Segment Reporting (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Revenues		$ 2,080	$ 4,475	$ 5,352	$ 8,167
Gross Profit	[1]	358	269	466	639
Operating Expenses		150	172	340	390
Operating income		208	97	126	249
Interest expense, net		(44)	(43)	(88)	(85)
Other income (expense), net		0	6	0	3
Net income		157	55	29	164
Depreciation, amortization and accretion		47	47	92	92
Non-cash unit-based compensation expense		3	3	7	6
Loss on disposal of assets and impairment charges		6	2	8	50
Unrealized loss (gain) on commodity derivatives		0	(3)	(6)	3
Inventory adjustments		(90)	(4)	137	(97)
Equity in earnings of unconsolidated affiliate		(1)	0	(2)	0
Income from operations before income taxes		165	60	40	167
Adjusted EBITDA related to unconsolidated affiliate		3	0	5	0
Other non-cash adjustments		5	(2)	10	5
Income tax expense		8	5	11	3
Adjusted EBITDA		182	152	391	305
Capital expenditures		18	31	59	57
Assets		5,121		5,121		$ 5,438
Fuel Distribution and Marketing [Member]
Segment Reporting Information [Line Items]
Revenues		1,979	4,240	5,059	7,733
All Other [Member]
Segment Reporting Information [Line Items]
Revenues		101	235	293	434
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues			(479)		(875)
Motor Fuel Sales [Member]
Segment Reporting Information [Line Items]
Revenues		1,992	4,366	5,158	7,949
Gross Profit	[1]	294	190	315	475
Motor Fuel Sales [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Revenues		62	173	189	314
Non Motor Fuel Sales [Member]
Segment Reporting Information [Line Items]
Revenues		54	74	125	148
Intersegment Sales [Member] | Fuel Distribution and Marketing [Member]
Segment Reporting Information [Line Items]
Revenues			463		827
Intersegment Sales [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Revenues			16		48
Intersegment Sales [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(152)	(479)	(445)	(875)
Lease Income [Member]
Segment Reporting Information [Line Items]
Revenues		34	35	69	70
Gross Profit	[1]	34	35	69	70
Lease Income [Member] | Fuel Distribution and Marketing [Member]
Segment Reporting Information [Line Items]
Revenues		29	31	59	63
Lease Income [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Revenues		5	4	10	7
Non Motor Fuel [Member]
Segment Reporting Information [Line Items]
Gross Profit	[1]	30	44	82	94
Non Motor Fuel [Member] | Fuel Distribution and Marketing [Member]
Segment Reporting Information [Line Items]
Revenues		20	16	31	35
Non Motor Fuel [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Revenues		34	58	94	113
Including Intercompany [Member] | Fuel Distribution and Marketing [Member]
Segment Reporting Information [Line Items]
Revenues			4,703		8,560
Including Intercompany [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Revenues			251		482
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(152)		(445)
Intersegment Eliminations [Member] | Intersegment Sales [Member] | Fuel Distribution and Marketing [Member]
Segment Reporting Information [Line Items]
Revenues		152		445
Intersegment Eliminations [Member] | Intersegment Sales [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Revenues		0		0
Operating Segments [Member] | Fuel Distribution and Marketing [Member]
Segment Reporting Information [Line Items]
Revenues		2,131		5,504
Gross Profit	[1]	317	215	352	522
Operating Expenses		117	139	272	274
Operating income		200	76	80	248
Interest expense, net		(37)	(35)	(75)	(71)
Other income (expense), net		0	0	0	3
Net income		161	39	4	176
Depreciation, amortization and accretion		36	37	73	71
Non-cash unit-based compensation expense		3	3	7	6
Loss on disposal of assets and impairment charges		0	0	0	(4)
Unrealized loss (gain) on commodity derivatives		0	3	6	(3)
Inventory adjustments		(87)	(4)	139	(97)
