Employee Benefit Plans (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Defined Benefit Plan, Amounts Recognized in Balance Sheet
Accrued expenses		$ (43)		$ (33)
Other long-term liabilities		(654)		(776)
Pension Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation Rollforward
Benefit obligation at beginning of year		2,926	[1]	2,567
Service cost		133		123		$ 111
Interest cost		91		86		84
Participant contributions		0		0
Benefits paid		(207)		(158)
Actuarial (gain) loss		(285)		286
Other		(19)		22
Benefit obligation at end of year		2,639	[1]	2,926	[1]	2,567
Defined Benefit Plan, Change in Fair Value of Plan Assets Rollforward
Fair value of plan assets at beginning of year	[1]	2,428		2,097
Actual return on plan assets	[1]	(130)		363
Valero contributions	[1]	156		110
Participant contributions	[1]	0		0
Benefits paid	[1]	(207)		(158)
Other	[1]	(11)		16
Fair value of plan assets as of end of year	[1]	2,236		2,428		$ 2,097
Reconciliation of funded status:
Funded status as of end of year	[1]	(403)		(498)
Accumulated benefit obligation		2,492		2,746
Defined Benefit Plan, Amounts Recognized in Balance Sheet
Deferred charges and other assets, net		2		5
Accrued expenses		(22)		(14)
Other long-term liabilities		(383)		(489)
Amounts recognized in balance sheet for defined benefit plans		$ (403)		$ (498)
Actuarial Gain (Loss), Discount Rates (Textual)
Discount rate		4.25%		3.58%		4.08%
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation Rollforward
Benefit obligation at beginning of year		$ 306	[1]	$ 302
Service cost		6		6		$ 7
Interest cost		10		10		12
Participant contributions		10		9
Benefits paid		(28)		(28)
Actuarial (gain) loss		(9)		6
Other		(3)		1
Benefit obligation at end of year		292	[1]	306	[1]	302
Defined Benefit Plan, Change in Fair Value of Plan Assets Rollforward
Fair value of plan assets at beginning of year	[1]	0		0
Actual return on plan assets	[1]	0		0
Valero contributions	[1]	18		19
Participant contributions	[1]	10		9
Benefits paid	[1]	(28)		(28)
Other	[1]	0		0
Fair value of plan assets as of end of year	[1]	0		0		$ 0
Reconciliation of funded status:
Funded status as of end of year	[1]	(292)		(306)
Defined Benefit Plan, Amounts Recognized in Balance Sheet
Deferred charges and other assets, net		0		0
Accrued expenses		(21)		(19)
Other long-term liabilities		(271)		(287)
Amounts recognized in balance sheet for defined benefit plans		$ (292)		$ (306)
Actuarial Gain (Loss), Discount Rates (Textual)
Discount rate		4.40%		3.72%

[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 19 for the assets associated with certain U.S. nonqualified pension plans.