Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands	12 Months Ended
	Apr. 30, 2017 USD ($) Customer	Apr. 30, 2016 USD ($) Customer	Apr. 30, 2015 USD ($) Customer
Accounting Policies [Abstract]
Foreign Currency Transaction Gain (Loss), before Tax	$ (800)	$ (400)	$ (1,000)
Other than Temporary Impairment Losses, Investments	0	0	$ 0
Allowance for doubtful accounts	$ 1,260	$ 2,362
Number of clients that accounted for more than 10% of account receivables | Customer	0	0
Number of clients that accounted for more than 10% of revenue | Customer	0	0	0
Stock-based expense	$ 16,282	$ 15,086	$ 12,201