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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Summary of Changes in Reserve for Future Abandonment Costs (Detail) (USD $)
In Thousands, unless otherwise specified
 6 Months Ended
Jun. 30, 2013
Jun. 30, 2012
Asset Retirement Obligations [Line Items]    
Future abandonment costs – beginning of period $ 16,387 $ 13,997
Accretion expense – continuing operations 494 331
Accretion expense – discontinued operations   19
New wells placed on production – continuing operations 313 503
New wells placed on production– discontinued operations   441
Liabilities settled and assets disposed of – continuing operations (534) (1,077)
Liabilities settled and assets disposed of – discontinued operations   (23)
Liabilities reclassified to discontinued operations   (1,179)
Future abandonment costs – end of period $ 16,660 $ 13,012