XML 73 R53.htm IDEA: XBRL DOCUMENT v3.8.0.1
Asset Retirement Obligation (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Changes to the Company's asset retirement obligation liability    
Asset retirement obligation, beginning of period $ 36,610 $ 42,556
Liabilities incurred 574 0
Liabilities settled (3,364) (3,296)
Accretion expense 2,252 2,515
Revisions in estimated cash flows (4,514) (1,746)
Divestiture of oil and gas properties (248) (3,419)
Asset retirement obligation, end of period 31,310 36,610
Less: current portion of asset retirement obligation (687) (4,160)
Long-term asset retirement obligation $ 30,623 32,450
Oklahoma Assets    
Changes to the Company's asset retirement obligation liability    
Divestiture of oil and gas properties   $ (3,300)