Description Of Business And Basis Of Presentation Description Of Business And Basis Of Presenation (Reclassifications) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Reclassifications [Line Items]
Research and development	$ 278	$ 282
Marketing and sales	147	151
General and administrative	85	88
As previously reported [Member]
Reclassifications [Line Items]
Research and development		290
Marketing and sales		145
General and administrative		86
Change [Member]
Reclassifications [Line Items]
Research and development		(8)
Marketing and sales		6
General and administrative		2
Reclassified balance [Member]
Reclassifications [Line Items]
Research and development		282
Marketing and sales		151
General and administrative		$ 88