Stock-Based Compensation And Employee Benefit Plans (Tables)

12 Months Ended

Mar. 31, 2017

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule Of Assumptions Used In The Black-Scholes Valuation Model

	Stock Option Grants		ESPP Purchase Rights
	Year Ended March 31,		Year Ended March 31,
	2015		2017		2016		2015
Risk-free interest rate	1.1 - 1.9%		0.5 - 0.8%		0.3 - 0.6%		0.04 - 0.2%
Expected volatility	36 - 40%		25 - 32%		32 - 36%		30 - 35%
Weighted-average volatility	38	%	27	%	33	%	34	%
Expected term	4.5 years		6 - 12 months		6 - 12 months		6 - 12 months
Expected dividends	None		None		None		None

Schedule Of Assumptions Used In Monte-Carlo Simulation Model

The assumptions used in the Monte-Carlo simulation model to value our market-based restricted stock units were as follows: 

	Year Ended March 31,
	2017		2016		2015
Risk-free interest rate	0.8	%	1.0	%	0.9	%
Expected volatility	16 - 57%		14 - 53%		16 - 79%
Weighted-average volatility	29	%	26	%	30	%
Expected dividends	None		None		None

Schedule Of Stock-Based Compensation Expense By Statement Of Operations

The following table summarizes stock-based compensation expense resulting from stock options, restricted stock units, market-based restricted stock units, and the ESPP purchase rights included in our Consolidated Statements of Operations (in millions):

	Year Ended March 31,
	2017		2016		2015
Cost of revenue	$	3	$	2	$	2
Research and development	109		103		82
Marketing and sales	31		24		21
General and administrative	53		49		39
Stock-based compensation expense	$	196	$	178	$	144

Summary Of Outstanding And Exercisable Stock Options

The following table summarizes outstanding and exercisable stock options as of March 31, 2017:

	Options Outstanding						Options Exercisable
Range of Exercise Prices	Number of Shares (in thousands)	Weighted- Average Remaining Contractual Term  (in years)	Weighted- Average Exercise Prices		Potential Dilution		Number of Shares (in thousands)	Weighted- Average Exercise Prices		Potential Dilution
$11.53 - $23.61	178	2.48	$	19.40	0.1	%	178	$	19.40	0.1	%
26.25 - 26.25	950	6.58	26.25		0.3	%	770	26.25		0.2	%
33.60 - 35.70	597	7.22	35.45		0.2	%	372	35.30		0.1	%
36.00 - 58.14	652	2.44	45.59		0.2	%	583	46.59		0.2	%
$11.53 - $58.14	2,377	5.30	$	33.35	0.8	%	1,903	$	33.61	0.6	%

Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity [Table Text Block]

The following table summarizes our ESPP activity for fiscal years ended March 31, 2017, 2016 and 2015:

	Shares Issued (in millions)	Exercise Prices for Purchase Rights	Weighted-Average Fair Values of Purchase Rights
Fiscal Year 2015	1.4	$22.64 - $32.16	$	8.26
Fiscal Year 2016	0.9	$32.16 - $54.78	$	12.97
Fiscal Year 2017	0.7	$54.60 - $67.56	$	17.93

Shares Repurchased and Retired

The following table summarizes total shares repurchased during fiscal years 2017, 2016, and 2015:

	May 2014 Program			May 2015 Program			February 2016 Program			Total
(In millions)	Shares	Amount		Shares	Amount		Shares	Amount		Shares	Amount
Fiscal Year 2015	8.2	$	337	—	$	—	—	$	—	8.2	$	337
Fiscal Year 2016	1.0	$	57	6.9	$	461	7.8	$	500	15.7	$	1,018
Fiscal Year 2017	—	$	—	6.5	$	508	—	$	—	6.5	$	508

Employee Stock Option [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Disclosure Of Stock-Based Compensation Arrangements By Stock-Based Payment Award

The following table summarizes our stock option activity for the fiscal year ended March 31, 2017:

	Options (in thousands)		Weighted- Average Exercise Prices		Weighted- Average Remaining Contractual Term  (in years)	Aggregate Intrinsic Value (in millions)
Outstanding as of March 31, 2016	3,278		$	35.09
Granted	6		74.93
Exercised	(876	)	40.04
Forfeited, cancelled or expired	(31	)	35.75
Outstanding as of March 31, 2017	2,377		$	33.35	5.30	$	134
Vested and expected to vest	2,358		$	33.38	5.29	$	132
Exercisable as of March 31, 2017	1,903		$	33.61	4.88	$	106

Restricted Stock Rights [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Disclosure Of Stock-Based Compensation Arrangements By Stock-Based Payment Award

Each restricted stock unit granted reduces the number of shares available for grant by 1.43 shares under our Equity Plan. The following table summarizes our restricted stock units activity, excluding market-based restricted stock unit activity which is discussed below, for the fiscal year ended March 31, 2017:

	Restricted Stock Units (in thousands)		Weighted- Average Grant Date Fair Values
Balance as of March 31, 2016	7,157		$	44.04
Granted	2,734		76.60
Vested	(4,126	)	37.28
Forfeited or cancelled	(612	)	58.34
Balance as of March 31, 2017	5,153		$	65.03

Market Based Restricted Stock Units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Disclosure Of Stock-Based Compensation Arrangements By Stock-Based Payment Award

The following table summarizes our market-based restricted stock unit activity for the year ended March 31, 2017:

	Market-Based Restricted  Stock Units (in thousands)		Weighted- Average  Grant Date Fair Value
Balance as of March 31, 2016	636		$	64.49
Granted	353		98.04
Vested	(558	)	50.08
Vested above target	238		44.99
Forfeited or cancelled	(28	)	84.94
Balance as of March 31, 2017	641		$	87.37