Railcar Leasing and Management Services Group - Selected consolidating financial information for the Leasing Group (Details) - USD ($) $ in Millions		Jun. 30, 2021		Dec. 31, 2020
Segment Reporting Information [Line Items]
Cash and cash equivalents		$ 91.0		$ 132.0
Receivables, net of allowance		218.3		199.0
Property, Plant and Equipment, Net		7,048.7		7,003.4
Restricted cash		164.7		96.4
Other assets		279.9		295.2
Total assets		8,617.0		8,701.8
Total debt		5,288.2		5,017.0
Deferred income taxes		1,049.3		1,047.5
Other liabilities		157.6		150.2
Total liabilities		6,959.1		6,685.8
Noncontrolling interest		268.0		277.2
Total Equity		1,389.9		1,738.8
Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Segment Reporting Information [Line Items]
Cash and cash equivalents		4.7		3.5
Receivables, net of allowance		105.0		90.4
Property, Plant and Equipment, Net		7,459.3		7,422.2
Restricted cash		164.7		96.3
Other assets		54.8		39.7
Total assets		7,788.5		7,652.1
Accounts payable and accrued liabilities		146.9		172.3
Total debt		4,839.8		4,568.8
Deferred income taxes		1,069.2		1,063.4
Other liabilities		37.9		25.7
Total liabilities		6,093.8		5,830.2
Noncontrolling interest		268.0		277.2
Total Equity		1,426.7		1,544.7
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net		(804.3)		(820.3)
Railcar Leasing and Management Services Group [Member]
Segment Reporting Information [Line Items]
Cash and cash equivalents		4.7		3.5
Receivables, net of allowance		105.0		90.4
Property, Plant and Equipment, Net		6,655.0		6,601.9
Restricted cash		164.7		96.3
Other assets		54.8		39.7
Total assets		6,984.2		6,831.8
Accounts payable and accrued liabilities		146.9		172.3
Total debt		4,839.8		4,568.8
Deferred income taxes		882.7		877.2
Other liabilities		37.9		25.7
Total liabilities		5,907.3		5,644.0
Noncontrolling interest		268.0		277.2
Total Equity		808.9		910.6
Wholly-owned subsidiaries | Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Segment Reporting Information [Line Items]
Cash and cash equivalents		4.7		3.5
Receivables, net of allowance		95.3		82.0
Property, Plant and Equipment, Net		5,853.7		5,795.9
Restricted cash		122.1		65.2
Other assets		53.4		38.1
Total assets		6,129.2		5,984.7
Accounts payable and accrued liabilities		114.4		141.4
Total debt		3,607.3		3,340.5
Deferred income taxes		1,068.1		1,062.3
Other liabilities		37.9		25.7
Total liabilities		4,827.7		4,569.9
Noncontrolling interest		0.0		0.0
Total Equity		1,301.5		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		9.7		8.4
Property, Plant and Equipment, Net		1,605.6		1,626.3
Restricted cash		42.6		31.1
Other assets		1.4		1.6
Total assets		1,659.3		1,667.4
Accounts payable and accrued liabilities		32.5		30.9
Total debt		1,232.5		1,228.3
Deferred income taxes		1.1		1.1
Other liabilities		0.0		0.0
Total liabilities		1,266.1		1,260.3
Noncontrolling interest		268.0		277.2
Total Equity		125.2		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]	(804.3)		(820.3)
Restricted cash		0.0		0.0
Other assets		0.0		0.0
Total assets		(804.3)	[1]	(820.3)
Accounts payable and accrued liabilities		0.0		0.0
Total debt		0.0		0.0
Deferred income taxes	[1]	(186.5)		(186.2)
Other liabilities		0.0		0.0
Total liabilities	[1]	(186.5)		(186.2)
Noncontrolling interest		0.0		0.0
Total Equity	[1]	$ (617.8)		$ (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.