Railcar Leasing and Management Services Group - Selected consolidating financial information for the Leasing Group (Details) - USD ($) $ in Millions	Sep. 30, 2018		Dec. 31, 2017
Consolidating Financial Information
Cash, cash equivalents, and short-term marketable securities	$ 427.4		$ 1,098.1
Property, plant, and equipment, net	6,538.0	[1]	6,134.7
Restricted cash	138.5	[1]	195.2
Debt:
Recourse	426.9		878.2
Less: unamortized discount			(8.5)
Less: unamortized debt issuance costs	(2.4)		(2.9)
Recourse, net of unamortized discount and unamortized debt issuance costs	424.2	[1]	866.8
Non-recourse debt	2,882.1		2,401.2
Less: unamortized debt issuance costs	(30.4)		(25.6)
Non-recourse debt, net of unamortized debt issuance costs	2,851.5		2,375.6
Total debt	3,275.7	[1]	3,242.4
Net deferred tax liabilities	736.0		723.9
Leasing Group
Debt:
Non-recourse debt, net of unamortized debt issuance costs	2,851.5		2,375.6
Operating Segments
Consolidating Financial Information
Property, plant, and equipment, net	7,369.4		6,944.8
Net deferred profit on railcars sold to the Leasing Group
Consolidating Financial Information
Property, plant, and equipment, net	(831.4)		(810.1)
Wholly-owned subsidiaries
Debt:
Non-recourse debt, net of unamortized debt issuance costs	1,531.0	[1]	1,024.8
Wholly-owned subsidiaries | Leasing Group
Debt:
Non-recourse debt	1,548.3		1,035.9
Less: unamortized debt issuance costs	(17.3)		(11.1)
Non-recourse debt, net of unamortized debt issuance costs	1,531.0		1,024.8
Wholly-owned subsidiaries | Operating Segments | Leasing Group
Consolidating Financial Information
Cash, cash equivalents, and short-term marketable securities	72.9		3.3
Property, plant, and equipment, net	4,608.4		4,147.5
Restricted cash	99.8		132.2
Debt:
Recourse	26.5		28.3
Less: unamortized discount	0.0		0.0
Less: unamortized debt issuance costs	0.0		0.0
Recourse, net of unamortized discount and unamortized debt issuance costs	26.5		28.3
Non-recourse debt	1,548.5		1,035.9
Less: unamortized debt issuance costs	(17.3)		(11.1)
Non-recourse debt, net of unamortized debt issuance costs	1,531.0		1,024.8
Total debt	1,557.5		1,053.1
Net deferred tax liabilities	682.0		653.7
Partially-owned subsidiaries
Consolidating Financial Information
Restricted cash	38.6	[1]	62.9
Debt:
Non-recourse debt, net of unamortized debt issuance costs	1,320.5	[1]	1,350.8
Partially-owned subsidiaries | Leasing Group
Debt:
Non-recourse debt	1,333.6		1,365.3
Less: unamortized debt issuance costs	(13.1)		(14.5)
Non-recourse debt, net of unamortized debt issuance costs	1,320.5		1,350.8
Partially-owned subsidiaries | Operating Segments | Leasing Group
Consolidating Financial Information
Cash, cash equivalents, and short-term marketable securities	0.0		0.0
Property, plant, and equipment, net	1,815.9		1,824.6
Restricted cash	38.6		62.9
Debt:
Recourse	0.0		0.0
Less: unamortized discount	0.0		0.0
Less: unamortized debt issuance costs	0.0		0.0
Recourse, net of unamortized discount and unamortized debt issuance costs	0.0		0.0
Non-recourse debt	1,333.6		1,365.3
Less: unamortized debt issuance costs	(13.1)		(14.5)
Non-recourse debt, net of unamortized debt issuance costs	1,320.5		1,350.8
Total debt	1,320.5		1,350.8
Net deferred tax liabilities	0.8		0.8
Manufacturing/ Corporate
Consolidating Financial Information
Property, plant, and equipment, net	945.1		972.7
Manufacturing/ Corporate | Operating Segments
Consolidating Financial Information
Property, plant, and equipment, net	945.1		972.7
Manufacturing/ Corporate | Operating Segments | Manufacturing/ Corporate
Consolidating Financial Information
Cash, cash equivalents, and short-term marketable securities	354.5		1,094.8
Restricted cash	0.1		0.1
Debt:
Recourse	400.4		849.9
Less: unamortized discount	0.0		(8.5)
Less: unamortized debt issuance costs	(2.4)		(2.9)
Recourse, net of unamortized discount and unamortized debt issuance costs	397.7		838.5
Non-recourse debt	0.0		0.0
Less: unamortized debt issuance costs	0.0		0.0
Non-recourse debt, net of unamortized debt issuance costs	0.0		0.0
Total debt	397.7		838.5
Net deferred tax liabilities	53.2		$ 69.4
Senior notes
Debt:
Less: unamortized discount	(0.3)
Senior notes | Manufacturing/ Corporate | Operating Segments | Manufacturing/ Corporate
Debt:
Less: unamortized discount	(0.3)
2018 secured railcar equipment notes
Debt:
Less: unamortized discount	(0.2)
2018 secured railcar equipment notes | Wholly-owned subsidiaries | Operating Segments | Leasing Group
Debt:
Less: unamortized discount	$ (0.2)

[1] (unaudited)