Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized loss on commodity investment	$ 2.0
Cash collateral	(0.4)	$ (10.0)
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	477.6	180.5
Liabilities	(789.7)	(795.2)
Net assets (liabilities)	(312.1)	(614.7)
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	15.8	0.0
Liabilities	0.0	0.0
Net assets (liabilities)	15.8	0.0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	461.8	180.5
Liabilities	(789.7)	(795.2)
Net assets (liabilities)	(327.9)	(614.7)
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0.0	0.0
Liabilities	0.0	0.0
Net assets (liabilities)	0.0	0.0
Fair Value, Measurements, Recurring | Commodity derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	459.8	178.0
Liabilities	(409.0)	(203.9)
Fair Value, Measurements, Recurring | Commodity derivatives | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0.0	0.0
Liabilities	0.0	0.0
Fair Value, Measurements, Recurring | Commodity derivatives | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	459.8	178.0
Liabilities	(409.0)	(203.9)
Fair Value, Measurements, Recurring | Commodity derivatives | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0.0	0.0
Liabilities	0.0	0.0
Fair Value, Measurements, Recurring | Commodity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	15.8
Fair Value, Measurements, Recurring | Commodity investments | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	15.8
Fair Value, Measurements, Recurring | Commodity investments | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0.0
Fair Value, Measurements, Recurring | Commodity investments | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0.0
Fair Value, Measurements, Recurring | RIN Commitment Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	2.0	1.4
Liabilities	(6.7)	(24.0)
Fair Value, Measurements, Recurring | RIN Commitment Contracts | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0.0	0.0
Liabilities	0.0	0.0
Fair Value, Measurements, Recurring | RIN Commitment Contracts | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	2.0	1.4
Liabilities	(6.7)	(24.0)
Fair Value, Measurements, Recurring | RIN Commitment Contracts | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0.0	0.0
Liabilities	0.0	0.0
Fair Value, Measurements, Recurring | Interest rate derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities		(0.9)
Fair Value, Measurements, Recurring | Interest rate derivatives | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities		0.0
Fair Value, Measurements, Recurring | Interest rate derivatives | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities		(0.9)
Fair Value, Measurements, Recurring | Interest rate derivatives | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities		0.0
Fair Value, Measurements, Recurring | RINs Obligation
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		1.1
Liabilities	(11.8)	(130.8)
Fair Value, Measurements, Recurring | RINs Obligation | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		0.0
Liabilities	0.0	0.0
Fair Value, Measurements, Recurring | RINs Obligation | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		1.1
Liabilities	(11.8)	(130.8)
Fair Value, Measurements, Recurring | RINs Obligation | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		0.0
Liabilities	0.0	0.0
Fair Value, Measurements, Recurring | J. Aron Step-out Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	(362.2)	(435.6)
Fair Value, Measurements, Recurring | J. Aron Step-out Liability | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0.0	0.0
Fair Value, Measurements, Recurring | J. Aron Step-out Liability | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	(362.2)	(435.6)
Fair Value, Measurements, Recurring | J. Aron Step-out Liability | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0.0	0.0
El Dorado Refinery
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Decrease in renewable identification numbers obligation and related cost of goods sold	59.3	$ 47.5
Krotz Spring Refinery
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Decrease in renewable identification numbers obligation and related cost of goods sold	$ 31.6