CRUDE OIL AND NATURAL GAS PROPERTIES - Fair Values of the Net Assets and Liabilities as of the Date of Acquisition (Details) - USD ($) $ / shares in Units, shares in Millions							12 Months Ended
	Jul. 01, 2019	Oct. 01, 2018	Sep. 17, 2018	Jul. 27, 2018	Jul. 17, 2018	Jun. 04, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair value of net assets:
Proved oil and natural gas properties							$ 4,178,605,000	$ 3,431,428,000
Total Assets							1,905,465,000	1,503,645,000
Asset retirement obligations							(17,299,000)	$ (12,501,000)	$ (9,128,000)
Fair value of consideration paid for net assets:
Total value of consideration transferred							53,400,000
VEN Bakken LLC
Fair value of net assets:
Proved oil and natural gas properties	$ 325,572,000
Asset retirement cost	2,680,000
Total Assets	328,252,000
Asset retirement obligations	(2,680,000)
Derivative instruments	(9,694,000)
Net assets acquired	315,878,000
Fair value of consideration paid for net assets:
Cash consideration	175,510,000
Issuance of common stock	11,708,000
Unsecured VEN Bakken Note	128,660,000
Total value of consideration transferred	$ 315,878,000
Closing price of common stock at date of acquisition (in dollars per share)	$ 2.09
W Energy Acquisition
Fair value of net assets:
Proved oil and natural gas properties		$ 341,633,000
Asset retirement cost		939,000
Total Assets		342,572,000
Asset retirement obligations		(939,000)
Net assets acquired		341,633,000
Fair value of consideration paid for net assets:
Cash consideration		97,838,000		$ 117,100,000
Issuance of common stock		220,836,000
Contingent consideration		22,959,000					0
Total value of consideration transferred		$ 341,633,000
Asset acquisition, shares issued (in shares)	5.6	51.5
Closing price of common stock at date of acquisition (in dollars per share)	$ 2.09	$ 4.29
Pivotal Entities
Fair value of net assets:
Proved oil and natural gas properties			$ 146,134,000
Asset retirement cost			644,000
Total Assets			146,778,000
Asset retirement obligations			(644,000)
Net assets acquired			146,134,000
Fair value of consideration paid for net assets:
Cash consideration			48,189,000		$ 68,400,000
Issuance of common stock			88,592,000
Contingent consideration			9,353,000				$ 0
Total value of consideration transferred			$ 146,134,000
Asset acquisition, shares issued (in shares)			25.8
Closing price of common stock at date of acquisition (in dollars per share)			$ 3.44
Salt Creek Oil And Gas, LLC
Fair value of net assets:
Proved oil and natural gas properties						$ 59,978,000
Asset retirement cost						154,000
Total Assets						60,132,000
Asset retirement obligations						(154,000)
Net assets acquired						59,978,000
Fair value of consideration paid for net assets:
Cash consideration						44,738,000
Issuance of common stock						15,240,000
Total value of consideration transferred						$ 59,978,000
Asset acquisition, shares issued (in shares)						6.0
Closing price of common stock at date of acquisition (in dollars per share)						$ 2.54