ACQUISITIONS (Details 3) (USD $)	3 Months Ended											12 Months Ended						1 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011		Jan. 31, 2011 Green River	Dec. 31, 2012 Green River	Dec. 31, 2012 Green River	Dec. 31, 2011 Green River
Business Acquisition
Total Revenues, As reported	$ 566,615,000	[1]	$ 537,136,000	$ 553,478,000	$ 547,970,000	$ 549,318,000	[1]	$ 511,348,000	[2]	$ 529,772,000	$ 443,492,000	$ 2,205,199,000	[3]	$ 2,033,930,000	[3]	$ 1,843,203,000	[3]
Total revenues, Pro forma																				2,061,273,000	1,957,241,000
Net income, As reported	98,887,000	[1]	86,750,000	103,573,000	102,384,000	96,126,000	[1]	58,733,000	[2]	93,881,000	82,486,000	391,594,000		331,226,000		386,343,000
Net income, Pro forma																				332,507,000	397,717,000
Revenue of acquired business reflected in consolidated statements of income																			81,600,000	81,600,000
Net income of acquired business reflected in consolidated statements of income																			7,600,000	7,600,000
Acquisition costs																		$ 600,000

[1] The comparability of our December 31, 2013 and 2012 quarterly results to other quarters presented were affected by a $12.9 million and $14.0 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 (Note 17).

[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 4).

[3] Revenues included in the Other and Corporate column are primarily attributable to Matrix Group revenues, Mt. Vernon transloading revenues and brokerage sales.