Income Taxes - Out of Period Adjustments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Jun. 30, 2013 Income tax benefit related to 2012 and 2011	Sep. 30, 2012 Income tax expense related to 2011 and 2010
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Out of period adjustments	$ 3	$ 3

Amount of each individual error being corrected in the correcting adjustment.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 250

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SAB TOPIC 1.N.Q3)

-URI http://asc.fasb.org/extlink&oid=26874127&loc=d3e30840-122693

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 1

-Section N

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