CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (9,455)	$ 10,929	$ (8,228)	$ 33,466
Other comprehensive income (loss):
Foreign currency translation adjustments, net of deferred income taxes of $(659) and $(1,383); and $(4,741) and $(252) for the three and six months ended June 30, 2020 and 2019, respectively	5,795	(8,950)	(52,771)	504
Net gain (loss) on cash flow hedging instruments, net of deferred income taxes of $(251) and $196; and $266 and $1,141 for the three and six months ended June 30, 2020 and 2019, respectively	328	(1,024)	(1,359)	(4,171)
Pension liability adjustments, net of deferred income taxes of $(323) and $(379); and $(2,033) and $(721) for the three and six months ended June 30, 2020 and 2019, respectively	6,921	13,562	37,190	11,771
Unrealized gain (loss) on marketable securities, net of deferred income taxes of $4 and $(3); and $12 and $(8) for the three and six months ended June 30, 2020 and 2019, respectively	(13)	10	(31)	25
Total other comprehensive income	13,031	3,598	(16,971)	8,129
Total comprehensive income	3,576	14,527	(25,199)	41,595
Less: Comprehensive (income) loss attributable to noncontrolling interests	(1,319)	(1,687)	(1,258)	(3,947)
Comprehensive income attributable to Harsco Corporation	$ 2,257	$ 12,840	$ (26,457)	$ 37,648