RELATED-PARTY TRANSACTIONS (Details) (USD $)	12 Months Ended			12 Months Ended	1 Months Ended			12 Months Ended			1 Months Ended	12 Months Ended					12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Jun. 30, 2007	Dec. 31, 2012 Other credit agreements bank	Dec. 31, 2012 ARLP	Dec. 31, 2011 ARLP	Dec. 31, 2012 SGP Other credit agreements	Dec. 31, 2012 SGP Tunnel Ridge	Dec. 31, 2011 SGP Tunnel Ridge	Dec. 31, 2010 SGP Tunnel Ridge T	Jan. 31, 2011 SGP Gibson County Coal	Dec. 31, 2012 SGP Gibson County Coal	Dec. 31, 2011 SGP Gibson County Coal	Dec. 31, 2010 SGP Gibson County Coal	Dec. 31, 2012 SGP ARLP	Mar. 01, 2012 SGP Land, LLC Airplanes item	Dec. 31, 2012 SGP Land, LLC MC Mining LLC	Dec. 31, 2011 SGP Land, LLC MC Mining LLC	Dec. 31, 2010 SGP Land, LLC MC Mining LLC	Dec. 31, 2012 SGP Land, LLC ARLP	Dec. 31, 2011 SGP Land, LLC ARLP	Dec. 31, 2010 SGP Land, LLC ARLP	Dec. 31, 2012 AGP	Dec. 31, 2011 AGP	Dec. 31, 2010 AGP	Dec. 31, 2012 ARH II	Dec. 31, 2011 ARH II	Dec. 31, 2010 ARH II	Dec. 31, 2012 JC Land ARLP
Related Party Transaction
Outstanding common units			47,863,000
Direct and indirect expenses																							$ 400,000	$ 400,000	$ 700,000
Revenue from administrative services																										100,000	200,000	200,000
Contributions from affiliates for general and administrative expenses	2,000,000	5,000,000			2,000,000	5,000,000
Number of airplanes acquired in merger																2
Number of airplanes acquired, previously subject to time sharing agreement																1
Cost of airplanes acquired																8,000,000
Annual minimum royalties								3,000,000									300,000
Reimbursement received for use of aircraft															100,000
Reimbursement paid for use of aircraft																				300,000	1,000,000	800,000							100,000
Payments for royalties								3,000,000	3,000,000	3,000,000							400,000	300,000	300,000
Cumulative annual minimum earned royalty																	6,000,000
Advance royalties	34,759,000	35,476,000						20,200,000									2,300,000
Additional clean tons of recoverable coal reserves										34,400,000
Lease payment								200,000
Lease agreement term								4 years
Lease expenses								200,000	200,000	200,000		600,000	800,000	2,600,000
Monthly lease payment											200,000	50,000
Number of banks				2
Letter of credit aggregate amount				31,100,000
Guaranteed outstanding letters of credit							$ 5,000,000