FAIR VALUE MEASUREMENTS (Change in Fair Value at Level 3) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Transfers into Level 3	$ 0	$ 0
Commodity Contract [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	1,521,000	(23,365,000)
Purchases	0	0
Settlements	(15,222,000)	(22,055,000)
Unrealized loss included in earnings	17,244,000	46,941,000
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at end of period	$ 3,543,000	$ 1,521,000