Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Balance at the beginning of the period	$ 738,369	$ 404,713
Changes to goodwill	153,897	330,230
Foreign currency translation	9,808	3,426
Balance at the end of the period	902,074	738,369
Harsco Environmental
Goodwill [Roll Forward]
Balance at the beginning of the period	395,113	391,687
Changes to goodwill	1,480	0
Foreign currency translation	9,808	3,426
Balance at the end of the period	406,401	395,113
Clean Earth
Goodwill [Roll Forward]
Balance at the beginning of the period	330,230	0
Changes to goodwill	152,417	(330,230)
Foreign currency translation	0	0
Balance at the end of the period	482,647	330,230
Harsco Rail
Goodwill [Roll Forward]
Balance at the beginning of the period	13,026	13,026
Changes to goodwill	0	0
Foreign currency translation	0	0
Balance at the end of the period	$ 13,026	$ 13,026