Stock-Based Compensation (Schedule Of Stock Option Activity) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	6 Months Ended
	Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options, Outstanding, Beginning Balance	7,802
Options, Granted	7
Options, Exercised	(1,822)
Options, Forfeited, cancelled or expired	(537)
Options, Outstanding, Ending Balance	5,450
Options, Vested and expected to vest	5,430
Options, Exercisable	5,204
Weighted-average exercise price of options outstanding, beginning balance	$ 34.17
Weighted-average exercise price of options granted during period	$ 21.02
Weighted-average exercise price of options exercised during the period	$ 17.98
Weighted-average exercise price of options forfeited, cancelled or expired during the period	$ 45.90
Weighted-average exercise price of options outstanding, ending balance	$ 38.41
Weighted-average exercise price of options vested and expected to vest	$ 38.49
Weighted-average exercise price of options exercisable	$ 39.46
Weighted-average remaining contractual term of options outstanding	3 years 10 months 5 days
Weighted-average remaining contractual term of options vested and expected to vest	3 years 10 months
Weighted-average remaining contractual term of options exercisable	3 years 7 months 28 days
Aggregate intrinsic value of options outstanding	$ 17
Aggregate intrinsic value of options vested and expected to vest	17
Aggregate intrinsic value of options exercisable	$ 14