Stockholders' Equity - Additional Information (Details) (USD $)	12 Months Ended				12 Months Ended								1 Months Ended	12 Months Ended			1 Months Ended												12 Months Ended		12 Months Ended			1 Months Ended		0 Months Ended	1 Months Ended		12 Months Ended		104 Months Ended	4 Months Ended	12 Months Ended		1 Months Ended
	Mar. 31, 2013 Approved_Plan	Mar. 31, 2012	Mar. 31, 2011	May 17, 2009	Mar. 31, 2013 RSU plan post May 2006 [Member]	Mar. 31, 2013 Minimum [Member]	Mar. 31, 2013 Maximum [Member]	Mar. 31, 2013 Structured stock repurchase agreements [Member]		Mar. 31, 2012 Structured stock repurchase agreements [Member]	Apr. 30, 2011 Company's 2011 Equity Incentive Plan [Member] Minimum [Member]	Apr. 30, 2011 Company's 2011 Equity Incentive Plan [Member] Maximum [Member]	Feb. 29, 2012 Restricted Stock Units (RSUs) [Member]	Mar. 31, 2013 Restricted Stock Units (RSUs) [Member]	Mar. 31, 2013 Restricted Stock Units (RSUs) [Member] RSU plan prior to May 2006 [Member]	Mar. 31, 2013 Restricted Stock Units (RSUs) [Member] RSU plan post May 2006 [Member] quarter	Nov. 30, 2011 Restricted Stock Units (RSUs) [Member] Minimum [Member] November 2011 and February 2012 Plan [Member]	Nov. 30, 2011 Restricted Stock Units (RSUs) [Member] Maximum [Member] November 2011 and February 2012 Plan [Member]	May 31, 2009 First Milestone - From Fiscal 2010 To 2013 [Member]	May 31, 2009 Second Milestone - From Fiscal 2010 To 2013 [Member]	May 31, 2009 Second Milestone - Fiscal 2014 [Member]	May 31, 2009 Third Milestone - Fiscal 2013 [Member]	May 31, 2009 Third Milestone - Fiscal 2010 To 2012 [Member]	May 31, 2012 Performance-Based RSU [Member]	May 31, 2009 Performance-Based RSU [Member] May 2009 Plan [Member]	Apr. 30, 2011 Performance-Based RSU [Member] April 2011 Plan [Member]	Feb. 29, 2012 Performance-Based RSU [Member] November 2011 and February 2012 Plan [Member]	Aug. 31, 2012 Employee Stock Purchase Plan [Member] 2012 Plan [Member]	Mar. 31, 2013 Employee Stock Purchase Plan [Member] 2012 Plan [Member]	Aug. 30, 2012 Employee Stock Purchase Plan [Member] 2012 Plan [Member]	Mar. 31, 2013 Employee Stock Purchase Plan [Member] 1998 Plan [Member]	Mar. 31, 2012 Employee Stock Purchase Plan [Member] 1998 Plan [Member]	Aug. 30, 2010 Employee Stock Purchase Plan [Member] 1998 Plan [Member]	Feb. 29, 2012 Chief Executive Officer [Member]	May 31, 2009 Chief Executive Officer [Member]	Mar. 31, 2013 August 2004 [Member]	Oct. 31, 2008 August 2004 [Member]	Aug. 31, 2004 August 2004 [Member]	Mar. 31, 2013 August 2004 [Member]	Mar. 31, 2012 August 2004 [Member]	Mar. 31, 2013 August 2004 [Member]	May 31, 2011 Rule 10b5-1 [Member]	Mar. 31, 2012 Rule 10b5-1 [Member]	Feb. 28, 2011 Rule 10b5-1 [Member]	May 31, 2012 First Vesting Period [Member] November 2011 and February 2012 Plan [Member]	May 31, 2012 Second Vesting Period [Member] November 2011 and February 2012 Plan [Member]
Stockholders Equity [Line Items]
Preferred stock, shares authorized for issuance	2,000,000	2,000,000
Common stock, shares authorized for issuance	375,000,000	375,000,000
Common stock, shares outstanding	67,952,000	61,879,000
Common stock, shares issued	67,952,000	61,879,000
Stock repurchase program, authorized amount	$ 300,000,000																																			$ 15,900,000		$ 200,000,000
Increase in the amount authorized for stock purchase program																																					100,000,000
Stock repurchase program, shares repurchased								9,989,000	[1]																														100,000	3,500,000	17,300,000	1,000,000	300,000
Stock repurchase program, weighted average price per share								$ 11.06	[1]																														$ 5.18	$ 5.98	$ 10.04	$ 10.00	$ 9.98
Shares authorized for repurchase																																												3,000,000
Structured stock repurchase agreement, amount										10,000,000
Structured stock repurchase agreement, shares received										1,000,000
Structured stock repurchase agreements, effective purchase price per share										$ 9.74
Gain recorded to additional paid-in-capital								12,800,000
Adjusted average price per share for repurchases								$ 9.78
Total repurchases, price per share, adjusted from gains settlements in cash	$ 9.97
Number of stockholder-approved plans	2
Number of plans unapproved by stockholders	4
Shares available for future issuance											4,200,000	10,900,000																		1,800,000
Options expiration period, in years	10 years
Vesting period, in years	3 years													4 years	4 years	4 years	1 year	18 months						1 year
Vesting and exercisable rate of new hire grants, percentage	25.00%
Vesting and exercisable rate of new hire grants, grant date						36 months	48 months
Awards granted	40,000	250,000	599,000										500,000																						300,000
Value of stock options awarded																																		3,700,000	1,100,000
Shares expected to vest	2,994,000	3,119,000	3,810,000																75,000	75,000		150,000
Annual target revenue																			270,000,000	310,000,000	350,000,000
Percentage of annual operating margin required for vesting of shares under milestone																						13.50%	15.00%
Pre-tax intrinsic value of options outstanding	500,000
Pre-tax intrinsic value of options exercisable	600,000
Pre-tax intrinsic value of options exercised	300,000
Number of shares vested					0
Award vesting period, quarters																12
Term of award																								P12M	P3Y	P3Y	P18M
Award vesting percentage																																													66.67%	33.33%
Weighted average remaining contractual term for the restricted stock units outstanding, in years	1 year 2 months 12 days
Aggregate pre-tax intrinsic value of restricted stock units outstanding which includes performance based awards which are subject to milestone attainments	47,800,000
Stock Issued During Period, Value, Restricted Stock Award, Gross	14,600,000
Common stock reserved for issuance	13,173,000																														4,800,000		6,300,000
Percentage of purchase price of common stock equal to fair market value																													85.00%
Common stock, shares issued, employee stock purchase plan																												1,200,000	600,000		400,000	900,000
Number of years of development work to be performed				5 years
Stock-based compensation expense related to the acceleration of Veloce warrants	$ 1,289,000	$ 0	$ 0

[1] The amounts above do not include gains recorded to additional paid-in-capital of $12.8 million from structured stock repurchase agreements which settled in cash. The average price per share for structured stock repurchase agreements adjusted for gains from settlements in cash would have been $9.78 per share and for total repurchases would have been $9.97 per share.