Information by Segment and Geographic Area (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) segment Customer	Dec. 31, 2017 USD ($) Customer	Dec. 31, 2016 USD ($) Customer
Revenue, Major Customer [Line Items]
Revenues	$ 1,722,380	$ 1,607,062	$ 1,451,223
Number of reportable segments | segment	3
Harsco Metals & Minerals
Revenue, Major Customer [Line Items]
Number of major customers | Customer	1	1	1
Harsco Industrial
Revenue, Major Customer [Line Items]
Number of major customers | Customer	0	1	0
Harsco Rail
Revenue, Major Customer [Line Items]
Number of major customers | Customer	1	1	1
All Other
Revenue, Major Customer [Line Items]
Revenues	$ 766,093	$ 762,775	$ 680,344
U.S. Plans
Revenue, Major Customer [Line Items]
Revenues	812,941	697,663	614,327
United Kingdom
Revenue, Major Customer [Line Items]
Revenues	$ 143,346	$ 146,624	$ 156,552