CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 10,929	$ 42,711	$ 33,466	$ 62,288
Other comprehensive income (loss):
Foreign currency translation adjustments, net of deferred income taxes of $(1,383) and $252; and $(2,579) and $(952) for the three and six months ended June 30, 2019 and 2018, respectively	(8,950)	(48,706)	504	(36,205)
Net gain (loss) on cash flow hedging instruments, net of deferred income taxes of $496 and $1,141; and $(1,046) and $(1,885) for the three and six months ended June 30, 2019 and 2018, respectively	(1,024)	2,902	(4,171)	5,579
Pension liability adjustments, net of deferred income taxes of $(379) and $(721); and $(288) and $(613) for the three and six months ended June 30, 2019 and 2018, respectively	13,562	28,627	11,771	19,626
Unrealized gain (loss) on marketable securities, net of deferred income taxes of $(3) and $(8); and $4 and $8 for the three and six months ended June 30, 2019 and 2018, respectively	10	(13)	25	(27)
Total other comprehensive income (loss)	3,598	(17,190)	8,129	(11,027)
Total comprehensive income	14,527	25,521	41,595	51,261
Less: Comprehensive (income) loss attributable to noncontrolling interests	(1,687)	296	(3,947)	(2,751)
Comprehensive income attributable to Harsco Corporation	$ 12,840	$ 25,817	$ 37,648	$ 48,510