Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances			$ 137,563	$ 310,803
Other comprehensive income (loss) before reclassifications			11,935	6,135
Amounts reclassified from accumulated other comprehensive loss			15,471	12,194
Realized (gains) losses reclassified from accumulated other comprehensive loss in connection with loss on dilution of equity method investment (See Note 4, Equity Method Investments)				28,743
Other comprehensive income (loss) from equity method investee				1,844
Total other comprehensive income	$ 10,885	$ 21,948	27,406	48,916
Other comprehensive income (loss) attributable to noncontrolling interests			(2,235)	413
Other comprehensive income (loss) attributable to Harsco Corporation			25,171	49,329
Balances	210,018	293,024	210,018	293,024
Cumulative Foreign Exchange Translation Adjustments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances			(144,534)	(125,561)
Other comprehensive income (loss) before reclassifications			42,391	(23,744)
Amounts reclassified from accumulated other comprehensive loss			0	0
Realized (gains) losses reclassified from accumulated other comprehensive loss in connection with loss on dilution of equity method investment (See Note 4, Equity Method Investments)				28,641
Other comprehensive income (loss) from equity method investee				1,943
Total other comprehensive income			42,391	6,840
Other comprehensive income (loss) attributable to noncontrolling interests			(2,235)	420
Other comprehensive income (loss) attributable to Harsco Corporation			40,156	7,260
Balances	(104,378)	(118,301)	(104,378)	(118,301)
Effective Portion of Deriviatives Designated as Hedging Instruments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances			(1,089)	(400)
Other comprehensive income (loss) before reclassifications			1,133	(2,199)
Amounts reclassified from accumulated other comprehensive loss			338	26
Realized (gains) losses reclassified from accumulated other comprehensive loss in connection with loss on dilution of equity method investment (See Note 4, Equity Method Investments)				1,636
Other comprehensive income (loss) from equity method investee				(405)
Total other comprehensive income			1,471	(942)
Other comprehensive income (loss) attributable to noncontrolling interests			0	(7)
Other comprehensive income (loss) attributable to Harsco Corporation			1,471	(949)
Balances	382	(1,349)	382	(1,349)
Cumulative Unrecognized Actuarial Losses on Pension Obligations
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances			(461,094)	(389,696)
Other comprehensive income (loss) before reclassifications			(31,600)	32,067
Amounts reclassified from accumulated other comprehensive loss			15,133	12,168
Realized (gains) losses reclassified from accumulated other comprehensive loss in connection with loss on dilution of equity method investment (See Note 4, Equity Method Investments)				(1,534)
Other comprehensive income (loss) from equity method investee				306
Total other comprehensive income			(16,467)	43,007
Other comprehensive income (loss) attributable to noncontrolling interests			0	0
Other comprehensive income (loss) attributable to Harsco Corporation			(16,467)	43,007
Balances	(477,561)	(346,689)	(477,561)	(346,689)
Unrealized Loss on Marketable Securities
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances			(5)	(31)
Other comprehensive income (loss) before reclassifications			11	11
Amounts reclassified from accumulated other comprehensive loss			0	0
Realized (gains) losses reclassified from accumulated other comprehensive loss in connection with loss on dilution of equity method investment (See Note 4, Equity Method Investments)				0
Other comprehensive income (loss) from equity method investee				0
Total other comprehensive income			11	11
Other comprehensive income (loss) attributable to noncontrolling interests			0	0
Other comprehensive income (loss) attributable to Harsco Corporation			11	11
Balances	6	(20)	6	(20)
Accumulated Other Comprehensive Loss
Components of Accumulated Other Comprehensive Income [Roll Forward]
Balances			(606,722)	(515,688)
Total other comprehensive income			25,171	49,329
Balances	$ (581,551)	$ (466,359)	$ (581,551)	$ (466,359)