Borrowings Borrowings, additional information (Details) (USD $) In Billions, unless otherwise specified		0 Months Ended
Sep. 29, 2012 Existing Line Of Credit Expiring 2015	Sep. 29, 2012 Existing Line of Credit Expiring 2017	Mar. 15, 2013 New 364 Day Line of Credit	Mar. 30, 2013 Minimum Line of Credit	Mar. 30, 2013 Maximum Line of Credit
Line of Credit Facility
Line of Credit Facility, Maximum Borrowing Capacity	$ 2.25	$ 2.25	$ 1.50
Line of Credit Facility, Maturity Year	2015	2017
Line of Credit Facility, Maturity Period			364 days
Debt Instrument Interest Over London Interbank Offered Rate Rate				0.23%	1.93%

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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