Review of Operations by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Operations by segment
Revenues	$ 569,820	$ 447,281	$ 1,098,675	$ 846,122
Operating income from continuing operations	36,219	1,868	61,043	4,749	$ 4,749
Interest income	638	816	1,223	1,009
Interest expense	(15,986)	(14,953)	(32,850)	(27,602)
Unused debt commitment fees, amendment fees and loss on extinguishment of debt	(50)	(1,432)	(5,308)	(1,920)
Defined benefit pension income (expense)	(3,974)	(1,723)	(7,927)	(3,312)
Income (loss) from continuing operations before income taxes and equity income	24,795	(11,978)	32,035	(20,452)
Capital Expenditures	41,264	23,320	68,646	51,107
Depreciation	32,156		64,904	61,512
Depreciation Excluding Industrial Segment		31,579		61,303
Amortization	8,816	9,115	17,783	15,672
Operating Segments
Operations by segment
Operating income from continuing operations	46,521	21,992	80,298	43,229
Corporate
Operations by segment
Operating income from continuing operations	(10,302)	(20,124)	(19,255)	(38,480)
Capital Expenditures	111	324	179	382
Depreciation	494	521	977	1,034
Amortization	633	764	1,384	1,403
Harsco Environmental Segment | Operating Segments
Operations by segment
Revenues	272,546	203,991	530,532	445,550
Operating income from continuing operations	30,223	13,563	56,158	24,083
Capital Expenditures	35,993	18,654	60,412	43,402
Depreciation	25,550	24,663	51,267	50,038
Amortization	2,035	1,921	4,083	3,857
Harsco Clean Earth Segment | Operating Segments
Operations by segment
Revenues	196,128	161,579	385,407	240,391
Operating income from continuing operations	7,386	(202)	10,564	4,043
Capital Expenditures	4,725	3,045	7,255	4,487
Depreciation	4,905	5,138	10,242	7,759
Amortization	6,063	6,347	12,146	10,245
Harsco Rail Segment | Operating Segments
Operations by segment
Revenues	101,146	81,711	182,736	160,181
Operating income from continuing operations	8,912	8,631	13,576	15,103
Capital Expenditures	435	1,297	800	2,836
Depreciation	1,207	1,257	2,418	2,472
Amortization	$ 85	$ 83	$ 170	$ 167