SUPPLEMENTAL INFORMATION ON OIL AND NATURAL GAS OPERATIONS - UNAUDITED - Summary of Standardized Measure of Discounted Future Net Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Extractive Industries [Abstract]
Future cash inflows				$ 1,236,097	$ 1,921,329	$ 6,635,751
Future production costs				(480,815)	(651,396)	(2,413,004)
Future development costs				(638,988)	(679,355)	(1,511,687)
Future income taxes				0	0	(609,516)
Future net cash flows				116,294	590,578	2,101,544
10% annual discount				109,628	13,259	(682,752)
Standardized measure of discounted future net cash flows	$ 603,837	$ 1,418,792	$ 1,685,002	$ 225,922	$ 603,837	$ 1,418,792
Increase (Decrease) in Standardized Measure of Discounted Future Net Cash Flow Relating to Proved Oil and Gas Reserves [Roll Forward]
Standardized measure at beginning of year	603,837	1,418,792	1,685,002
Sales and transfers of oil, natural gas and NGLs produced, net of production costs	(223,948)	(340,477)	(486,232)
Changes in price, net of future production costs	(448,861)	(237,747)	(864,118)
Extensions and discoveries, net of future production and development costs	5,243	1,573	549,649
Changes in estimated future development costs, net of development costs incurred during the period	54,406	731,115	203,026
Revisions of quantity estimates	139,759	(1,458,652)	(27,495)
Accretion of discount	60,384	174,456	222,009
Net change in income taxes	0	325,768	209,323
Purchases of reserves in-place	0	3,493	0
Sales of reserves in-place	0	0	(152,787)
Changes in production rates due to timing and other	35,102	(14,484)	80,415
Net decrease in standardized measure	(377,915)	(814,955)	(266,210)
Standardized measure at end of year	$ 225,922	$ 603,837	$ 1,418,792