Goodwill and Other Intangible Assets - Changes in Carrying Amounts of Goodwill by Segment (Details) $ in Thousands	9 Months Ended
Sep. 30, 2020 USD ($)
Changes in carrying amounts of goodwill
Balance at December 31, 2019	$ 738,369
Goodwill, Other Increase (Decrease)	145,763
Foreign currency translation	(2,221)
Balance at September 30, 2020	881,911
Harsco Environmental Segment
Changes in carrying amounts of goodwill
Balance at December 31, 2019	395,113
Goodwill, Other Increase (Decrease)	1,480
Foreign currency translation	(2,221)
Balance at September 30, 2020	394,372
Harsco Clean Earth Segment
Changes in carrying amounts of goodwill
Balance at December 31, 2019	330,230
Goodwill, Other Increase (Decrease)	144,283
Foreign currency translation	0
Balance at September 30, 2020	474,513
Harsco Rail Segment
Changes in carrying amounts of goodwill
Balance at December 31, 2019	13,026
Goodwill, Other Increase (Decrease)	0
Foreign currency translation	0
Balance at September 30, 2020	$ 13,026

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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Amount of increase (decrease), classified as other, of an asset representing the future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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