Goodwill and Intangible Assets - Schedule of Goodwill (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Balance at beginning of period		$ 107,187	$ 105,732
Balance at end of period		153,397	107,187
Wyoming Refining Company
Goodwill [Roll Forward]
Adjustment to goodwill	$ 1,500		$ 1,455
Northwest Retail
Goodwill [Roll Forward]
Acquisition during period		$ 46,210