Fair Value Measurements (Reconciliation For Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2013 Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Dec. 31, 2012 Level 3 [Member] Fair Value, Measurements, Recurring [Member]
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings	$ (23)
Balance, December 31, 2012		(379)	(356)
Balance, March 31, 2013		$ (379)	$ (356)

Amount of realized and unrealized gain (loss) included in earnings, which have arisen from the use of significant unobservable inputs (level 3) to measure fair value of assets, liabilities, and financial instruments classified in shareholders' equity.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration