Reconciliation of Basic and Diluted Shares - Reconciliation of Basic and Diluted Shares (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Earnings Per Share [Abstract]
Income (loss) from continuing operations attributable to Harsco Corporation common stockholders	$ 625	$ 5,040	$ (113,408)	$ 12,015
Weighted-average shares outstanding - basic (in shares)	79,531	79,287	79,469	79,214
Dilutive effect of stock-based compensation (in shares)	36	988	0	1,142
Weighted-average shares outstanding - diluted (in shares)	79,567	80,275	79,469	80,356
Earnings (loss) from continuing operations per common share, attributable to Harsco Corporation common stockholders:
Basic (in dollars per share)	$ 0.01	$ 0.06	$ (1.43)	$ 0.15
Diluted (in dollars per share)	$ 0.01	$ 0.06	$ (1.43)	$ 0.15