SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 3) (USD $)	3 Months Ended	12 Months Ended		12 Months Ended
	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2013 Plant and equipment assets, other than preparation plants and processing facilities Minimum	Dec. 31, 2013 Plant and equipment assets, other than preparation plants and processing facilities Maximum	Dec. 31, 2013 Mining Equipment Minimum	Dec. 31, 2013 Mining Equipment Maximum	Dec. 31, 2013 Buildings, Office Equipment And Improvements Minimum	Dec. 31, 2013 Buildings, Office Equipment And Improvements Maximum	Dec. 31, 2013 Land And Mineral Rights Minimum	Dec. 31, 2013 Land And Mineral Rights Maximum
Property, Plant and Equipment
Estimated useful life				1 year	20 years	1 year	20 years	2 years	20 years	2 years	20 years
Coal reserves not subject to depletion		$ 118,200,000	$ 45,500,000
Mine development costs
Capitalized mine development costs		32,600,000	33,100,000
Long lived assets
Asset impairment charge related to ARLP partnership	$ 19,000,000	$ 19,031,000