DEFERRED REVENUE - Rollforward of deferred revenue (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	$ 11,467
Current deferred revenue, Additions	20,726
Current deferred revenue, Less revenue recognized	19,598
Current deferred revenue, ending balance	12,595
Noncurrent deferred revenue, beginning balance	39,504
Noncurrent deferred revenue, Additions	11,627
Noncurrent deferred revenue, Less reclassification to current deferred revenue	11,297
Noncurrent deferred revenue, ending balance	39,834
Utica Shale
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	18
Current deferred revenue, Additions	14
Current deferred revenue, Less revenue recognized	14
Current deferred revenue, ending balance	18
Noncurrent deferred revenue, beginning balance	21
Noncurrent deferred revenue, Additions	0
Noncurrent deferred revenue, Less reclassification to current deferred revenue	14
Noncurrent deferred revenue, ending balance	7
Williston Basin
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	1,414
Current deferred revenue, Additions	1,779
Current deferred revenue, Less revenue recognized	1,259
Current deferred revenue, ending balance	1,934
Noncurrent deferred revenue, beginning balance	4,393
Noncurrent deferred revenue, Additions	1,940
Noncurrent deferred revenue, Less reclassification to current deferred revenue	2,225
Noncurrent deferred revenue, ending balance	4,108
Piceance Basin
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	7,616
Current deferred revenue, Additions	14,650
Current deferred revenue, Less revenue recognized	15,324
Current deferred revenue, ending balance	6,942
Noncurrent deferred revenue, beginning balance	17,942
Noncurrent deferred revenue, Additions	4,857
Noncurrent deferred revenue, Less reclassification to current deferred revenue	4,775
Noncurrent deferred revenue, ending balance	18,024
DJ Basin
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	739
Current deferred revenue, Additions	3,020
Current deferred revenue, Less revenue recognized	1,745
Current deferred revenue, ending balance	2,014
Noncurrent deferred revenue, beginning balance	7,284
Noncurrent deferred revenue, Additions	3,637
Noncurrent deferred revenue, Less reclassification to current deferred revenue	3,020
Noncurrent deferred revenue, ending balance	7,901
Barnett Shale
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	1,642
Current deferred revenue, Additions	1,235
Current deferred revenue, Less revenue recognized	1,228
Current deferred revenue, ending balance	1,649
Noncurrent deferred revenue, beginning balance	9,628
Noncurrent deferred revenue, Additions	1,193
Noncurrent deferred revenue, Less reclassification to current deferred revenue	1,235
Noncurrent deferred revenue, ending balance	9,586
Marcellus Shale
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	38
Current deferred revenue, Additions	28
Current deferred revenue, Less revenue recognized	28
Current deferred revenue, ending balance	38
Noncurrent deferred revenue, beginning balance	236
Noncurrent deferred revenue, Additions	0
Noncurrent deferred revenue, Less reclassification to current deferred revenue	28
Noncurrent deferred revenue, ending balance	$ 208