Debt - Remaining principal payments under existing debt agreements $ in Millions	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
2018	$ 134.7
2019	252.0
2020	118.1
2021	138.2
2022	140.3
Thereafter	2,496.1
Corporate
Debt Instrument [Line Items]
2018	0.1
2019	0.1
2020	0.2
2021	0.1
2022	0.0
Thereafter	849.4
Railcar Leasing and Management Services Group | Capital lease obligations
Debt Instrument [Line Items]
2018	28.3
2019	0.0
2020	0.0
2021	0.0
2022	0.0
Thereafter	0.0
Railcar Leasing and Management Services Group | Secured debt | 2006 secured railcar equipment notes
Debt Instrument [Line Items]
2018	25.5
2019	28.0
2020	29.8
2021	29.2
2022	29.9
Thereafter	16.1
Railcar Leasing and Management Services Group | Secured debt | 2009 secured railcar equipment notes
Debt Instrument [Line Items]
2018	6.4
2019	11.2
2020	6.6
2021	13.4
2022	14.1
Thereafter	114.5
Railcar Leasing and Management Services Group | Secured debt | 2010 secured railcar equipment notes
Debt Instrument [Line Items]
2018	10.0
2019	7.6
2020	14.2
2021	20.1
2022	21.0
Thereafter	194.0
Railcar Leasing and Management Services Group | Secured debt | TRL 2012 secured railcar equipment notes
Debt Instrument [Line Items]
2018	22.9
2019	21.9
2020	19.3
2021	19.9
2022	19.6
Thereafter	299.2
Railcar Leasing and Management Services Group | Secured debt | TRIP Master Funding secured railcar equipment notes
Debt Instrument [Line Items]
2018	20.0
2019	23.8
2020	32.9
2021	40.4
2022	40.6
Thereafter	804.8
Railcar Leasing and Management Services Group | 2017 Promissory notes | 2017 secured railcar equipment notes
Debt Instrument [Line Items]
2018	15.1
2019	15.1
2020	15.1
2021	15.1
2022	15.1
Thereafter	218.1
Railcar Leasing and Management Services Group | Line of credit | Revolving credit facility | TILC warehouse facility
Debt Instrument [Line Items]
2018	6.4
2019	1.6
2020	0.0
2021	0.0
2022	0.0
Thereafter	0.0
Railcar Leasing and Management Services Group | Line of credit | Revolving credit facility | Facility termination payments - TILC Warehouse facility
Debt Instrument [Line Items]
2018	0.0
2019	142.7
2020	0.0
2021	0.0
2022	0.0
Thereafter	$ 0.0