Variable Interest Entities (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Jun. 30, 2019
Assets
Cash and cash equivalents		$ 2,982	$ 2,033
Property, plant, and equipment, net		28,848	28,784
Liabilities
Current liabilities, including current portion of debt and finance lease obligations		10,724	12,548
Debt and finance lease obligations, less current portion		8,871	9,167
Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents		235	167
Other current assets		198	209
Property, plant, and equipment, net		2,254	925
Liabilities
Current liabilities, including current portion of debt and finance lease obligations		182	272
Debt and finance lease obligations, less current portion		1,024	34
Valero Energy Partners LP [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents	[1]	152
Other current assets	[1]	2
Property, plant, and equipment, net	[1]	1,409
Liabilities
Current liabilities, including current portion of debt and finance lease obligations	[1]	27
Debt and finance lease obligations, less current portion	[1]	990
Diamond Green Diesel Holdings LLC [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents		65	139
Other current assets		112	101
Property, plant, and equipment, net		576	614
Liabilities
Current liabilities, including current portion of debt and finance lease obligations		28	44
Debt and finance lease obligations, less current portion		0	1
Central Mexico Terminals [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents		0	0
Other current assets		20	20
Property, plant, and equipment, net		156	201
Liabilities
Current liabilities, including current portion of debt and finance lease obligations		118	216
Debt and finance lease obligations, less current portion		0	0
Other Variable Interest Entities [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents		18	28
Other current assets		64	88
Property, plant, and equipment, net		113	110
Liabilities
Current liabilities, including current portion of debt and finance lease obligations		9	12
Debt and finance lease obligations, less current portion		$ 34	$ 33
Limited Partner [Member] | Valero Energy Partners LP [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity (Textual)
Ownership percentage (percent)		66.20%
Limited Partner [Member] | Valero Energy Partners LP [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity (Textual)
Ownership percentage (percent)		31.80%
General Partner [Member] | Valero Energy Partners LP [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity (Textual)
Ownership percentage (percent)		2.00%

[1] Prior to the completion of the Merger Transaction with VLP on January 10, 2019 as discussed in Note 2, VLP was a publicly traded master limited partnership that we had determined was a VIE. VLP was formed by us to own, operate, develop, and acquire crude oil and refined petroleum products pipelines, terminals, and other transportation and logistics assets. As of December 31, 2018, we owned a 66.2 percent limited partner interest and a 2.0 percent general partner interest in VLP, and public unitholders owned a 31.8 percent limited partner interest. Upon completion of the Merger Transaction, VLP became our indirect wholly owned subsidiary and, as a result, was no longer a VIE.