Earnings (Loss) Per Share and Stock Repurchase Program - Schedule of EPS (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator for EPS - continuing operations
Income from continuing operations	$ 32.0	$ 60.0	$ 84.6	$ 154.4	$ 127.6	$ 185.8	$ 87.5	$ (17.3)	$ 331.0	$ 383.6	$ 328.5
Less: Income from continuing operations attributed to non-controlling interest	5.3				5.8				25.6	26.7	33.8
Income from continuing operations attributable to Delek (numerator for basic EPS - continuing operations attributable to Delek)	26.7				121.8				305.4	356.9	294.7
Interest on convertible debt, net of tax	0.0				0.0				0.0	2.6	0.0
Numerator for diluted EPS - continuing operations attributable to Delek									305.4	359.5	294.7
Numerator for EPS - discontinued operations
Income (loss) from discontinued operations, including gain (loss) on sale of discontinued operations									6.6	(10.9)	(8.6)
Income tax expense (benefit)									1.4	(2.2)	(2.7)
Income (loss) from discontinued operations, net of tax	$ 6.0				$ (0.2)				5.2	(8.7)	(5.9)
Less: Income from discontinued operations attributed to non-controlling interest									0.0	8.1	0.0
Income (loss) from discontinued operations attributable to Delek									$ 5.2	$ (16.8)	$ (5.9)
Denominator:
Weighted average common shares outstanding (in shares)	74,042,343				81,321,240				75,853,187	82,797,110	71,566,225
Dilutive effect of convertible debt (in shares)									0	1,525,846	0
Dilutive effect of warrants (in shares)	0				260,838				0	967,352	0
Dilutive effect of stock-based awards (in shares)	658,583				946,261				720,904	1,478,093	736,858
Weighted average common shares outstanding, assuming dilution (in shares)	74,700,926				82,528,339				76,574,091	86,768,401	72,303,083
Basic income (loss) per share:
Income (loss) from continuing operations (USD per share)	$ 0.36	$ 0.68	$ 1.02	$ 1.92	$ 1.50	$ 2.15	$ 0.95	$ (0.29)	$ 4.03	$ 4.31	$ 4.12
(Loss) income from discontinued operations (USD per share)	0.08				0				0.07	(0.20)	(0.08)
Total basic income (loss) per share (USD per share)	0.44				1.50				4.10	4.11	4.04
Diluted income (loss) per share:
Income (loss) from continuing operations (USD per share)	0.36	$ 0.68	$ 1.01	$ 1.90	1.48	$ 2.02	$ 0.90	$ (0.29)	3.99	4.14	4.08
(Loss) income from discontinued operations (USD per share)	0.08				0				0.07	(0.19)	(0.08)
Total diluted income (loss) per share (USD per share)	$ 0.44				$ 1.48				$ 4.06	$ 3.95	$ 4.00
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,925,207				1,749,569
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)									1,932,179	1,462,112	4,080,723
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
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)									1,932,179	1,462,112	4,080,723
Antidilutive convertible debt instruments (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	0	2,811,652
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	0	2,811,652
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	0	2,806,291
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	0	2,806,291