Note 11. Restructuring Activities (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve		$ 1.4	$ 3.4
Severance Costs		7.8	3.8
Payments for Restructuring		(10.4)
Restructuring activities, net		11.0	14.7	$ 0.0
Loss on Contract Termination		0.6
Gain (Loss) on Disposition of Assets		(2.7)
Non-cash impact of restructuring activities		5.3	10.9	$ 0.0
Restructuring and Related Cost, Incurred Cost		8.4
Tangible Asset Impairment Charges		2.6
Non-cash impact of restructuring activities	$ 5.2		10.9
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve		1.4	3.4
Payments for Restructuring		(9.8)
Contract Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve		0.0	0.0
Payments for Restructuring		(0.6)
Railcar Leasing and Management Services Group [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs		1.4	0.2
Restructuring activities, net		1.4	0.2
Loss on Contract Termination		0.0
Gain (Loss) on Disposition of Assets		0.0
Non-cash impact of restructuring activities		0.0	0.0
Other Segments [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs		0.2	0.5
Restructuring activities, net		0.4	11.4
Loss on Contract Termination		0.0
Gain (Loss) on Disposition of Assets		0.2
Non-cash impact of restructuring activities		0.0	10.9
Rail Products Group [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs		4.0	0.7
Restructuring activities, net		1.3	0.7
Loss on Contract Termination		0.2
Gain (Loss) on Disposition of Assets		(2.9)
Non-cash impact of restructuring activities		0.0	0.0
Corporate Segment [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs		2.2	2.4
Restructuring activities, net		7.9	2.4
Loss on Contract Termination		0.4
Gain (Loss) on Disposition of Assets		0.0
Non-cash impact of restructuring activities		$ 5.3	$ 0.0