Components of Accumulated Other Comprehensive Loss - Accumulated Other Comprehensive Income Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 805,770	$ 713,399
Other comprehensive income (loss) before reclassifications	7,136	(5,057)
Amounts reclassified from accumulated other comprehensive loss	4,872	6,286
Total other comprehensive income (loss)	12,008	1,229
OCI attributable to noncontrolling interests	482	1,066
Other comprehensive income (loss) attributable to Harsco Corporation	12,490	2,295
Ending balance	781,095	716,583
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(134,889)	(125,392)
Other comprehensive income (loss) before reclassifications	(2,847)	(3,296)
Amounts reclassified from accumulated other comprehensive loss		0
Total other comprehensive income (loss)	(2,847)	(3,296)
OCI attributable to noncontrolling interests	482	1,066
Other comprehensive income (loss) attributable to Harsco Corporation	(2,365)	(2,230)
Ending balance	(137,254)	(127,622)
Effective Portion of Deriviatives Designated as Hedging Instruments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(3,024)	(5,840)
Other comprehensive income (loss) before reclassifications	802	119
Amounts reclassified from accumulated other comprehensive loss	338	570
Total other comprehensive income (loss)	1,140	689
OCI attributable to noncontrolling interests		0
Other comprehensive income (loss) attributable to Harsco Corporation	1,140	689
Ending balance	(1,884)	(5,151)
Cumulative Unrecognized Actuarial Losses on Pension Obligations
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(422,248)	(514,500)
Other comprehensive income (loss) before reclassifications	9,184	(1,897)
Amounts reclassified from accumulated other comprehensive loss	4,534	5,716
Total other comprehensive income (loss)	13,718	3,819
OCI attributable to noncontrolling interests		0
Other comprehensive income (loss) attributable to Harsco Corporation	13,718	3,819
Ending balance	(408,530)	(510,681)
Unrealized Loss on Marketable Securities
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	22	(9)
Other comprehensive income (loss) before reclassifications	(3)	17
Amounts reclassified from accumulated other comprehensive loss		0
Total other comprehensive income (loss)	(3)	17
OCI attributable to noncontrolling interests		0
Other comprehensive income (loss) attributable to Harsco Corporation	(3)	17
Ending balance	19	8
Accumulated Other Comprehensive Loss
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(560,139)	(645,741)
Total other comprehensive income (loss)	12,490	2,295
Ending balance	$ (547,649)	$ (643,446)