CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 34,651	$ 13,796	$ 96,939	$ 43,664
Other comprehensive income (loss):
Foreign currency translation adjustments, net of deferred income taxes of $(91) and $(1,747), and $(1,043) and $3,598 for the three and nine months ended September 30, 2018 and 2017, respectively	(3,953)	16,005	(40,157)	42,391
Net gain (loss) on cash flow hedging instruments, net of deferred income taxes of $(306) and $21, and $(2,191) and $888 for the three and nine months ended September 30, 2018 and 2017, respectively	502	2,199	6,081	1,471
Pension liability adjustments, net of deferred income taxes of $(289) and $(523), and $(902) and $(1,567) for the three and nine months ended September 30, 2018 and 2017, respectively	4,668	(7,324)	24,294	(16,467)
Unrealized gain (loss) on marketable securities, net of deferred income taxes of $(3) and $(3), and $5 and $(6) for the three and nine months September 30, 2018 and 2017, respectively	8	5	(19)	11
Total other comprehensive income	1,225	10,885	(9,801)	27,406
Total comprehensive income	35,876	24,681	87,138	71,070
Less: Comprehensive (income) loss attributable to noncontrolling interests	(432)	(1,200)	(3,183)	(4,674)
Comprehensive income attributable to Harsco Corporation	$ 35,444	$ 23,481	$ 83,955	$ 66,396