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ASSET RETIREMENT OBLIGATIONS (Reconciliations Of Asset Retirement Obligations) (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2013
Sep. 30, 2012
Asset Retirement Obligations        
Balance at beginning of period $ 222,851 $ 150,413 $ 150,072 $ 153,979
Liabilities incurred 3,524 82 69,111 127
Liabilities settled (2,328) (822) (8,839) (2,241)
Accretion expense 2,908 1,973 7,731 5,990
Revisions up (down), net 6,606 (2,923) 15,486 (9,132)
Balance at end of period $ 233,561 $ 148,723 $ 233,561 $ 148,723