Stock-Based Compensation And Employee Benefit Plans (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended					12 Months Ended											12 Months Ended				12 Months Ended					1 Months Ended	12 Months Ended		17 Months Ended	1 Months Ended	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2014 Minimum [Member]	Mar. 31, 2014 Maximum [Member]	Mar. 31, 2014 Restricted Stock Rights [Member]	Mar. 31, 2013 Restricted Stock Rights [Member]	Mar. 31, 2012 Restricted Stock Rights [Member]	Mar. 31, 2014 Employee Stock Option [Member]	Mar. 31, 2013 Employee Stock Option [Member]	Mar. 31, 2012 Employee Stock Option [Member]	Mar. 31, 2014 Performance Based Restricted Stock Units [Member]	Mar. 31, 2014 Market Based Restricted Stock Units [Member]	Mar. 31, 2013 Market Based Restricted Stock Units [Member]	Mar. 31, 2012 Market Based Restricted Stock Units [Member]	Mar. 31, 2014 Market Based Restricted Stock Units [Member] Target	Mar. 31, 2014 Employee Stock [Member]	Mar. 31, 2013 Employee Stock [Member]	Mar. 31, 2012 Employee Stock [Member]	Jul. 31, 2013 Employee Stock [Member]	Mar. 31, 2014 Employee Stock [Member] Minimum [Member]	Mar. 31, 2014 Employee Stock [Member] Maximum [Member]	Mar. 31, 2014 Equity Plan [Member]	Jul. 31, 2013 Equity Plan [Member]	Jul. 26, 2012 Equity Plan [Member]	Feb. 28, 2011 February 2011 Repurchase Program [Member]	Mar. 31, 2013 February 2011 Repurchase Program [Member]	Mar. 31, 2012 February 2011 Repurchase Program [Member]	Jun. 30, 2012 February 2011 Repurchase Program [Member]	Jul. 31, 2012 July 2012 Repurchase Program [Member]	Mar. 31, 2013 July 2012 Repurchase Program [Member]	Mar. 31, 2014 Fiscal Year 2014 Repurchase Program [Member]	Mar. 31, 2013 Repurchase Program, Total [Member]	Mar. 31, 2012 Repurchase Program, Total [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to stock-based compensation						$ 220			$ 9				$ 14
Weighted-average service period						1 year 7 months			3 years 7 months
Tax costs from exercise of stock options									(13)		(3)
Tax benefit from stock options exercised										1
Deferred tax write-offs										1	1
Excess tax benefit from stock-based compensation	13	0	4								4
Percentage discount that employees, officers and directors may purchase of stock lesser of market value																							100.00%
Number of years in which stock options generally expire (years)																							10 years
Percentage in which stock options become exercisable for after one year from date of grant																							24.00%
Number of months in which stock options ratably exercise after one year																							38 months
Increase in number of shares authorized																				7,000,000				18,000,000
Number of shares available for grant						17,000,000			24,200,000
Options Outstanding, Weighted-Average Remaining Contractual Term (in years)	4 years 7 months 1 day
Options outstanding, aggregate intrinsic value	18
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value									$ 8.61	$ 4.64	$ 7.27
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value									16		4
Shares used as denominator for computation of potential dilution from options outstanding	311,000,000	302,000,000
Reduction in shares available per grant of stock right						1.43
Weighted-average grant date fair value of stock-based compensation granted during period						$ 23.01	$ 12.85	$ 21.38					$ 29.52	$ 12.41	$ 33.70		$ 4.67	$ 4.83	$ 4.98
Grant date fair value of stock-based compensation vested during period						120.0	143.0	165.0				1.0	4.9	3.7
Percentage range of shares received at vesting based on total stockholder return ("TSR")				0.00%	200.00%
Target percentage of presented shares granted that may potentially vest																100.00%
Maximum number of common shares to be earned during the performance period, Grants													1,100,000
Maximum number of common shares to be earned during the performance period, Outstanding													2,000,000
Minimum Percentage That Employees Authorized For Payroll Deductions																	2.00%
Maximum percentage that employees authorized for payroll deductions																	10.00%
Discount percent																	85.00%
Shares issued under the Employee Stock Purchase Plan during period																	2,000,000
Exercise prices for purchase rights																					$ 11.33	$ 22.64
Assets value under deferred compensation plan	9	11
Liabilities under deferred compensation plan	9	12
Contribution to 401 (k) plan and Registered Retirement Savings Plan	9	14	13
Stock Repurchase Program, Authorized Amount																										600				500		750
Stock repurchase program, period in force																										18 months
Stock repurchased and retired during period, shares																											4,000,000	25,000,000	32,000,000		22,000,000		26,000,000	25,000,000
Repurchase and retirement of common stock			(471)																								(71)	(471)			(278)		349	(471)
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized																								4,000,000	2,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value									$ 2	$ 11	$ 15