Acquisitions and Dispositions - Acquisitions Narrative (Details) - USD ($)			1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 06, 2020	Jun. 28, 2019	Jan. 31, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018	Jan. 01, 2020
Business Acquisition [Line Items]
Total revenues				$ 447,281,000	$ 350,898,000	$ 846,122,000	$ 680,800,000
Operating income from continuing operations				1,868,000	17,799,000	4,749,000	37,623,000	$ 37,623,000
Additional interest expense				14,953,000	6,103,000	27,602,000	11,610,000
Receivable with Imputed Interest, Face Amount				40,000,000		40,000,000
Receivables, Fair Value Disclosure			$ 34,300,000	34,700,000		34,700,000			$ 34,300,000
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax			18,400,000	(91,000)	0	18,371,000	0
Stericycle [Member]
Business Acquisition [Line Items]
Corporate charge					8,900,000	8,900,000	17,800,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Harsco Industrial IKG [Member]
Business Acquisition [Line Items]
Selling price									$ 85,000,000
Receivable with Imputed Interest, Face Amount			40,000,000.0
Disposal Group, Net Gain on Disposal			$ 9,000,000
Discontinued Operations, Held-for-sale | Harsco Industrial
Business Acquisition [Line Items]
Corporate overhead expenses					1,400,000		2,800,000
Harsco Clean Earth Segment
Business Acquisition [Line Items]
Percentage of interests acquired		100.00%
Enterprise valuation		$ 625,000,000
Cash consideration		628,000,000
Goodwill to be deductible for income tax purposes		16,300,000
Direct acquisition costs					12,000,000.0		12,500,000
Estimated reimbursements		8,000,000
ESOL
Business Acquisition [Line Items]
Percentage of interests acquired	100.00%
Cash consideration	$ 438,800,000	$ 462,500,000
Goodwill to be deductible for income tax purposes				36,800,000		36,800,000
Total revenues				107,500,000		107,500,000
Operating income from continuing operations				1,900,000		1,900,000
Direct acquisition costs				$ 17,200,000		30,300,000
Clean Earth and ESOL
Business Acquisition [Line Items]
Additional interest expense					$ 14,800,000	$ 4,700,000	$ 29,400,000