DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Fair Value Measurement Inputs (Details) - Significant Unobservable Inputs (Level 3)	Dec. 31, 2020 $ / MMBTU
Measurement Input, Risk Free Interest Rate | Minimum
Embedded Derivative [Line Items]
Preferred Units embedded derivative	0.0732
Measurement Input, Risk Free Interest Rate | Maximum
Embedded Derivative [Line Items]
Preferred Units embedded derivative	0.1173
Measurement Input Interest Rate Volatility
Embedded Derivative [Line Items]
Preferred Units embedded derivative	0.3708