Fair Value Accounting (Details 2) - USD ($) $ in Millions	Jun. 30, 2017		Dec. 31, 2016
Carrying amounts and estimated fair values of long-term debt
Convertible subordinated notes	$ 880.2		$ 881.5
Less: unamortized discount	(17.9)	[1]	(27.1)
Less: unamortized debt issuance costs	(3.3)		(3.8)
Recourse, net of unamortized discount and unamortized debt issuance costs	859.0	[1]	850.6
Non-recourse debt	2,438.2		2,232.4
Less: unamortized debt issuance costs	(27.2)		(26.4)
Non-recourse debt, net of unamortized debt issuance costs	2,411.0		2,206.0
Total debt	3,270.0	[1]	3,056.6
Carrying Value
Carrying amounts and estimated fair values of long-term debt
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	862.4		854.4
Less: unamortized debt issuance costs	(3.4)		(3.8)
Recourse, net of unamortized discount and unamortized debt issuance costs	859.0		850.6
Non-recourse debt	2,438.2		2,232.4
Less: unamortized debt issuance costs	(27.2)		(26.4)
Non-recourse debt, net of unamortized debt issuance costs	2,411.0		2,206.0
Total debt	3,270.0		3,056.6
Carrying Value | 2006 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	170.5		194.2
Carrying Value | 2009 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	169.4		172.5
Carrying Value | 2010 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	273.5		280.6
Carrying Value | 2017 promissory notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	301.1		0.0
Carrying Value | TRL 2012 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	413.8		425.5
Carrying Value | TRIP Master Funding secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	942.3		955.5
Carrying Value | Senior notes
Carrying amounts and estimated fair values of long-term debt
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	399.7		399.6
Carrying Value | Convertible subordinated notes
Carrying amounts and estimated fair values of long-term debt
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	431.8		422.7
Convertible subordinated notes	449.4		449.4
Less: unamortized discount	(17.6)		(26.7)
Carrying Value | Capital lease obligations
Carrying amounts and estimated fair values of long-term debt
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	30.3		32.1
Carrying Value | Other
Carrying amounts and estimated fair values of long-term debt
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	0.6		0.0
Carrying Value | Line of credit | TILC warehouse facility | Revolving credit facility
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	167.6		204.1
Estimated Fair Value
Carrying amounts and estimated fair values of long-term debt
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	1,001.2		993.9
Non-recourse debt	2,395.0		2,236.0
Total debt	3,396.2		3,229.9
Estimated Fair Value | 2006 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	173.9		201.5
Estimated Fair Value | 2009 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	180.0		189.9
Estimated Fair Value | 2010 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	267.5		284.3
Estimated Fair Value | 2017 promissory notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	301.1		0.0
Estimated Fair Value | TRL 2012 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	378.5		395.6
Estimated Fair Value | TRIP Master Funding secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	926.4		960.6
Estimated Fair Value | Senior notes
Carrying amounts and estimated fair values of long-term debt
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	404.9		386.3
Estimated Fair Value | Convertible subordinated notes
Carrying amounts and estimated fair values of long-term debt
Convertible subordinated notes	565.4		575.5
Estimated Fair Value | Capital lease obligations
Carrying amounts and estimated fair values of long-term debt
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	30.3		32.1
Estimated Fair Value | Other
Carrying amounts and estimated fair values of long-term debt
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	0.6		0.0
Estimated Fair Value | Line of credit | TILC warehouse facility | Revolving credit facility
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	$ 167.6		$ 204.1

[1] (unaudited)