Components of Accumulated Other Comprehensive Loss - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 448,687	$ 449,599	$ 546,124	$ 575,408	$ 449,599	$ 575,408
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax					9,158	(21,573)
Amounts reclassified from AOCI, net of tax					9,593	7,674
Total other comprehensive income (loss)	10,033	8,718	(6,240)	(7,659)	18,751	(13,899)
Less: OCI attributable to noncontrolling interests					(1,155)	1,045
Ending balance	417,831	448,687	528,798	546,124	417,831	528,798
Cumulative Foreign Exchange Translation Adjustments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance		(228,698)		(183,499)	(228,698)	(183,499)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax					38,670	(27,340)
Amounts reclassified from AOCI, net of tax					0	0
Total other comprehensive income (loss)					38,670	(27,340)
Less: OCI attributable to noncontrolling interests					(1,155)	1,045
OCI attributable to Enviri Corporation					37,515	(26,295)
Ending balance	(191,183)		(209,794)		(191,183)	(209,794)
Effective Portion of Derivatives Designated as Hedging Instruments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance		3,769		(470)	3,769	(470)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax					(5,019)	3,712
Amounts reclassified from AOCI, net of tax					422	(1,721)
Total other comprehensive income (loss)					(4,597)	1,991
Less: OCI attributable to noncontrolling interests					0	0
OCI attributable to Enviri Corporation					(4,597)	1,991
Ending balance	(828)		1,521		(828)	1,521
Cumulative Unrecognized Actuarial Losses on Pension Obligations
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance		(314,057)		(355,740)	(314,057)	(355,740)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax					(24,499)	2,058
Amounts reclassified from AOCI, net of tax					9,171	9,395
Total other comprehensive income (loss)					(15,328)	11,453
Less: OCI attributable to noncontrolling interests					0	0
OCI attributable to Enviri Corporation					(15,328)	11,453
Ending balance	(329,385)		(344,287)		(329,385)	(344,287)
Unrealized Gain (Loss) on Marketable Securities
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance		22		15	22	15
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax					6	(3)
Amounts reclassified from AOCI, net of tax					0	0
Total other comprehensive income (loss)					6	(3)
Less: OCI attributable to noncontrolling interests					0	0
OCI attributable to Enviri Corporation					6	(3)
Ending balance	28		12		28	12
Accumulated Other Comprehensive Loss
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(530,613)	(538,964)	(546,532)	(539,694)	(538,964)	(539,694)
Total other comprehensive income (loss)	9,245	8,351	(6,016)	(6,838)
OCI attributable to Enviri Corporation					17,596	(12,854)
Ending balance	$ (521,368)	$ (530,613)	$ (552,548)	$ (546,532)	$ (521,368)	$ (552,548)