Accounts Receivable and Inventories (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2016
Accounts receivable
Trade accounts receivable	$ 301,439		$ 295,847
Less: Allowance for doubtful accounts	(4,644)		(4,634)
Trade accounts receivable, net	296,795		291,213
Other receivables	51,130		54,182
Provision for doubtful accounts related to trade accounts receivable	26	$ (46)
Inventories
Finished goods	19,089		17,223
Work-in-process	21,715		21,787
Raw materials and purchased parts	82,983		72,194
Stores and supplies	23,909		21,907
Inventories	147,696		133,111
Inventory for Contracts
Loss provision that exceeds accumulated contract costs	6,800
Net customer advances	64,500		69,000
Contract estimated forward loss provision for Harsco Rail Segment			$ 1,800	$ 45,100
Revenues	447,288	408,038
SBB [Member]
Inventory for Contracts
Revenues	$ 4,700	$ 7,900
Contract 2 [Member] | SBB [Member]
Inventory for Contracts
Percentage complete	30.00%