FAIR VALUE MEASUREMENTS - Recurring Measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jan. 31, 2020	Dec. 31, 2019
Current:
Derivative instruments	$ 23,263		$ 0
Non-current:
Derivative instruments	5,487		0
Fair Value, Recurring | Derivative instruments
Current:
Total Gross Fair Value	3,856
Gross Amounts Offset in Balance Sheet	3,856
Derivative instruments	0
Non-current:
Total Gross Fair Value	2,347
Gross Amounts Offset in Balance Sheet	2,347
Derivative instruments	0
Current:
Total Gross Fair Value	27,119
Gross Amounts Offset in Balance Sheet	3,856
Derivative instruments	23,263
Non-current:
Total Gross Fair Value	7,834
Gross Amounts Offset in Balance Sheet	2,347
Derivative instruments	5,487
Derivative assets		$ 0
Derivative liabilities		$ 0
Fair Value, Recurring | Investment
Non-current:
Total Gross Fair Value	5,434		19,357
Gross Amounts Offset in Balance Sheet	0		0
Derivative instruments	5,434		19,357
Fair Value, Recurring | Level 1 | Derivative instruments
Current:
Total Gross Fair Value	0
Non-current:
Total Gross Fair Value	0
Current:
Total Gross Fair Value	0
Non-current:
Total Gross Fair Value	0
Fair Value, Recurring | Level 1 | Investment
Non-current:
Total Gross Fair Value	5,434		19,357
Fair Value, Recurring | Level 2 | Derivative instruments
Current:
Total Gross Fair Value	3,856
Non-current:
Total Gross Fair Value	2,347
Current:
Total Gross Fair Value	27,119
Non-current:
Total Gross Fair Value	7,834
Fair Value, Recurring | Level 2 | Investment
Non-current:
Total Gross Fair Value	0		0
Fair Value, Recurring | Level 3 | Derivative instruments
Current:
Total Gross Fair Value	0
Non-current:
Total Gross Fair Value	0
Current:
Total Gross Fair Value	0
Non-current:
Total Gross Fair Value	0
Fair Value, Recurring | Level 3 | Investment
Non-current:
Total Gross Fair Value	$ 0		$ 0