Overview - Additional Information (Detail) mbpd in Thousands	12 Months Ended
	Dec. 31, 2018 mbpd segment gasoline_store_facility refinery	Oct. 18, 2018	Feb. 28, 2018	Mar. 01, 2016	Feb. 29, 2016
Operating segments | segment	3
Number of owned and operated refineries | refinery	3
Oil and gas refinery | mbpd	200
Number of retail outlets	124
Number of branded retail sites	76
Convenience stores, rebranded	24
Convenience store facilities	34
Laramie Energy Company
Ownership of Laramie Energy, LLC	46.00%	46.00%	39.10%	42.30%	32.40%