Commitments and Contingencies (Details 2) bbl in Thousands, $ in Thousands	Dec. 31, 2016 USD ($) bbl
Fixed Price Sales [Member]
Summary Of Purchase And Sale Commitments
Sale commitments, Volume (barrels) | bbl	8,670
Sale commitments, Value | $	$ 453,647
Floating Price Sales [Member]
Summary Of Purchase And Sale Commitments
Sale commitments, Volume (barrels) | bbl	13,573
Sale commitments, Value | $	$ 738,245
Fixed Price Purchases [Member]
Summary Of Purchase And Sale Commitments
Purchase commitments, Volume (barrels) | bbl	2,359
Purchase commitments, Value | $	$ 120,064
Floating Price Purchases [Member]
Summary Of Purchase And Sale Commitments
Purchase commitments, Volume (barrels) | bbl	3,577
Purchase commitments, Value | $	$ 179,237