LONG TERM DEBT - Accounts Receivable Securitization and Hamilton (Details) - USD ($) $ in Thousands				12 Months Ended
	Oct. 29, 2015	Oct. 16, 2015	Jul. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Long-Term Debt
Outstanding balance of debt repaid				$ 205,000	$ 18,000	$ 18,000
ARLP Securitization facility
Long-Term Debt
Revolving credit facility				$ 100,000
ARLP Hamilton Revolving Credit Facility
Long-Term Debt
Revolving credit facility			$ 10,000
Outstanding balance of debt repaid	$ 10,000
ARLP Hamilton Revolving Credit Facility | Prime rate
Long-Term Debt
Basis spread on variable rate (as a percent)			0.10%
ARLP Hamilton Equipment Financing Agreement
Long-Term Debt
Aggregate principal amount			$ 100,000
Frequency of installments			monthly
Amount of equal installments			$ 2,100
Outstanding balance of debt repaid		$ 80,600