XML 91 R65.htm IDEA: XBRL DOCUMENT v3.8.0.1
Acquisitions and Divestitures - Divestitures (Details) - USD ($)
$ in Thousands
12 Months Ended
Apr. 01, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Proceeds from sale of property $ 12,800 $ 5,774 $ 12,333 $ 1,075
Impairment   6,887 4,684 46,109
Proved oil and gas properties        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Impairment   $ 3,600   9,400
Non-operated oil and natural gas properties        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Impairment     $ 3,600 $ 9,400
Secured Promissory Note Due March 2017        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Debt principal amount $ 4,000      
Debt stated interest rate (percent) 10.00%