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COMMITMENTS AND CONTINGENCIES - Narrative (Detail) numberOfPlantiffs in Thousands	Sep. 17, 2019 numberOfPlantiffs	Apr. 28, 2017 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Apr. 26, 2017 USD ($)	Jan. 29, 2016	Apr. 30, 2011 USD ($)	May 31, 2009 USD ($)	Dec. 20, 2000 a
Southbridge Landfill
Loss Contingencies [Line Items]
Risk free interest percentage rate			2.60%
Environmental remediation liability			$ 4,205,000	$ 4,596,000	$ 4,846,000	$ 5,173,000
Potsdam Environmental Remediation
Loss Contingencies [Line Items]
Risk free interest percentage rate			1.50%
Scrap yard and solid waste transfer station (in acres) | a											25
Undiscounted costs preferred remedies									$ 12,130,000	$ 10,219,000
Remediation activities, participant share percentage								15.00%
Environmental remediation liability			$ 1,151,000	$ 1,151,000
21E Settlement and Water System Construction Funding Agreement | Bonds
Loss Contingencies [Line Items]
Bond period		20 years
21E Settlement and Water System Construction Funding Agreement | Bonds | Maximum
Loss Contingencies [Line Items]
Anticipated cost		$ 4,089,000
Notice of Intent to Sue under the Resource Conservation and Recovery Act
Loss Contingencies [Line Items]
Estimate of possible loss							$ 5,000,000
Notice of Intent to Sue under the Resource Conservation and Recovery Act | MADEP and Casella Waste Systems
Loss Contingencies [Line Items]
Estimate of possible loss							$ 10,000,000
Ontario County, New York Class Action Litigation
Loss Contingencies [Line Items]
Number of citizens seeking damages | numberOfPlantiffs	1
Notice of Intent to Sue for Violations of the CWA | NCES Landfil
Loss Contingencies [Line Items]
Estimate of possible loss			$ 1,424,000

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