SUPPLEMENTAL INFORMATION - NATURAL GAS AND CRUDE OIL PROPERTIES Results of Operations for Natural Gas and Crude Oil Producing Activities (Unaudited) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) bbl	Dec. 31, 2016 USD ($) bbl	Dec. 31, 2015 USD ($) bbl
Results of Operations for Oil and Gas Producing Activities, by Geographic Area [Line Items]
Extensions, Discoveries, and Other Additions | bbl	6,005,000	1,531,000	131,494,000
Purchases of Reserves | bbl	86,778,000	133,583,000	76,000
Revisions of Previous Estimates | bbl	52,457,000	(42,631,000)	(93,471,000)
Production | bbl	31,830,000	22,176,000	15,369,000
Infill Reserve Additions | bbl		16.8
Dispositions | bbl	1,900,000	1,725,000	34,000
Lease operating expenses	$ 89,641	$ 59,950	$ 56,992
Production taxes	60,717	31,410	18,443
Transportation, gathering, and processing expenses	33,220	18,415	10,151
Results of Operations for Crude Oil and Natural Gas Producing Activities
Results of Operations for Oil and Gas Producing Activities, by Geographic Area [Line Items]
Natural gas, NGL and crude oil sales	913,084	497,353	378,713
Commodity price risk management	(3,936)	(125,681)	203,183
Total Revenues from Oil and Gas Producing Activities	909,148	371,672	581,896
Lease operating expenses	89,641	59,950	56,992
Production taxes	60,717	31,410	18,443
Transportation, gathering, and processing expenses	33,220	18,415	10,151
Exploration Expense	47,334	4,669	1,102
Impairment of Oil and Gas Properties	285,887	9,973	161,620
Depreciation, Depletion and Amortization	462,482	413,105	298,760
Accretion of Asset Retirement Obligations	6,306	7,080	6,293
(Gain) loss on Sale of Properties and Equipment	(766)	(43)	(385)
Total Expense from Oil and Gas Producing Activities	984,821	544,559	552,976
Results of Operations of Natural Gas and Crude Oil Producing Activities, Income before Income Taxes	(75,673)	(172,887)	28,920
Provision for Income Taxes	47,247	64,733	(10,394)
Results of operations for natural gas and crude oil producing activities, excluding corporate overhead and interest costs	$ (28,426)	$ (108,154)	$ 18,526
Proved Developed Reserves [Member]
Results of Operations for Oil and Gas Producing Activities, by Geographic Area [Line Items]
Extensions, Discoveries, and Other Additions | bbl	2,292,000	1,531,000	8,703,000
Purchases of Reserves | bbl	1,305,000	10,229,000	76,000
Revisions of Previous Estimates | bbl	18,291,000	6,112,000	(26,875,000)
Production | bbl	31,830,000	22,176,000	15,369,000
Dispositions | bbl	20,000	99,000	34,000