(Schedule Of Stock-Based Compensation Expense By Statement Of Operations Line Item) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Stock-based compensation expense $ 144 $ 150 $ 164
Cost of revenue [Member]      
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Stock-based compensation expense 2 2 2
Research And Development      
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Stock-based compensation expense 82 90 94
Marketing and sales      
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Stock-based compensation expense 21 26 30
General And Administrative [Member]      
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Stock-based compensation expense $ 39 $ 32 $ 38