Components of Accumulated Other Comprehensive Loss - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 627,407	$ 623,952	$ 623,042	$ 651,703	$ 781,095	$ 805,770	$ 623,042	$ 805,770
OCI before reclassifications							2,145	(55,688)
Amounts reclassified from AOCI, net of tax							13,101	12,955
Total other comprehensive income (loss)	(6,307)	14,401	7,152	(25,615)	(29,126)	12,008	15,246	(42,733)
Less: OCI attributable to noncontrolling interests							2,056	6,108
OCI attributable to Enviri Corporation							17,302	(36,625)
Ending balance	613,765	627,407	623,952	626,135	651,703	781,095	613,765	626,135
Cumulative Foreign Exchange Translation Adjustments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance			(213,104)			(134,889)	(213,104)	(134,889)
OCI before reclassifications							1,902	(116,407)
Amounts reclassified from AOCI, net of tax							0	0
Total other comprehensive income (loss)							1,902	(116,407)
Less: OCI attributable to noncontrolling interests							2,056	6,108
OCI attributable to Enviri Corporation							3,958	(110,299)
Ending balance	(209,146)			(245,188)			(209,146)	(245,188)
Effective Portion of Derivatives Designated as Hedging Instruments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance			157			(3,024)	157	(3,024)
OCI before reclassifications							3,671	2,971
Amounts reclassified from AOCI, net of tax							(547)	32
Total other comprehensive income (loss)							3,124	3,003
Less: OCI attributable to noncontrolling interests							0	0
OCI attributable to Enviri Corporation							3,124	3,003
Ending balance	3,281			(21)			3,281	(21)
Cumulative Unrecognized Actuarial Losses on Pension Obligations
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance			(354,699)			(422,248)	(354,699)	(422,248)
OCI before reclassifications							(3,430)	57,768
Amounts reclassified from AOCI, net of tax							13,648	12,923
Total other comprehensive income (loss)							10,218	70,691
Less: OCI attributable to noncontrolling interests							0	0
OCI attributable to Enviri Corporation							10,218	70,691
Ending balance	(344,481)			(351,557)			(344,481)	(351,557)
Unrealized Gain (Loss) on Marketable Securities
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance			10			22	10	22
OCI before reclassifications							2	(20)
Amounts reclassified from AOCI, net of tax							0	0
Total other comprehensive income (loss)							2	(20)
Less: OCI attributable to noncontrolling interests							0	0
OCI attributable to Enviri Corporation							2	(20)
Ending balance	12			2			12	2
Accumulated Other Comprehensive Loss
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(544,606)	(560,842)	(567,636)	(573,872)	(547,649)	(560,139)	(567,636)	(560,139)
Total other comprehensive income (loss)	(5,728)	16,236	6,794	(22,892)	(26,223)	12,490
Ending balance	$ (550,334)	$ (544,606)	$ (560,842)	$ (596,764)	$ (573,872)	$ (547,649)	$ (550,334)	$ (596,764)