Commitments and Contingencies - Environmental Health and Safety (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended
	Jan. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Other current liabilities
Loss Contingencies [Line Items]
Environmental liabilities, current			$ 7.2
El Dorado refinery prior owner case
Loss Contingencies [Line Items]
Estimated time frame to resolve contingency		P30Y
Accrual for Environmental Loss Contingencies, Including Undiscounted Amounts		$ 143.3
El Dorado refinery prior owner case | Other current liabilities
Loss Contingencies [Line Items]
Environmental liabilities, current		$ 7.6
Alon | Big Spring refinery
Loss Contingencies [Line Items]
Negotiation period		10 years
Required payment estimated upon finalization of the Consent Decree		$ 0.5
Estimated time frame to resolve contingency		P5Y
Payments for Legal Settlements	$ 0.4
Magnolia Station Spill [Member] | Magnolia Station Spill [Member] | Other current liabilities
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies		$ 1.0