CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 437,857	$ 34,651	$ 471,323	$ 96,939
Other comprehensive income (loss):
Foreign currency translation adjustments, net of deferred income taxes of $(1,834) and $(91); and $(2,086) and $(1,043) for the three and nine months ended September 30, 2019 and 2018, respectively	(22,780)	(3,952)	(22,276)	(40,157)
Net gain (loss) on cash flow hedging instruments, net of deferred income taxes of $54 and $(306); and $1,195 and $(2,191) for the three and nine months ended September 30, 2019 and 2018, respectively	(314)	502	(4,485)	6,081
Pension liability adjustments, net of deferred income taxes of $(340) and $(289); and $(1,061) and $(902) for the three and nine months ended September 30, 2019 and 2018, respectively	13,880	4,668	25,651	24,294
Unrealized gain (loss) on marketable securities, net of deferred income taxes of $2 and $(3); and $(6) and $5 for the three and nine months ended September 30, 2019 and 2018, respectively	(6)	8	19	(19)
Total other comprehensive income (loss)	(9,220)	1,226	(1,091)	(9,801)
Total comprehensive income	428,637	35,877	470,232	87,138
Less: Comprehensive (income) loss attributable to noncontrolling interests	(821)	(432)	(4,768)	(3,183)
Comprehensive income attributable to Harsco Corporation	$ 427,816	$ 35,445	$ 465,464	$ 83,955