Stock-Based Compensation (Schedule Of Stock Option Activity) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	9 Months Ended
	Dec. 31, 2011 years
Stock-Based Compensation [Abstract]
Options, Outstanding, Beginning Balance	12,899
Options, Granted	431
Exercised	(1,145)
Options, Forfeited, cancelled or expired	(2,151)
Options, Outstanding, Ending Balance	10,034
Options, Exercisable	8,440
Weighted-average exercise price of options outstanding, beginning balance	$ 31.39
Weighted-average exercise price of options granted during period	$ 20.79
Weighted-average exercise price of options exercised during the period	$ 19.61
Weighted-average exercise price of options forfeited, cancelled or expired during the period	$ 23.90
Weighted-average exercise price of options outstanding, ending balance	$ 33.90
Weighted-average exercise price of options exercisable	$ 35.43
Weighted-average remaining contractual term (in years) of options outstanding	5.15
Weighted-average remaining contractual term (in years) of options exercisable	4.69
Aggregate intrinsic value of options outstanding	$ 10
Aggregate intrinsic value of options exercisable	$ 9