Variable Interest Entities, Consolidated (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 4,451	$ 5,850	$ 5,207	$ 4,816
Property, plant, and equipment, net	28,180	27,480
Liabilities
Current liabilities	11,341	11,071
Debt and capital lease obligations, less current portion	8,876	8,750
Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents	283	179
Other current assets	64	72
Property, plant, and equipment, net	2,168	2,029
Liabilities
Current liabilities	125	95
Debt and capital lease obligations, less current portion	1,027	948
Valero Energy Partners LP [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents	100	42
Other current assets	1	2
Property, plant, and equipment, net	1,413	1,416
Liabilities
Current liabilities	27	27
Debt and capital lease obligations, less current portion	989	905
Diamond Green Diesel Holdings LLC [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents	167	123
Other current assets	50	66
Property, plant, and equipment, net	529	435
Liabilities
Current liabilities	29	33
Debt and capital lease obligations, less current portion	0	0
Central Mexico Terminals [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents	2	1
Other current assets	13	4
Property, plant, and equipment, net	107	51
Liabilities
Current liabilities	63	26
Debt and capital lease obligations, less current portion	0	0
Other Variable Interest Entities [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents	14	13
Other current assets	0	0
Property, plant, and equipment, net	119	127
Liabilities
Current liabilities	6	9
Debt and capital lease obligations, less current portion	$ 38	$ 43