Separation of Retail Business (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended		0 Months Ended		1 Months Ended	3 Months Ended		0 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	May 01, 2013 Spinoff [Member]	Apr. 30, 2013 Spinoff [Member]	Nov. 30, 2013 Spinoff [Member]	Jun. 30, 2013 Spinoff [Member]	May 01, 2013 Spinoff [Member]	May 01, 2013 Spinoff [Member] Notes Payable to Banks [Member]	Apr. 16, 2013 Spinoff [Member] Sourced From Parent's Short-Term Borrowings [Member] Notes Payable to Banks [Member]	May 01, 2013 Spinoff [Member] Sourced From Entity Spunoff [Member]
Separation of Retail Business (Textual)
Spinoff transaction, ownership percentage by Valero stockholders							80.00%
Cash distributed to Valero by CST Brands, Inc.	$ 0	$ 500	$ 1,050							$ 500
Proceeds from short-term debt in anticipation of separation	0	550							550
Senior unsecured bonds of CST issued to us								550
CST securities exchanged in settlement of short-term borrowings								550
Cash held and retained by CST Brands, Inc. upon separation	0	315		315
Cost of separation in general and administrative expense						$ 30
Retained ownership percentage disposed					20.00%