Financial Instruments and Fair Value - Schedule of Fair Value of Financial Instruments Measured on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2014
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities	$ 29,872
Money market funds [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities	1,614
Corporate bonds [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities	24,712
Commercial paper [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities	3,546
Level 1 [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities	1,614
Level 1 [Member] | Money market funds [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities	1,614
Level 1 [Member] | Corporate bonds [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities
Level 1 [Member] | Commercial paper [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities
Level 2 [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities	28,258
Level 2 [Member] | Money market funds [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities
Level 2 [Member] | Corporate bonds [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities	24,712
Level 2 [Member] | Commercial paper [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities	3,546
Level 3 [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities
Level 3 [Member] | Money market funds [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities
Level 3 [Member] | Corporate bonds [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities
Level 3 [Member] | Commercial paper [Member]
Schedule Of Available For Sale Securities Fair Value Hierarchy [Line Items]
Total cash equivalents and marketable securities