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		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Earnings Per Share [Abstract]
Income (loss) from continuing operations, net of tax	$ (106,700)	$ 8,540	$ (114,033)	$ 6,975
Weighted-average shares outstanding - basic (in shares)	79,509	79,265	79,437	79,177
Dilutive effect of stock-based compensation (in shares)	0	1,509	0	1,220
Weighted-average shares outstanding - diluted (in shares)	79,509	80,774	79,437	80,397
Earnings (loss) from continuing operations per common share, attributable to Harsco Corporation common stockholders:
Basic (in dollars per share)	$ (1.34)	$ 0.11	$ (1.44)	$ 0.09
Diluted (in dollars per share)	$ (1.34)	$ 0.11	$ (1.44)	$ 0.09