QUARTERLY FINANCIAL DATA (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								7 Months Ended	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Midstream service revenue - Affiliate and other	$ 28,305	$ 25,437	$ 12,517	$ 12,099	$ 8,204	$ 5,368	$ 1,570	$ 0	$ 0	$ 78,358	$ 15,142
Net income (loss) before income taxes	4,014	284	(7,468)	(7,570)	(6,051)	(3,354)	(2,129)	0	0	(10,740)	(11,534)
Net income (loss) attributable to Class A common shareholders	$ 632	$ 19,208	$ (11,621)	$ (12,607)	$ (12,318)	$ (3,828)	$ (2,429)	$ 0	$ 0	$ (4,388)	$ (18,575)
Net income (loss) attributable to Class A common shareholders, per share:
Basic (in USD per share)	$ 0.004	$ 0.09	$ (0.06)	$ (0.09)	$ (0.11)	$ (0.05)	$ (0.05)	$ 0.00	$ 0.00	$ (0.03)	$ (0.30)
Diluted (in USD per share)	$ 0.004	$ 0.09	$ (0.06)	$ (0.09)	$ (0.11)	$ (0.05)	$ (0.05)	$ 0.00	$ 0.00	$ (0.03)	$ (0.30)