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ASSET RETIREMENT OBLIGATIONS (Reconciliations Of Asset Retirement Obligations) (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Asset Retirement Obligations    
Balance at beginning of period $ 226,565us-gaap_AssetRetirementObligation $ 228,234us-gaap_AssetRetirementObligation
Liabilities incurred 1,820us-gaap_AssetRetirementObligationLiabilitiesIncurred 0us-gaap_AssetRetirementObligationLiabilitiesIncurred
Liabilities settled (6,730)us-gaap_AssetRetirementObligationLiabilitiesSettled (5,250)us-gaap_AssetRetirementObligationLiabilitiesSettled
Accretion expense 2,851us-gaap_AssetRetirementObligationAccretionExpense 2,940us-gaap_AssetRetirementObligationAccretionExpense
Revisions up (down), net 14,183us-gaap_AssetRetirementObligationRevisionOfEstimate (93)us-gaap_AssetRetirementObligationRevisionOfEstimate
Balance at end of period $ 238,689us-gaap_AssetRetirementObligation $ 225,831us-gaap_AssetRetirementObligation