Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Advances to suppliers for crude oil purchases	$ 38,300	$ 36,247
Collateral posted with broker for derivative instruments	2,714	20,926
Prepaid insurance	7,504	6,773
Derivative assets	161	4,577
Other	4,701	6,914
Total	$ 53,380	$ 75,437