Stock Plans 6 (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Summarizes Information on Shares Exercised [Abstract]
Cash received from options exercised	$ 37	$ 10	$ 11
Intrinsic value of options exercised	9	2	2
Excess tax benefits from options exercised	$ 3
Excess tax benefits from options exercised		Less than $1 million	Less than $1 million

The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph c(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (d)(2)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration