Goodwill (Changes In Carrying Amount Of Goodwill) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Goodwill [Line Items]
Balance	$ 842
Acquisitions	88	[1]
Balance	930
Refining & Marketing [Member]
Goodwill [Line Items]
Balance	551
Acquisitions		[1]
Balance	551
Speedway [Member]
Goodwill [Line Items]
Balance	129
Acquisitions	88	[1]
Balance	217
Pipeline Transportation [Member]
Goodwill [Line Items]
Balance	162
Acquisitions		[1]
Balance	$ 162

[1] See Note 4 for information on the acquisitions.