Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018	Jan. 01, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances	$ 215,165	$ 137,563	$ 310,803
Adoption of new accounting standard (See Note 2)				$ 2,374	$ 397
Other comprehensive income (loss) before reclassifications	(39,875)	43,143
Amounts reclassified from accumulated other comprehensive loss, net of tax	18,370	20,041
Total other comprehensive income (loss)	(21,505)	63,184	(93,614)
Less: Other comprehensive loss attributable to noncontrolling interests	2,500	(3,044)
Other comprehensive income (loss) attributable to Harsco Corporation	(19,005)	60,140
Balances	313,376	215,165	137,563
Cumulative Foreign Exchange Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances	(111,567)	(144,534)
Other comprehensive income (loss) before reclassifications	(50,743)	36,011
Amounts reclassified from accumulated other comprehensive loss, net of tax	0	0
Total other comprehensive income (loss)	(50,743)	36,011
Less: Other comprehensive loss attributable to noncontrolling interests	2,500	(3,044)
Other comprehensive income (loss) attributable to Harsco Corporation	(48,243)	32,967
Balances	(159,810)	(111,567)	(144,534)
Effective Portion of Derivatives Designated as Hedging Instruments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances	808	(1,089)
Other comprehensive income (loss) before reclassifications	2,466	1,967
Amounts reclassified from accumulated other comprehensive loss, net of tax	(365)	(70)
Total other comprehensive income (loss)	2,101	1,897
Less: Other comprehensive loss attributable to noncontrolling interests	0	0
Other comprehensive income (loss) attributable to Harsco Corporation	2,101	1,897
Balances	1,389	808	(1,089)
Cumulative Unrecognized Actuarial Losses on Pension Obligations
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances	(435,840)	(461,094)
Other comprehensive income (loss) before reclassifications	8,450	5,143
Amounts reclassified from accumulated other comprehensive loss, net of tax	18,735	20,111
Total other comprehensive income (loss)	27,185	25,254
Less: Other comprehensive loss attributable to noncontrolling interests	0	0
Other comprehensive income (loss) attributable to Harsco Corporation	27,185	25,254
Balances	(408,655)	(435,840)	(461,094)
Unrealized Loss on Marketable Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances	17	(5)
Other comprehensive income (loss) before reclassifications	(48)	22
Amounts reclassified from accumulated other comprehensive loss, net of tax	0	0
Total other comprehensive income (loss)	(48)	22
Less: Other comprehensive loss attributable to noncontrolling interests	0	0
Other comprehensive income (loss) attributable to Harsco Corporation	(48)	22
Balances	(31)	17	(5)
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances	(546,582)	(606,722)	(515,688)
Adoption of new accounting standard (See Note 2)				(1,520)
Total other comprehensive income (loss)	(19,005)	60,140	(91,034)
Balances	(567,107)	(546,582)	$ (606,722)
Accounting Standards Update 2014-09
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances	(548,102)
Adoption of new accounting standard (See Note 2)				(1,520)
Balances		(548,102)
Accounting Standards Update 2014-09 | Cumulative Foreign Exchange Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances	(111,567)
Balances		(111,567)
Accounting Standards Update 2014-09 | Effective Portion of Derivatives Designated as Hedging Instruments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances	(712)
Balances		(712)
Accounting Standards Update 2014-09 | Cumulative Unrecognized Actuarial Losses on Pension Obligations
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances	(435,840)
Balances		(435,840)
Accounting Standards Update 2014-09 | Unrealized Loss on Marketable Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balances	$ 17
Balances		$ 17
Accounting Standards Update 2014-09 | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Adoption of new accounting standard (See Note 2)				$ (1,520)