COMMITMENTS & CONTINGENCIES - Litigation (Details) - USD ($) $ in Millions			1 Months Ended	3 Months Ended	12 Months Ended
	Aug. 16, 2016	Aug. 15, 2016	Mar. 31, 2017	Mar. 31, 2017	Dec. 31, 2015
Loss Contingencies [Line Items]
Shares forfeited (in shares)				145,946	375,875
Quiet title action in North Dakota [Member]
Loss Contingencies [Line Items]
Possible revenue to be reversed due to pending litigation			$ 6.8	$ 6.8
Quiet title action in North Dakota [Member] | Other Noncurrent Assets, Net [Member]
Loss Contingencies [Line Items]
Loss contingency accounts receivable			$ 6.8	$ 6.8
Chief Executive Officer [Member] | Common Stock [Member]
Loss Contingencies [Line Items]
Shares forfeited (in shares)		1,530,796	85,383
Michael Reger [Member] | Chief Executive Officer [Member]
Loss Contingencies [Line Items]
Damages sought	$ 1.6