Derivative Instruments - Fair value gains (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Summary of realized and unrealized gains (losses) on derivative instruments
Commodity derivative fair value gains (losses)	$ (65,957)	$ 530,334	$ 458,459	$ 125,624
Revenue
Summary of realized and unrealized gains (losses) on derivative instruments
Commodity derivative fair value gains (losses)	(65,957)	$ 530,334	458,459	$ 125,624
Commodity derivative fair value gains (losses) on derivatives monetized prior to settlement dates	$ 750,000		$ 750,000