Stock-Based Compensation And Employee Benefit Plans (Schedule of Share Repurchases) (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended		23 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016
Equity, Class of Treasury Stock [Line Items]
Stock Repurchased and Retired During Period, Value	$ 1,018	$ 337
July 2012 Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount	750		$ 750
Stock Repurchased and Retired During Period, Value	$ 461	$ 0
Stock repurchased and retired during period, Shares	6.9	0.0
Fiscal Year 2016 Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount		$ 1,000
Stock Repurchased and Retired During Period, Value	$ 500	$ 0
Stock repurchased and retired during period, Shares	7.8	0.0
Repurchase program, total
Equity, Class of Treasury Stock [Line Items]
Stock Repurchased and Retired During Period, Value	$ 1,018	$ 337
Stock repurchased and retired during period, Shares	15.7	8.2
May 2014 Repurchase Program [Member] [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchased and Retired During Period, Value	$ 57	$ 337	$ 394
Stock repurchased and retired during period, Shares	1.0	8.0	9.2