Segment Information - Financial information for segments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
External Revenue	$ 472.7	$ 330.7
Revenues, Total	472.7	330.7
Operating Profit (Loss)	54.8	51.5
Restructuring activities, net	0.0	0.3
Other (income) expense	41.9	52.5
Provision (benefit) for income taxes	3.0	4.0
Income (loss) from discontinued operations, net of provision (benefit) for income taxes of $(2.0) and $2.3	(6.9)	6.3
Loss on sale of discontinued operations, net of benefit for income taxes of $0.4 and $—	(1.1)	0.0
Net income	1.9	1.3
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues, Total	472.7	330.7
Operating Profit (Loss)	80.6	69.5
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues	0.0	0.0
Intersegment Eliminations [Member] | Consolidated Subsidiaries, Leasing [Member]
Segment Reporting Information [Line Items]
External Revenue	0.0	0.0
Intersegment Revenues	(101.3)	(111.3)
Revenues, Total	(101.3)	(111.3)
Operating Profit (Loss)	(8.8)	(1.8)
Intersegment Eliminations [Member] | Consolidated Subsidiaries, Excluding Leasing [Member]
Segment Reporting Information [Line Items]
External Revenue	0.0	0.0
Intersegment Revenues	(0.2)	(2.5)
Revenues, Total	(0.2)	(2.5)
Operating Profit (Loss)	(1.3)	(0.4)
Railcar Leasing and Management Services Group [Member]
Segment Reporting Information [Line Items]
External Revenue	182.9	183.3
Operating Profit (Loss)	79.8	78.3
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues, Total	183.1	183.5
Operating Profit (Loss)	79.8	78.3
Railcar Leasing and Management Services Group [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues	0.2	0.2
Rail Products Group [Member]
Segment Reporting Information [Line Items]
External Revenue	289.8	147.4
Operating Profit (Loss)	0.8	(8.8)
Rail Products Group [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues, Total	391.1	261.0
Rail Products Group [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues	101.3	113.6
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Operating Profit (Loss)	$ (15.7)	$ (16.1)