COMMITMENTS AND CONTINGENCIES - Environmental Matters (Details) - Meadowlark Midstream Gathering System $ in Thousands	3 Months Ended
Mar. 31, 2021 USD ($)
Accrual for Environmental Loss Contingencies [Roll Forward]
Accrued environmental remediation, beginning balance	$ 2,929
Payments made	(86)
Additional accruals	410
Accrued environmental remediation, ending balance	$ 3,253

Total costs accrued as of the balance sheet date for environmental loss contingencies.

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Amount of cash outflow to settle environmental loss contingencies.

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Increase (decrease) in the accrual for environmental loss contingencies during the reporting period.

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