Goodwill and Acquired Intangibles Goodwill and Acquired Intangibles, Goodwill (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Goodwill [Roll Forward]
Balance as of beginning of year	$ 36	$ 46
Goodwill write-off	0	(10)	(43)
Balance as of end of year	36	36	46
Refining [Member]
Goodwill [Roll Forward]
Balance as of end of year	31	31
Retail [Member]
Goodwill [Roll Forward]
Balance as of end of year	$ 5	$ 5