Separation of Retail Business (Details) - USD ($)					3 Months Ended	12 Months Ended
	Nov. 14, 2013	May. 01, 2013	Apr. 30, 2013	Apr. 16, 2013	Jun. 30, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Separation of Retail Business (Textual)
Proceeds from short-term debt in anticipation of separation						$ 0	$ 0	$ 550,000,000
Cash distributed to Valero by CST Brands, Inc.						0	0	500,000,000
Senior unsecured bonds of CST Brands, Inc. issued to us						247,000,000	256,000,000
Cash held and retained by CST Brands, Inc. upon separation						0	0	315,000,000
Gain on disposition of retained interest in CST Brands, Inc.						$ 0	$ 0	$ 325,000,000
Spinoff [Member]
Separation of Retail Business (Textual)
Spinoff transaction, ownership percentage by Valero stockholders		80.00%
Aggregate proceeds received related to separation of CST Brands, Inc		$ 1,050,000,000.00
Cash distributed to Valero by CST Brands, Inc.		500,000,000
Senior unsecured bonds of CST Brands, Inc. issued to us		550,000,000
Cash held and retained by CST Brands, Inc. upon separation			$ 315,000,000
Cost of separation in general and administrative expenses					$ 30,000,000
Retained ownership percentage disposed	20.00%
Gain on disposition of retained interest in CST Brands, Inc.	$ 325,000,000
Spinoff [Member] | Notes Payable to Banks [Member]
Separation of Retail Business (Textual)
Proceeds from short-term debt in anticipation of separation				$ 550,000,000
CST Brands, Inc. securities exchanged in settlement of short-term borrowings	$ 467,000,000	$ 550,000,000