DISTRIBUTIONS OF AVAILABLE CASH (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended												12 Months Ended
	Jan. 26, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2015	Jun. 16, 2014
Distribution Made to Member or Limited Partner
Percentage of available cash distributed														100.00%
Period following quarter end for distribution of available cash														50 days
Quarterly distribution paid (in dollars per share)		$ 0.9600	$ 0.9600	$ 0.9375	$ 0.9150	$ 0.8925	$ 0.8700	$ 0.8475	$ 0.8275	$ 0.8075	$ 0.7850	$ 0.7625	$ 0.7400
Distributions declared (in dollars per unit)	$ 0.96
Approximate distribution to be paid (in dollars)	$ 57.5
ARLP
Distribution Made to Member or Limited Partner
Units owned by parent		31,088,338												31,088,338	31,088,338
Subsidiaries general partner interest percentage														1.98%
Common units percentage														42.00%
MGP
Distribution Made to Member or Limited Partner
Subsidiaries holding percentage														100.00%
Alliance Coal
Distribution Made to Member or Limited Partner
Subsidiaries holding percentage														0.001%