Revenue Recognition - Summary of Revenues by Primary Geographical Markets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,863,864	$ 1,503,742	$ 1,347,672
Environmental services related to resource recovery for metals manufacturing; and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	781,060	888,850	927,969
Applied Products [Member]
Disaggregation of Revenue [Line Items]
Total revenues	120,432	127,875	128,488
Aluminum Dross and Scrap Processing Systems [Member]
Disaggregation of Revenue [Line Items]
Total revenues	12,953	18,122	11,847
Railway Track Maintenance Equipment [Member]
Disaggregation of Revenue [Line Items]
Total revenues	184,076	145,968	112,547
After-market Parts and Services; Safety and Diagnostic Technology [Member]
Disaggregation of Revenue [Line Items]
Total revenues	116,600	132,249	139,020
Railway Contracting Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues	29,155	21,156	27,727
Waste Processing and Reuse Solutions [Member]
Disaggregation of Revenue [Line Items]
Total revenues	619,588	169,522
General Corporate
Disaggregation of Revenue [Line Items]
Total revenues			74
North America
Disaggregation of Revenue [Line Items]
Total revenues	1,087,130	685,613	507,524
Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	455,615	431,162	438,856
Latin America
Disaggregation of Revenue [Line Items]
Total revenues	126,555	148,628	155,863
Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	114,154	159,441	167,850
Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	63,427	60,402	50,003
Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	16,983	18,496	27,576
Corporate
Disaggregation of Revenue [Line Items]
Total revenues	0	0	74
Corporate | Environmental services related to resource recovery for metals manufacturing; and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Corporate | Applied Products [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Corporate | Aluminum Dross and Scrap Processing Systems [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Corporate | Railway Track Maintenance Equipment [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Corporate | After-market Parts and Services; Safety and Diagnostic Technology [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Corporate | Railway Contracting Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Corporate | Waste Processing and Reuse Solutions [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Corporate | General Corporate
Disaggregation of Revenue [Line Items]
Total revenues			74
Corporate | North America
Disaggregation of Revenue [Line Items]
Total revenues	0	0	74
Corporate | Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Corporate | Latin America
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Corporate | Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Corporate | Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Corporate | Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Harsco Environmental | Operating segments
Disaggregation of Revenue [Line Items]
Total revenues	914,445	1,034,847	1,068,304
Harsco Environmental | Operating segments | Environmental services related to resource recovery for metals manufacturing; and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	781,060	888,850	927,969
Harsco Environmental | Operating segments | Applied Products [Member]
Disaggregation of Revenue [Line Items]
Total revenues	120,432	127,875	128,488
Harsco Environmental | Operating segments | Aluminum Dross and Scrap Processing Systems [Member]
Disaggregation of Revenue [Line Items]
Total revenues	12,953	18,122	11,847
Harsco Environmental | Operating segments | Railway Track Maintenance Equipment [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Harsco Environmental | Operating segments | After-market Parts and Services; Safety and Diagnostic Technology [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Harsco Environmental | Operating segments | Railway Contracting Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Harsco Environmental | Operating segments | Waste Processing and Reuse Solutions [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Harsco Environmental | Operating segments | General Corporate
Disaggregation of Revenue [Line Items]
Total revenues			0
Harsco Environmental | Operating segments | North America
Disaggregation of Revenue [Line Items]
Total revenues	249,904	294,367	302,238
Harsco Environmental | Operating segments | Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	377,066	386,593	390,840
Harsco Environmental | Operating segments | Latin America
Disaggregation of Revenue [Line Items]
Total revenues	119,457	146,040	151,886
Harsco Environmental | Operating segments | Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	87,608	128,949	145,761
Harsco Environmental | Operating segments | Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	63,427	60,402	50,003
Harsco Environmental | Operating segments | Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	16,983	18,496	27,576
Clean Earth | Operating segments
Disaggregation of Revenue [Line Items]
Total revenues	619,588	169,522	0
Clean Earth | Operating segments | Environmental services related to resource recovery for metals manufacturing; and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Clean Earth | Operating segments | Applied Products [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Clean Earth | Operating segments | Aluminum Dross and Scrap Processing Systems [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Clean Earth | Operating segments | Railway Track Maintenance Equipment [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Clean Earth | Operating segments | After-market Parts and Services; Safety and Diagnostic Technology [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Clean Earth | Operating segments | Railway Contracting Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Clean Earth | Operating segments | Waste Processing and Reuse Solutions [Member]
Disaggregation of Revenue [Line Items]
Total revenues	619,588	169,522
Clean Earth | Operating segments | North America
Disaggregation of Revenue [Line Items]
Total revenues	619,588	169,522	0
Clean Earth | Operating segments | Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Clean Earth | Operating segments | Latin America
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Clean Earth | Operating segments | Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Clean Earth | Operating segments | Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Clean Earth | Operating segments | Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Harsco Rail | Operating segments
Disaggregation of Revenue [Line Items]
Total revenues	329,831	299,373	279,294
Harsco Rail | Operating segments | Environmental services related to resource recovery for metals manufacturing; and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Harsco Rail | Operating segments | Applied Products [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Harsco Rail | Operating segments | Aluminum Dross and Scrap Processing Systems [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Harsco Rail | Operating segments | Railway Track Maintenance Equipment [Member]
Disaggregation of Revenue [Line Items]
Total revenues	184,076	145,968	112,547
Harsco Rail | Operating segments | After-market Parts and Services; Safety and Diagnostic Technology [Member]
Disaggregation of Revenue [Line Items]
Total revenues	116,600	132,249	139,020
Harsco Rail | Operating segments | Railway Contracting Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues	29,155	21,156	27,727
Harsco Rail | Operating segments | Waste Processing and Reuse Solutions [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Harsco Rail | Operating segments | North America
Disaggregation of Revenue [Line Items]
Total revenues	217,638	221,724	205,212
Harsco Rail | Operating segments | Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	78,549	44,569	48,016
Harsco Rail | Operating segments | Latin America
Disaggregation of Revenue [Line Items]
Total revenues	7,098	2,588	3,977
Harsco Rail | Operating segments | Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	26,546	30,492	22,089
Harsco Rail | Operating segments | Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Harsco Rail | Operating segments | Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 0