Business Combinations - Additional Information (Detail) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended	9 Months Ended			3 Months Ended	9 Months Ended			1 Months Ended			3 Months Ended	9 Months Ended		1 Months Ended
	Jan. 31, 2013	Jan. 31, 2013	Jan. 31, 2012	Nov. 04, 2012	Jan. 31, 2012 PowerReviews, Inc.	Jan. 31, 2012 PowerReviews, Inc.	Jan. 31, 2013 PowerReviews, Inc.	Jun. 12, 2012 PowerReviews, Inc.	Jun. 30, 2012 PowerReviews, Inc. Common Stock	Jan. 31, 2013 Longboard Media, Inc	Nov. 05, 2012 Longboard Media, Inc	Jan. 31, 2013 Longboard Media, Inc Contingent Consideration Subject to Certain Requirements	Jan. 31, 2013 Longboard Media, Inc Contingent Consideration Subject to Certain Requirements	Nov. 05, 2012 Longboard Media, Inc Contingent Consideration Subject to Certain Requirements	Nov. 30, 2012 Longboard Media, Inc Common Stock
Business Acquisition [Line Items]
Cash paid in business acquisition							$ 31,059,000	$ 31,100,000			$ 26,900,000
Shares of common Stock issued in business acquisition									6.4						0.5
Number of vested and unvested options equivalent to the acquired company's option								1.7
Closing price of common stock	$ 17.20	$ 17.20		$ 12.60
Contingent consideration payables											11,000,000			2,000,000
Compensation expense												200,000	200,000
Contingent consideration acquisition fair value							9,950,000			4,270,000	4,270,000
Amortization of acquired intangible assets	1,165,000	2,543,000			1,600,000
Incremental Stock-based expense		19,072,000	5,758,000		600,000
Stock based compensation related to post service combination service arrangements			1,700,000			4,900,000
Acquisition Costs			$ 4,800,000			$ 9,800,000