CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 22,537	$ 19,577
Other comprehensive income (loss):
Foreign currency translation adjustments, net of deferred income taxes of $1,131 and $1,627 for the three months ended March 31, 2019 and 2018, respectively	9,454	12,501
Net gain (loss) on cash flow hedging instruments, net of deferred income taxes of $945 and $(839) for the three months ended March 31, 2019 and 2018, respectively	(3,147)	2,677
Pension liability adjustments, net of deferred income taxes of $(342) and $(325) for the three months ended March 31, 2019 and 2018, respectively	(1,791)	(9,001)
Unrealized gain (loss) on marketable securities, net of deferred income taxes of $(5) and $4 for the three months ended March 31, 2019 and 2018, respectively	15	(14)
Total other comprehensive income	4,531	6,163
Total comprehensive income	27,068	25,740
Less: Comprehensive (income) loss attributable to noncontrolling interests	(2,260)	(3,047)
Comprehensive income attributable to Harsco Corporation	$ 24,808	$ 22,693