Stock-Based Compensation And Employee Benefit Plans (Schedule Of Stock Option Activity) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Outstanding as of March 31, 2012	9,774
Options, Granted	296
Options, Exercised	(69)
Options, Forfeited, cancelled or expired	(2,199)
Options, Outstanding as of March 31, 2013	7,802
Options, Vested and expected to vest	7,755
Options, Exercisable	7,293
Weighted-Average Exercise Prices, Outstanding as of March 31, 2012	$ 34.17
Weighted-Average Exercise Prices, Granted	$ 13.15
Weighted-Average Exercise Prices, Exercised	$ 15.17
Weighted-Average Exercise Prices, Forfeited, cancelled or expired	$ 32.02
Weighted-Average Exercise Prices, Outstanding as of March 31, 2013	$ 34.17
Weighted Average Exercise Price, Vested and Expected to Vest	$ 34.28
Weighted-Average Exercise Prices, Exercisable	$ 35.38
Weighted Average Remaining Contractual Term, Outstanding as of March 31, 2013	4 years 6 months 15 days
Weighted Average Remaining Contractual Term, Vested and Expected to Vest	4 years 6 months 0 days
Weighted-Average Remaining Contractual Term, Exercisable	4 years 3 months 15 days
Aggregate Intrinsic Value, Outstanding as of March 31, 2013	$ 4
Aggregate Intrinsic Value, Vested and expected to vest	3
Aggregate Intrinsic Value, Exercisable	$ 3