CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 15,080	$ (9,455)	$ 16,645	$ (8,228)
Other comprehensive income (loss):
Foreign currency translation adjustments, net of deferred income taxes	15,446	5,795	12,150	(52,771)
Net loss on cash flow hedging instruments, net of deferred income taxes	234	328	923	(1,359)
Pension liability adjustments, net of deferred income taxes	2,225	6,921	6,044	37,190
Unrealized gain (loss) on marketable securities, net of deferred income taxes	8	(13)	25	(31)
Total other comprehensive income	17,913	13,031	19,142	(16,971)
Total comprehensive income	32,993	3,576	35,787	(25,199)
Less: Comprehensive (income) loss attributable to noncontrolling interests	(2,365)	(1,319)	(2,729)	(1,258)
Comprehensive income attributable to Harsco Corporation	$ 30,628	$ 2,257	$ 33,058	$ (26,457)