Stock Plans 2 (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2013
Unrecognized share-based compensation costs
Unrecognized share-based compensation costs	$ 86
Weighted average period expected to be recognized	1 year 10 months 24 days
Stock Option Awards [Member]
Unrecognized share-based compensation costs
Unrecognized share-based compensation costs	6
Weighted average period expected to be recognized	2 years 3 months 18 days
Restricted Stock Units [Member]
Unrecognized share-based compensation costs
Unrecognized share-based compensation costs	15
Weighted average period expected to be recognized	1 year 10 months 24 days
Restricted Stock Awards [Member]
Unrecognized share-based compensation costs
Unrecognized share-based compensation costs	54
Weighted average period expected to be recognized	1 year 8 months 12 days
Performance Share Units [Member]
Unrecognized share-based compensation costs
Unrecognized share-based compensation costs	$ 11
Weighted average period expected to be recognized	2 years 8 months 12 days