Variable Interest Entities, Consolidated (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Mar. 31, 2019
Assets
Cash and cash equivalents		$ 2,982	$ 2,777
Property, plant, and equipment, net		28,848	28,408
Liabilities
Current liabilities, including current portion of debt and finance lease obligations		10,724	12,913
Debt and finance lease obligations, less current portion		8,871	9,006
Other long-term liabilities		2,867	3,530
Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents		235	107
Other current assets		198	226
Property, plant, and equipment, net		2,254	835
Liabilities
Current liabilities, including current portion of debt and finance lease obligations		182	259
Debt and finance lease obligations, less current portion		1,024	35
Other long-term liabilities		5	45
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
Other long-term liabilities	[1]	1
Diamond Green Diesel Holdings LLC [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents		65	85
Other current assets		112	137
Property, plant, and equipment, net		576	584
Liabilities
Current liabilities, including current portion of debt and finance lease obligations		28	35
Debt and finance lease obligations, less current portion		0	1
Other long-term liabilities		0	1
Central Mexico Terminals [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents		0	2
Other current assets		20	21
Property, plant, and equipment, net		156	140
Liabilities
Current liabilities, including current portion of debt and finance lease obligations		118	157
Debt and finance lease obligations, less current portion		0	0
Other long-term liabilities		3	38
Other Variable Interest Entities [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents		18	20
Other current assets		64	68
Property, plant, and equipment, net		113	111
Liabilities
Current liabilities, including current portion of debt and finance lease obligations		9	67
Debt and finance lease obligations, less current portion		34	34
Other long-term liabilities		$ 1	$ 6
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.