Inventories (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2018	Dec. 31, 2016
Revenue from External Customer [Line Items]
Contract estimated forward loss provision for Harsco Rail Segment					$ 1,800,000	$ 45,100,000
Loss provision that exceeds accumulated contract costs	$ 7,000,000.0		$ 7,000,000.0
Revenues	447,281,000	$ 350,898,000	846,122,000	$ 680,800,000
Contract Margin			0
SBB [Member]
Revenue from External Customer [Line Items]
Revenues	$ 7,600,000	$ 5,900,000	$ 17,700,000	$ 10,600,000
Contract 2 [Member] | SBB [Member]
Revenue from External Customer [Line Items]
Percentage complete	56.00%		56.00%