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Summary of Significant Accounting Policies - Summary of Changes in Reserve for Future Abandonment Costs (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Asset Retirement Obligations Noncurrent [Abstract]    
Future abandonment costs — beginning of period $ 20,093 $ 14,900
Accretion expense 274 198
New wells placed on production 1 213
Assets held for sale (3,442)  
Liabilities settled and assets disposed of (826)  
Future abandonment costs — end of period $ 16,100 $ 15,311