Stock-Based Compensation (Tables)

3 Months Ended

Jun. 30, 2015

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

Schedule of assumptions used in the Black-Scholes valuation model

	Three Months Ended June 30,
	2014
Risk-free interest rate	1.1 - 1.8%
Expected volatility	37 - 40%
Weighted-average volatility	38	%
Expected term	4.5 years
Expected dividends	None

Schedule Of Assumptions Used In Monte Carlo Simulation Model

	Three Months Ended June 30,
	2015		2014
Risk-free interest rate	1.0	%	0.9	%
Expected volatility	14 - 50%		16 - 79%
Weighted-average volatility	26	%	30	%
Expected dividends	None		None

Schedule Of Stock-Based Compensation Expense By Statement Of Operations

	Three Months Ended June 30,
	2015		2014
Research and development	$	26	$	16
Marketing and sales	5		4
General and administrative	14		9
Stock-based compensation expense	$	45	$	29

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

	Options (in thousands)		Weighted- Average Exercise Prices		Weighted- Average Remaining Contractual Term  (in years)	Aggregate Intrinsic Value (in millions)
Outstanding as of March 31, 2015	4,920		$	37.44
Granted	2		59.33
Exercised	(985	)	45.79
Forfeited, cancelled or expired	(49	)	35.41
Outstanding as of June 30, 2015	3,888		$	35.35	5.84	$	126
Vested and expected to vest	3,648		$	35.61	5.65	$	117
Exercisable as of June 30, 2015	2,456		$	37.59	4.18	$	74

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

	Restricted Stock Rights (in thousands)		Weighted- Average Grant Date Fair Values
Balance as of March 31, 2015	10,855		$	26.20
Granted	2,177		62.64
Vested	(4,714	)	20.55
Forfeited or cancelled	(368	)	29.96
Balance as of June 30, 2015	7,950		$	39.35

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

	Market-Based Restricted  Stock Units (in thousands)		Weighted- Average  Grant Date Fair Value
Balance as of March 31, 2015	663		$	31.82
Granted	395		79.81
Vested	(742	)	25.77
Vested above target	371		25.77
Forfeited or cancelled	(45	)	34.84
Balance as of June 30, 2015	642		$	69.51