Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Advances to suppliers for crude oil purchases	$ 67,808	$ 0
Collateral posted with broker for derivative instruments	1,321	2,759
Prepaid insurance	7,240	7,727
Deferred financing costs	470	0
Derivative assets	1,483	5,164
Other	5,348	12,720
Total	$ 83,670	$ 28,370