ASSET RETIREMENT OBLIGATIONS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Asset Retirement Obligations
Balance at beginning of year	$ 173,008	$ 154,026
Liabilities incurred	4,114	13,015
Liability settlements and disposals	(25,061)	(27,036)
Accretion expense	7,682	7,583
Revisions of estimated liabilities	4,362	25,420
Balance at end of year	173,008	154,026	$ 164,105	$ 173,008
Less current obligation			10,248	13,216
Long-term asset retirement obligation			$ 153,857	$ 159,792
Liability settlements and disposals related to properties that were sold	$ 13,300	$ 11,200