Derivative Instruments - Derivative Assets and Liabilities (Details) $ in Millions		3 Months Ended
		Mar. 31, 2019 USD ($) bbl rins	Dec. 31, 2018 USD ($) bbl rins
Derivatives, Fair Value [Line Items]
Assets		$ 217.4	$ 461.8
Liabilities		(180.8)	(415.7)
Counterparty netting and cash collateral, Assets	[1]	183.0	399.9
Counterparty netting and cash collateral, Liabilities	[1]	(161.6)	(399.5)
Total net fair value of derivative assets		34.4	61.9
Total net fair value of derivative liabilities		(19.2)	(16.2)
Footnote [Abstract]
Cash collateral		$ 21.4	$ (0.4)
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		67,840,734	39,277,822
RIN commitment contracts
Footnote [Abstract]
Derivative open contract | rins		256,025,000	137,750,000
Derivatives not designated as hedging instruments: | OTC commodity swaps | Other current assets
Derivatives, Fair Value [Line Items]
Assets	[2]	$ 100.7	$ 158.3
Liabilities	[2]	(101.9)	(142.4)
Derivatives not designated as hedging instruments: | OTC commodity swaps | Other current liabilities
Derivatives, Fair Value [Line Items]
Assets	[2]	7.4	0.0
Liabilities	[2]	(12.5)	(8.4)
Derivatives not designated as hedging instruments: | OTC commodity swaps | Other long-term assets
Derivatives, Fair Value [Line Items]
Assets	[2]	0.6	2.1
Liabilities	[2]	(0.4)	(2.4)
Derivatives not designated as hedging instruments: | OTC commodity swaps | Other long-term liabilities
Derivatives, Fair Value [Line Items]
Assets	[2]	25.3	93.0
Liabilities	[2]	(30.3)	(94.0)
Derivatives not designated as hedging instruments: | RIN commitment contracts | Other current assets
Derivatives, Fair Value [Line Items]
Assets	[3]	4.0	2.0
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]	$ (6.4)	$ (6.7)
Derivatives designated as hedging instruments: | OTC commodity swaps
Footnote [Abstract]
Derivative open contract | bbl		9,093,000	16,461,000
Derivatives designated as hedging instruments: | OTC commodity swaps | Other current assets
Derivatives, Fair Value [Line Items]
Assets	[2]	$ 76.4	$ 200.3
Liabilities	[2]	(27.2)	(157.0)
Derivatives designated as hedging instruments: | OTC commodity swaps | Other current liabilities
Derivatives, Fair Value [Line Items]
Assets	[2]	0.5	0.0
Liabilities	[2]	(0.3)	0.0
Derivatives designated as hedging instruments: | OTC commodity swaps | Other long-term assets
Derivatives, Fair Value [Line Items]
Assets	[2]	2.5	6.1
Liabilities	[2]	$ (1.8)	$ (4.8)
Alon Retail Credit Facilities | Term loan
Derivatives, Fair Value [Line Items]
Percent of outstanding principal, coverage by derivative		77.00%

[1] As of March 31, 2019 and December 31, 2018, $21.4 million and $0.4 million, respectively, of cash obligation held by counterparties has been netted with the derivatives with each counterparty.

[2] As of March 31, 2019 and December 31, 2018, we had open derivative positions representing 67,840,734 and 39,277,822 barrels, respectively, of crude oil and refined petroleum products. Of these open positions, contracts representing 9,093,000 and 16,461,000 barrels were designated as cash flow hedging instruments as of March 31, 2019 and December 31, 2018, respectively.

[3] As of March 31, 2019 and December 31, 2018, we had open RIN commitment contracts representing 256,025,000 and 137,750,000 RINs, respectively.