Fair Value Measurements - Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Mar. 23, 2018	Dec. 31, 2017	Dec. 31, 2016	Jul. 14, 2016
Goodwill	$ 153,397		$ 107,187	$ 105,732
Northwest Retail
Net working capital		$ 3,822
Property, plant and equipment		30,230
Goodwill		46,210
Long-term capital lease obligations		(5,244)
Other non-current liabilities		(487)
Total		$ 74,531
Wyoming Refining Company
Net working capital					$ (11,092)
Property, plant and equipment					254,367
Goodwill					66,449
Long-term debt					(68,136)
Other non-current liabilities					(32,222)
Total					$ 209,366