Railcar Leasing and Management Services Group - Future operating lease obligations and future contractual minimum rental revenues (Details) - Railcar Leasing and Management Services Group $ in Millions	Jun. 30, 2018 USD ($)
Railroad transportation equipment leased from independent owner trusts
Future operating lease obligations
Remaining six months of 2018	$ 14.6
2018	28.8
2019	26.1
2020	26.1
2021	24.9
Thereafter	93.1
Total	213.6
Future contractual minimum rental revenues
Remaining six months of 2018	20.9
2018	29.7
2019	19.8
2020	14.5
2021	9.9
Thereafter	8.1
Total	102.9
Operating leases other than leases with the Trusts
Future operating lease obligations
Remaining six months of 2018	5.9
2018	9.7
2019	7.7
2020	7.6
2021	6.8
Thereafter	7.1
Total	44.8
Future contractual minimum rental revenues
Remaining six months of 2018	5.6
2018	8.6
2019	5.7
2020	3.9
2021	3.2
Thereafter	1.3
Total	$ 28.3