Railcar Leasing and Management Services Group - Schedule of proceeds from leased railcars (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)
Property Subject to or Available for Operating Lease [Line Items]
Proceeds from sale leased railcars	$ 42.7	$ 15.5
Payments to Acquire Equipment on Lease	$ 218.4
Railcars Acquired	6,779
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	$ 13.3	0.0
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	$ 29.4	$ 15.5