SEGMENT INFORMATION - Schedule of Adjustments Related to Minimum Volume Commitments Shortfall Payments (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Net change in deferred revenue for MVC shortfall payments	$ 0	$ (1,186,000)	$ 0	$ (39,671,000)
Expected MVC shortfall adjustments	(3,542,000)	6,764,000	(3,542,000)	16,609,000
Total adjustments related to MVC shortfall payments	(3,542,000)	5,578,000	(3,542,000)	(23,062,000)
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	(3,386,000)	1,982,000	(3,386,000)	3,964,000
Total adjustments related to MVC shortfall payments	(3,386,000)	1,982,000	(3,386,000)	(33,729,000)
Piceance/DJ Basins
Segment Reporting Information [Line Items]
Net change in deferred revenue for MVC shortfall payments	0	(1,186,000)	0	(1,978,000)
Expected MVC shortfall adjustments	(93,000)	6,522,000	(93,000)	13,067,000
Total adjustments related to MVC shortfall payments	(93,000)	5,336,000	(93,000)	11,089,000
Barnett Shale
Segment Reporting Information [Line Items]
Net change in deferred revenue for MVC shortfall payments	0	0	0	0
Expected MVC shortfall adjustments	(63,000)	(1,740,000)	(63,000)	(422,000)
Total adjustments related to MVC shortfall payments	$ (63,000)	$ (1,740,000)	$ (63,000)	$ (422,000)