Business Combinations (Details Textual) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended				6 Months Ended			3 Months Ended	6 Months Ended		1 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2012	Oct. 31, 2011	Nov. 05, 2012	Apr. 30, 2012	Oct. 31, 2012 Developed Technology [Member]	Oct. 31, 2012 Maximum [Member] Customer Relationships [Member]	Oct. 31, 2012 Minimum [Member] Customer Relationships [Member]	Oct. 31, 2011 Power Reviews [Member]	Oct. 31, 2011 Power Reviews [Member]	Jun. 12, 2012 Power Reviews [Member]	Jun. 30, 2012 Power Reviews [Member] Common Stock
Business Acquisition [Line Items]
PowerReviews acquired in cash					$ 26,900,000							$ 31,100,000
PowerReviews acquired in shares of common stock			0.5										6.4
Vested and unvested options of PowerReviews												1.7
Incremental Stock-based expense			15,933,000	3,255,000							9,800,000
Amortization of Acquired Intangible Assets	898,000		1,378,000							1,400,000	2,700,000
Acquisition Costs		1,000,000									2,400,000
Estimated Useful life							3 years	10 years	3 years
Stock based compensation related to post service combination service arrangements		600,000									1,100,000
Business Combinations (Textual) [Abstract]
Goodwill	$ 113,152,000		$ 113,152,000
Consideration paid per share	$ 17.20		$ 17.20