ASSET RETIREMENT OBLIGATIONS - Components of Changes in ARO (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance of ARO, beginning	$ 89,990	$ 94,060	$ 108,533
Liabilities incurred	230	981	2,266
Liabilities settled	(758)	(686)	(1,543)
Accretion expense	6,672	7,108	7,859
Revision in estimated cash flows	(12,875)		(692)
Reclassification associated with held for sale properties	(1,715)	(11,473)	(23,747)
Balance of ARO, end	$ 81,544	$ 89,990	94,060
Accretion expense of discontinued operations			$ 251