Railcar Leasing and Management Services Group - Future operating lease obligations and future contractual minimum rental revenues (Details) $ in Millions	Sep. 30, 2020 USD ($)
Future contractual minimum rental revenues
Total operating lease payments	$ 123.3
Railcar Leasing and Management Services Group [Member]
Future operating lease obligations
Remaining three months of 2020	2.1
2021	8.2
2022	7.5
2023	5.7
2024	2.5
Thereafter	0.9
Total	26.9
Future contractual minimum rental revenues
Total operating lease payments	29.0
Railcar Leasing and Management Services Group [Member] | Building [Member]
Future contractual minimum rental revenues
Total operating lease payments	2.1
Railcar Leasing and Management Services Group [Member] | Property Lease Guarantee [Member]
Future contractual minimum rental revenues
Guarantor Obligations, Maximum Exposure, Undiscounted	2.1
Railcar Leasing and Management Services Group [Member] | Operating leases
Future contractual minimum rental revenues
Remaining three months of 2020	1.7
2021	5.3
2022	3.7
2023	1.7
2024	0.7
Thereafter	0.1
Total	$ 13.2