Interest And Other Income (Expense), Net (Schedule Of Interest And Other Income (Expense), Net) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Interest and Other Income [Abstract]
Loss on Conversion of Convertible Notes	$ 0	$ 0	$ (10)
Interest expense	(44)	(47)	(28)
Interest income	50	25	15
Net gain (loss) on foreign currency transactions	18	(40)	(14)
Net gain (loss) on foreign currency forward contracts	(16)	46	15
Other income, net	7	2	1
Interest and other income (expense), net	$ 15	$ (14)	$ (21)