Railcar Leasing and Management Services Group - Future operating lease obligations and future contractual minimum rental revenues (Details) $ in Millions	Mar. 31, 2020 USD ($)
Sale Leaseback Transaction [Line Items]
Lessee, Operating Lease, Liability, Payments, Due	$ 50.0
Railcar Leasing and Management Services Group
Sale Leaseback Transaction [Line Items]
Lessee, Operating Lease, Liability, Payments, Due	34.5
Future operating lease obligations
Minimum Lease Payments, Sale Leaseback Transactions, Remainder of Fiscal Year	7.5
Minimum Lease Payments, Sale Leaseback Transactions, within Two Years	8.2
Minimum Lease Payments, Sale Leaseback Transactions, within Three Years	7.5
Minimum Lease Payments, Sale Leaseback Transactions, within Four Years	5.5
Minimum Lease Payments, Sale Leaseback Transactions, within Five Years	2.3
Thereafter	0.9
Total	31.9
Railcar Leasing and Management Services Group | Operating leases
Future contractual minimum rental revenues
Future Minimum Sublease Rentals, Sale Leaseback Transactions, Remainder of Fiscal Year	5.8
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Two Years	6.2
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Three Years	4.6
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Four Years	2.2
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Five Years	0.5
Thereafter	0.3
Total	19.6
Building [Member] | Railcar Leasing and Management Services Group
Sale Leaseback Transaction [Line Items]
Lessee, Operating Lease, Liability, Payments, Due	$ 2.6