FAIR VALUE - Financial Instruments Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent Consideration – Current Liabilities	$ 0	$ (58,069)
Debt Exchange Derivatives – Current Liabilities	0	(18,183)
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity Derivatives – Current Asset	0	0
Commodity Derivatives - Noncurrent Asset	0	0
Contingent Consideration – Current Liabilities	0	0
Debt Exchange Derivatives – Current Liabilities		0
Commodity Derivatives - Noncurrent Liability	0	0
Total	0	0
Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity Derivatives – Current Asset	5,628	115,870
Commodity Derivatives - Noncurrent Asset	8,554	61,843
Contingent Consideration – Current Liabilities	(11,298)	0
Debt Exchange Derivatives – Current Liabilities		0
Commodity Derivatives - Noncurrent Liability	(8,079)	0
Total	(5,195)	177,713
Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity Derivatives – Current Asset	0	0
Commodity Derivatives - Noncurrent Asset	0	0
Contingent Consideration – Current Liabilities	0	(58,069)
Debt Exchange Derivatives – Current Liabilities		(18,183)
Commodity Derivatives - Noncurrent Liability	0	0
Total	$ 0	$ (76,252)