Information by Segment and Geographic Area (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Total revenues	$ 2,240,358	$ 2,343,137	$ 2,366,187
Selling, general and administrative costs	382,005	359,388	353,985
Goodwill and other intangible asset impairment charges	0	15,866	0
Other segment activities	25,601	2,904	3,211
Property, plant and equipment impairment charge	7,797	23,444	14,099
Remeasurement of long-lived assets	0	10,695	0
Gain (Loss) on Disposition of Business	0	(10,478)	0
Other Operating Income (Expense), Net	(30,002)	(5,437)	1,591
Operating income from continuing operations	4,249	30,714	87,513
Interest income	2,191	6,795	6,809
Interest expense	(110,962)	(112,217)	(107,081)
Loss on early extinguishment of debt	(10,662)	(11,265)	(10,762)
Defined benefit pension income (expense)	(21,635)	(17,607)	(22,326)
Income (loss) from continuing operations before income taxes and equity income	(136,819)	(103,580)	(45,847)
Depreciation	153,382	148,329	138,956
Amortization	30,575	31,471	32,408
Capital expenditures	141,279	136,591	139,025
Total assets	2,708,671	2,634,511	2,834,524
Service and Product
Segment Reporting Information [Line Items]
Cost of services and products sold	1,820,706	1,910,604	1,907,379
Operating segments
Segment Reporting Information [Line Items]
Total revenues	2,240,358	2,343,137	2,366,187
Selling, general and administrative costs	322,083	318,684	309,414
Goodwill and other intangible asset impairment charges		15,866
Other segment activities	13,465	8,767	4,782
Property, plant and equipment impairment charge	7,797	23,444	14,099
Remeasurement of long-lived assets		10,695
Gain (Loss) on Disposition of Business		(10,029)
Operating income from continuing operations	76,462	65,106	130,513
Depreciation	152,410	147,074	136,823
Amortization	26,599	27,268	28,613
Capital expenditures	141,070	136,355	138,598
Total assets	2,699,431	2,607,312	2,767,080
Operating segments | Service and Product
Segment Reporting Information [Line Items]
Cost of services and products sold	1,820,551	1,910,604	1,907,379
Operating segments | Harsco Environmental
Segment Reporting Information [Line Items]
Total revenues	1,019,411	1,111,512	1,141,935
Selling, general and administrative costs	105,402	113,845	109,131
Goodwill and other intangible asset impairment charges		2,840
Other segment activities	6,258	808	(2,180)
Property, plant and equipment impairment charge	7,797	23,444	14,099
Remeasurement of long-lived assets		0
Gain (Loss) on Disposition of Business		(10,029)
Operating income from continuing operations	42,177	32,013	78,666
Depreciation	108,168	109,756	113,571
Amortization	2,242	3,068	4,030
Capital expenditures	84,494	98,845	104,045
Total assets	1,329,132	1,263,031	1,417,278
Operating segments | Harsco Environmental | Service and Product
Segment Reporting Information [Line Items]
Cost of services and products sold	857,777	948,591	942,219
Operating segments | Clean Earth
Segment Reporting Information [Line Items]
Total revenues	973,853	940,337	927,457
Selling, general and administrative costs	169,728	156,378	154,513
Goodwill and other intangible asset impairment charges		0
Other segment activities	797	1,151	2,078
Property, plant and equipment impairment charge	0	0	0
Remeasurement of long-lived assets		0
Gain (Loss) on Disposition of Business		0
Operating income from continuing operations	91,662	92,648	76,702
Depreciation	39,778	33,840	23,252
Amortization	23,644	23,976	24,583
Capital expenditures	49,459	32,754	32,100
Total assets	1,036,916	993,107	979,871
Operating segments | Clean Earth | Service and Product
Segment Reporting Information [Line Items]
Cost of services and products sold	711,666	690,160	694,164
Operating segments | Harsco Rail
Segment Reporting Information [Line Items]
Total revenues	247,094	291,288	296,795
Selling, general and administrative costs	46,953	48,461	45,770
Goodwill and other intangible asset impairment charges		13,026
Other segment activities	6,410	6,808	4,884
Property, plant and equipment impairment charge	0	0	0
Remeasurement of long-lived assets		10,695
Gain (Loss) on Disposition of Business		0
Operating income from continuing operations	(57,377)	(59,555)	(24,855)
Depreciation	4,464	3,478	0
Amortization	713	224	0
Capital expenditures	7,117	4,756	2,453
Total assets	333,383	351,174	369,931
Operating segments | Harsco Rail | Service and Product
Segment Reporting Information [Line Items]
Cost of services and products sold	251,108	271,853	270,996
Corporate
Segment Reporting Information [Line Items]
Total revenues	0	0	0
Selling, general and administrative costs	59,922	40,704	44,571
Goodwill and other intangible asset impairment charges		0
Other segment activities	12,136	(5,863)	(1,571)
Property, plant and equipment impairment charge	0	0	0
Remeasurement of long-lived assets		0
Gain (Loss) on Disposition of Business		(449)
Operating income from continuing operations	(72,213)	(34,392)	(43,000)
Depreciation	972	1,255	2,133
Amortization	3,976	4,203	3,795
Capital expenditures	209	236	427
Total assets	9,240	27,199	67,444
Corporate | Service and Product
Segment Reporting Information [Line Items]
Cost of services and products sold	$ 155	$ 0	$ 0