OIL AND NATURAL GAS OPERATIONS (Unaudited) - Capitalized Costs (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Extractive Industries [Abstract]
Proved	$ 7,543,464	$ 7,911,554
Unproved	196,888	150,674
Total capitalized costs	7,740,352	8,062,228
Accumulated depreciation, depletion and amortization	3,723,669	3,673,569
Capitalized costs, net	$ 4,016,683	$ 4,388,659