Operating Performance (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Costs and Expenses [Abstract]
Net sales (excluding intercompany fees and sales)	$ 1,364.1	$ 1,554.2	$ 1,693.1	$ 1,150.6	$ 1,761.7	$ 2,322.2	$ 2,374.7	$ 1,865.7	$ 5,762.0	$ 8,324.3	$ 8,706.8
Intercompany fees and sales									0.0	0.0	0.0
Cost of goods sold									5,015.6	7,315.2	7,880.7
Operating expenses									406.6	398.8	387.4
Segment Contribution Margin									339.8	610.3	438.7
General and administrative expenses									126.0	133.4	111.2
Depreciation and amortization									134.0	111.5	89.8
Other operating income									(0.9)	(1.1)	0.0
Operating income	(15.0)	$ 23.8	$ 79.8	$ (7.9)	71.9	$ 120.9	$ 106.0	$ 67.7	80.7	366.5	237.7
Total assets	3,324.9				2,888.7				3,324.9	2,888.7
Capital spending (excluding business combinations)									218.6	256.9	222.3
Operating Segments [Member] | Refining [Member]
Operating Costs and Expenses [Abstract]
Net sales (excluding intercompany fees and sales)									3,820.8	5,728.4	6,005.1
Intercompany fees and sales									619.4	622.1	430.7
Cost of goods sold									4,022.2	5,664.8	5,865.2
Operating expenses									225.4	221.0	222.8
Segment Contribution Margin									192.6	464.7	347.8
Total assets	1,895.7				1,937.7				1,895.7	1,937.7
Capital spending (excluding business combinations)									164.5	199.1	123.6
Operating Segments [Member] | Retail [Member]
Operating Costs and Expenses [Abstract]
Net sales (excluding intercompany fees and sales)									1,490.2	1,869.3	1,871.4
Intercompany fees and sales									0.0	0.0	0.0
Cost of goods sold									1,288.9	1,671.5	1,691.3
Operating expenses									137.6	136.8	132.5
Segment Contribution Margin									63.7	61.0	47.6
Total assets	445.0				447.1				445.0	447.1
Capital spending (excluding business combinations)									18.3	26.2	37.9
Operating Segments [Member] | Logistics [Member]
Operating Costs and Expenses [Abstract]
Net sales (excluding intercompany fees and sales)									447.0	726.7	829.8
Intercompany fees and sales									142.7	114.6	77.6
Cost of goods sold									436.3	697.2	811.3
Operating expenses									44.9	39.5	35.9
Segment Contribution Margin									108.5	104.6	60.2
Total assets	375.3				331.3				375.3	331.3
Capital spending (excluding business combinations)									18.6	9.2	25.8
Corporate, other and eliminations [Member]
Operating Costs and Expenses [Abstract]
Net sales (excluding intercompany fees and sales)									4.0	(0.1)	0.5
Intercompany fees and sales									(762.1)	(736.7)	(508.3)
Cost of goods sold									(731.8)	(718.3)	(487.1)
Operating expenses									(1.3)	1.5	(3.8)
Segment Contribution Margin									(25.0)	(20.0)	(16.9)
Total assets	$ 608.9				$ 172.6				608.9	172.6
Capital spending (excluding business combinations)									$ 17.2	$ 22.4	$ 35.0