Subsequent Events - Additional Information (Detail) (USD $)	1 Months Ended					0 Months Ended
Jul. 31, 2012	Oct. 29, 2012	Sep. 30, 2012	Sep. 30, 2011	Oct. 24, 2012 Dividend Declared	Oct. 19, 2012 Repurchase of Equity	Oct. 29, 2012 Payment Covered Litigation
Settlement payable		$ (350,000,000)	$ (719,000,000)	$ (449,000,000)			$ 350,000,000
Dividends, per share amount declared			$ 0.22		$ 0.33
Share repurchase plan, authorized amount	$ 1,000,000,000					$ 1,500,000,000

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 32

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

Name:	us-gaap_DividendsPayableAmountPerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant