SEGMENT INFORMATION - EBITDA Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2016	Dec. 31, 2015		Dec. 31, 2014
Reconciliation of consolidated Segment Adjusted EBITDA to net income
Consolidated Segment Adjusted EBITDA			$ 764,818	$ 814,243	[1],[2]	$ 875,847	[1],[2]
General and administrative			(75,087)	(69,076)		(76,699)
Depreciation, depletion and amortization			(322,509)	(333,713)		(274,566)
Asset impairment charge	$ (89,400)	$ (10,700)		(100,130)
Interest expense, net			(30,655)	(29,693)		(31,913)
Acquisition gain, net	$ 22,500			22,548
Income tax expense			(14)	(21)
NET INCOME			$ 336,553	$ 304,158		$ 492,669

[1] Includes equity in loss of affiliates for the years ended December 31, 2015 and 2014 of $48.5 million and $16.6 million, respectively, for the Illinois Basin segment.

[2] Segment Adjusted EBITDA is defined as net income (prior to the allocation of noncontrolling interest) before net interest expense, income taxes, depreciation, depletion and amortization, asset impairment, acquisition gain, net and general and administrative expenses. Management therefore is able to focus solely on the evaluation of segment operating profitability as it relates to the ARLP Partnership's revenues and operating expenses, which are primarily controlled by our segments.