Summary of Fair Value of Financial Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2013		Apr. 30, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 26,740		$ 25,045
Short-term investments	58,053		70,290
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents			7,209
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	5,254		8,523
Restricted cash	604		604
Short-term investments	58,053		70,290
Total assets	63,911		79,417
Contingent consideration	3,270	[1]	3,270	[1]
Total liabilities	3,270		3,270
Fair Value, Measurements, Recurring | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0		7,209
Short-term investments	47,846		61,055
Fair Value, Measurements, Recurring | Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	10,207		9,235
Fair Value, Measurements, Recurring | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	5,254		1,314
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	5,254		8,523
Restricted cash	604		604
Short-term investments	47,846		61,055
Total assets	53,704		70,182
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0		7,209
Short-term investments	47,846		61,055
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	5,254		1,314
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	10,207		9,235
Total assets	10,207		9,235
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	10,207		9,235
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	3,270	[1]	3,270	[1]
Total liabilities	$ 3,270		$ 3,270

[1] On November 5, 2012, the Company acquired Longboard Media, Inc. ("Longboard Media") for approximately $26.9 million in cash, 0.5 million shares of the Company's common stock and future contingent consideration with an acquisition date fair value of $4.3 million. The contingent consideration is payable on Longboard Media's achievement of certain performance goals as of December 31, 2013. The estimated fair value of contingent consideration was determined using a weighted average probability of various outcomes of achieving the performance goals. Changes in the fair value of this contingent consideration are recorded in the income statement through the date of payout. As of July 31, 2013 and April 30, 2013, the fair value of the contingent consideration included in the purchase consideration, which is recorded in accrued expenses and other current liabilities, was $3.3 million. The fair value of the contingent consideration included in the purchase consideration will continue to be re-measured at the end of each reporting period. At April 30, 2013, the additional contingent consideration payable to the identified key individuals conditional upon being employed with the Company, was re-measured to $1.5 million which is being recorded over the remaining period for which services are provided. As of July 31, 2013, the Company has accrued $1.0 million for this additional contingent consideration.