Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income		Retained Earnings	Treasury Stock	Non-Controlling Interest in Subsidiaries	Commodity contract	Commodity contract Accumulated Other Comprehensive Income	Commodity contract Non-Controlling Interest in Subsidiaries	Interest Rate Contracts	Interest Rate Contracts Accumulated Other Comprehensive Income
Beginning balance (shares) at Dec. 31, 2015		66,946,721					(4,809,701)
Beginning balance at Dec. 31, 2015	$ 1,353.9	$ 0.7	$ 639.2	$ (45.3)		$ 713.5	$ (154.8)	$ 200.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(133.4)					(153.7)		20.3
Other comprehensive income related to commodity contracts or interest rate contracts	23.5			23.5					$ 23.5			$ 0.0
Other comprehensive income from equity method investments	0.8			0.8
Other comprehensive income related to postretirement benefit plans	0.0
Foreign currency translation gain (loss)	0.2			0.2
Common stock dividends	(37.5)					(37.5)
Equity-based compensation expense	16.4		15.7					0.7
Distribution to non-controlling interest	(24.1)							(24.1)
Repurchase of common stock (shares)							(386,090)
Repurchase of common stock	(6.0)						$ (6.0)
Repurchase of non-controlling interest	(6.9)							(6.9)
Income tax benefit from equity-based compensation expense	(2.9)		(2.9)
Taxes due to the net settlement of equity-based compensation	$ (1.5)		(1.5)
Exercise of equity-based awards (shares)	203,631	203,631
Exercise of equity-based awards	$ 0.0		0.0
Ending balance at Dec. 31, 2016	1,182.5	$ 0.7	650.5	(20.8)		522.3	$ (160.8)	190.6
Ending balance (shares) at Dec. 31, 2016		67,150,352					(5,195,791)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	322.6					288.8		33.8
Other comprehensive income related to commodity contracts or interest rate contracts									23.8	$ 23.8		0.4	$ 0.4
Other comprehensive income from equity method investments	4.1			4.1	[1]
Other comprehensive income related to postretirement benefit plans	(0.6)			(0.6)
Foreign currency translation gain (loss)	0.1			0.1
Common stock dividends	(44.0)					(44.0)
Issuance of equity in connection with Delek/Alon Merger (in shares)		19,250,795
Issuance of equity in connection with Delek/Alon Merger	530.7	$ 0.1	399.0					131.6
Retirement of Treasury shares in connection with Delek/Alon Merger (in shares)		(5,195,791)					5,195,791
Retirement of Treasury shares in connection with Delek/Alon Merger			(160.8)				$ 160.8
Equity-based compensation expense	17.5		16.9					0.6
Distribution to non-controlling interest	(35.7)							(35.7)
Repurchase of common stock (shares)							(762,623)
Repurchase of common stock	(32.3)						$ (25.0)	(7.3)
Issuance costs in connection with Delek/Alon Merger	(0.2)		(0.2)
Taxes due to the net settlement of equity-based compensation	$ (5.0)		(5.0)
Exercise of equity-based awards (shares)	332,156	328,192
Exercise of equity-based awards	$ 0.0							0.0
Other	0.3		(0.3)	(0.1)		0.7		0.0
Ending balance at Dec. 31, 2017	1,964.2	$ 0.8	900.1	6.9		767.8	$ (25.0)	313.6
Ending balance (shares) at Dec. 31, 2017		81,533,548					(762,623)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification for stranded tax effects resulting from the the Tax Reform Act	1.6
Beginning balance (shares) at Dec. 31, 2017		81,533,548					(762,623)
Beginning balance at Dec. 31, 2017	1,964.2	$ 0.8	900.1	6.9		767.8	$ (25.0)	313.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	374.9					340.1		34.8
Other comprehensive income related to commodity contracts or interest rate contracts									$ 26.2	$ 26.2	$ 0.0	$ (0.5)	$ (0.5)
Other comprehensive income from equity method investments	0.0
Other comprehensive income related to postretirement benefit plans	(4.7)			(4.7)
Foreign currency translation gain (loss)	(0.9)							0.0
Common stock dividends	(80.1)					(80.1)		0.0
Equity-based compensation expense	21.4		20.9					0.5
Issuance of stock for non-controlling interest repurchase, net of tax (in shares)		5,649,373
Issuance of stock for non-controlling interest repurchase, net of tax	13.5	$ 0.1	140.4					(127.0)
De-recognition of non-controlling interest	(18.7)							(18.7)
Reclassification for stranded tax effects resulting from the the Tax Reform Act				1.6		(1.6)
Shares issued in connection with settlement of Convertible Notes (in shares)		2,692,218
Shares issued in connection with settlement of Convertible Notes	(0.3)		(0.3)
Shares received in connection with exercise of Call Options	0.3		124.2				$ (123.9)
Shares received in connection with exercise of Call Options (shares)							(2,692,771)
Distribution to non-controlling interest	$ (27.7)							(27.7)
Repurchase of common stock (shares)	(9,022,386)						(9,022,386)
Repurchase of common stock	$ (365.3)						$ (365.3)	0.0
Warrant reclassification to liability award	(35.9)		(35.9)
Taxes due to the net settlement of equity-based compensation	$ (11.5)		(11.5)					0.0
Exercise of equity-based awards (shares)	580,455	602,936
Exercise of equity-based awards	$ 0.0							0.0
Other	(2.4)		(2.5)				(0.1)	0.0
Ending balance at Dec. 31, 2018	1,808.1	$ 0.9	$ 1,135.4	$ 28.6		981.8	$ (514.1)	175.5
Ending balance (shares) at Dec. 31, 2018		90,478,075					(12,477,780)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of adopting accounting principle regarding income tax effect of intra-equity transfers	$ (44.4)					$ (44.4)		$ 0.0

[1] Includes reversal of $4.1 million of accumulated other comprehensive loss related to the pre-Merger equity method investment in Alon.