Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Apr. 30, 2019	Apr. 30, 2018
Accounting Policies [Line Items]
Total revenues	$ 27,399	$ 26,886
Sales commission capitalized	2,400			$ 2,500
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Accounting Policies [Line Items]
Total revenues	(384)
Sales commission capitalized	$ 1,100
Sales commission capitalized, economic benefit period	6 years
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Scenario, Forecast
Accounting Policies [Line Items]
Total revenues			$ 1,200
Upfront recognition of revenue under new standard			70.00%