Other Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net gains	$ (3,868)	$ (5,136)	$ (1,764)
Employee termination benefit costs	4,983	7,350	10,777
Costs to exit activities	428	1,633	440
Impaired asset write-downs	113	1,025	399
Harsco Metals & Minerals Segment contingent consideration adjustments	(2,939)	0	0
Metals and Minerals Separation Costs	0	0	3,235
Other expense	(239)	(231)	(467)
Total	$ (1,522)	4,641	12,620
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	35.00%
Harsco Metals & Minerals
Segment Reporting Information [Line Items]
Net gains	$ (2,650)	(1,354)	(1,828)
Employee termination benefit costs	2,853	4,411	8,491
Costs to exit activities	352	706	220
Impaired asset write-downs	104	706	399
Harsco Industrial
Segment Reporting Information [Line Items]
Net gains	0	(3,782)	64
Employee termination benefit costs	220	617	947
Costs to exit activities	258	371	40
Impaired asset write-downs	9	151	0
Harsco Rail
Segment Reporting Information [Line Items]
Employee termination benefit costs	704	1,133	297
Corporate
Segment Reporting Information [Line Items]
Net gains	(1,218)	0	0
Employee termination benefit costs	1,206	1,189	1,042
Costs to exit activities	(182)	556	180
Impaired asset write-downs	$ 0	$ 168	$ 0