Employee Benefit Plans (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Defined Benefit Plan, Amounts Recognized in Balance Sheet
Accrued expenses		$ (37)		$ (43)
Other long-term liabilities		(834)		(654)
Pension Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation Rollforward
Benefit obligation at beginning of year		2,639	[1]	2,926
Service cost		119		133		$ 123
Interest cost		98		91		86
Participant contributions		0		0
Benefits paid		(154)		(207)
Actuarial (gain) loss		528		(285)
Other		9		(19)
Benefit obligation at end of year		3,239	[1]	2,639	[1]	2,926
Defined Benefit Plan, Change in Fair Value of Plan Assets Rollforward
Fair value of plan assets at beginning of year	[1]	2,236		2,428
Actual return on plan assets	[1]	490		(130)
Valero contributions	[1]	128		156
Participant contributions	[1]	0		0
Benefits paid	[1]	(154)		(207)
Other	[1]	9		(11)
Fair value of plan assets as of end of year	[1]	2,709		2,236		$ 2,428
Reconciliation of funded status:
Funded status as of end of year	[1]	(530)		(403)
Accumulated benefit obligation		3,039		2,492
Defined Benefit Plan, Amounts Recognized in Balance Sheet
Deferred charges and other assets, net		5		2
Accrued expenses		(17)		(22)
Other long-term liabilities		(518)		(383)
Amounts recognized in balance sheet for defined benefit plans		$ (530)		$ (403)
Actuarial Gain (Loss), Discount Rates (Textual)
Discount rate		3.14%		4.25%		3.58%
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation Rollforward
Benefit obligation at beginning of year		$ 292	[1]	$ 306
Service cost		5		6		$ 6
Interest cost		11		10		10
Participant contributions		11		10
Benefits paid		(29)		(28)
Actuarial (gain) loss		41		(9)
Other		5		(3)
Benefit obligation at end of year		336	[1]	292	[1]	306
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		18
Participant contributions	[1]	11		10
Benefits paid	[1]	(29)		(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]	(336)		(292)
Defined Benefit Plan, Amounts Recognized in Balance Sheet
Deferred charges and other assets, net		0		0
Accrued expenses		(20)		(21)
Other long-term liabilities		(316)		(271)
Amounts recognized in balance sheet for defined benefit plans		$ (336)		$ (292)
Actuarial Gain (Loss), Discount Rates (Textual)
Discount rate		3.32%		4.40%

[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.