Debt - Remaining principal payments under existing debt agreements (Details) $ in Millions	Dec. 31, 2018 USD ($)
Debt Instrument [Line Items]
2020	$ 178.0
2021	199.1
2022	530.7
2023	174.6
Thereafter	2,813.4
Long-term Debt and Capital Lease Obligations, Maturities, Repayments of Principal Remainder of Fiscal Year	171.1
Corporate
Debt Instrument [Line Items]
2020	0.0
2021	0.0
2022	0.0
2023	0.0
Thereafter	400.0
Long-term Debt and Capital Lease Obligations, Maturities, Repayments of Principal Remainder of Fiscal Year	0.0
Railcar Leasing and Management Services Group | Secured debt | 2006 secured railcar equipment notes
Debt Instrument [Line Items]
2020	29.8
2021	29.2
2022	29.9
2023	16.2
Thereafter	0.0
Long-term Debt and Capital Lease Obligations, Maturities, Repayments of Principal Remainder of Fiscal Year	28.3
Railcar Leasing and Management Services Group | Secured debt | 2009 secured railcar equipment notes
Debt Instrument [Line Items]
2020	6.6
2021	13.4
2022	14.1
2023	11.8
Thereafter	102.6
Long-term Debt and Capital Lease Obligations, Maturities, Repayments of Principal Remainder of Fiscal Year	11.2
Railcar Leasing and Management Services Group | Secured debt | 2010 secured railcar equipment notes
Debt Instrument [Line Items]
2020	14.2
2021	20.1
2022	21.0
2023	22.5
Thereafter	171.6
Long-term Debt and Capital Lease Obligations, Maturities, Repayments of Principal Remainder of Fiscal Year	7.6
Railcar Leasing and Management Services Group | Secured debt | 2018 Secured Railcar Equipment Notes [Domain]
Debt Instrument [Line Items]
2020	20.0
2021	20.0
2022	20.0
2023	20.0
Thereafter	372.4
Long-term Debt and Capital Lease Obligations, Maturities, Repayments of Principal Remainder of Fiscal Year	20.0
Railcar Leasing and Management Services Group | Secured debt | TRIHC 2018 Secured Railcar Equipment Notes [Member]
Debt Instrument [Line Items]
2020	11.0
2021	11.9
2022	9.3
2023	11.6
Thereafter	223.5
Long-term Debt and Capital Lease Obligations, Maturities, Repayments of Principal Remainder of Fiscal Year	14.2
Railcar Leasing and Management Services Group | Secured debt | TRL 2012 secured railcar equipment notes
Debt Instrument [Line Items]
2020	19.3
2021	19.9
2022	19.6
2023	22.4
Thereafter	283.1
Long-term Debt and Capital Lease Obligations, Maturities, Repayments of Principal Remainder of Fiscal Year	21.9
Railcar Leasing and Management Services Group | Secured debt | TRIP Master Funding secured railcar equipment notes
Debt Instrument [Line Items]
2020	32.9
2021	40.5
2022	41.8
2023	37.0
Thereafter	765.7
Long-term Debt and Capital Lease Obligations, Maturities, Repayments of Principal Remainder of Fiscal Year	23.8
Railcar Leasing and Management Services Group | 2017 Promissory notes | 2017 secured railcar equipment notes
Debt Instrument [Line Items]
2020	33.2
2021	33.1
2022	33.2
2023	33.1
Thereafter	494.5
Long-term Debt and Capital Lease Obligations, Maturities, Repayments of Principal Remainder of Fiscal Year	33.1
Railcar Leasing and Management Services Group | Line of credit | Revolving credit facility | TILC warehouse facility
Debt Instrument [Line Items]
2020	11.0
2021	11.0
2022	1.9
2023	0.0
Thereafter	0.0
Long-term Debt and Capital Lease Obligations, Maturities, Repayments of Principal Remainder of Fiscal Year	11.0
Railcar Leasing and Management Services Group | Line of credit | Revolving credit facility | Facility termination payments - TILC Warehouse facility
Debt Instrument [Line Items]
2020	0.0
2021	0.0
2022	339.9
2023	0.0
Thereafter	0.0
Long-term Debt and Capital Lease Obligations, Maturities, Repayments of Principal Remainder of Fiscal Year	$ 0.0