Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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

Debt (Details) (USD $)	3 Months Ended			3 Months Ended		12 Months Ended
Debt (Details) (USD $)	Mar. 31, 2013 Revolving Credit Facility	Jan. 31, 2013 Revolving Credit Facility	Sep. 30, 2012 Revolving Credit Facility	Mar. 31, 2013 Revolving Credit Facility Minimum	Mar. 31, 2013 Revolving Credit Facility Maximum	Feb. 09, 2014 Commercial paper	Feb. 07, 2013 Commercial paper	Feb. 06, 2013 Commercial paper
Debt Instrument [Line Items]
Commercial Paper Program, Amount							$ 3,000,000,000	$ 500,000,000
Commercial Paper Program, Maturity Period						397 days
Credit Facility Maximum Borrowing Capacity		$ 3,000,000,000	$ 3,000,000,000
Credit Facility Interest Rate During Period				0.00%	0.75%
Credit Facility Commitment Fee Percentage	0.05%