Income Taxes (Income Tax-related Interest Accrued) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012
Income Taxes [Abstract]
Interest accrued	$ 17
Tax-related interest and penalties for the quarter ended March 31, 2012	$ 1

The amount of estimated penalties and interest accrued as of the balance sheet date arising from income tax examinations.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319

Name:	us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant