Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Goodwill [Roll Forward]
Balance at the beginning of the period	$ 739,758	$ 780,978
Changes to goodwill		(19,031)
Goodwill, Impairment Loss		(13,026)
Foreign currency translation	18,922	(9,163)
Balance at the end of the period	758,680	739,758
Harsco Environmental
Goodwill [Roll Forward]
Balance at the beginning of the period	360,459	388,653
Changes to goodwill		(19,031)
Goodwill, Impairment Loss		0
Foreign currency translation	18,922	(9,163)
Balance at the end of the period	379,381	360,459
Clean Earth
Goodwill [Roll Forward]
Balance at the beginning of the period	379,299	379,299
Changes to goodwill		0
Goodwill, Impairment Loss		0
Foreign currency translation	0	0
Balance at the end of the period	379,299	379,299
Harsco Rail
Goodwill [Roll Forward]
Balance at the beginning of the period	0	13,026
Changes to goodwill		0
Goodwill, Impairment Loss		(13,026)
Foreign currency translation	0	0
Balance at the end of the period	$ 0	$ 0