Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments - Fair value gains (losses) (Details)

v3.10.0.1
Derivative Instruments - Fair value gains (losses) (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2018
Dec. 31, 2017
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Summary of realized and unrealized gains (losses) on derivative instruments          
Commodity derivative fair value gains $ 55,336   $ 85,641 $ 77,773 $ 524,416
Gains on settled marketing derivatives       94,158  
Marketing derivative gains (losses) (110) $ (21,400)   94,124  
Revenue          
Summary of realized and unrealized gains (losses) on derivative instruments          
Commodity derivative fair value gains 55,336   $ 85,641 77,773 $ 524,416
Marketing derivative gains (losses) $ (110)     $ 94,124