Other Expenses (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net gains		$ (6,303)	$ (3,868)	$ (1,354)
Employee termination benefit costs		6,619	4,763	6,733
Costs to exit activities		4,208	170	1,262
Impaired asset write-downs		773	104	874
Contingent Consideration Adjustments		7,681	2,939	0
Other expense		(237)	(431)	(188)
Total		$ (2,621)	(2,201)	7,327
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		35.00%
Clean Earth
Segment Reporting Information [Line Items]
Employee termination benefit costs		$ 1,960	0	0
Contingent Consideration Adjustments		825	0
Harsco Rail
Segment Reporting Information [Line Items]
Employee termination benefit costs		2,393	704	1,133
Costs to exit activities		3,042	0	0
Impaired asset write-downs		141	0	0
Corporate
Segment Reporting Information [Line Items]
Net gains		0	(1,218)	0
Employee termination benefit costs		1,012	1,206	1,189
Costs to exit activities		196	(182)	556
Impaired asset write-downs		0	0	168
Harsco Environmental
Segment Reporting Information [Line Items]
Net gains		(6,303)	(2,650)	(1,354)
Employee termination benefit costs		1,254	2,853	4,411
Costs to exit activities		970	352	706
Impaired asset write-downs		632	104	706
Contingent Consideration Adjustments	$ 8,500	$ 8,506	$ (2,939)	$ 0