Equity in earnings of unconsolidated affiliate		(1)	0	(2)	0
Income from operations before income taxes		164	41	7	180
Adjusted EBITDA related to unconsolidated affiliate		3	0	5	0
Other non-cash adjustments		5	4	10	5
Income tax expense		3	2	3	4
Adjusted EBITDA		160	119	320	237
Capital expenditures		15	28	40	48
Assets		4,014		4,014		4,189
Operating Segments [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Revenues		101		293
Gross Profit	[1]	41	54	114	117
Operating Expenses		33	33	68	116
Operating income		8	21	46	1
Interest expense, net		(7)	(8)	(13)	(14)
Other income (expense), net			6		0
Net income		(4)	16	25	(12)
Depreciation, amortization and accretion		11	10	19	21
Non-cash unit-based compensation expense		0	0	0	0
Loss on disposal of assets and impairment charges		(6)	(2)	(8)	(46)
Unrealized loss (gain) on commodity derivatives		0	0	0	0
Inventory adjustments		(3)	0	(2)	0
Equity in earnings of unconsolidated affiliate		0	0	0	0
Income from operations before income taxes		1	19	33	(13)
Adjusted EBITDA related to unconsolidated affiliate		0	0	0	0
Other non-cash adjustments		0	(6)	0	0
Income tax expense		5	3	8	(1)
Adjusted EBITDA		22	33	71	68
Capital expenditures		3	3	19	9
Assets		1,107		1,107		$ 1,249
Operating Segments [Member] | Motor Fuel Sales [Member] | Fuel Distribution and Marketing [Member]
Segment Reporting Information [Line Items]
Gross Profit	[1]	275	171	269	429
Operating Segments [Member] | Motor Fuel Sales [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Gross Profit	[1]	19	19	46	46
Operating Segments [Member] | Lease Income [Member] | Fuel Distribution and Marketing [Member]
Segment Reporting Information [Line Items]
Gross Profit	[1]	29	31	59	63
Operating Segments [Member] | Lease Income [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Gross Profit	[1]	5	4	10	7
Operating Segments [Member] | Non Motor Fuel [Member] | Fuel Distribution and Marketing [Member]
Segment Reporting Information [Line Items]
Gross Profit	[1]	13	13	24	30
Operating Segments [Member] | Non Motor Fuel [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Gross Profit	[1]	17	31	58	64
External Revenue [Member] | Motor Fuel Sales [Member]
Segment Reporting Information [Line Items]
Revenues		1,992	4,366	5,158	7,949
External Revenue [Member] | Motor Fuel Sales [Member] | Fuel Distribution and Marketing [Member]
Segment Reporting Information [Line Items]
Revenues		1,930	4,193	4,969	7,635
External Revenue [Member] | Motor Fuel Sales [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Revenues		62	173	189	314
External Revenue [Member] | Non Motor Fuel Sales [Member] | Fuel Distribution and Marketing [Member]
Segment Reporting Information [Line Items]
Revenues		20		31
External Revenue [Member] | Non Motor Fuel Sales [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Revenues		34		94
External Revenue [Member] | Lease Income [Member]
Segment Reporting Information [Line Items]
Revenues		34	35	69	70
External Revenue [Member] | Lease Income [Member] | Fuel Distribution and Marketing [Member]
Segment Reporting Information [Line Items]
Revenues		29	31	59	63
External Revenue [Member] | Lease Income [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Revenues		5	4	10	7
External Revenue [Member] | Non Motor Fuel [Member]
Segment Reporting Information [Line Items]
Revenues		$ 54	74	$ 125	148
External Revenue [Member] | Non Motor Fuel [Member] | Fuel Distribution and Marketing [Member]
Segment Reporting Information [Line Items]
Revenues			16		35
External Revenue [Member] | Non Motor Fuel [Member] | All Other [Member]
Segment Reporting Information [Line Items]
Revenues			$ 58		$ 113

[1] Excludes depreciation, amortization and accretion.