Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018	Apr. 30, 2019	May 01, 2018
Accounting Policies [Line Items]
Revenues	$ 27,003	$ 30,117	$ 82,435	$ 83,340
Sales commission capitalized	32,947		32,947			$ 32,852
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Accounting Policies [Line Items]
Revenues	401		456
Sales commission capitalized	$ 1,100		$ 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]
Revenues					$ 1,200
Upfront recognition of revenue under new standard					70.00%