WHITE OAK TRANSACTIONS (Details) (White Oak, USD $)	0 Months Ended	2 Months Ended	12 Months Ended		15 Months Ended	27 Months Ended	0 Months Ended			12 Months Ended	15 Months Ended	12 Months Ended	0 Months Ended	12 Months Ended				0 Months Ended
	Sep. 22, 2011	Feb. 28, 2014	Dec. 31, 2013 item Person	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2013 Person	Sep. 22, 2011 Minimum	Sep. 22, 2011 Maximum	Sep. 22, 2011 Reserve Acquisition	Dec. 31, 2013 Reserve Acquisition	Dec. 31, 2012 Reserve Acquisition	Dec. 31, 2013 Reserve Acquisition Forecast	Sep. 22, 2011 Reserve Acquisition, rights purchased on Transaction Date T	Dec. 31, 2013 Reserve Acquisition, rights purchased on Transaction Date T	Dec. 31, 2013 Reserve Acquisition, rights purchased during fiscal year 2013 T	Dec. 31, 2013 Services Agreement T	Dec. 31, 2012 Services Agreement	Jun. 18, 2012 Equipment Financing Commitment	Sep. 22, 2011 Equipment Financing Commitment
White oak transactions
Amount funded by partnership	$ 69,500,000					$ 216,700,000
Total expected funding by partnership							300,500,000	425,500,000
Coal reserves, rights purchased (in tons)													204,900,000		90,100,000
Coal reserves developed for future mining (in tons)														105,200,000	45,900,000
Payment for acquisition of coal reserves and other assets									33,800,000	25,300,000
Payment for development of acquired coal reserves											51,600,000
Commitment for additional coal reserve acquisitions										29,300,000
Minimum monthly royalties receivable												1,625,000
Purchase of equity investment	35,700,000	23,000,000	62,500,000		66,800,000
Remaining equity investment commitment							114,300,000
Equity investment commitment							150,000,000	275,000,000
Additional equity investment commitment								125,000,000
Number of ARLP representatives on White Oak board of directors			2			2
Total number of White Oak directors			5			5
Equity method investment, net			165,000,000			165,000,000
Percentage of distributions which Series A Units are entitled to receive			100.00%
Potential ownership interest (as a percent)							20.00%	40.00%
Percentage of distributions which the partnership is entitled to receive							20.00%
Voting Interest(as a percent)			21.60%	14.60%	14.60%	21.60%
Number of primary activities that impact economic performance			4
Distributions from White Oak						0
Allocated losses			25,300,000	15,300,000
Throughput fee up to minimum throughput quantity (in dollars per ton)																5.00
Throughput fee beyond minimum throughput quantity (in dollars per ton)																2.40
Minimum throughput quantity of feedstock coal, per month																666,667
Throughput fees																2,100,000
Additional commitment for construction loan																10,500,000
Term of construction loan																20 years
Construction Loan utilized																10,500,000	3,000,000
Equipment financing commitment																			100,000,000
Term of equipment financing commitment loan years																			5 years
Repayment of prior advances on equipment financing commitment loan																		2,200,000
Cancellation fee																		$ 2,000,000