Revenue Recognition - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total contract assets	$ 99.4		$ 99.4		$ 86.9
Total advances on contracts	30.5		30.5		$ 38.6
Revenue recognized	$ 9.8	$ 10.9	$ 20.5	$ 22.5
SBB
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Percentage complete	89.00%		89.00%
Provisions recognized		6.1	$ 0.2
Network Rail
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Provisions recognized	$ 2.0	23.6
Deutsche Bahn
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Percentage complete	44.00%		44.00%
Provisions recognized	$ 7.2	$ 8.4
Contract | Network Rail
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Percentage complete	62.00%		62.00%
Harsco Environmental Segment
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 77.0		$ 77.0
Harsco Environmental Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	21.6		21.6
Harsco Environmental Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	18.9		18.9
Harsco Environmental Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	14.5		14.5
Harsco Environmental Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	11.6		11.6
Harsco Rail Segment
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	128.7		128.7
Harsco Rail Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	60.7		60.7
Harsco Rail Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	34.2		34.2
Harsco Rail Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	21.8		21.8
Harsco Rail Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 8.0		$ 8.0