Review of Operations by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Operations by segment
Total revenues	$ 562,254	$ 609,993	$ 1,110,538	$ 1,210,310
Selling, general and administrative expenses	95,503	90,454	184,611	177,580
Intangible asset impairment charge	0	2,840	0	2,840
Gain on sale of business	0	(1,877)	0	(1,877)
Property, plant and equipment impairment charge	7,386	0	7,386	0
Remeasurement of long-lived assets	0	0	0	10,695
Other segment activities	865	3,900	5,350	3,418
Operating income (loss) from continuing operations	(7,191)	31,255	23,464	57,068
Interest income	470	3,435	924	5,132
Interest expense	(27,600)	(27,934)	(54,174)	(56,056)
Facility fees and debt-related income (expense)			(5,231)	(5,709)
Defined benefit pension income (expense)	(5,387)	(4,166)	(10,420)	(8,342)
Income (loss) from continuing operations before income taxes and equity in income	(42,327)	(330)	(45,437)	(7,907)
Depreciation	37,901	37,026	74,343	73,946
Amortization	7,561	8,006	14,964	16,180
Capital Expenditures	39,035	33,639	60,659	60,520
Service and Product
Operations by segment
Cost of services and products sold	465,691	483,421	889,727	960,586
Operating Segments
Operations by segment
Total revenues	562,254	609,993	1,110,538	1,210,310
Selling, general and administrative expenses	78,329	80,839	155,501	158,768
Intangible asset impairment charge		2,840		2,840
Gain on sale of business		(1,877)		(1,877)
Property, plant and equipment impairment charge	7,386		7,386
Remeasurement of long-lived assets				10,695
Other segment activities	2,312	3,691	8,495	7,099
Operating income (loss) from continuing operations	8,536	41,079	49,429	72,199
Depreciation	37,646	36,722	73,807	73,285
Amortization	6,603	7,031	13,055	14,238
Capital Expenditures	39,027	33,568	60,553	60,420
Operating Segments | Service and Product
Operations by segment
Cost of services and products sold	465,691	483,421	889,727	960,586
Operating Segments | Harsco Environmental Segment
Operations by segment
Total revenues	258,009	292,929	501,115	592,048
Selling, general and administrative expenses	25,494	29,173	52,122	58,075
Intangible asset impairment charge		2,840		2,840
Gain on sale of business		(1,877)		(1,877)
Property, plant and equipment impairment charge	7,386		7,386
Remeasurement of long-lived assets				0
Other segment activities	684	2,944	5,072	4,781
Operating income (loss) from continuing operations	4,251	20,286	14,324	39,874
Depreciation	27,046	27,450	52,555	56,239
Amortization	571	975	1,111	1,993
Capital Expenditures	25,257	24,216	39,351	44,769
Operating Segments | Harsco Environmental Segment | Service and Product
Operations by segment
Cost of services and products sold	220,194	239,563	422,211	488,355
Operating Segments | Clean Earth Segment
Operations by segment
Total revenues	246,282	236,105	481,513	462,135
Selling, general and administrative expenses	41,512	38,881	80,474	75,810
Intangible asset impairment charge		0		0
Gain on sale of business		0		0
Property, plant and equipment impairment charge	0		0
Remeasurement of long-lived assets				0
Other segment activities	226	(155)	211	(95)
Operating income (loss) from continuing operations	24,610	23,882	47,275	44,475
Depreciation	9,549	8,249	19,169	15,662
Amortization	5,926	5,989	11,771	12,156
Capital Expenditures	12,140	8,730	18,792	14,064
Operating Segments | Clean Earth Segment | Service and Product
Operations by segment
Cost of services and products sold	179,934	173,497	353,553	341,945
Operating Segments | Harsco Rail Segment
Operations by segment
Total revenues	57,963	80,959	127,910	156,127
Selling, general and administrative expenses	11,323	12,785	22,905	24,883
Intangible asset impairment charge		0		0
Gain on sale of business		0		0
Property, plant and equipment impairment charge	0		0
Remeasurement of long-lived assets				10,695
Other segment activities	1,402	902	3,212	2,413
Operating income (loss) from continuing operations	(20,325)	(3,089)	(12,170)	(12,150)
Depreciation	1,051	1,023	2,083	1,384
Amortization	106	67	173	89
Capital Expenditures	1,630	622	2,410	1,587
Operating Segments | Harsco Rail Segment | Service and Product
Operations by segment
Cost of services and products sold	65,563	70,361	113,963	130,286
Corporate
Operations by segment
Total revenues	0	0	0	0
Selling, general and administrative expenses	17,174	9,615	29,110	18,812
Intangible asset impairment charge		0		0
Gain on sale of business		0		0
Property, plant and equipment impairment charge	0		0
Remeasurement of long-lived assets				0
Other segment activities	(1,447)	209	(3,145)	(3,681)
Operating income (loss) from continuing operations	(15,727)	(9,824)	(25,965)	(15,131)
Depreciation	255	304	536	661
Amortization	958	975	1,909	1,942
Capital Expenditures	8	71	106	100
Corporate | Service and Product
Operations by segment
Cost of services and products sold	$ 0	$ 0	$ 0	$ 0