Stockholders' Equity (Details Textual) (USD $)	1 Months Ended			6 Months Ended			6 Months Ended					1 Months Ended	6 Months Ended		1 Months Ended	6 Months Ended		1 Months Ended							1 Months Ended			6 Months Ended	1 Months Ended								6 Months Ended						1 Months Ended
	May 31, 2012	Oct. 31, 2008	Aug. 31, 2004	Sep. 30, 2012 Approved_Plan	Mar. 31, 2012	May 15, 2006	Sep. 30, 2012 Minimum [Member]	Sep. 30, 2012 Maximum [Member]	Sep. 30, 2012 Employee Stock Purchase Plan [Member]	Sep. 30, 2011 Employee Stock Purchase Plan [Member]	Aug. 30, 2010 Employee Stock Purchase Plan [Member]	Aug. 31, 2012 Employee Stock Purchase Plan [Member] Two Thousand Twelve Plan [Member]	Sep. 30, 2012 Employee Stock Purchase Plan [Member] All Previous Stock Plans [Member]	Sep. 30, 2012 1992 Stock Option Plan [Member]	Aug. 31, 2004 Stock Repurchase Program - Open Market [Member]	Sep. 30, 2012 Stock Repurchase Program - Open Market [Member]	Sep. 30, 2011 Stock Repurchase Program - Open Market [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]	Sep. 30, 2012 Common Stock Subject to Repurchase [Member]	Mar. 31, 2012 Common Stock Subject to Repurchase [Member]	May 31, 2012 Restricted Stock Units [Member]	Feb. 29, 2012 Restricted Stock Units [Member]	May 31, 2006 Restricted Stock Units [Member]	Sep. 30, 2012 Restricted Stock Units [Member]	Nov. 30, 2011 Restricted Stock Units [Member] Minimum [Member]	Nov. 30, 2011 Restricted Stock Units [Member] Maximum [Member]	May 31, 2012 Performance-Based RSU [Member]	Feb. 29, 2012 Performance-Based RSU [Member]	Nov. 30, 2011 Performance-Based RSU [Member]	Apr. 30, 2011 Performance-Based RSU [Member]	May 31, 2009 Performance-Based RSU [Member]	Aug. 31, 2004 Structured stock repurchase agreements [Member]	Sep. 30, 2012 Structured stock repurchase agreements [Member]	Sep. 30, 2011 Structured stock repurchase agreements [Member]	Sep. 30, 2012 Settlement of Structured Stock Repurchase Agreement [Member]	Sep. 30, 2012 Company's 2011 Equity Incentive Plan [Member] Minimum [Member]	Apr. 30, 2011 Company's 2011 Equity Incentive Plan [Member] Minimum [Member]	Sep. 30, 2012 Company's 2011 Equity Incentive Plan [Member] Maximum [Member]	Feb. 29, 2012 Chief Executive Officer [Member]	May 31, 2009 Chief Executive Officer [Member]	May 17, 2009 Veloce Technologies, Inc. [Member]
Stockholders Equity [Line Items]
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
Preferred stock authorized for issuance				2,000,000	2,000,000
Common stock, shares authorized				375,000,000	375,000,000
Common stock, shares issued				65,317,000	61,879,000
Common stock, shares outstanding				65,317,000	61,879,000
Common stock reserved for issuance									4,800,000		6,300,000
Common stock, shares issued, employee stock purchase plan									400,000	400,000		1,800,000	6,600,000
Percentage of purchase price of common stock equal to fair market value									85.00%
Shares available for future issuance									1,800,000																															0	4,200,000	10,900,000
Stock repurchase program, authorized amount			200,000,000	300,000,000
Increase in the amount authorized for stock purchase program		100,000,000
Stock repurchase program, shares repurchased				27,273,000											17,300,000	100,000	3,500,000																				9,989,000
Open market repurchased shares				100,000
Open market repurchased shares average cost per share				$ 5.18
Stock repurchase program, weighted average price per share			$ 10.04	$ 10.42												$ 5.18	$ 5.98																				$ 11.06
Structured stock repurchase agreement, amount																																				277,500,000		10,000,000
Structured stock repurchase agreement, shares received																																						1,000,000	10,000,000
Structured stock repurchase agreements, effective purchase price per share																																						$ 9.74	$ 9.78
Cash received from shares settled under structured stock agreements																																							179,800,000
Number of stockholder-approved plans				2
Number of plans unapproved by stockholders				4
Awards granted				40,000										0												500,000																		300,000
Options expiration period, in years				10 years
Vesting and exercisable rate of new hire grants, percentage				25.00%
Value of stock options awarded																																											3,700,000	1,100,000
Shares expected to vest				3,133,000														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%
Shares outstanding				3,938,000	4,164,000																		0	0
Weighted average remaining contractual term for options outstanding				3 years 9 months 18 days
Weighted average remaining contractual term for options vested				3 years 9 months 18 days
Aggregate pretax intrinsic value of options exercised				11,000
Aggregate pre-tax intrinsic value of options outstanding and exercisable				10,000
Vesting and exercisable rate of new hire grants, grant date							36 months	48 months
Aggregate pre-tax intrinsic value of options outstanding
Common stock, closing price per share				$ 5.06																								$ 5.06
Number of shares vested				8,642,000	9,244,000	0
Term of award																															12-month	18-month	18-month	three-year	three-year
Vesting of restricted stock units first tranch	67.00%
Vesting of restricted stock units second tranch	33.00%
Weighted average remaining contractual term for the restricted stock units outstanding, in years				1 year 3 months 22 days
Aggregate pre-tax intrinsic value of restricted stock units outstanding which includes performance based awards which are subject to milestone attainments				43,700,000
Aggregate pre-tax intrinsic value of RSUs released				1,800,000
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
Outstanding Structured Stock Repurchase Agreement				$ 15,872,000
Vesting period, in years																									1 year		4 years	4 years	1 year	18 months