Description Of Business And Basis Of Presenation (Reclassifications) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reclassifications [Line Items]
Research and development	$ 283	$ 306	$ 561	$ 588
Marketing and sales	164	219	311	370
General and administrative	129	100	214	188
As previously reported
Reclassifications [Line Items]
Research and development		314		604
Marketing and sales		212		357
General and administrative		99		185
Change
Reclassifications [Line Items]
Research and development		(8)		(16)
Marketing and sales		7		13
General and administrative		1		3
Reclassified balance
Reclassifications [Line Items]
Research and development		306		588
Marketing and sales		219		370
General and administrative		$ 100		$ 188