Acquisitions - Schedule of Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenues		$ 2,474.1	$ 2,768.9	$ 2,636.9	$ 2,353.2	$ 2,483.7	$ 2,370.6	$ 1,230.7	$ 1,182.2	$ 10,233.1	$ 7,267.1	$ 4,197.9
Acquisition related transaction costs										3.0
Income (loss) from continuing operations before income tax expense										$ 485.5	299.3	(391.2)
Alon USA Energy, Inc.
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net revenues	[1],[2]										9,477.8	8,100.9
Net income attributable to Delek	[1],[2]										$ 223.6	$ 16.3
Basic (USD per share)	[1],[2]										$ 2.75	$ 0.20
Diluted (USD per share)	[1],[2]										$ 2.73	$ 0.20
Parent Company's Equity Income Elimination Adjustment | Alon USA Energy, Inc.
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenues											$ (59.0)	$ (10.4)
Acquisition related transaction costs											(32.2)	(13.7)
Income (loss) from continuing operations before income tax expense											$ 3.2	$ (42.2)
Tax Effect Adjustment | Alon USA Energy, Inc.
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
U.S. income tax statutory blended rate (percentage)											37.00%	35.00%

[1] The pro forma information for the years ended December 31, 2017 and 2016 has been updated to reflect the final purchase price allocation in the table above.

[2] The unaudited pro forma statements of operations reflect the following adjustments: • To eliminate transactions between Delek and Alon for purchases and sales of refined products, reducing revenue and the associated cost of materials and other. Such pro forma eliminations resulted in a decrease to combined pro forma revenues by $59.0 million and $10.4 million million for the years ended December 31, 2017 and 2016, respectively. • To eliminate the non-recurring transaction costs incurred during the historical periods. Such adjustments to general and administrative expense have been estimated to result in an increase to pro forma pre-tax income attributable to Delek totaling $32.2 million and $13.7 million million for the years ended December 31, 2017 and 2016. • To retrospectively reflect depreciation of property, plant and equipment and amortization of intangibles based on the fair value of the assets as of the acquisition date, as if that fair value had been reflected beginning January 1, 2016, and to retrospectively eliminate the amortization of any previously recorded intangibles. Such adjustments to depreciation and amortization have been estimated to result in an increase to pro forma pre-tax income attributable to Delek totaling $34.7 million and $70.8 million million for the years ended December 31, 2017 and 2016, respectively. • To retrospectively reflect the accretion of asset retirement obligations and certain environmental liabilities. Such adjustments to general and administrative expense have been estimated to result in a decrease to pro forma pre-tax income attributable to Delek totaling $0.8 million and $1.6 million million for the years ended December 31, 2017 and 2016, respectively. • To retrospectively reflect adjustments to interest expense, including the impact of discounts or premiums created by the difference in fair value and outstanding amounts as of the acquisition date (collectively, the “new effective yield”), by applying the new effective yield to historical outstanding amounts in the pro forma period and reversing previously recognized interest expense. Such net adjustments to interest expense have been estimated to result in an increase to pro forma pre-tax income attributable to Delek totaling $9.4 million and $20.7 million million for the years ended December 31, 2017 and 2016, respectively. • To eliminate Delek’s equity income previously recorded on its equity method investment in Alon, prior to the Merger. Such pro forma elimination resulted in an (increase) decrease to pro forma pre-tax income totaling $3.2 million and $(42.2) million million for the years ended December 31, 2017 and 2016, respectively. • To eliminate the impairment charge on the equity method investment in Alon totaling $245.3 million recognized in the year ended December 31, 2016, and to eliminate the gain on remeasurement of the equity method investment in Alon totaling $190.1 million recognized during the year ended December 31, 2017. • To record the tax effect on pro forma adjustments and additional tax benefit associated with dividends received from Alon at a combined U.S. (federal and state) income tax statutory blended rate of approximately 37% for the year ended December 31, 2017, and approximately 35% for the year ended December 31, 2016.
• To adjust the weighted average number of shares outstanding based on 0.504 of a share of Delek common stock for each share of Alon common stock outstanding as of July 1, 2017, as if they were outstanding for the entire year ended December 31, 2017, reflecting the elimination of Alon historical weighted average shares outstanding and the addition of the estimated New Delek incremental shares issued.