Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances			$ 215,165	$ 137,563
Accumulated other comprehensive loss					$ (2,374)		$ (397)
Other comprehensive income (loss) before reclassifications			(20,735)	6,294
Amounts reclassified from accumulated other comprehensive loss			9,708	10,227
Total other comprehensive loss	$ (17,190)	$ (864)	(11,027)	16,521
Other comprehensive loss attributable to noncontrolling interests			1,240	(1,534)
Other comprehensive income (loss) attributable to Harsco Corporation			(9,787)	14,987
Balances	266,153	186,896	266,153	186,896
Cumulative Foreign Exchange Translation Adjustments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances			(111,567)	(144,534)
Other comprehensive income (loss) before reclassifications			(36,205)	26,386
Amounts reclassified from accumulated other comprehensive loss			0	0
Total other comprehensive loss			(36,205)	26,386
Other comprehensive loss attributable to noncontrolling interests			1,240	(1,534)
Other comprehensive income (loss) attributable to Harsco Corporation			(34,965)	24,852
Balances	(146,532)	(119,682)	(146,532)	(119,682)
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			5,482	(913)
Amounts reclassified from accumulated other comprehensive loss			97	185
Total other comprehensive loss			5,579	(728)
Other comprehensive loss attributable to noncontrolling interests			0	0
Other comprehensive income (loss) attributable to Harsco Corporation			5,579	(728)
Balances	4,867	(1,817)	4,867	(1,817)
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			10,015	(19,185)
Amounts reclassified from accumulated other comprehensive loss			9,611	10,042
Total other comprehensive loss			19,626	(9,143)
Other comprehensive loss attributable to noncontrolling interests			0	0
Other comprehensive income (loss) attributable to Harsco Corporation			19,626	(9,143)
Balances	(416,214)	(470,237)	(416,214)	(470,237)
Unrealized Loss on Marketable Securities
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances			17	(5)
Other comprehensive income (loss) before reclassifications			(27)	6
Amounts reclassified from accumulated other comprehensive loss			0	0
Total other comprehensive loss			(27)	6
Other comprehensive loss attributable to noncontrolling interests			0	0
Other comprehensive income (loss) attributable to Harsco Corporation			(27)	6
Balances	(10)	1	(10)	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 loss			(9,787)	14,987
Balances	$ (557,889)	$ (591,735)	(557,889)	$ (591,735)
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)