LEASES, COMMITMENTS AND CONTINGENCIES - Environmental Matters (Details) - Meadowlark Midstream Gathering System $ in Thousands	9 Months Ended
Sep. 30, 2019 USD ($)
Accrual for Environmental Loss Contingencies [Roll Forward]
Accrued environmental remediation, beginning balance	$ 5,636
Payments made	(2,025)
Additional accruals	767
Accrued environmental remediation, ending balance	$ 4,378

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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