Railcar Leasing and Management Services Group - Schedule of proceeds received from sale of leased railcars (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property Subject to or Available for Operating Lease [Line Items]
Proceeds from sale leased railcars	$ 344.4	$ 460.3	$ 171.9
Railcar Leasing and Management Services Group | Railcars owned one year or less at the time of sale
Property Subject to or Available for Operating Lease [Line Items]
Proceeds from sale leased railcars	113.9	99.6	126.1
Railcar Leasing and Management Services Group | Railcars owned more than one year at the time of sale
Property Subject to or Available for Operating Lease [Line Items]
Proceeds from sale leased railcars	230.5	360.7	37.7
Rail Products Group
Property Subject to or Available for Operating Lease [Line Items]
Proceeds from sale leased railcars	$ 0.0	$ 0.0	$ 8.1