CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 13,796	$ (31,544)	$ 43,664	$ (65,437)
Other comprehensive income (loss):
Foreign currency translation adjustments, net of deferred income taxes of $1,747 and $(16,992), and $3,598 and $(27,680) for the three and nine months ended September 30, 2017 and 2016, respectively	16,005	9,613	42,391	6,840
Net gain (loss) on cash flow hedging instruments, net of deferred income taxes of $21 and $(813), and $888 and $(398) for the three and nine months ended September 30, 2017 and 2016, respectively	2,199	1,609	1,471	(942)
Pension liability adjustments, net of deferred income taxes of $(523) and $254, and $(1,567) and $(1,002) for the three and nine months September 30, 2017 and 2016, respectively	(7,324)	10,712	(16,467)	43,007
Unrealized gain (loss) on marketable securities, net of deferred income taxes of $(3) and $(9), and $(6) and $(7) for the three and nine months ended September 30, 2017 and 2016, respectively	5	14	11	11
Total other comprehensive income	10,885	21,948	27,406	48,916
Total comprehensive income (loss)	24,681	(9,596)	71,070	(16,521)
Less: Comprehensive income attributable to noncontrolling interests	(1,200)	(1,448)	(4,674)	(4,179)
Comprehensive income (loss) attributable to Harsco Corporation	$ 23,481	$ (11,044)	$ 66,396	$ (20,700)