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ASSET RETIREMENT OBLIGATIONS (Reconciliations Of Asset Retirement Obligations) (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2015
Jun. 30, 2014
Jun. 30, 2015
Jun. 30, 2014
Asset Retirement Obligations        
Balance at beginning of period $ 238,689 $ 225,831 $ 226,565 $ 228,234
Liabilities incurred 4,339 0 6,159 0
Liabilities settled (1,270) (7,593) (8,000) (12,843)
Accretion expense 2,936 2,913 5,787 5,852
Revisions up (down), net (9,775) 3,966 4,408 3,874
Balance at end of period $ 234,919 $ 225,117 $ 234,919 $ 225,117