Other Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net gains	$ (5,136)	$ (1,764)	$ (10,613)
Employee termination benefit costs	7,350	10,777	14,914
Costs to exit activities	1,633	440	13,451
Impaired asset write-downs	1,025	399	8,170
Foreign currency gains related to Harsco Rail Segment advances on contracts	0	0	(10,940)
Metals and Minerals Separation Costs	0	3,235	9,922
Subcontractor settlement	0	0	4,220
Other expense	(231)	(467)	1,449
Total	4,641	12,620	30,573
Other Nonrecurring Expense			$ 7,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners			35.00%
Harsco Metals & Minerals
Segment Reporting Information [Line Items]
Net gains	(1,354)	(1,828)	$ (7,059)
Employee termination benefit costs	4,411	8,491	11,454
Costs to exit activities	706	220	12,638
Impaired asset write-downs	706	399	8,170
Harsco Industrial
Segment Reporting Information [Line Items]
Net gains	(3,782)	64	(3,554)
Employee termination benefit costs	617	947	561
Costs to exit activities	371	40	0
Impaired asset write-downs	151	0	0
Harsco Rail
Segment Reporting Information [Line Items]
Employee termination benefit costs	1,133	297	145
Corporate
Segment Reporting Information [Line Items]
Employee termination benefit costs	1,189	1,042	2,754
Costs to exit activities	556	180	813
Impaired asset write-downs	$ 168	$ 0	0
Parent
Segment Reporting Information [Line Items]
Other Nonrecurring Expense			$ 4,600