Summary of Significant Accounting Policies (Tables)

12 Months Ended

Mar. 31, 2013

Accounting Policies [Abstract]

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

The following table summarizes stock-based compensation expense related to stock options and restricted stock units for the three fiscal years ended March 31, 2013, which is as follows (in thousands, except per share data):

	Fiscal Year Ended March 31,
	2013		2012			2011
Stock-based compensation expense by type of award
Stock options (including employee stock purchase program) and warrants	$	3,469	$	5,289		$	5,600
Restricted stock units	20,620		13,148			11,062
Total stock-based compensation	24,089		18,437			16,662
Stock-based compensation expensed from (capitalized to) inventory	147		(63		)	22
Total stock-based compensation expense	$	24,236	$	18,374		$	16,684

Summary of Stock-Based Compensation Expense

The following table summarizes stock-based compensation expense as it relates to the Company’s statements of operations (in thousands):

	Fiscal Year Ended March 31,
	2013		2012			2011
Stock-based compensation expense by cost centers
Cost of revenues	$	545	$	495		$	628
Research and development	11,760		10,496			9,001
Selling, general and administrative	11,784		7,446			7,033
Total stock-based compensation	24,089		18,437			16,662
Stock-based compensation expensed from (capitalized to) inventory	147		(63		)	22
Total stock-based compensation expense	$	24,236	$	18,374		$	16,684

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

The fair values of the options and employee stock purchase plan awards granted are estimated as of the grant date using the Black-Scholes option-pricing model assuming the weighted-average assumptions listed in the following table:

	Employee Stock Options									Employee Stock Purchase Plans
	Fiscal Years Ended March 31,									Fiscal Years Ended March 31,
	2013			2012			2011			2013			2012			2011
Expected life (years)	4.4			3.8			4.0			0.5			0.5			0.5
Risk-free interest rate	0.7		%	1.4		%	1.6		%	—		%	0.1		%	0.2		%
Volatility	0.54			0.48			0.51			0.50			0.55			0.50
Dividend yield	—		%	—		%	—		%	—		%	—		%	—		%
Expected forfeiture rate	6.6		%	6.8		%	6.6		%	—		%	—		%	—		%
Weighted average fair value	$	2.47		$	3.83		$	4.85		$	1.77		$	2.13		$	3.09