Segment Information - Financial information for segments (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
External Revenue	$ 841.4		$ 722.4		$ 1,651.0	$ 1,364.1
Intersegment Revenues	0.0		0.0		0.0	0.0
Revenues, Total	841.4		722.4		1,651.0	1,364.1
Operating Profit (Loss)	141.9		99.1		257.1	168.1
Restructuring activities, net	0.0		1.8		0.0	2.2
Other (income) expense	66.7		68.2		139.2	131.9
Provision (benefit) for income taxes	17.1		7.4		28.1	(4.1)
Loss from discontinued operations, net of benefit for income taxes of $0.5, $0.7, $1.8, and $1.5	(1.7)		(2.3)		(6.0)	(5.4)
Net income	56.4	$ 27.4	21.2	$ 13.7	83.8	34.9
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues, Total	841.4		722.4		1,651.0	1,364.1
Operating Profit (Loss)	178.4		140.4		322.5	249.1
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues	(74.2)		(201.3)		(217.2)	(380.1)
Revenues, Total	(74.2)		(201.3)		(217.2)	(380.1)
Operating Profit (Loss)	(3.2)		(11.5)		(5.6)	(25.6)
Leasing & Services
Segment Reporting Information [Line Items]
External Revenue	280.5		267.8		564.8	500.5
Leasing & Services | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues, Total	281.4		268.3		566.6	501.2
Operating Profit (Loss)	128.0		116.1		228.3	200.7
Leasing & Services | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues	0.9		0.5		1.8	0.7
Rail Products Group [Member]
Segment Reporting Information [Line Items]
External Revenue	560.9		454.6		1,086.2	863.6
Rail Products Group [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues, Total	634.2		655.4		1,301.6	1,243.0
Operating Profit (Loss)	50.4		24.3		94.2	48.4
Rail Products Group [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues	73.3		200.8		215.4	379.4
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Operating Profit (Loss)	$ (33.3)		$ (31.6)		$ (59.8)	$ (57.6)