Fair Value Measurements (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Liabilities
Cash collateral	$ 109.9		$ 10.0
Fair Value, Measurements, Recurring
Assets
Total assets	504.6		180.5
Liabilities
Total liabilities	(1,060.5)		(795.2)
Net liabilities	(555.9)		(614.7)
Fair Value, Measurements, Recurring | OTC commodity swaps
Assets
Total assets	474.4		178.0
Liabilities
Total liabilities	(570.9)		(203.9)
Fair Value, Measurements, Recurring | Commodities Investment
Assets
Total assets	18.1
Fair Value, Measurements, Recurring | RIN commitment contracts
Assets
Total assets	8.0		1.4
Liabilities
Total liabilities	(12.0)		(24.0)
Fair Value, Measurements, Recurring | RINs Obligation
Assets
Total assets	4.1		1.1
Liabilities
Total liabilities	(6.4)		(130.8)
Fair Value, Measurements, Recurring | Interest rate derivatives
Liabilities
Total liabilities			(0.9)
Fair Value, Measurements, Recurring | J. Aron step-out liability
Liabilities
Total liabilities	(471.2)		(435.6)
Fair Value, Measurements, Recurring | Level 1
Assets
Total assets	18.1		0.0
Liabilities
Total liabilities	0.0		0.0
Net liabilities	18.1		0.0
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
Investment in Physical Commodities	18.1
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		0.0
Liabilities
Total liabilities	0.0		0.0
Fair Value, Measurements, Recurring | Level 1 | Interest rate derivatives
Liabilities
Total liabilities			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	486.5		180.5
Liabilities
Total liabilities	(1,060.5)		(795.2)
Net liabilities	(574.0)		(614.7)
Fair Value, Measurements, Recurring | Level 2 | OTC commodity swaps
Assets
Total assets	474.4		178.0
Liabilities
Total liabilities	(570.9)		(203.9)
Fair Value, Measurements, Recurring | Level 2 | Commodities Investment
Assets
Total assets	0.0
Fair Value, Measurements, Recurring | Level 2 | RIN commitment contracts
Assets
Total assets	8.0		1.4
Liabilities
Total liabilities	(12.0)		(24.0)
Fair Value, Measurements, Recurring | Level 2 | RINs Obligation
Assets
Total assets			1.1
Liabilities
Total liabilities	(6.4)		(130.8)
Fair Value, Measurements, Recurring | Level 2 | Interest rate derivatives
Liabilities
Total liabilities			(0.9)
Fair Value, Measurements, Recurring | Level 2 | J. Aron step-out liability
Liabilities
Total liabilities	(471.2)		(435.6)
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
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		0.0
Liabilities
Total liabilities	0.0		0.0
Fair Value, Measurements, Recurring | Level 3 | Interest rate derivatives
Liabilities
Total liabilities			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	$ 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
Other current assets
Assets
Investment in Physical Commodities	18.1		$ 0.0
Other current assets | Fair Value, Measurements, Recurring | Level 2 | RINs Obligation
Assets
Total assets	$ 4.1