Information by Segment and Geographic Area (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 1,863,864	$ 1,503,742	$ 1,347,672
Operating income from continuing operations	21,081	104,279	130,695
Total assets	2,993,287	2,367,467	1,632,867
Depreciation	125,765	119,803	122,135
Depreciation Excluding Industrial Segment	125,556	117,063	116,212
Amortization	33,937	18,592	10,650
Amortization Excluding Deferred Financing Costs	33,937	18,031	8,844
Capital Expenditures	120,118	176,600	124,607
Interest income	2,174	1,975	2,155
Interest expense	(59,689)	(36,586)	(21,531)
Defined benefit pension income (expense)	7,229	(5,493)	3,457
Loss on early extinguishment of debt	(1,920)	(7,704)	(1,127)
Income (loss) from continuing operations before income taxes and equity income	(31,125)	56,471	113,649
Clean Earth
Segment Reporting Information [Line Items]
Operating income from continuing operations	16,096	20,009	0
Total assets	1,279,387	745,410	0
Depreciation	17,450	4,932	0
Amortization	22,814	7,923	0
Capital Expenditures	12,612	5,870	0
Operating segments
Segment Reporting Information [Line Items]
Operating income from continuing operations	95,321	156,015	158,536
Operating segments | Harsco Environmental
Segment Reporting Information [Line Items]
Revenues	914,445	1,034,847	1,068,304
Operating income from continuing operations	59,006	112,298	121,195
Total assets	1,322,731	1,296,061	1,230,152
Depreciation	100,971	104,840	109,494
Amortization	7,825	7,286	5,565
Capital Expenditures	99,056	153,694	114,142
Operating segments | Clean Earth
Segment Reporting Information [Line Items]
Revenues	619,588	169,522	0
Operating segments | Harsco Industrial
Segment Reporting Information [Line Items]
Total assets	0	53,582	163,324
Operating segments | Harsco Rail
Segment Reporting Information [Line Items]
Revenues	329,831	299,373	279,294
Operating income from continuing operations	20,219	23,708	37,341
Total assets	334,191	246,377	186,049
Depreciation	5,113	4,554	3,981
Amortization	337	322	306
Capital Expenditures	7,962	15,274	9,152
Corporate
Segment Reporting Information [Line Items]
Revenues	0	0	74
Operating income from continuing operations	(74,240)	(51,736)	(27,841)
Total assets	56,978	26,037	53,342
Depreciation	2,022	2,737	2,737
Amortization	2,961	2,500	2,973
Capital Expenditures	$ 488	$ 1,762	$ 1,313