Employee Benefit Plans (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Changes in plan assets (a):
Fair value of plan assets at beginning of year		$ 2,097
Fair value of plan assets at end of year		2,428		$ 2,097
Defined Benefit Plan, Amounts Recognized in Balance Sheet
Accrued expenses		(33)		(32)
Other long-term liabilities		(776)		(742)
Employee Benefit Plans (Textual)
Contributions to defined contribution plans		70		67		$ 65
Pension Plans [Member]
Changes in benefit obligation:
Benefit obligation at beginning of year		2,567	[1]	2,365
Service cost		123		111		109
Interest cost		86		84		98
Participant contributions		0		0
Benefits paid		(158)		(130)
Actuarial (gain) loss		286		171
Other		22		(34)
Benefit obligation at end of year		2,926	[1]	2,567	[1]	2,365
Changes in plan assets (a):
Fair value of plan assets at beginning of year	[1]	2,097		1,947
Actual return on plan assets	[1]	363		165
Valero contributions	[1]	110		141
Participant contributions	[1]	0		0
Benefits paid	[1]	(158)		(130)
Other	[1]	16		(26)
Fair value of plan assets at end of year	[1]	2,428		2,097		1,947
Reconciliation of funded status (a):
Funded status as of end of year	[1]	(498)		(470)
Accumulated benefit obligation		2,746		2,419
Defined Benefit Plan, Amounts Recognized in Balance Sheet
Deferred charges and other assets, net		5		2
Accrued expenses		(14)		(13)
Other long-term liabilities		(489)		(459)
Amounts recognized in balance sheet for defined benefit plans		(498)		(470)
Other Postretirement Benefit Plans [Member]
Changes in benefit obligation:
Benefit obligation at beginning of year		302	[1]	336
Service cost		6		7		8
Interest cost		10		12		14
Participant contributions		9		8
Benefits paid		(28)		(27)
Actuarial (gain) loss		6		(35)
Other		1		1
Benefit obligation at end of year		306	[1]	302	[1]	336
Changes in plan assets (a):
Fair value of plan assets at beginning of year	[1]	0		0
Actual return on plan assets	[1]	0		0
Valero contributions	[1]	19		18
Participant contributions	[1]	9		8
Benefits paid	[1]	(28)		(27)
Other	[1]	0		1
Fair value of plan assets at end of year	[1]	0		0		$ 0
Reconciliation of funded status (a):
Funded status as of end of year	[1]	(306)		(302)
Defined Benefit Plan, Amounts Recognized in Balance Sheet
Deferred charges and other assets, net		0		0
Accrued expenses		(19)		(19)
Other long-term liabilities		(287)		(283)
Amounts recognized in balance sheet for defined benefit plans		$ (306)		$ (302)

[1] Plan assets include only the assets associated with pension plans subject to legal minimum funding standards. Plan assets associated with U.S. nonqualified pension plans are not included here because they are not protected from our creditors and therefore cannot be reflected as a reduction from our obligations under the pension plans. As a result, the reconciliation of funded status does not reflect the effect of plan assets that exist for all of our defined benefit plans. See Note 18 for the assets associated with certain U.S. nonqualified pension plans.