Summary of Significant Accounting Policies (Tables)

12 Months Ended

Mar. 31, 2015

Summary of Stock-Based Compensation Expense of Stock Options and Restricted Stock Units

The following tables summarize the allocation of the stock-based compensation expense (in thousands):



	Fiscal Years Ended March 31,
	2015		2014			2013
Stock-based compensation expense by type of grant:
Option grants and employee stock purchase rights	$	1,408	$	2,520		$	3,469
Restricted stock units	16,892		14,517			20,620
	18,300		17,037			24,089
Stock-based compensation expensed from (capitalized to) inventory	5		(16		)	147
Total stock-based compensation expense	$	18,305	$	17,021		$	24,236

Summary of Stock-Based Compensation Expense



	Fiscal Years Ended March 31,
	2015		2014			2013
Stock-based compensation expense by cost centers:
Cost of revenues	$	285	$	460		$	545
Research and development	11,657		6,371			11,760
Selling, general and administrative	6,358		10,206			11,784
	18,300		17,037			24,089
Stock-based compensation expensed from (capitalized to) inventory	5		(16		)	147
Total stock-based compensation expense	$	18,305	$	17,021		$	24,236

Schedule of Weighted-Average Assumptions Used to Estimate the Fair Value of Stock Options

The fair values of the options and employee stock purchase rights granted are estimated as of the grant date using the Black-Scholes option-pricing model with the following weighted-average assumptions:



	Options							Employee Stock Purchase Rights
	Fiscal Years Ended March 31,							Fiscal Years Ended March 31,
	2015	2014			2013			2015			2014			2013
Expected life (years)	*	4.4			4.4			0.5			0.5			0.5
Risk-free interest rate	*	0.6		%	0.7		%	0.1		%	—		%	—		%
Volatility	*	0.49			0.54			0.57			0.56			0.50
Dividend yield	*	—		%	—		%	—		%	—		%	—		%
Expected forfeiture rate	*	5.8		%	6.6		%	—		%	—		%	—		%
Weighted average fair value	*	$	2.95		$	2.47		$	2.17		$	3.40		$	1.77

* The Company did not grant options during the twelve months ended March 31, 2015.