COMMITMENTS AND CONTINGENCIES Long-term fIrm transportation costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Transportation, gathering, and processing expenses	$ 33,220	$ 18,415	$ 10,151
Utica Shale natural gas and Wattenberg Field crude oil [Member]
Loss Contingencies [Line Items]
Transportation, gathering, and processing expenses	$ 10,000	$ 10,000	$ 4,700