SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Asset Retirement Obligations) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Asset Retirement Obligation, Roll Forward Analysis
Asset retirement obligations at beginning of period	$ 58,585	$ 78,938
Accretion expense	2,982	6,663	6,082
Liabilities incurred	2,362	1,412
Liabilities settled	(2,726)	(5,650)
Disposition of properties	(42,082)	(27,418)
Revisions of estimated liabilities	6,234	4,640
Asset retirement obligations at end of period	25,355	58,585	78,938
Less: current asset retirement obligations	(2,726)	(2,430)
Long-term asset retirement obligations	$ 22,629	$ 56,155