SEGMENT INFORMATION - Segment Results (Details) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) segment		Dec. 31, 2014 USD ($)		Dec. 31, 2013 USD ($)
Segment information
Number of reportable segments | segment										2
Reportable segment results
Total revenues		$ 542,050	$ 566,342	$ 604,619	$ 560,300	$ 590,696	$ 569,230	$ 598,464	$ 541,934	$ 2,273,311	[1]	$ 2,300,324	[1]	$ 2,205,199	[1]
Segment Adjusted EBITDA Expense	[2]									1,376,425		1,381,808		1,398,902
Segment Adjusted EBITDA	[3],[4]									814,243		875,847		749,214
Total assets	[5]	2,368,360				2,288,755				2,368,360		2,288,755		2,126,679
Capital expenditures	[6]									212,797		311,469		354,423
Additional information
Equity in (loss) income of affiliates										(49,046)		(16,648)		(24,441)
Investments in affiliate		64,509				224,611				64,509		224,611
Payments to affiliate for acquisition and development of coal reserves												4,082		25,272
White Oak
Additional information
Payments to affiliate for acquisition and development of coal reserves												4,100		25,300
Operating segments | Illinois Basin
Reportable segment results
Total revenues	[1]									1,636,217		1,647,694		1,631,283
Segment Adjusted EBITDA Expense	[2]									949,271		1,000,028		953,798
Segment Adjusted EBITDA	[3],[4]									617,148		616,727		632,175
Total assets	[5]	1,694,044				1,581,279				1,694,044		1,581,279		1,394,592
Capital expenditures	[6]									145,352		243,167		272,861
Additional information
Equity in (loss) income of affiliates										(48,500)		(16,600)		(25,300)
Investments in affiliate						211,700						211,700		128,700
Operating segments | Appalachia
Reportable segment results
Total revenues	[1]									596,299		630,452		493,689
Segment Adjusted EBITDA Expense	[2]									400,681		364,689		375,923
Segment Adjusted EBITDA	[3],[4]									183,908		254,037		105,123
Total assets	[5]	517,972				604,352				517,972		604,352		594,466
Capital expenditures	[6]									61,279		56,840		72,926
Operating segments | Other and Corporate
Reportable segment results
Total revenues	[1]									180,622		33,693		97,910
Segment Adjusted EBITDA Expense	[2]									153,720		25,487		86,864
Segment Adjusted EBITDA	[3],[4]									25,767		8,202		11,916
Total assets	[5]	270,891				262,120				270,891		262,120		138,696
Capital expenditures	[6]									6,166		11,462		8,636
Additional information
Equity in (loss) income of affiliates										(500)		(3)		900
Investments in affiliate		64,500				12,900				64,500		12,900		1,700
Elimination
Reportable segment results
Total revenues	[1],[7]									(139,827)		(11,515)		(17,683)
Segment Adjusted EBITDA Expense	[2],[7]									(127,247)		(8,396)		(17,683)
Segment Adjusted EBITDA	[3],[4],[7]									(12,580)		(3,119)
Total assets	[5],[7]	$ (114,547)				$ (158,996)				$ (114,547)		$ (158,996)		$ (1,075)

[1] Revenues included in Other and Corporate column are primarily attributable to the Matrix Group revenues, Mt. Vernon transloading revenues, administrative service revenues from affiliates, MAC revenues, Wildcat Insurance revenues, brokerage sales and Pontiki’s coal sales revenue (2013 only).

[2] Segment Adjusted EBITDA Expense includes operating expenses, outside coal purchases and other income. Transportation expenses are excluded as these expenses are passed through to the ARLP Partnership's customers and consequently it does not realize any gain or loss on transportation revenues. We review Segment Adjusted EBITDA Expense per ton for cost trends.

[3] Includes equity in income (loss) of affiliates for the years ended December 31, 2015, 2014 and 2013 of $(48.5) million, $(16.6) million and $(25.3) million, respectively, for the Illinois Basin segment and $(0.5) million, $(3) thousand and $0.9 million, respectively, for Other and Corporate.

[4] 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 charge, 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.

[5] Total assets at December 31, 2015, 2014 and 2013 include investments in affiliate of $64.5 million, $12.9 million and $1.7 million, respectively, within Other and Corporate. Total assets at December 31, 2014 and 2013 include investments in affiliate of $211.7 million and $128.7 million, respectively, for the Illinois Basin segment.

[6] Capital expenditures shown above include funding to White Oak of $4.1 million and $25.3 million, for the years ended December 31, 2014 and 2013, respectively, for the acquisition and development of coal reserves from White Oak, which is described as Payments to affiliate for acquisition and development of coal reserves in our consolidated statements of cash flow. Capital expenditures shown above exclude the Hamilton Acquisition on July 31, 2015, the Patriot acquisition on February 3, 2015, the MAC acquisition on January 1, 2015 and purchase of coal supply agreements from Patriot on December 31, 2014 (Note 3 - Acquisitions).

[7] The elimination column represents the elimination of intercompany transactions and is primarily comprised of sales from the Matrix Group and MAC to the ARLP Partnership’s mining operations, coal sales and purchases between operations within different segments, sales of receivables to AROP Funding and insurance premiums paid to Wildcat Insurance (2015 and 2014 only).