NONCONTROLLING INTERESTS - Net Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Noncontrolling Interest
Net income attributable to noncontrolling interest	$ 21,821	$ 40,337	$ 91,661	$ 92,643
SGP
Noncontrolling Interest
Net income attributable to noncontrolling interest	3	14	23	32
Non-Affiliates (ARLP's non-affiliate limited partners)
Noncontrolling Interest
Net income attributable to noncontrolling interest	21,663	40,279	91,213	92,571
Affiliate (Cavalier Minerals)
Noncontrolling Interest
Net income attributable to noncontrolling interest	$ 155	$ 44	$ 425	$ 40