Components of Accumulated Other Comprehensive Loss - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 449,599	$ 575,408
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	4,246	(11,358)
Amounts reclassified from AOCI, net of tax	4,472	3,699
Total other comprehensive income (loss)	8,718	(7,659)
Less: OCI attributable to noncontrolling interests	(367)	821
OCI attributable to Enviri Corporation	8,351	(6,838)
Ending balance	448,687	546,124
Cumulative Foreign Exchange Translation Adjustments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(228,698)	(183,499)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	15,723	(16,535)
Amounts reclassified from AOCI, net of tax	0	0
Total other comprehensive income (loss)	15,723	(16,535)
Less: OCI attributable to noncontrolling interests	(367)	821
OCI attributable to Enviri Corporation	15,356	(15,714)
Ending balance	(213,342)	(199,213)
Effective Portion of Derivatives Designated as Hedging Instruments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	3,769	(470)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(2,824)	2,865
Amounts reclassified from AOCI, net of tax	27	(1,002)
Total other comprehensive income (loss)	(2,797)	1,863
Less: OCI attributable to noncontrolling interests	0	0
OCI attributable to Enviri Corporation	(2,797)	1,863
Ending balance	972	1,393
Cumulative Unrecognized Actuarial Losses on Pension Obligations
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(314,057)	(355,740)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(8,651)	2,310
Amounts reclassified from AOCI, net of tax	4,445	4,701
Total other comprehensive income (loss)	(4,206)	7,011
Less: OCI attributable to noncontrolling interests	0	0
OCI attributable to Enviri Corporation	(4,206)	7,011
Ending balance	(318,263)	(348,729)
Unrealized Gain (Loss) on Marketable Securities
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	22	15
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(2)	2
Amounts reclassified from AOCI, net of tax	0	0
Total other comprehensive income (loss)	(2)	2
Less: OCI attributable to noncontrolling interests	0	0
OCI attributable to Enviri Corporation	(2)	2
Ending balance	20	17
Accumulated Other Comprehensive Loss
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(538,964)	(539,694)
Total other comprehensive income (loss)	8,351	(6,838)
Ending balance	$ (530,613)	$ (546,532)