Fair Value Accounting (Details 2) - USD ($) $ in Millions	Mar. 31, 2017		Dec. 31, 2016
Carrying amounts and estimated fair values of long-term debt
Convertible subordinated notes	$ 880.6		$ 881.5
Less: unamortized discount	(22.5)	[1]	(27.1)
Less: unamortized debt issuance costs	(3.6)		(3.8)
Recourse, net of unamortized discount and unamortized debt issuance costs	854.5	[1]	850.6
Non-recourse debt	2,206.6		2,232.4
Less: unamortized debt issuance costs	(25.1)		(26.4)
Non-recourse debt, net of unamortized debt issuance costs	2,181.5		2,206.0
Total debt	3,036.0	[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	858.1		854.4
Less: unamortized debt issuance costs	(3.6)		(3.8)
Recourse, net of unamortized discount and unamortized debt issuance costs	854.5		850.6
Non-recourse debt	2,206.6		2,232.4
Less: unamortized debt issuance costs	(25.1)		(26.4)
Non-recourse debt, net of unamortized debt issuance costs	2,181.5		2,206.0
Total debt	3,036.0		3,056.6
Carrying Value | 2006 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	188.2		194.2
Carrying Value | 2009 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	171.0		172.5
Carrying Value | 2010 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	277.1		280.6
Carrying Value | TRL 2012 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	419.7		425.5
Carrying Value | TRIP Master Funding secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	948.6		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	427.2		422.7
Convertible subordinated notes	449.4		449.4
Less: unamortized discount	(22.2)		(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	31.2		32.1
Carrying Value | Line of credit | TILC warehouse facility | Revolving credit facility
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	202.0		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	979.5		993.9
Non-recourse debt	2,209.9		2,236.0
Total debt	3,189.4		3,229.9
Estimated Fair Value | 2006 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	195.0		201.5
Estimated Fair Value | 2009 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	187.9		189.9
Estimated Fair Value | 2010 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	280.8		284.3
Estimated Fair Value | TRL 2012 secured railcar equipment notes
Carrying amounts and estimated fair values of long-term debt
Non-recourse debt	390.6		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	953.6		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	400.3		386.3
Estimated Fair Value | Convertible subordinated notes
Carrying amounts and estimated fair values of long-term debt
Convertible subordinated notes	548.0		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	31.2		32.1
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	$ 202.0		$ 204.1

[1] (unaudited)