Revenue Recognition - Revenues by Primary Geographical Markets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Total revenues	$ 481,052	$ 468,674	$ 933,849	$ 915,939
Waste Processing and Reuse Solutions
Disaggregation of Revenue [Line Items]
Total revenues	203,453	196,128	394,199	385,407
Environmental services related to resource recovery for metals manufacturing and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	236,165	233,523	463,854	458,583
Applied Products
Disaggregation of Revenue [Line Items]
Total revenues	38,083	34,830	70,048	64,615
Aluminum Dross and Scrap Processing Systems
Disaggregation of Revenue [Line Items]
Total revenues	3,351	4,193	5,748	7,334
North America
Disaggregation of Revenue [Line Items]
Total revenues	284,162	265,863	545,987	522,323
Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	99,591	116,981	201,670	229,152
Latin America
Disaggregation of Revenue [Line Items]
Total revenues	39,202	33,799	75,007	64,452
Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	31,950	26,922	60,018	50,292
Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	20,762	19,873	40,648	39,994
Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	5,385	5,236	10,519	9,726
Operating Segments | Harsco Environmental Segment
Disaggregation of Revenue [Line Items]
Total revenues	277,599	272,546	539,650	530,532
Operating Segments | Harsco Environmental Segment | Waste Processing and Reuse Solutions
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Environmental Segment | Environmental services related to resource recovery for metals manufacturing and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	236,165	233,523	463,854	458,583
Operating Segments | Harsco Environmental Segment | Applied Products
Disaggregation of Revenue [Line Items]
Total revenues	38,083	34,830	70,048	64,615
Operating Segments | Harsco Environmental Segment | Aluminum Dross and Scrap Processing Systems
Disaggregation of Revenue [Line Items]
Total revenues	3,351	4,193	5,748	7,334
Operating Segments | Harsco Environmental Segment | North America
Disaggregation of Revenue [Line Items]
Total revenues	80,709	69,735	151,788	136,916
Operating Segments | Harsco Environmental Segment | Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	99,591	116,981	201,670	229,152
Operating Segments | Harsco Environmental Segment | Latin America
Disaggregation of Revenue [Line Items]
Total revenues	39,202	33,799	75,007	64,452
Operating Segments | Harsco Environmental Segment | Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	31,950	26,922	60,018	50,292
Operating Segments | Harsco Environmental Segment | Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	20,762	19,873	40,648	39,994
Operating Segments | Harsco Environmental Segment | Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	5,385	5,236	10,519	9,726
Operating Segments | Harsco Clean Earth Segment
Disaggregation of Revenue [Line Items]
Total revenues	203,453	196,128	394,199	385,407
Operating Segments | Harsco Clean Earth Segment | Waste Processing and Reuse Solutions
Disaggregation of Revenue [Line Items]
Total revenues	203,453	196,128	394,199	385,407
Operating Segments | Harsco Clean Earth Segment | 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 Clean Earth Segment | Applied Products
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | Aluminum Dross and Scrap Processing Systems
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | North America
Disaggregation of Revenue [Line Items]
Total revenues	203,453	196,128	394,199	385,407
Operating Segments | Harsco Clean Earth Segment | Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | Latin America
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 0	$ 0