VARIABLE INTEREST ENTITIES - Cavalier Minerals (Details) - USD ($) $ in Thousands	2 Months Ended	12 Months Ended			14 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Oct. 06, 2015	Nov. 10, 2014
Variable Interest Entities
Funding contributed		$ 64,540	$ 111,376	$ 62,500
Contributions from noncontrolling owner		2,147	$ 481
AllDale Minerals | Cavalier Minerals
Variable Interest Entities
Remaining funding commitment		$ 83,100			$ 83,100
All Dale I | Cavalier Minerals
Variable Interest Entities
Noncontrolling ownership interest (as a percent)		71.70%			71.70%
Initial funding commitment							$ 49,000
All Dale II | Cavalier Minerals
Variable Interest Entities
Noncontrolling ownership interest (as a percent)		72.80%			72.80%
Initial funding commitment						$ 100,000
Cavalier Minerals | Variable Interest Entity, Primary Beneficiary
Variable Interest Entities
Initial funding commitment							48,000
Noncontrolling owner's initial funding commitment							$ 2,000
Additional funding commitment						96,000
Noncontrolling owner's additional funding commitment						$ 4,000
Funding contributed	$ 11,500	$ 51,600			$ 63,100
Remaining funding commitment		80,900			80,900
Contributions from noncontrolling owner					2,600
Remaining funding committed by noncontrolling owners		$ 3,400			$ 3,400
Incentive distribution for noncontrolling owners (as a percent)		25.00%
Ownership interest in VIE (as a percent)		96.00%