Fair Value Measurements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018		Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net income (loss)	$ 154.4	$ (25.5)	[1]
Unrealized gain (loss) on commodity contracts	(1.0)
Liabilities
Cash collateral	21.4			$ (0.4)
Fair Value, Measurements, Recurring
Assets
Total assets	222.8			477.6
Liabilities
Total liabilities	(577.1)			(789.7)
Net liabilities	(354.3)			(312.1)
Fair Value, Measurements, Recurring | OTC commodity swaps
Assets
Total assets	213.4			459.8
Liabilities
Total liabilities	(174.4)			(409.0)
Fair Value, Measurements, Recurring | Commodities Investment
Assets
Total assets	5.4			15.8
Fair Value, Measurements, Recurring | RIN commitment contracts
Assets
Total assets	4.0			2.0
Liabilities
Total liabilities	(6.4)			(6.7)
Fair Value, Measurements, Recurring | RINs Obligation
Assets
Total assets				0.0
Liabilities
Total liabilities	(11.5)			(11.8)
Fair Value, Measurements, Recurring | J. Aron step-out liability
Liabilities
Total liabilities	(384.8)			(362.2)
Fair Value, Measurements, Recurring | Level 1
Assets
Total assets	5.4			15.8
Liabilities
Total liabilities	0.0			0.0
Net liabilities	5.4			15.8
Fair Value, Measurements, Recurring | Level 1 | OTC commodity swaps
Assets
Total assets	0.0			0.0
Liabilities
Total liabilities	0.0			0.0
Fair Value, Measurements, Recurring | Level 1 | Commodities Investment
Assets
Total assets	5.4			15.8
Fair Value, Measurements, Recurring | Level 1 | RIN commitment contracts
Assets
Total assets	0.0			0.0
Liabilities
Total liabilities	0.0			0.0
Fair Value, Measurements, Recurring | Level 1 | RINs Obligation
Assets
Total assets				0.0
Liabilities
Total liabilities	0.0			0.0
Fair Value, Measurements, Recurring | Level 1 | J. Aron step-out liability
Liabilities
Total liabilities	0.0			0.0
Fair Value, Measurements, Recurring | Level 2
Assets
Total assets	217.4			461.8
Liabilities
Total liabilities	(577.1)			(789.7)
Net liabilities	(359.7)			(327.9)
Fair Value, Measurements, Recurring | Level 2 | OTC commodity swaps
Assets
Total assets	213.4			459.8
Liabilities
Total liabilities	(174.4)			(409.0)
Fair Value, Measurements, Recurring | Level 2 | Commodities Investment
Assets
Total assets	0.0			0.0
Fair Value, Measurements, Recurring | Level 2 | RIN commitment contracts
Assets
Total assets	4.0			2.0
Liabilities
Total liabilities	(6.4)			(6.7)
Fair Value, Measurements, Recurring | Level 2 | RINs Obligation
Assets
Total assets				0.0
Liabilities
Total liabilities	(11.5)			(11.8)
Fair Value, Measurements, Recurring | Level 2 | J. Aron step-out liability
Liabilities
Total liabilities	384.8			(362.2)
Fair Value, Measurements, Recurring | Level 3
Assets
Total assets	0.0			0.0
Liabilities
Total liabilities	0.0			0.0
Net liabilities	0.0			0.0
Fair Value, Measurements, Recurring | Level 3 | OTC commodity swaps
Assets
Total assets	0.0			0.0
Liabilities
Total liabilities	0.0			0.0
Fair Value, Measurements, Recurring | Level 3 | Commodities Investment
Assets
Total assets	0.0			0.0
Fair Value, Measurements, Recurring | Level 3 | RIN commitment contracts
Assets
Total assets	0.0			0.0
Liabilities
Total liabilities	0.0			0.0
Fair Value, Measurements, Recurring | Level 3 | RINs Obligation
Assets
Total assets				0.0
Liabilities
Total liabilities	0.0			0.0
Fair Value, Measurements, Recurring | Level 3 | J. Aron step-out liability
Liabilities
Total 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
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
Other current assets
Assets
Investment in Physical Commodities	$ 5.4			$ 15.6

[1] Income tax benefit for the quarter ended March 31, 2018 reflects a correction made in our 2018 Annual Report on Form 10-K (filed on March 1, 2019) to record additional deferred tax expense totaling $5.5 million related to the recognition of a valuation allowance on deferred tax assets recognized in connection with the Big Spring Logistic Assets Acquisition (see Note 5) not previously reported in our March 31, 2018 Quarterly Report on Form 10-Q filed on May 10, 2018. Such amount is not considered material to the financial statements or the trend of earnings for that period. See Note 23 to our annual audited consolidated financial statements included in Part II, Item 8 of our 2018 Annual Report on Form 10-K filed on March 1, 2019 for further discussion.