Casper Terminal Acquisition - Pro Forma Information (Details) - Casper Crude to Rail, LLC - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Business Acquisition [Line Items]    
Total revenues $ 112,325 $ 44,536
Operating income 30,997 1,682
Net income (loss) $ 21,310 $ (12,043)
Earnings (loss) per common unit (basic) (in dollars per share) $ 0.93 $ (0.52)
Earnings (loss) per common unit (diluted) (in dollars per share) $ 0.93 $ (0.52)