Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Advances to suppliers for crude oil purchases	$ 0	$ 38,300
Collateral posted with broker for derivative instruments	4,005	2,714
Prepaid insurance	2,608	7,504
Derivative assets	630	161
Other	6,326	4,701
Total	$ 13,569	$ 53,380