PROPERTIES AND EQUIPMENT Properties and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Proved Natural Gas and Crude Oil Properties	$ 3,499,718	$ 2,881,189
Unproved Natural Gas and Crude Oil Properties	1,874,671	60,498
Total Natural Gas and Crude Oil Properties	5,374,389	2,941,687
Transportation and Other Equipment	62,093	30,098
Land and Buildings	12,165	12,667
Construction in Progress	122,591	113,115
Property and Equipment, at cost	5,571,238	3,097,567
Accumulated Depreciation, Depletion and Amortization	(1,562,972)	(1,157,015)
Property and Equipment, Net	$ 4,008,266	$ 1,940,552