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Ceiling Test Write-down (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2016
USD ($)
$ / mcf
$ / bbl
$ / Mcfe
Dec. 31, 2015
USD ($)
$ / mcf
$ / bbl
$ / Mcfe
Dec. 31, 2014
USD ($)
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]      
Ceiling test write-down $ 40,304 $ 266,562 $ 0
Mcf of natural gas      
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]      
Average sales prices (usd per unit) | $ / mcf 2.51 2.42  
Barrel of oil      
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]      
Average sales prices (usd per unit) | $ / bbl 40.85 50.29  
Natural Gas Liquids      
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]      
Average sales prices (usd per unit) | $ / Mcfe 1.82 2.21  
Cash Flow Hedging | Commodity Contract      
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]      
Ceiling test write-downs decrease   $ 1,100