Stock Plans - Additional Information (Detail) (USD $)	12 Months Ended				12 Months Ended	1 Months Ended			1 Months Ended	12 Months Ended				12 Months Ended			12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010	Mar. 31, 2013 Employee Stock	Sep. 30, 2011 2011 Employee stock purchase plan	Sep. 07, 2011 2011 Employee stock purchase plan	Mar. 31, 2013 1999 Stock option and incentive plan	Sep. 30, 2011 2007 Equity incentive plan	Mar. 31, 2013 2007 Equity incentive plan	Mar. 31, 2012 2007 Equity incentive plan	Mar. 31, 2011 2007 Equity incentive plan	Sep. 07, 2011 2007 Equity incentive plan	Mar. 31, 2013 2007 Equity incentive plan Minimum	Mar. 31, 2013 2007 Equity incentive plan Maximum Y	Sep. 07, 2011 2007 Equity incentive plan Common Stock Voting	Mar. 31, 2013 Incentive options Maximum Y
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, equity awards reserved for issuance							2,500,000						13,000,000			8,000,000
Maximum payroll deductions for purchase of shares by participants							20.00%
Maximum number of shares available for purchased by participants						2,000
Cap on fair value of shares available for purchase by participants						$ 25,000
Percentage of common stock price for employees						85.00%
Shares purchased by employees					184,936
Shares issued under ESPP plan, weighted average purchase price per share					$ 24.58
Shares available for future issuance under the ESPP					2,315,064
Stock Options, Number of Shares, Outstanding - March 31, 2013	154,000	240,892	325,519	813,741				154,000
Weighted average exercise price per outstanding option	$ 6.63	$ 6.63	$ 6.35	$ 7.60				$ 6.63
Restoration ratio of restricted stock unit grants withheld									2
Reduction for each share of common stock pursuant to option										1
Reduction for each share of common stock pursuant to other than option										2
Equity awards outstanding										1,871,148
Percentage of incentive stock option granted										110.00%
Share-based awards generally vest, years										4 years
Percentage of fair market value of common stock														100.00%
Percentage of voting stock														10.00%
Term of options granted, years															10		5
Percentage of annualized forfeiture rate for awards granted to directors										0.00%	0.00%	0.00%
Percentage of annualized forfeiture rate for awards granted to senior executives and remaining employees										10.00%	10.00%	10.00%
Shares available for grant										7,602,328
Total unrecognized cost related to restricted stock unit awards	$ 8,700,000
Unrecognized cost, period for recognition, years	1 year 9 months 18 days