SUPPLEMENTAL CASH FLOW INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Paid For:
Interest		$ 30,438	$ 34,005	$ 35,362
Income taxes		21
Non-Cash Activity:
Accounts payable for purchase of property, plant and equipment		12,634	15,654	17,924
Assets acquired by capital lease		99,543
Market value of ARLP common units vested in ARLP's Long-Term Incentive Plan and Directors Deferred Compensation Plans before minimum statutory tax withholding requirements		7,389	8,417	8,583
Acquisition of business:
Fair value of assets assumed, net of cash acquired		519,384
Contingent consideration		(20,907)
Settlement of pre-existing relationships		(124,379)
Previously held equity-method investment		(122,764)
Cash paid, net of cash acquired		(74,953)
Fair value of liabilities assumed		176,381
Disposition of property, plant and equipment:
Gain recognized		$ (1)	(4,409)	$ 3,475
Other and Corporate | Pontiki mining complex
Disposition of property, plant and equipment:
Net change in assets			846
Book value of liabilities transferred			(5,246)
Gain recognized	$ (4,400)		$ (4,400)