Railcar Leasing and Management Services Group - Future operating lease obligations and future contractual minimum rental revenues (Details) $ in Millions	Jun. 30, 2020 USD ($)
Sale Leaseback Transaction [Line Items]
Lessee, Operating Lease, Liability, Payments, Due	$ 123.8
Railcar Leasing and Management Services Group [Member]
Sale Leaseback Transaction [Line Items]
Lessee, Operating Lease, Liability, Payments, Due	31.3
Minimum Lease Payments, Sale Leaseback Transactions, Fiscal Year Maturity [Abstract]
Minimum Lease Payments, Sale Leaseback Transactions, Remainder of Fiscal Year	4.7
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
Minimum Lease Payments, Sale Leaseback Transactions, Thereafter	0.9
Minimum Lease Payments, Sale Leaseback Transactions, Total	29.1
Railcar Leasing and Management Services Group [Member] | Operating leases
Future contractual minimum rental revenues
Future Minimum Sublease Rentals, Sale Leaseback Transactions, Remainder of Fiscal Year	3.6
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Two Years	5.7
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Three Years	3.9
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Four Years	1.7
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Five Years	0.8
Future Minimum Sublease Rentals, Sale Leaseback Transactions, Thereafter	0.5
Future Minimum Sublease Rentals, Sale Leaseback Transactions, Total	16.2
Building [Member] | Railcar Leasing and Management Services Group [Member]
Sale Leaseback Transaction [Line Items]
Lessee, Operating Lease, Liability, Payments, Due	$ 2.2