SEGMENT INFORMATION - Schedule of Adjustments Related to Minimum Volume Commitments Shortfall Payments (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Net change in deferred revenue for MVC shortfall payments	$ 0	$ 0	$ 0	$ (39,671,000)
Expected MVC shortfall adjustments	(2,999,000)	(10,124,000)	(6,541,000)	6,485,000
Total adjustments related to MVC shortfall payments	(2,999,000)	(10,124,000)	(6,541,000)	(33,186,000)
Williston Basin
Segment Reporting Information [Line Items]
Net change in deferred revenue for MVC shortfall payments	0	0	0	(37,693,000)
Expected MVC shortfall adjustments	2,032,000	1,982,000	(1,354,000)	5,946,000
Total adjustments related to MVC shortfall payments	2,032,000	1,982,000	(1,354,000)	(31,747,000)
Piceance/DJ Basins
Segment Reporting Information [Line Items]
Net change in deferred revenue for MVC shortfall payments	0	0	0	(1,978,000)
Expected MVC shortfall adjustments	0	(12,200,000)	(93,000)	867,000
Total adjustments related to MVC shortfall payments	0	(12,200,000)	(93,000)	(1,111,000)
Barnett Shale
Segment Reporting Information [Line Items]
Net change in deferred revenue for MVC shortfall payments	0	0	0	0
Expected MVC shortfall adjustments	(5,031,000)	94,000	(5,094,000)	(328,000)
Total adjustments related to MVC shortfall payments	$ (5,031,000)	$ 94,000	$ (5,094,000)	$ (328,000)