Summary of Significant Accounting Policies (Tables)

12 Months Ended

Mar. 31, 2014

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 Year Ended March 31,
	2014			2013		2012
Stock-based compensation expense by type of award:
Option grants and employee stock purchase rights	$	2,520		$	3,469	$	5,289
Restricted stock units	14,517			20,620		13,148
Total stock-based compensation	17,037			24,089		18,437
Stock-based compensation expensed from (capitalized to) inventory	(16		)	147		(63		)
Total stock-based compensation expense	$	17,021		$	24,236	$	18,374

Summary of Stock-Based Compensation Expense



	Fiscal Year Ended March 31,
	2014			2013		2012
Stock-based compensation expense by cost centers:
Cost of revenues	$	460		$	545	$	495
Research and development	6,371			11,760		10,496
Selling, general and administrative	10,206			11,784		7,446
Total stock-based compensation	17,037			24,089		18,437
Stock-based compensation expensed from (capitalized to) inventory	(16		)	147		(63		)
Total stock-based compensation expense	$	17,021		$	24,236	$	18,374

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,
	2014			2013			2012			2014			2013			2012
Expected life (years)	4.4			4.4			3.8			0.5			0.5			0.5
Risk-free interest rate	0.6		%	0.7		%	1.4		%	—		%	—		%	0.1		%
Volatility	0.49			0.54			0.48			0.56			0.50			0.55
Dividend yield	—		%	—		%	—		%	—		%	—		%	—		%
Expected forfeiture rate	5.8		%	6.6		%	6.8		%	—		%	—		%	—		%
Weighted average fair value	$	2.95		$	2.47		$	3.83		$	3.40		$	1.77		$	2.13