COMMITMENTS AND CONTINGENCIES - Environmental Remediation Liability (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019
Southbridge Landfill
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	$ 4,596	$ 5,173
Accretion expense	90	94
Obligations incurred	28	0
Revisions in estimates	(188)	0
Obligations settled	(293)	(556)
Ending balance	4,233	4,711
Potsdam Environmental Remediation
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	1,151	5,614
Obligations settled	(212)	(1,764)
Ending balance	$ 939	$ 3,850

Accrual For Environmental Loss Contingencies, Obligations Incurred

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- Definition

Total costs accrued as of the balance sheet date for environmental loss contingencies.

+ References

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- Definition

Amount of expense for newly incurred environmental loss contingencies. Includes, but is not limited to, remediation expense and interest accretion.

+ References

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- Definition

Amount of expense (reversal of expense) which increases (decreases) the accrual for environmental loss contingencies from revisions in estimates to existing obligations. Excludes changes related to business acquisitions, divestitures, or currency movement.

+ References

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Amount of cash outflow to settle environmental loss contingencies.

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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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