FAIR VALUE MEASUREMENTS (Change in Fair Value at Level 3) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Change in Fair Value Measurement Categorized in Level 3 [Roll Forward]
Transfers into Level 3			$ 0	$ 0
Commodity Contract [Member]
Change in Fair Value Measurement Categorized in Level 3 [Roll Forward]
Balance at beginning of period	$ 1,915,000	$ 9,678,000	3,543,000	1,521,000
Purchases	0	0	0	0
Settlements	(746,000)	(10,111,000)	(1,003,000)	(11,311,000)
Unrealized loss included in earnings	(676,000)	2,338,000	(2,047,000)	11,695,000
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance at end of period	$ 493,000	$ 1,905,000	$ 493,000	$ 1,905,000