Revenue - Disaggregation of Revenue (Details) - USD ($) $ 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
Disaggregation of Revenue [Line Items]
Total revenues	$ 4,098	$ 4,331	$ 4,475	$ 3,692	$ 3,877	$ 4,761	$ 4,607	$ 3,749	$ 16,596	$ 16,994	$ 11,723
Non Motor Fuel Sales [Member]
Disaggregation of Revenue [Line Items]
Total revenues									278	360	724
Lease income [Member]
Disaggregation of Revenue [Line Items]
Total revenues									142	130	89
Motor Fuel Sales [Member]
Disaggregation of Revenue [Line Items]
Total revenues									16,176	16,504	10,910
Fuel Distribution and Marketing [Member]
Disaggregation of Revenue [Line Items]
Total revenues										17,281	10,932
All Other [Member]
Disaggregation of Revenue [Line Items]
Total revenues										1,482	2,388
External Revenue [Member]
Disaggregation of Revenue [Line Items]
Total revenues									16,596	16,994
External Revenue [Member] | Non Motor Fuel Sales [Member]
Disaggregation of Revenue [Line Items]
Total revenues									278	360	724
External Revenue [Member] | Lease income [Member]
Disaggregation of Revenue [Line Items]
Total revenues									142	130	89
External Revenue [Member] | Motor Fuel Sales [Member]
Disaggregation of Revenue [Line Items]
Total revenues									16,176	16,504	10,910
External Revenue [Member] | Fuel Distribution and Marketing [Member]
Disaggregation of Revenue [Line Items]
Total revenues									15,715	15,632
External Revenue [Member] | Fuel Distribution and Marketing [Member] | Dealer Revenue [Member]
Disaggregation of Revenue [Line Items]
Total revenues									3,542	3,639
External Revenue [Member] | Fuel Distribution and Marketing [Member] | Distributor Revenue [Member]
Disaggregation of Revenue [Line Items]
Total revenues									7,645	7,873
External Revenue [Member] | Fuel Distribution and Marketing [Member] | Unbranded Wholesale Revenue [Member]
Disaggregation of Revenue [Line Items]
Total revenues									2,729	2,577
External Revenue [Member] | Fuel Distribution and Marketing [Member] | Commission Agent Revenue [Member]
Disaggregation of Revenue [Line Items]
Total revenues									1,606	1,377
External Revenue [Member] | Fuel Distribution and Marketing [Member] | Non Motor Fuel Sales [Member]
Disaggregation of Revenue [Line Items]
Total revenues									62	48	50
External Revenue [Member] | Fuel Distribution and Marketing [Member] | Lease income [Member]
Disaggregation of Revenue [Line Items]
Total revenues									131	118	77
External Revenue [Member] | Fuel Distribution and Marketing [Member] | Motor Fuel Sales [Member]
Disaggregation of Revenue [Line Items]
Total revenues									15,522	15,466	9,333
External Revenue [Member] | All Other [Member]
Disaggregation of Revenue [Line Items]
Total revenues									881	1,362
External Revenue [Member] | All Other [Member] | Non Motor Fuel Sales [Member]
Disaggregation of Revenue [Line Items]
Total revenues									216	312	674
External Revenue [Member] | All Other [Member] | Lease income [Member]
Disaggregation of Revenue [Line Items]
Total revenues									11	12	12
External Revenue [Member] | All Other [Member] | Motor Fuel Sales [Member]
Disaggregation of Revenue [Line Items]
Total revenues									$ 654	$ 1,038	$ 1,577