Stockholders' Equity - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended		3 Months Ended												1 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Apr. 30, 2013	Apr. 30, 2012	Jul. 31, 2013 General and administrative	Jul. 31, 2012 General and administrative	Jul. 31, 2013 Former President And Chief Executive Officer as financial targets for the fiscal year ended April 30, 2010	Jul. 31, 2013 2004 Incentive Stock Plan Y	Jul. 31, 2013 Stock Options	Jul. 31, 2012 Stock Options	Jul. 31, 2013 RSUs and PSUs	Jul. 31, 2012 RSUs and PSUs	Jul. 31, 2013 RSUs and PSUs Executive Officer	Jul. 31, 2013 RSUs and PSUs Non-Executive Officer	Jul. 31, 2013 Restricted Stock Units (RSUs)	Jul. 31, 2013 Tender Offer	Sep. 04, 2013 Subsequent Event	Jul. 31, 2013 Maximum	Apr. 30, 2013 Maximum	Jul. 31, 2013 Maximum Tender Offer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase authorization																		$ 100,000,000	$ 35,000,000	$ 75,000,000
Repurchasing shares			2,099,603													1,417,233	1,821,756
Repurchase shares value			20,000,000													15,600,000	20,000,000
Stock repurchase remaining authorized amount	84,400,000		15,000,000														64,400,000
Stock repurchase program, expiration date			Jun. 17, 2014
Fees and expenses incurred related to tender offer	404,000
Number of common stock issuable with antidilutive effect									162,448	384,764
Number of stock option plans	2
Percentage of common stock authorized								15.00%
Authorized of common stock								10,000,000
Period to award vested and calculate volatility rate								3 years
Period of award vested exercisable								10
Option granted							500,000
Exercise price per share							$ 1.47
Options outstanding	2,907,660	3,809,664	3,019,127	3,988,164			250,000
Expiration date of options outstanding							Dec. 06, 2014
Intrinsic value of stock vested	19,700,000	21,900,000
Intrinsic value of stock exercisable	14,500,000	12,900,000
Intrinsic value of stock exercised	584,000	511,000
Unrecognized compensation cost of outstanding options	1,100,000
Weighted average remaining contractual term									9 months 4 days		1 year 3 months 18 days
Stock-based compensation expense					2,200,000	898,000					1,600,000	150,000
Stock-based compensation expense related to the loss on sale of our discontinued operations					45,000	45,000
Performance period	3 years
Percentage of maximum aggregate award granted	200.00%
Percentage of stock outperform in order for target award to be earned	10.00%
Stock Units, Awarded											406,418	4,500	250,000	151,418
Stock Units, Forfeited											2,887	11,665			2,887
Stock Units, Vested											3,019	7,000			3,019
Market value of Vested shares												44,000			32,000
Unrecognized compensation cost related to unvested RSUs and PSUs	$ 6,400,000