Investments (Schedule of Investments in Marketable Equity Securities and Other) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Investments [Abstract]
Marketable equity securities	$ 45	$ 45
Equity method and other investments	821	1,008
Total Investments	$ 866	$ 1,053

For an unclassified balance sheet, this item represents investments in common and preferred stocks and other forms of securities that provide ownership interests in a corporation.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph b

-Article 7

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(b))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Name:	us-gaap_MarketableSecuritiesEquitySecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant