Crude Oil Supply and Inventory Purchase Agreement - Payable (Receivable) Under Supply and Offtake Agreements (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Oil and Gas, Delivery Commitment [Line Items]
Revolving over/short product financing liability	$ 207.0	$ 46.9
Revolving Step-Out Liability (prior to January 2019 amendments)		265.7
Total Obligations Under Supply and Offtake Agreements	477.3	362.2
Less: Current portion	332.5	312.6
Obligations Under Supply and Offtake Agreements - Noncurrent portion	144.8	49.6
Other receivable for monthly activity true-up (included in current receivables)	(23.0)	(6.8)
Baseline Step-Out Liability
Oil and Gas, Delivery Commitment [Line Items]
Baseline Step-Out Liability	270.3	49.6
El Dorado
Oil and Gas, Delivery Commitment [Line Items]
Revolving over/short product financing liability	93.0	0.0
Revolving Step-Out Liability (prior to January 2019 amendments)		152.6
Total Obligations Under Supply and Offtake Agreements	218.5	152.6
Less: Current portion	218.5	152.6
Obligations Under Supply and Offtake Agreements - Noncurrent portion	0.0	0.0
Other receivable for monthly activity true-up (included in current receivables)	(16.4)	(7.8)
El Dorado | Baseline Step-Out Liability
Oil and Gas, Delivery Commitment [Line Items]
Baseline Step-Out Liability	125.5	0.0
Big Spring
Oil and Gas, Delivery Commitment [Line Items]
Revolving over/short product financing liability	73.5	46.9
Revolving Step-Out Liability (prior to January 2019 amendments)		0.0
Total Obligations Under Supply and Offtake Agreements	130.7	96.5
Less: Current portion	73.5	46.9
Obligations Under Supply and Offtake Agreements - Noncurrent portion	57.2	49.6
Other receivable for monthly activity true-up (included in current receivables)	(3.1)	(0.4)
Big Spring | Baseline Step-Out Liability
Oil and Gas, Delivery Commitment [Line Items]
Baseline Step-Out Liability	57.2	49.6
Krotz Springs
Oil and Gas, Delivery Commitment [Line Items]
Revolving over/short product financing liability	40.5	0.0
Revolving Step-Out Liability (prior to January 2019 amendments)		113.1
Total Obligations Under Supply and Offtake Agreements	128.1	113.1
Less: Current portion	40.5	113.1
Obligations Under Supply and Offtake Agreements - Noncurrent portion	87.6	0.0
Other receivable for monthly activity true-up (included in current receivables)	(3.5)	1.4
Krotz Springs | Baseline Step-Out Liability
Oil and Gas, Delivery Commitment [Line Items]
Baseline Step-Out Liability	$ 87.6	$ 0.0