CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 11,844	$ (79,753)	$ 6,332
Other comprehensive income (loss):
Foreign currency translation adjustments, net of deferred income taxes of $3,471, $(13,670) and $(2,314) in 2017, 2016 and 2015, respectively	36,011	(21,560)	(88,255)
Net gain (loss) on cash flow hedging instruments, net of deferred income taxes of $(759), $(544) and $(975) in 2017, 2016 and 2015, respectively	1,897	(682)	8,617
Pension liability adjustments, net of deferred income taxes of $(4,084), $34 and $1,443 in 2017, 2016 and 2015, respectively	25,254	(71,398)	93,582
Unrealized gain (loss) on marketable securities, net of deferred income taxes of $(12), $(16) and $10 in 2017, 2016 and 2015, respectively	22	26	(16)
Total other comprehensive income (loss)	63,184	(93,614)	13,928
Total comprehensive income (loss)	75,028	(173,367)	20,260
Less: Comprehensive (income) loss attributable to noncontrolling interests	(7,068)	(3,334)	2,496
Comprehensive income (loss) attributable to Harsco Corporation	$ 67,960	$ (176,701)	$ 22,756