Derivative Instruments - Derivative Assets and Liabilities (Details) $ in Millions		6 Months Ended
		Jun. 30, 2018 USD ($) bbl rins	Dec. 31, 2017 USD ($) bbl rins
Derivatives, Fair Value [Line Items]
Assets		$ 482.4	$ 179.4
Liabilities		(582.9)	(228.8)
Counterparty netting and cash collateral, Assets	[1]	441.8	163.5
Counterparty netting and cash collateral, Liabilities	[1]	(551.6)	(173.6)
Total net fair value of derivative assets		40.6	15.9
Total net fair value of derivative liabilities		(31.3)	(55.2)
Footnote [Abstract]
Cash collateral		$ 109.9	$ 10.0
OTC commodity swaps
Derivatives, Fair Value [Line Items]
Maturity period for derivatives generally used to achieve objectives (or less)		3 years
Footnote [Abstract]
Derivative open contract | bbl		108,416,649	35,978,000
RIN commitment contracts
Footnote [Abstract]
Derivative open contract | rins		117,375,000	163,361,320
Derivatives not designated as hedging instruments: | OTC commodity swaps | Other current assets
Derivatives, Fair Value [Line Items]
Assets	[2]	$ 402.2	$ 164.6
Liabilities	[2]	(425.6)	(162.0)
Derivatives not designated as hedging instruments: | OTC commodity swaps | Other current liabilities
Derivatives, Fair Value [Line Items]
Assets	[2]	13.1	13.4
Liabilities	[2]	27.8	(28.3)
Derivatives not designated as hedging instruments: | OTC commodity swaps | Other long-term assets
Derivatives, Fair Value [Line Items]
Assets	[2]	24.2	0.0
Liabilities	[2]	(26.1)	0.0
Derivatives not designated as hedging instruments: | OTC commodity swaps | Other long-term liabilities
Derivatives, Fair Value [Line Items]
Assets	[2]	0.1	0.0
Liabilities	[2]	(0.3)	0.0
Derivatives not designated as hedging instruments: | RIN commitment contracts | Other current assets
Derivatives, Fair Value [Line Items]
Assets	[3]	8.0	1.4
Liabilities	[3]	0.0	0.0
Derivatives not designated as hedging instruments: | RIN commitment contracts | Other current liabilities
Derivatives, Fair Value [Line Items]
Assets	[3]	0.0	0.0
Liabilities	[3]	$ (12.0)	$ (24.0)
Derivatives designated as hedging instruments: | OTC commodity swaps
Footnote [Abstract]
Derivative open contract | bbl		15,547,000	575,000
Derivatives designated as hedging instruments: | OTC commodity swaps | Other current assets
Derivatives, Fair Value [Line Items]
Assets	[2]	$ 18.7	$ 0.0
Liabilities	[2]	(72.8)	0.0
Derivatives designated as hedging instruments: | OTC commodity swaps | Other current liabilities
Derivatives, Fair Value [Line Items]
Assets	[2]	0.1	0.0
Liabilities	[2]	(4.9)	(13.6)
Derivatives designated as hedging instruments: | OTC commodity swaps | Other long-term assets
Derivatives, Fair Value [Line Items]
Assets	[2]	16.0	0.0
Liabilities	[2]	(13.4)	0.0
Derivatives designated as hedging instruments: | Interest rate derivatives | Other long-term liabilities
Derivatives, Fair Value [Line Items]
Assets		0.0	0.0
Liabilities		$ 0.0	$ (0.9)
Alon Retail Credit Facilities | Term loan
Derivatives, Fair Value [Line Items]
Percent of outstanding principal, coverage by derivative		77.00%

[1] As of June 30, 2018 and December 31, 2017, $109.9 million and $10.0 million, respectively, of cash collateral held by counterparties has been netted with the derivatives with each counterparty.

[2] As of June 30, 2018 and December 31, 2017, we had open derivative positions representing 108,416,649 and 35,978,000 barrels, respectively, of crude oil and refined petroleum products. Of these open positions, contracts representing 15,547,000 and 575,000 barrels were designated as cash flow hedging instruments as of June 30, 2018 and December 31, 2017, respectively.

[3] As of June 30, 2018 and December 31, 2017, we had open RIN commitment contracts representing 117,375,000 and 163,361,320 RINs, respectively.