Revenue Recognition - Revenues by Primary Geographical Markets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation of Revenue [Line Items]
Total revenues	$ 574,815	$ 573,627	$ 1,685,353	$ 1,783,937
Environmental services related to resource recovery for metals manufacturing and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	241,417	235,490	709,072	747,303
Ecoproducts
Disaggregation of Revenue [Line Items]
Total revenues	14,980	36,663	38,497	107,190
Environmental systems for aluminum dross and scrap processing
Disaggregation of Revenue [Line Items]
Total revenues	4,734	6,995	14,677	16,703
Railway Track Maintenance Equipment
Disaggregation of Revenue [Line Items]
Total revenues	18,538	19,099	67,258	79,535
After-market Parts and Services; Safety and Diagnostic Technology
Disaggregation of Revenue [Line Items]
Total revenues	31,227	23,495	78,498	89,502
Railway Contracting Services
Disaggregation of Revenue [Line Items]
Total revenues	13,868	15,094	45,787	44,778
Hazardous waste processing solutions
Disaggregation of Revenue [Line Items]
Total revenues	212,952	194,557	622,129	581,341
Soil and dredged materials processing and reuse solutions
Disaggregation of Revenue [Line Items]
Total revenues	37,099	42,234	109,435	117,585
North America
Disaggregation of Revenue [Line Items]
Total revenues	341,666	338,751	1,003,612	1,066,598
Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	123,324	130,003	376,318	389,922
Latin America
Disaggregation of Revenue [Line Items]
Total revenues	39,127	38,442	109,230	125,601
Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	39,211	35,836	105,440	108,766
Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	26,562	26,327	76,668	79,858
Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	4,925	4,268	14,085	13,192
Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	574,815	573,627	1,685,353	1,783,937
Operating Segments \| Harsco Environmental
Disaggregation of Revenue [Line Items]
Total revenues	261,131	279,148	762,246	871,196
Operating Segments \| Harsco Environmental \| Environmental services related to resource recovery for metals manufacturing and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	241,417	235,490	709,072	747,303
Operating Segments \| Harsco Environmental \| Ecoproducts
Disaggregation of Revenue [Line Items]
Total revenues	14,980	36,663	38,497	107,190
Operating Segments \| Harsco Environmental \| Environmental systems for aluminum dross and scrap processing
Disaggregation of Revenue [Line Items]
Total revenues	4,734	6,995	14,677	16,703
Operating Segments \| Harsco Environmental \| Railway Track Maintenance Equipment
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Harsco Environmental \| After-market Parts and Services; Safety and Diagnostic Technology
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Harsco Environmental \| Railway Contracting Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Harsco Environmental \| Hazardous waste processing solutions
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Harsco Environmental \| Soil and dredged materials processing and reuse solutions
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Harsco Environmental \| North America
Disaggregation of Revenue [Line Items]
Total revenues	57,750	70,316	170,589	238,553
Operating Segments \| Harsco Environmental \| Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	101,108	108,709	304,056	328,604
Operating Segments \| Harsco Environmental \| Latin America
Disaggregation of Revenue [Line Items]
Total revenues	38,815	38,195	106,485	122,396
Operating Segments \| Harsco Environmental \| Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	31,971	31,333	90,363	88,593
Operating Segments \| Harsco Environmental \| Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	26,562	26,327	76,668	79,858
Operating Segments \| Harsco Environmental \| Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	4,925	4,268	14,085	13,192
Operating Segments \| Clean Earth
Disaggregation of Revenue [Line Items]
Total revenues	250,051	236,791	731,564	698,926
Operating Segments \| Clean Earth \| Environmental services related to resource recovery for metals manufacturing and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Clean Earth \| Ecoproducts
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Clean Earth \| Environmental systems for aluminum dross and scrap processing
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Clean Earth \| Railway Track Maintenance Equipment
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Clean Earth \| After-market Parts and Services; Safety and Diagnostic Technology
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Clean Earth \| Railway Contracting Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Clean Earth \| Hazardous waste processing solutions
Disaggregation of Revenue [Line Items]
Total revenues	212,952	194,557	622,129	581,341
Operating Segments \| Clean Earth \| Soil and dredged materials processing and reuse solutions
Disaggregation of Revenue [Line Items]
Total revenues	37,099	42,234	109,435	117,585
Operating Segments \| Clean Earth \| North America
Disaggregation of Revenue [Line Items]
Total revenues	250,051	236,791	731,564	698,926
Operating Segments \| Clean Earth \| Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Clean Earth \| Latin America
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Clean Earth \| Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Clean Earth \| Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Clean Earth \| Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Harsco Rail
Disaggregation of Revenue [Line Items]
Total revenues	63,633	57,688	191,543	213,815
Operating Segments \| Harsco Rail \| Environmental services related to resource recovery for metals manufacturing and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Harsco Rail \| Ecoproducts
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Harsco Rail \| Environmental systems for aluminum dross and scrap processing
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Harsco Rail \| Railway Track Maintenance Equipment
Disaggregation of Revenue [Line Items]
Total revenues	18,538	19,099	67,258	79,535
Operating Segments \| Harsco Rail \| After-market Parts and Services; Safety and Diagnostic Technology
Disaggregation of Revenue [Line Items]
Total revenues	31,227	23,495	78,498	89,502
Operating Segments \| Harsco Rail \| Railway Contracting Services
Disaggregation of Revenue [Line Items]
Total revenues	13,868	15,094	45,787	44,778
Operating Segments \| Harsco Rail \| Hazardous waste processing solutions
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Harsco Rail \| Soil and dredged materials processing and reuse solutions
Disaggregation of Revenue [Line Items]
Total revenues			0	0
Operating Segments \| Harsco Rail \| North America
Disaggregation of Revenue [Line Items]
Total revenues	33,865	31,644	101,459	129,119
Operating Segments \| Harsco Rail \| Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	22,216	21,294	72,262	61,318
Operating Segments \| Harsco Rail \| Latin America
Disaggregation of Revenue [Line Items]
Total revenues	312	247	2,745	3,205
Operating Segments \| Harsco Rail \| Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	7,240	4,503	15,077	20,173
Operating Segments \| Harsco Rail \| Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments \| Harsco Rail \| Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 0	$ 0