NONCONTROLLING INTERESTS - Net Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Noncontrolling Interest
Net income attributable to noncontrolling interest	$ 20,289	$ 36,259	$ 69,840	$ 52,306
SGP
Noncontrolling Interest
Net income attributable to noncontrolling interest	3	12	20	18
Non-Affiliates (ARLP's non-affiliate limited partners)
Noncontrolling Interest
Net income attributable to noncontrolling interest	20,164	36,249	69,550	52,292
Affiliate (Cavalier Minerals)
Noncontrolling Interest
Net income attributable to noncontrolling interest	$ 122	$ (2)	$ 270	$ (4)