Crude Oil Supply and Inventory Purchase Agreement (Details) bbl in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) bbl / pure bbl	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) bbl
El Dorado Refinery
Oil and Gas Delivery Commitments and Contracts [Line Items]
(Payable) receivable recorded related to monthly settlement	$ 15.8		$ 7.8
El Dorado Refinery | J. Aron
Oil and Gas Delivery Commitments and Contracts [Line Items]
Barrels of inventory consigned to J Aron | bbl	3.5		2.8
Liabilities recorded associated with consigned inventory	$ 190.9		$ 152.6
Letters of credit outstanding	150.0		120.0
El Dorado Refinery | J. Aron | Interest expense
Oil and Gas Delivery Commitments and Contracts [Line Items]
Inventory financing expense	$ 2.4	$ 2.7
El Dorado Refinery | J. Aron
Oil and Gas Delivery Commitments and Contracts [Line Items]
Maximum barrels per day supplied under Supply and Offtake Agreement (bpd)	100,000
Alon Refinery | J. Aron
Oil and Gas Delivery Commitments and Contracts [Line Items]
Letters of credit outstanding	$ 44.0		$ 24.0
Alon Refinery | J. Aron | Interest expense
Oil and Gas Delivery Commitments and Contracts [Line Items]
Inventory financing expense	3.7	$ 3.4
Krotz Spring Refinery | J. Aron
Oil and Gas Delivery Commitments and Contracts [Line Items]
Gain on change in fair value resulting from modification of instruments	3.5
Fees incurred, charged to interest expense	1.8
Change in fair value of nonderivative instrument	$ (1.1)
Barrels of inventory consigned to J Aron | bbl	1.4		1.8
Liabilities recorded associated with consigned inventory	$ 102.4		$ 113.1
Big Spring refinery
Oil and Gas Delivery Commitments and Contracts [Line Items]
Purchase settlement payable	$ 17.2		$ (1.0)
Big Spring refinery | J. Aron
Oil and Gas Delivery Commitments and Contracts [Line Items]
Barrels of inventory consigned to J Aron | bbl	1.5		1.7
Liabilities recorded associated with consigned inventory	$ 91.5		$ 96.5
Big Spring refinery | J. Aron
Oil and Gas Delivery Commitments and Contracts [Line Items]
Period of prior notice required to terminate Supply and Offtake Agreement	6 months
Baseline Step-Out Liability | J. Aron
Oil and Gas Delivery Commitments and Contracts [Line Items]
Change in fair value of nonderivative instrument	$ (2.5)
Baseline Step-Out Liability | El Dorado Refinery | J. Aron
Oil and Gas Delivery Commitments and Contracts [Line Items]
Gain on change in fair value resulting from modification of instruments	4.1
Fees incurred, charged to interest expense	$ 3.2
Barrels of inventory consigned to J Aron | bbl	2.0
Fair value of nonderivative instruments	$ (103.6)
Baseline Step-Out Liability | Krotz Spring Refinery | J. Aron
Oil and Gas Delivery Commitments and Contracts [Line Items]
Barrels of inventory consigned to J Aron | bbl	1.3
Fair value of nonderivative instruments	$ (74.2)
Baseline Step-Out Liability | Big Spring refinery | J. Aron
Oil and Gas Delivery Commitments and Contracts [Line Items]
Change in fair value of nonderivative instrument	$ (1.5)
Barrels of inventory consigned to J Aron | bbl	0.8
Fair value of nonderivative instruments	$ (48.1)		$ (49.6)