Organization and Basis of Presentation (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Dec. 31, 2011	Jun. 30, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Increase in income tax expense resulting from purchase accounting adjustment		$ 20
Decrease in goodwill resulting from purchase accounting adjustment	$ (20)

Purchase accounting adjustments needed to revise the carrying amount of goodwill to fair value.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Subparagraph e

-Paragraph 45

-Clause 7

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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