Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances	$ 215,165	$ 137,563
Accumulated other comprehensive loss		(397)	$ (2,387)
Other comprehensive income (loss) before reclassifications	1,310	12,238
Amounts reclassified from accumulated other comprehensive loss	4,853	5,147
Total other comprehensive income	6,163	17,385
Other comprehensive loss attributable to noncontrolling interests	(1,278)	(386)
Other comprehensive income (loss) attributable to Harsco Corporation	4,885	16,999
Balances	246,345	168,533
Cumulative Foreign Exchange Translation Adjustments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances	(111,567)	(144,534)
Other comprehensive income (loss) before reclassifications	12,501	16,561
Amounts reclassified from accumulated other comprehensive loss	0	0
Total other comprehensive income	12,501	16,561
Other comprehensive loss attributable to noncontrolling interests	(1,278)	(386)
Other comprehensive income (loss) attributable to Harsco Corporation	11,223	16,175
Balances	(100,344)	(128,359)
Effective Portion of Deriviatives Designated as Hedging Instruments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances	808	(1,089)
Other comprehensive income (loss) before reclassifications	2,768	(536)
Amounts reclassified from accumulated other comprehensive loss	(91)	149
Total other comprehensive income	2,677	(387)
Other comprehensive loss attributable to noncontrolling interests	0	0
Other comprehensive income (loss) attributable to Harsco Corporation	2,677	(387)
Balances	1,965	(1,476)
Cumulative Unrecognized Actuarial Losses on Pension Obligations
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances	(435,840)	(461,094)
Other comprehensive income (loss) before reclassifications	(13,945)	(3,793)
Amounts reclassified from accumulated other comprehensive loss	4,944	4,998
Total other comprehensive income	(9,001)	1,205
Other comprehensive loss attributable to noncontrolling interests	0	0
Other comprehensive income (loss) attributable to Harsco Corporation	(9,001)	1,205
Balances	(444,841)	(459,889)
Unrealized Loss on Marketable Securities
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances	17	(5)
Other comprehensive income (loss) before reclassifications	(14)	6
Amounts reclassified from accumulated other comprehensive loss	0	0
Total other comprehensive income	(14)	6
Other comprehensive loss attributable to noncontrolling interests	0	0
Other comprehensive income (loss) attributable to Harsco Corporation	(14)	6
Balances	3	1
Accumulated Other Comprehensive Loss
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances	(546,582)	(606,722)
Accumulated other comprehensive loss			1,520
Total other comprehensive income	4,885	16,999
Balances	(543,217)	$ (589,723)
Accounting Standards Update 2014-09 | Cumulative Foreign Exchange Translation Adjustments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances	(111,567)
Accounting Standards Update 2014-09 | Effective Portion of Deriviatives Designated as Hedging Instruments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances	(712)
Accumulated other comprehensive loss			(1,520)
Accounting Standards Update 2014-09 | Cumulative Unrecognized Actuarial Losses on Pension Obligations
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances	(435,840)
Accounting Standards Update 2014-09 | Unrealized Loss on Marketable Securities
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances	17
Accounting Standards Update 2014-09 | Accumulated Other Comprehensive Loss
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances	$ (548,102)
Accumulated other comprehensive loss			$ (1,520)