Segment Information - Financial information for segments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
External Revenue	$ 809.6	$ 641.7
Intersegment Revenues	0.0	0.0
Revenues, Total	809.6	641.7
Operating Profit (Loss)	115.2	69.0
Restructuring activities, net	0.0	0.4
Other (income) expense	72.5	63.7
Provision (benefit) for income taxes	11.0	(11.5)
Loss from discontinued operations, net of benefit for income taxes of $1.3 and $0.8	(4.3)	(3.1)
Net income	27.4	13.7
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues, Total	809.6	641.7
Operating Profit (Loss)	144.1	108.7
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues	(143.0)	(178.8)
Revenues, Total	(143.0)	(178.8)
Operating Profit (Loss)	(2.4)	(14.1)
Leasing & Services
Segment Reporting Information [Line Items]
External Revenue	284.3	232.7
Leasing & Services | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues, Total	285.2	232.9
Operating Profit (Loss)	100.3	84.6
Leasing & Services | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues	0.9	0.2
Rail Products Group [Member]
Segment Reporting Information [Line Items]
External Revenue	525.3	409.0
Rail Products Group [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues, Total	667.4	587.6
Operating Profit (Loss)	43.8	24.1
Rail Products Group [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues	142.1	178.6
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Operating Profit (Loss)	$ (26.5)	$ (26.0)