Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Advances to suppliers for crude oil purchases	$ 7,793	$ 38,300
Collateral posted with broker for derivative instruments	3,190	2,714
Prepaid insurance	5,088	7,504
Derivative assets	3,437	161
Other	5,138	4,701
Total	$ 24,646	$ 53,380