DEFERRED REVENUE (Narrative) (Details) (USD $)	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2012 T	Mar. 31, 2014 agreement T	Dec. 31, 2013 T	Dec. 31, 2013 Maximum T	Dec. 31, 2012 Maximum T	Mar. 31, 2015 Scenario, Forecast [Member] Minimum	Mar. 31, 2015 Scenario, Forecast [Member] Maximum
Deferred Revenue Arrangement [Line Items]
Number of volumetric production payment transactions		2
Proceeds from sale of future production, net of transaction costs (Note 19)	$ 73,644,000		$ 153,282,000
Volumetric production payment termination date	Dec. 31, 2052		Sep. 30, 2051
Tons subject to volumetric production payment				250,800,000	143,200,000
Volumetric production payment estimated percentage sold	10.50%		11.50%
Volumetric production payment estimated tons to be delivered	15,000,000		29,000,000
Estimated deferred revenue to be recognized in the next 12 months						$ 4,600,000	$ 5,600,000