Goodwill (Changes In Carrying Amount Of Goodwill) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Goodwill [Line Items]
Beginning balance	$ 842		$ 837
Purchase price adjustment			(3)
Acquisition	88	[1]	9	[1]
Disposition			(1)
Ending balance	930		842
Refining & Marketing [Member]
Goodwill [Line Items]
Beginning balance			554
Purchase price adjustment			(2)
Disposition			(1)
Ending balance	551		551
Speedway [Member]
Goodwill [Line Items]
Beginning balance	129		120
Acquisition	88	[1]	9	[1]
Ending balance	217		129
Pipeline Transportation [Member]
Goodwill [Line Items]
Beginning balance			163
Purchase price adjustment			(1)
Ending balance	$ 162		$ 162

[1] See Note 6 for information on the acquisitions.