FAIR VALUE OF FINANCIAL INSTRUMENTS - Assets Measured at Fair Value on Non-Recurring Basis (Details) - Fair Value, Measurements, Nonrecurring - Southbridge landfill asset group - long-lived assets $ in Thousands	Jun. 30, 2017 USD ($)
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Southbridge landfill asset group - long-lived assets	$ 0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Southbridge landfill asset group - long-lived assets	0
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Southbridge landfill asset group - long-lived assets	$ 8,017