Earnings (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended												12 Months Ended
	Dec. 31, 2020	[1]	Sep. 30, 2020	[1],[2]	Jun. 30, 2020	[2]	Mar. 31, 2020	[2]	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings (loss) per common share
Net income (loss) attributable to Valero stockholders	$ (359)		$ (464)		$ 1,253		$ (1,851)		$ 1,060	$ 609	$ 612	$ 141	$ (1,421)	$ 2,422	$ 3,122
Less: Income allocated to participating securities													5	7	9
Net income (loss) available to common shareholders													$ (1,426)	$ 2,415	$ 3,113
Weighted-average common shares outstanding (shares)													407	413	426
Earnings (loss) per common share (in usd per share)	$ (0.88)		$ (1.14)		$ 3.07		$ (4.54)		$ 2.58	$ 1.48	$ 1.47	$ 0.34	$ (3.50)	$ 5.84	$ 7.30
Earnings (loss) per common share – assuming dilution
Net income (loss) attributable to Valero stockholders	$ (359)		$ (464)		$ 1,253		$ (1,851)		$ 1,060	$ 609	$ 612	$ 141	$ (1,421)	$ 2,422	$ 3,122
Less: Income allocated to participating securities													5	7	9
Net income (loss) available to common shareholders													$ (1,426)	$ 2,415	$ 3,113
Weighted-average common shares outstanding (shares)													407	413	426
Effect of dilutive securities (shares)													0	1	2
Weighted-average common shares outstanding – assuming dilution (shares)													407	414	428
Earnings per common share – assuming dilution (in usd per share)	$ (0.88)		$ (1.14)		$ 3.07		$ (4.54)		$ 2.58	$ 1.48	$ 1.47	$ 0.34	$ (3.50)	$ 5.84	$ 7.29

[1] We recorded a charge of $326 million in September 2020 due to the expected liquidation of LIFO inventory layers as described in Note 5. We recognized a benefit of $102 million in December 2020 to adjust the $326 million estimate to the $224 million actual charge for the year ended December 31, 2020.

[2] The market value of our inventories accounted for under the LIFO method fell below their historical cost on an aggregate basis as of March 31, 2020. As a result, we recorded an LCM inventory valuation adjustment of $2.5 billion in March 2020 as described in Note 5. The market value of our LIFO inventories improved due to the subsequent recovery in market prices, which resulted in a reversal of $2.2 billion in the quarter ended June 30, 2020 and the remaining amount in the quarter ended September 30, 2020.