813.0)		(820.3)
Restricted cash		0.0		0.0
Other assets		0.0		0.0
Total assets		(813.0)	[1]	(820.3)
Accounts payable and accrued liabilities		0.0		0.0
Total debt		0.0		0.0
Deferred income taxes	[1]	(188.6)		(186.2)
Other liabilities		0.0		0.0
Total liabilities	[1]	(188.6)		(186.2)
Noncontrolling interest		0.0		0.0
Total Equity	[1]	$ (624.4)		$ (634.1)

[1] Net deferred profit on railcars sold to the Leasing Group consists of intersegment profit that is eliminated in consolidation. Net deferred profit and the related deferred tax impact are included as adjustments to the property, plant, and equipment, net and deferred income taxes line items, respectively, in the Eliminations – Lease Subsidiary column above to reflect the net book value of the railcars purchased by the Leasing Group from the Rail Products Group based on manufacturing cost. See Note 4 and Note 7 for a further discussion regarding our investment in our partially-owned leasing subsidiaries and the related indebtedness.