Acquisitions and Investments Acquisitions and Investments (Acquisitions of Convenience Stores) (Details) (Speedway, USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2013 Store
Speedway
Business Acquisition [Line Items]
Number of convenience stores acquired	9
Goodwill acquired during period	$ 8

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Name:	us-gaap_GoodwillAcquiredDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration