Recently Adopted and Recently Issued Accounting Standards - Condensed Consolidated Statements of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2018	Sep. 30, 2017
Revenues from continuing operations:
Total revenues	$ 445,475		$ 384,653		$ 1,285,485	$ 1,152,092
Costs and expenses from continuing operations:
Selling, general and administrative costs	59,297		59,993		175,307	168,315
Total costs and expenses	388,366		350,024		1,138,210	1,045,707
Operating income from continuing operations	57,109		34,629		147,275	106,385
Interest expense	(9,665)		(12,122)		(29,241)	(36,180)
Income from continuing operations before income taxes	48,821		22,437		121,195	69,766
Income tax (expense) benefit	(13,833)		(8,270)		(24,043)	(25,757)
Income from continuing operations	34,988		14,167		97,152	44,009
Net income	34,651		13,796		96,939	43,664
Net Income (Loss) Attributable to Noncontrolling Interest	(1,804)		(498)		(5,795)	(2,438)
Amounts attributable to Harsco Corporation common stockholders:
Income from continuing operations, net of tax	33,184		13,669		91,357	41,571
Net income attributable to Harsco Corporation common stockholders	$ 32,847		$ 13,298		$ 91,144	$ 41,226
Basic earnings per common share attributable to Harsco Corporation common stockholders:
Continuing operations (in dollars per share)	$ 0.41		$ 0.17		$ 1.13	$ 0.52
Basic earnings per share attributable to Harsco Corporation common stockholders (in dollars per share)	0.41		0.16	[1]	1.13	0.51	[1]
Diluted earnings per common share attributable to Harsco Corporation common stockholders:
Continuing operations (in dollars per share)	0.40		0.16		1.09	0.50
Diluted earnings per share attributable to Harsco Corporation common stockholders (in dollars per share)	$ 0.39	[1]	$ 0.16		$ 1.09	$ 0.50
Service Revenues [Member]
Revenues from continuing operations:
Total revenues	$ 250,890		$ 246,144		$ 763,815	$ 738,059
Costs and expenses from continuing operations:
Cost of services and products sold	194,459		194,483		589,738	577,200
Product Revenues [Member]
Revenues from continuing operations:
Total revenues	194,585		138,509		521,670	414,033
Costs and expenses from continuing operations:
Cost of services and products sold	132,262		$ 95,849		367,218	$ 295,367
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Revenues from continuing operations:
Total revenues	(14,899)				(30,087)
Costs and expenses from continuing operations:
Selling, general and administrative costs	66				103
Total costs and expenses	(10,640)				(26,008)
Operating income from continuing operations	(4,259)				(4,079)
Interest expense	550				1,453
Income from continuing operations before income taxes	(3,709)				(2,626)
Income tax (expense) benefit	932				919
Income from continuing operations	(2,777)				(1,707)
Net income	(2,777)				(1,707)
Net Income (Loss) Attributable to Noncontrolling Interest	(10)				(8)
Amounts attributable to Harsco Corporation common stockholders:
Income from continuing operations, net of tax	(2,787)				(1,715)
Net income attributable to Harsco Corporation common stockholders	$ (2,787)				$ (1,715)
Basic earnings per common share attributable to Harsco Corporation common stockholders:
Continuing operations (in dollars per share)	$ (0.03)				$ (0.02)
Basic earnings per share attributable to Harsco Corporation common stockholders (in dollars per share)	(0.03)				(0.02)
Diluted earnings per common share attributable to Harsco Corporation common stockholders:
Continuing operations (in dollars per share)	(0.03)				(0.02)
Diluted earnings per share attributable to Harsco Corporation common stockholders (in dollars per share)	$ (0.03)				$ (0.02)
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Service Revenues [Member]
Revenues from continuing operations:
Total revenues	$ 512				$ 4,182
Costs and expenses from continuing operations:
Cost of services and products sold	1,273				3,980
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Product Revenues [Member]
Revenues from continuing operations:
Total revenues	(15,411)				(34,269)
Costs and expenses from continuing operations:
Cost of services and products sold	(11,979)				(30,091)
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenues from continuing operations:
Total revenues	430,576				1,255,398
Costs and expenses from continuing operations:
Selling, general and administrative costs	59,363				175,410
Total costs and expenses	377,726				1,112,202
Operating income from continuing operations	52,850				143,196
Interest expense	(9,115)				(27,788)
Income from continuing operations before income taxes	45,112				118,569
Income tax (expense) benefit	(12,901)				(23,124)
Income from continuing operations	32,211				95,445
Net income	31,874				95,232
Net Income (Loss) Attributable to Noncontrolling Interest	(1,814)				(5,803)
Amounts attributable to Harsco Corporation common stockholders:
Income from continuing operations, net of tax	30,397				89,642
Net income attributable to Harsco Corporation common stockholders	$ 30,060				$ 89,429
Basic earnings per common share attributable to Harsco Corporation common stockholders:
Continuing operations (in dollars per share)	$ 0.38				$ 1.11
Basic earnings per share attributable to Harsco Corporation common stockholders (in dollars per share)	0.37				1.11
Diluted earnings per common share attributable to Harsco Corporation common stockholders:
Continuing operations (in dollars per share)	0.36				1.07
Diluted earnings per share attributable to Harsco Corporation common stockholders (in dollars per share)	$ 0.36				$ 1.07
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Service Revenues [Member]
Revenues from continuing operations:
Total revenues	$ 251,402				$ 767,997
Costs and expenses from continuing operations:
Cost of services and products sold	195,732				593,718
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Product Revenues [Member]
Revenues from continuing operations:
Total revenues	179,174				487,401
Costs and expenses from continuing operations:
Cost of services and products sold	$ 120,283				$ 337,127

[1] Does not total due to rounding