SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended											12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011		Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)
Revenues	$ 549,318	[1]	$ 511,348	[2]	$ 529,772	$ 443,492	$ 474,519	[1],[3]	$ 487,657	$ 457,855	$ 423,172	$ 2,033,930	$ 1,843,203	$ 1,609,743
Income from operations	106,184	[1]	68,561	[2]	103,886	91,501	89,106	[1],[3]	111,688	106,284	102,830	370,132	409,908	348,050
Net income	96,126	[1]	58,733	[2]	93,881	82,486	90,949	[1],[3]	103,667	97,286	94,441	331,226	386,343	317,301
Net income of AHGP	$ 52,895	[1]	$ 39,495	[2]	$ 54,364	$ 49,314	$ 52,116	[1],[3]	$ 57,108	$ 53,412	$ 51,507	$ 196,068	$ 214,143	$ 174,344
Basic and diluted net income per limited partner unit (in dollars per share)	$ 0.88	[1]	$ 0.66	[2]	$ 0.91	$ 0.82	$ 0.87	[1],[3]	$ 0.95	$ 0.89	$ 0.86	$ 3.28	$ 3.58	$ 2.91
Weighted average number of units outstanding - basic and diluted (in shares)	59,863,000	[1]	59,863,000	[2]	59,863,000	59,863,000	59,863,000	[1],[3]	59,863,000	59,863,000	59,863,000	59,863,000	59,863,000	59,863,000

[1] The comparability of our December 31, 2012 and 2011 quarterly results were affected by a $14.0 million and $13.6 million, respectively, decrease in the ARLP Partnership's workers' compensation liability, excluding discount rate changes, due to the completion of its annual actuarial study, which reflected a favorable development in the ARLP Partnership's disability emergence patterns and claims estimates, as well as improved visibility of the Mettiki (WV) claims experience.

[2] During the quarter ended September 30, 2012, the ARLP Partnership recorded a $19.0 million impairment of the carrying value of assets at the Pontiki mine (Note 5).

[3] During the quarter ended December 31, 2011, the ARLP Partnership corrected the interest rate used to account for capitalized interest to utilize the Partnership's overall borrowing rate. This correction resulted in a $10.0 million increase in property, plant and equipment (net of $1.2 million of related depreciation, depletion and amortization) and an $11.2 million offsetting decrease to interest expense ($9.4 million of which was related to prior years). Management concluded the effect of the correction was not material to prior periods, 2011 results or the trend of earnings.