Earnings (Loss) Per Share and Stock Repurchase Program Schedule of Basic and Diluted Earnings per Share (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
Numerator for EPS - continuing operations
Income (loss) from continuing operations	$ 127.6	$ 185.8	$ 87.5	$ (17.3)	$ 226.9	$ 118.5	$ (32.2)	$ 15.3	$ 383.6	$ 328.5	$ (219.7)
Less: Income from continuing operations attributed to non-controlling interest									26.7	33.8	20.3
Income (loss) from continuing operations attributable to Delek (numerator for basic EPS - continuing operations attributable to Delek)	121.8				212.9				356.9	294.7	(240.0)
Interest on convertible debt, net of tax	0.0				0.7				2.6	0.0	0.0
Numerator for diluted EPS - continuing operations attributable to Delek									359.5	294.7	(240.0)
Numerator for EPS - discontinued operations
Income (loss) from discontinued operations	$ (0.2)				$ (1.8)				(8.7)	(5.9)	86.3
Less: Income from discontinued operations attributed to non-controlling interest									8.1	0.0	0.0
Income (loss) from discontinued operations attributable to Delek									$ (16.8)	$ (5.9)	$ 86.3
Denominator:
Weighted average common shares outstanding (in shares)	81,321,240				81,338,755				82,797,110	71,566,225	61,921,787
Dilutive effect of convertible debt (in shares)	0				526,464				1,525,846	0	0
Dilutive effect of warrants (in shares)	260,838				0				967,352	0	0
Dilutive effect of stock-based awards (in shares)	946,261				779,841				1,478,093	736,858	0
Weighted average common shares outstanding, assuming dilution (in shares)	82,528,339				82,645,060				86,768,401	72,303,083	61,921,787
Basic income (loss) per share:
Income (loss) from continuing operations (USD per share)	$ 1.50	$ 2.15	$ 0.95	$ (0.29)	$ 2.62	$ 1.30	$ (0.61)	$ 0.18	$ 4.31	$ 4.12	$ (3.88)
(Loss) income from discontinued operations (USD per share)	0				(0.02)				(0.20)	(0.08)	1.39
Total basic income (loss) per share (USD per share)	1.50				2.60				4.11	4.04	(2.49)
Diluted income (loss) per share:
Income (loss) from continuing operations (USD per share)	1.48	$ 2.02	$ 0.90	$ (0.29)	2.58	$ 1.29	$ (0.61)	$ 0.18	4.14	4.08	(3.88)
(Loss) income from discontinued operations (USD per share)	0				(0.02)				(0.19)	(0.08)	1.39
Total diluted income (loss) per share (USD per share)	$ 1.48				$ 2.56				$ 3.95	$ 4.00	$ (2.49)
Antidilutive stock-based compensation (because average share price is less than exercise price)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,749,569				3,660,354				1,462,112		2,297,127
Antidilutive due to loss
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0				0				0		276,094
Total antidilutive stock-based compensation
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,749,569				3,660,354				1,462,112	0	2,573,221
Antidilutive convertible debt instruments
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0				5,623,304				0	2,811,652	0
Total antidilutive convertible debt instruments
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)									0	2,811,652	0
Antidilutive warrants (because average share price is less than exercise price)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0				5,612,581				0	2,806,291	0
Total antidilutive warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)									0	2,806,291	0