Commitments and Contingencies (Details)		6 Months Ended	35 Months Ended
	Mar. 23, 2015	Jun. 30, 2019 USD ($) claim	Jun. 30, 2019 USD ($) claim
Long-term Purchase Commitment [Line Items]
Site contingency, recovery from third party of environmental remediation cost			$ 12,200,000
Number of remaining claim to be resolved | claim		2	2
Bankruptcy claims amount of claims to be settled		$ 22,400,000	$ 22,400,000
Estimated value of claims remaining to be settled		500,000	500,000
Maximum bankruptcy claims remaining		$ 22,400,000	$ 22,400,000
Predecessor working ownership percentage		3.40%	3.40%
Allowed claims, settlement ratio		0.0544
Wyoming Refinery One
Long-term Purchase Commitment [Line Items]
Environmental remediation accrual		$ 17,000,000	$ 17,000,000
Environmental costs recognized, period for recognition of one third costs		5 years
Environmental costs recognized, remainder, period for recognition		30 years
Wyoming Refinery Two | Waste Water Treatment System
Long-term Purchase Commitment [Line Items]
Environmental remediation accrual		$ 11,600,000	11,600,000
Wyoming Refinery
Long-term Purchase Commitment [Line Items]
Loss contingency, range of possible loss		100,000	100,000
United Steelworkers Union
Long-term Purchase Commitment [Line Items]
Collective bargaining arrangement, extension term	4 years
Tesoro Corporation | Indemnification Agreement
Long-term Purchase Commitment [Line Items]
Deductible for indemnification obligation		1,000,000	1,000,000
Indemnification obligation cap		$ 15,000,000	$ 15,000,000