Railcar Leasing and Management Services Group - Selected consolidating financial information for the Leasing Group (Details) - USD ($) $ in Millions	Mar. 31, 2018		Dec. 31, 2017
Consolidating Financial Information
Cash, cash equivalents, and short-term marketable securities	$ 846.2		$ 1,098.1
Property, plant, and equipment, net	6,393.5	[1]	6,134.7
Restricted cash	177.3	[1]	195.2
Debt:
Recourse	877.3		878.2
Less: unamortized discount	(3.6)	[1]	(8.5)
Less: unamortized debt issuance costs	(2.7)		(2.9)
Recourse, net of unamortized discount and unamortized debt issuance costs	871.0	[1]	866.8
Non-recourse	2,380.3		2,401.2
Less: unamortized debt issuance costs	(27.9)		(25.6)
Non-recourse debt, net of unamortized debt issuance costs	2,352.4		2,375.6
Total debt	3,223.4	[1]	3,242.4
Net deferred tax liabilities	737.3		723.9
Leasing Group
Debt:
Non-recourse debt, net of unamortized debt issuance costs	2,352.4		2,375.6
Operating Segments
Consolidating Financial Information
Property, plant, and equipment, net	7,222.7		6,944.8
Net deferred profit on railcars sold to the Leasing Group
Consolidating Financial Information
Property, plant, and equipment, net	(829.2)		(810.1)
Wholly-owned subsidiaries
Debt:
Non-recourse debt, net of unamortized debt issuance costs	1,012.3	[1]	1,024.8
Wholly-owned subsidiaries | Leasing Group
Debt:
Non-recourse	1,026.2		1,035.9
Less: unamortized debt issuance costs	(13.9)		(11.1)
Non-recourse debt, net of unamortized debt issuance costs	1,012.3		1,024.8
Wholly-owned subsidiaries | Operating Segments | Leasing Group
Consolidating Financial Information
Cash, cash equivalents, and short-term marketable securities	6.1		3.3
Property, plant, and equipment, net	4,427.7		4,147.5
Restricted cash	123.4		132.2
Debt:
Recourse	27.4		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	27.4		28.3
Non-recourse	1,026.2		1,035.9
Less: unamortized debt issuance costs	(13.9)		(11.1)
Non-recourse debt, net of unamortized debt issuance costs	1,012.3		1,024.8
Total debt	1,039.7		1,053.1
Net deferred tax liabilities	660.9		653.7
Partially-owned subsidiaries
Consolidating Financial Information
Restricted cash	53.8	[1]	62.9
Debt:
Non-recourse debt, net of unamortized debt issuance costs	1,340.1	[1]	1,350.8
Partially-owned subsidiaries | Leasing Group
Debt:
Non-recourse	1,354.1		1,365.3
Less: unamortized debt issuance costs	(14.0)		(14.5)
Non-recourse debt, net of unamortized debt issuance costs	1,340.1		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	1,822.8		1,824.6
Restricted cash	53.8		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	1,354.1		1,365.3
Less: unamortized debt issuance costs	(14.0)		(14.5)
Non-recourse debt, net of unamortized debt issuance costs	1,340.1		1,350.8
Total debt	1,340.1		1,350.8
Net deferred tax liabilities	0.8		0.8
Manufacturing/ Corporate
Consolidating Financial Information
Property, plant, and equipment, net	972.2		972.7
Manufacturing/ Corporate | Operating Segments
Consolidating Financial Information
Property, plant, and equipment, net	972.2		972.7
Manufacturing/ Corporate | Operating Segments | Manufacturing/ Corporate
Consolidating Financial Information
Cash, cash equivalents, and short-term marketable securities	840.1		1,094.8
Restricted cash	0.1		0.1
Debt:
Recourse	849.9		849.9
Less: unamortized discount	(3.6)		(8.5)
Less: unamortized debt issuance costs	(2.7)		(2.9)
Recourse, net of unamortized discount and unamortized debt issuance costs	843.6		838.5
Non-recourse	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	843.6		838.5
Net deferred tax liabilities	$ 75.6		$ 69.4

[1] (unaudited)