Segment Information (Details) (USD $)	3 Months Ended											12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 segments	Dec. 31, 2011	Dec. 31, 2010	Nov. 30, 2010
Segment information for our three reportable segments
Operating revenues	$ 34,695,000,000	$ 34,726,000,000	$ 34,662,000,000	$ 35,167,000,000	[1]	$ 34,673,000,000	[2]	$ 33,713,000,000	[3]	$ 31,293,000,000	$ 26,308,000,000	$ 139,250,000,000	$ 125,987,000,000	$ 82,233,000,000
Intersegment revenues												9,061,000,000	8,810,000,000	6,661,000,000
Depreciation and amortization expense												1,574,000,000	1,534,000,000	1,405,000,000
Operating income (loss)	1,584,000,000	1,309,000,000	1,361,000,000	(244,000,000)	[1]	167,000,000	[2]	1,979,000,000	[3]	1,290,000,000	244,000,000	4,010,000,000	3,680,000,000	1,876,000,000
Total expenditures for long-lived assets												3,413,000,000	2,987,000,000	2,234,000,000
Segment Information (Textual)
Number of reportable segments												3
Equity method investment, ownership percentage															50.00%
Refining [Member]
Segment information for our three reportable segments
Operating revenues												122,925,000,000	109,138,000,000	69,854,000,000
Intersegment revenues												8,946,000,000	8,665,000,000	6,416,000,000
Depreciation and amortization expense												1,370,000,000	1,338,000,000	1,210,000,000
Operating income (loss)												4,450,000,000	3,516,000,000	1,903,000,000
Total expenditures for long-lived assets												3,147,000,000	2,708,000,000	2,084,000,000
Retail [Member]
Segment information for our three reportable segments
Operating revenues												12,008,000,000	11,699,000,000	9,339,000,000
Intersegment revenues												0	0	0
Depreciation and amortization expense												119,000,000	115,000,000	108,000,000
Operating income (loss)												348,000,000	381,000,000	346,000,000
Total expenditures for long-lived assets												164,000,000	134,000,000	102,000,000
Ethanol [Member]
Segment information for our three reportable segments
Operating revenues												4,317,000,000	5,150,000,000	3,040,000,000
Intersegment revenues												115,000,000	145,000,000	245,000,000
Depreciation and amortization expense												42,000,000	39,000,000	36,000,000
Operating income (loss)												(47,000,000)	396,000,000	209,000,000
Total expenditures for long-lived assets												36,000,000	32,000,000	0
Corporate [Member]
Segment information for our three reportable segments
Operating revenues												0	0	0
Intersegment revenues												0	0	0
Depreciation and amortization expense												43,000,000	42,000,000	51,000,000
Operating income (loss)												(741,000,000)	(613,000,000)	(582,000,000)
Total expenditures for long-lived assets												66,000,000	113,000,000	48,000,000
Scenario, Plan [Member]
Segment Information (Textual)
Pro rata distribution of CST common stock to Valero stockholders	80.00%											80.00%
Expected proceeds from separation of retail business												1,100,000,000
Expected tax liability related to retail separation	$ 230,000,000											$ 230,000,000
Equity method investment, ownership percentage	20.00%											20.00%
Expected holding period for remaining 20 percent of CST outstanding common shares												18 months

[1] The operations of the Aruba Refinery were suspended in March 2012.

[2] Includes the operations related to the Meraux Acquisition beginning October 1, 2011.

[3] Includes the operations related to the Pembroke Acquisition beginning August 1, 2011.