Fair Value Accounting - Carrying amounts and estimated fair values of long-term debt - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Gross	$ 878.2	$ 881.5
Less: unamortized discount	(8.5)	(27.1)
Less: unamortized debt issuance costs	(2.9)	(3.8)
Recourse, net of unamortized discount and unamortized debt issuance costs	866.8	850.6
Non-recourse debt	2,401.2	2,232.4
Less: unamortized debt issuance costs	(25.6)	(26.4)
Non-recourse debt, net of unamortized debt issuance costs	2,375.6	2,206.0
Total debt	3,242.4	3,056.6
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	869.7	854.4
Less: unamortized debt issuance costs	(2.9)	(3.8)
Recourse, net of unamortized discount and unamortized debt issuance costs	866.8	850.6
Non-recourse debt	2,401.2	2,232.4
Less: unamortized debt issuance costs	(25.6)	(26.4)
Non-recourse debt, net of unamortized debt issuance costs	2,375.6	2,206.0
Total debt	3,242.4	3,056.6
Carrying Value \| 2006 secured railcar equipment notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recourse debt	158.5	194.2
Carrying Value \| 2009 secured railcar equipment notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recourse debt	166.2	172.5
Carrying Value \| 2010 secured railcar equipment notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recourse debt	266.9	280.6
Carrying Value \| 2017 secured railcar equipment notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recourse debt	293.6	0.0
Carrying Value \| TRL 2012 secured railcar equipment notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recourse debt	402.8	425.5
Carrying Value \| TRIP Master Funding secured railcar equipment notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recourse debt	962.5	955.5
Carrying Value \| Senior notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	399.7	399.6
Carrying Value \| Convertible subordinated notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	441.2	422.7
Long-term Debt, Gross	449.4	449.4
Less: unamortized discount	(8.2)	(26.7)
Carrying Value \| Capital lease obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	28.3	32.1
Carrying Value \| Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	0.5	0.0
Carrying Value \| Line of credit \| TILC warehouse facility \| Revolving credit facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recourse debt	150.7	204.1
Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	1,144.1	993.9
Non-recourse debt	2,459.5	2,236.0
Total debt	3,603.6	3,229.9
Estimated Fair Value \| 2006 secured railcar equipment notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recourse debt	165.7	201.5
Estimated Fair Value \| 2009 secured railcar equipment notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recourse debt	169.6	189.9
Estimated Fair Value \| 2010 secured railcar equipment notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recourse debt	281.9	284.3
Estimated Fair Value \| 2017 secured railcar equipment notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recourse debt	293.6	0.0
Estimated Fair Value \| TRL 2012 secured railcar equipment notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recourse debt	390.4	395.6
Estimated Fair Value \| TRIP Master Funding secured railcar equipment notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recourse debt	1,007.6	960.6
Estimated Fair Value \| Senior notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	400.3	386.3
Estimated Fair Value \| Convertible subordinated notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Gross	715.0	575.5
Estimated Fair Value \| Capital lease obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	28.3	32.1
Estimated Fair Value \| Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including unamortized debt issuance costs, net of unamortized discount	0.5	0.0
Estimated Fair Value \| Line of credit \| TILC warehouse facility \| Revolving credit facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-recourse debt	$ 150.7	$ 204.1

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Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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