Leases - Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Thousands			9 Months Ended
	Jun. 28, 2019	Jan. 01, 2019	Sep. 30, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Cash flows from operating activities - Operating leases			$ 10,881
Cash flows from financing activities - Finance leases			953
Right-of-use assets obtained in exchange for lease obligations:
Operating leases		$ 34,000	57,607
Finance leases			$ 1,671
Harsco Clean Earth Segment
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$ 21,300