Railcar Leasing and Management Services Group - Schedule of proceeds from leased railcars (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Property Subject to or Available for Operating Lease [Line Items]
Sales-type Lease, Revenue	$ 0.0	$ 32.3	$ 0.0	$ 34.2
Total operating profit (loss)	(307.3)	107.0	(234.3)	198.8
Operating Segments [Member] | Railcar Leasing and Management Services Group [Member]
Property Subject to or Available for Operating Lease [Line Items]
Total operating profit (loss)	$ 82.9	$ 104.8	$ 175.8	$ 190.6
Operating Profit Margin	43.00%	37.80%	41.00%	39.90%
Operating Segments [Member] | Railcar Owned One Year or Less [Member] | Railcar Leasing and Management Services Group [Member]
Property Subject to or Available for Operating Lease [Line Items]
Proceeds From Sale Of Property Subject To Or Available For Operating Lease	$ 10.1	$ 87.7	$ 54.4	$ 101.0
Total operating profit (loss)	$ (1.3)	$ 8.4	$ 0.4	$ 9.2
Operating Profit Margin	(12.90%)	9.60%	0.70%	9.10%
Operating Segments [Member] | Railcar Owned Greater than One Year [Member] | Railcar Leasing and Management Services Group [Member]
Property Subject to or Available for Operating Lease [Line Items]
Proceeds From Sale Of Property Subject To Or Available For Operating Lease	$ 63.7	$ 70.5	$ 132.2	$ 99.9
Total operating profit (loss)	$ 5.7	$ 18.7	$ 14.4	$ 26.6
Operating Profit Margin	8.90%	26.50%	10.90%	26.60%
Operating Segments [Member] | Sales of Leased Railcars [Domain] | Railcar Leasing and Management Services Group [Member]
Property Subject to or Available for Operating Lease [Line Items]
Proceeds From Sale Of Property Subject To Or Available For Operating Lease	$ 73.8	$ 158.2	$ 186.6	$ 200.9
Total operating profit (loss)	$ 4.4	$ 27.1	$ 14.8	$ 35.8
Operating Profit Margin	6.00%	17.10%	7.90%	17.80%