Components of Accumulated Other Comprehensive Loss - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 651,703	$ 781,095	$ 805,770	$ 749,383	$ 716,583	$ 713,399	$ 805,770	$ 713,399
OCI before reclassifications							(55,688)	(8,527)
Amounts reclassified from AOCI, net of tax							12,955	18,672
Total other comprehensive income (loss)	(25,615)	(29,126)	12,008	(8,997)	17,913	1,229	(42,733)	10,145
Less: OCI attributable to noncontrolling interests							(6,108)	(837)
OCI attributable to Harsco Corporation							(36,625)	10,982
Ending balance	626,135	651,703	781,095	753,227	749,383	716,583	626,135	753,227
Cumulative Foreign Exchange Translation Adjustments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance			(134,889)			(125,392)	(134,889)	(125,392)
OCI before reclassifications							(116,407)	(15,437)
Amounts reclassified from AOCI, net of tax							0	0
Total other comprehensive income (loss)							(116,407)	(15,437)
Less: OCI attributable to noncontrolling interests							(6,108)	(837)
OCI attributable to Harsco Corporation							(110,299)	(14,600)
Ending balance	(245,188)			(139,992)			(245,188)	(139,992)
Effective Portion of Derivatives Designated as Hedging Instruments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance			(3,024)			(5,840)	(3,024)	(5,840)
OCI before reclassifications							2,971	257
Amounts reclassified from AOCI, net of tax							32	1,488
Total other comprehensive income (loss)							3,003	1,745
Less: OCI attributable to noncontrolling interests							0	0
OCI attributable to Harsco Corporation							3,003	1,745
Ending balance	(21)			(4,095)			(21)	(4,095)
Cumulative Unrecognized Actuarial Losses on Pension Obligations
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance			(422,248)			(514,500)	(422,248)	(514,500)
OCI before reclassifications							57,768	6,628
Amounts reclassified from AOCI, net of tax							12,923	17,184
Total other comprehensive income (loss)							70,691	23,812
Less: OCI attributable to noncontrolling interests							0	0
OCI attributable to Harsco Corporation							70,691	23,812
Ending balance	(351,557)			(490,688)			(351,557)	(490,688)
Unrealized Gain (Loss) on Marketable Securities
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance			22			(9)	22	(9)
OCI before reclassifications							(20)	25
Amounts reclassified from AOCI, net of tax							0	0
Total other comprehensive income (loss)							(20)	25
Less: OCI attributable to noncontrolling interests							0	0
OCI attributable to Harsco Corporation							(20)	25
Ending balance	2			16			2	16
Accumulated Other Comprehensive Loss
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(573,872)	(547,649)	(560,139)	(626,206)	(643,446)	(645,741)	(560,139)	(645,741)
Total other comprehensive income (loss)	(22,892)	(26,223)	12,490	(8,553)	17,240	2,295
Ending balance	$ (596,764)	$ (573,872)	$ (547,649)	$ (634,759)	$ (626,206)	$ (643,446)	$ (596,764)	$ (634,759)