CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (8,339)	$ 437,857	$ (16,567)	$ 471,323
Other comprehensive income (loss):
Foreign currency translation adjustments, net of deferred income taxes	17,527	(22,780)	(35,244)	(22,276)
Net loss on cash flow hedging instruments, net of deferred income taxes	(263)	(314)	(1,622)	(4,485)
Pension liability adjustments, net of deferred income taxes	(9,153)	13,880	28,037	25,651
Unrealized gain (loss) on marketable securities, net of deferred income taxes	9	(6)	(22)	19
Total other comprehensive income (loss)	8,120	(9,220)	(8,851)	(1,091)
Total comprehensive income (loss)	(219)	428,637	(25,418)	470,232
Less: Comprehensive (income) loss attributable to noncontrolling interests	(2,795)	(821)	(4,053)	(4,768)
Comprehensive income (loss) attributable to Harsco Corporation	$ (3,014)	$ 427,816	$ (29,471)	$ 465,464