Segment Information - Financial information for segments (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
External Revenue	$ 798.8			$ 821.3			$ 2,449.8	$ 2,185.4
Intersegment Revenues	0.0			0.0			0.0	0.0
Revenues, Total	798.8			821.3			2,449.8	2,185.4
Operating Profit (Loss)	122.4			100.2			379.5	268.3
Restructuring activities, net	0.0			0.0			0.0	2.2
Other (income) expense	66.0			67.9			205.2	199.8
Provision (benefit) for income taxes	15.6			6.0			43.7	1.9
Loss from discontinued operations, net of benefit for income taxes of $1.7, $0.7, $3.5, and $2.2	(5.3)			(2.7)			(11.3)	(8.1)
Net income	35.5	$ 56.4	$ 27.4	23.6	$ 21.2	$ 13.7	119.3	58.5
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues, Total	798.8			821.3			2,449.8	2,185.4
Operating Profit (Loss)	164.1			125.2			486.6	374.3
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues	(93.9)			(64.5)			(311.1)	(444.6)
Revenues, Total	(93.9)			(64.5)			(311.1)	(444.6)
Operating Profit (Loss)	(8.6)			0.2			(14.2)	(25.4)
Leasing & Services
Segment Reporting Information [Line Items]
External Revenue	289.2			261.3			854.0	761.8
Leasing & Services | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues, Total	289.5			261.7			856.1	762.9
Operating Profit (Loss)	115.2			95.8			343.5	296.5
Leasing & Services | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues	0.3			0.4			2.1	1.1
Rail Products Group [Member]
Segment Reporting Information [Line Items]
External Revenue	509.6			560.0			1,595.8	1,423.6
Rail Products Group [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues, Total	603.2			624.1			1,904.8	1,867.1
Operating Profit (Loss)	48.9			29.4			143.1	77.8
Rail Products Group [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment Revenues	93.6			64.1			309.0	443.5
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Operating Profit (Loss)	$ (33.1)			$ (25.2)			$ (92.9)	$ (82.8)