Railcar Leasing and Management Services Group - Schedule of proceeds received from sale of leased railcars - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property Subject to or Available for Operating Lease [Line Items]
Proceeds from sale leased railcars	$ 460.3	$ 171.9	$ 1,180.0
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	99.6	126.1	404.9
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	360.7	37.7	514.6
Rail Group
Property Subject to or Available for Operating Lease [Line Items]
Proceeds from sale leased railcars	$ 0.0	$ 8.1	$ 260.5