Railcar Leasing and Management Services Group - Schedule of rental revenues (Details) - Railcar Leasing and Management Services Group - Other Third Parties $ in Millions	Dec. 31, 2018 USD ($)
Future operating lease obligations
Minimum Lease Payments, Sale Leaseback Transactions, Remainder of Fiscal Year	$ 13.5
2020	8.4
2021	7.6
2022	6.8
2023	4.9
Thereafter	1.7
Total	42.9
Future contractual minimum rental revenues
Future Minimum Sublease Rentals, Sale Leaseback Transactions, Remainder of Fiscal Year	10.6
2020	7.1
2021	5.2
2022	3.6
2023	1.4
Thereafter	0.0
Total	$ 27.9