Stockholders Equity - Summary of Stock Options (Detail) - Apr. 30, 2015 - $ / shares shares in Thousands	Total
$0.00 - $4.85
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range	$ 0.00
Exercise Price Upper Range	$ 4.85
Options Outstanding, Number of Options	523
Options Outstanding, Weighted Average Exercise Price	$ 2.69
Options Outstanding, Weighted Average Remaining Contractual Term (in years)	3 years 6 months
Options Exercisable, Number of Options	522
Exercisable Weighted Average Exercise Price	$ 2.69
$4.86 - $5.75
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range	4.86
Exercise Price Upper Range	$ 5.75
Options Outstanding, Number of Options	538
Options Outstanding, Weighted Average Exercise Price	$ 5.14
Options Outstanding, Weighted Average Remaining Contractual Term (in years)	5 years 2 months 9 days
Options Exercisable, Number of Options	387
Exercisable Weighted Average Exercise Price	$ 4.91
$6.28 - $6.58
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range	6.28
Exercise Price Upper Range	$ 6.58
Options Outstanding, Number of Options	536
Options Outstanding, Weighted Average Exercise Price	$ 6.47
Options Outstanding, Weighted Average Remaining Contractual Term (in years)	7 years 29 days
Options Exercisable, Number of Options	383
Exercisable Weighted Average Exercise Price	$ 6.44
$7.08 - $7.36
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range	7.08
Exercise Price Upper Range	$ 7.36
Options Outstanding, Number of Options	560
Options Outstanding, Weighted Average Exercise Price	$ 7.22
Options Outstanding, Weighted Average Remaining Contractual Term (in years)	8 years 9 months
Options Exercisable, Number of Options	147
Exercisable Weighted Average Exercise Price	$ 7.19
$7.39 - $7.50
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range	7.39
Exercise Price Upper Range	$ 7.50
Options Outstanding, Number of Options	596
Options Outstanding, Weighted Average Exercise Price	$ 7.42
Options Outstanding, Weighted Average Remaining Contractual Term (in years)	8 years 2 months 9 days
Options Exercisable, Number of Options	270
Exercisable Weighted Average Exercise Price	$ 7.41
$7.53 - $8.10
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range	7.53
Exercise Price Upper Range	$ 8.10
Options Outstanding, Number of Options	585
Options Outstanding, Weighted Average Exercise Price	$ 7.63
Options Outstanding, Weighted Average Remaining Contractual Term (in years)	9 years 29 days
Options Exercisable, Number of Options	27
Exercisable Weighted Average Exercise Price	$ 8.10
$8.58 - $9.46
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range	8.58
Exercise Price Upper Range	$ 9.46
Options Outstanding, Number of Options	362
Options Outstanding, Weighted Average Exercise Price	$ 8.90
Options Outstanding, Weighted Average Remaining Contractual Term (in years)	6 years 8 months 23 days
Options Exercisable, Number of Options	265
Exercisable Weighted Average Exercise Price	$ 8.80
$9.51 - $9.51
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range	9.51
Exercise Price Upper Range	$ 9.51
Options Outstanding, Number of Options	550
Options Outstanding, Weighted Average Exercise Price	$ 9.51
Options Outstanding, Weighted Average Remaining Contractual Term (in years)	8 years 1 month 6 days
Options Exercisable, Number of Options	264
Exercisable Weighted Average Exercise Price	$ 9.51
$9.52 - $12.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range	9.52
Exercise Price Upper Range	$ 12.00
Options Outstanding, Number of Options	515
Options Outstanding, Weighted Average Exercise Price	$ 11.59
Options Outstanding, Weighted Average Remaining Contractual Term (in years)	6 years 7 days
Options Exercisable, Number of Options	378
Exercisable Weighted Average Exercise Price	$ 11.62
$13.95 - $18.67
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range	13.95
Exercise Price Upper Range	$ 18.67
Options Outstanding, Number of Options	328
Options Outstanding, Weighted Average Exercise Price	$ 14.89
Options Outstanding, Weighted Average Remaining Contractual Term (in years)	6 years 2 months 23 days
Options Exercisable, Number of Options	248
Exercisable Weighted Average Exercise Price	$ 14.94
$0.00 - $18.67
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range	0.00
Exercise Price Upper Range	$ 18.67
Options Outstanding, Number of Options	5,093
Options Outstanding, Weighted Average Exercise Price	$ 7.83
Options Outstanding, Weighted Average Remaining Contractual Term (in years)	7 years
Options Exercisable, Number of Options	2,891
Exercisable Weighted Average Exercise Price	$ 7.60