Recently Adopted and Recently Issued Accounting Standards - Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Trade accounts receivable, net	$ 304,165	$ 288,566	$ 288,034
Inventories	137,768	118,500	178,293
Current portion of contract assets	27,870	18,248	0
Other current assets	42,068	39,511	39,332
Total current assets	631,578	551,258	592,092
Contract assets	3,566	3,566	0
Deferred income tax assets	39,824		51,574
Other assets	21,002	16,600	15,263
Total assets	1,660,417	1,542,754	1,578,685
Current liabilities:
Current portion of advances on contracts	43,682	39,451	117,958
Other current liabilities	121,887	147,363	133,368
Total current liabilities	431,074	409,616	474,128
Advances on contracts	10,322	24,564	0
Other liabilities	54,273	42,426	40,846
Liabilities	1,356,026	1,325,152	1,363,520
HARSCO CORPORATION STOCKHOLDERS' EQUITY
Accumulated other comprehensive loss	(555,291)	(548,102)	(546,582)
Retained earnings	1,252,840	1,161,758	1,157,801
Stockholders' Equity Attributable to Parent	261,551	172,888	170,451
Stockholders' Equity Attributable to Noncontrolling Interest	42,840		44,714
Total equity	304,391	217,602	215,165	$ 210,018	$ 137,563
Total liabilities and equity	1,660,417	1,542,754	1,578,685
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Current assets:
Trade accounts receivable, net	303,630		288,034
Inventories	229,053		178,293
Current portion of contract assets	0		0
Other current assets	41,911		39,332
Total current assets	694,301		592,092
Contract assets	0		0
Deferred income tax assets	41,698
Other assets	19,962		15,263
Total assets	1,720,408		1,578,685
Current liabilities:
Current portion of advances on contracts	126,803		117,958
Other current liabilities	113,279		133,368
Total current liabilities	505,587		474,128
Advances on contracts	0		0
Other liabilities	54,057		40,846
Liabilities	1,420,001		1,363,520
HARSCO CORPORATION STOCKHOLDERS' EQUITY
Accumulated other comprehensive loss	(553,612)		(546,582)
Retained earnings	1,247,169		1,157,801
Stockholders' Equity Attributable to Parent	257,559		170,451
Stockholders' Equity Attributable to Noncontrolling Interest	42,848
Total equity	300,407		215,165
Total liabilities and equity	1,720,408		$ 1,578,685
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Current assets:
Trade accounts receivable, net	(535)	532
Inventories	91,285	(59,793)
Current portion of contract assets	(27,870)	18,248
Other current assets	(157)	179
Total current assets	62,723	(40,834)
Contract assets	(3,566)	3,566
Deferred income tax assets	1,874
Other assets	(1,040)	1,337
Total assets	59,991	(35,931)
Current liabilities:
Current portion of advances on contracts	83,121	(78,507)
Other current liabilities	(8,608)	13,995
Total current liabilities	74,513	(64,512)
Advances on contracts	(10,322)	24,564
Other liabilities	(216)	1,580
Liabilities	63,975	(38,368)
HARSCO CORPORATION STOCKHOLDERS' EQUITY
Accumulated other comprehensive loss	1,679	(1,520)
Retained earnings	(5,671)	3,957
Stockholders' Equity Attributable to Parent	(3,992)	2,437
Stockholders' Equity Attributable to Noncontrolling Interest	8
Total equity	(3,984)	2,437
Total liabilities and equity	$ 59,991	$ (35,931)