Railcar Leasing and Management Services Group - Selected consolidating financial information for the Leasing Group (Details) - USD ($) $ in Millions		Sep. 30, 2021		Dec. 31, 2020
Segment Reporting Information [Line Items]
Cash and cash equivalents		$ 221.8		$ 132.0
Receivables, net of allowance		246.3		199.0
Property, Plant and Equipment, Net		6,800.1		7,003.4
Restricted cash		123.3		96.4
Other assets		292.9		295.2
Total assets		8,495.6		8,701.8
Total debt		5,176.5		5,017.0
Deferred income taxes		1,060.3		1,047.5
Other liabilities		157.4		150.2
Total liabilities		6,899.2		6,685.8
Noncontrolling interest		265.4		277.2
Total Equity		1,331.0		1,738.8
Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Segment Reporting Information [Line Items]
Cash and cash equivalents		2.6		3.5
Receivables, net of allowance		113.3		90.4
Property, Plant and Equipment, Net		7,198.1		7,422.2
Restricted cash		123.3		96.3
Other assets		64.6		39.7
Total assets		7,501.9		7,652.1
Accounts payable and accrued liabilities		171.4		172.3
Total debt		4,778.0		4,568.8
Deferred income taxes		1,088.5		1,063.4
Other liabilities		39.1		25.7
Total liabilities		6,077.0		5,830.2
Noncontrolling interest		265.4		277.2
Total Equity		1,159.5		1,544.7
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net		(782.6)		(820.3)
Railcar Leasing and Management Services Group [Member]
Segment Reporting Information [Line Items]
Cash and cash equivalents		2.6		3.5
Receivables, net of allowance		113.3		90.4
Property, Plant and Equipment, Net		6,415.5		6,601.9
Restricted cash		123.3		96.3
Other assets		64.6		39.7
Total assets		6,719.3		6,831.8
Accounts payable and accrued liabilities		171.4		172.3
Total debt		4,778.0		4,568.8
Deferred income taxes		908.3		877.2
Other liabilities		39.1		25.7
Total liabilities		5,896.8		5,644.0
Noncontrolling interest		265.4		277.2
Total Equity		557.1		910.6
Wholly-owned subsidiaries | Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Segment Reporting Information [Line Items]
Cash and cash equivalents		2.6		3.5
Receivables, net of allowance		101.9		82.0
Property, Plant and Equipment, Net		5,603.4		5,795.9
Restricted cash		81.1		65.2
Other assets		63.3		38.1
Total assets		5,852.3		5,984.7
Accounts payable and accrued liabilities		137.7		141.4
Total debt		3,553.5		3,340.5
Deferred income taxes		1,087.4		1,062.3
Other liabilities		39.1		25.7
Total liabilities		4,817.7		4,569.9
Noncontrolling interest		0.0		0.0
Total Equity		1,034.6		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		11.4		8.4
Property, Plant and Equipment, Net		1,594.7		1,626.3
Restricted cash		42.2		31.1
Other assets		1.3		1.6
Total assets		1,649.6		1,667.4
Accounts payable and accrued liabilities		33.7		30.9
Total debt		1,224.5		1,228.3
Deferred income taxes		1.1		1.1
Other liabilities		0.0		0.0
Total liabilities		1,259.3		1,260.3
Noncontrolling interest		265.4		277.2
Total Equity		124.9		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]	(782.6)		(820.3)
Restricted cash		0.0		0.0
Other assets		0.0		0.0
Total assets		(782.6)	[1]	(820.3)
Accounts payable and accrued liabilities		0.0		0.0
Total debt		0.0		0.0
Deferred income taxes	[1]	(180.2)		(186.2)
Other liabilities		0.0		0.0
Total liabilities	[1]	(180.2)		(186.2)
Noncontrolling interest		0.0		0.0
Total Equity	[1]	$ (602.4)		$ (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.