Accrued Expenses and Deferred Revenue - Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Oct. 31, 2019	Apr. 30, 2019
Payables And Accruals [Abstract]
Accrued taxes other than income	$ 6,648	$ 6,078
Accrued rebates and promotions	6,473	4,877
Accrued employee benefits	5,966	5,241
Deferred revenue	5,502	12,213
Right-of-use lease liabilities	2,833
Accrued distributor incentives	3,194	1,895
Accrued professional fees	2,942	2,649
Accrued commissions	1,581	1,004
Interest payable	1,077	737
Current portion of capital lease obligation	946	681
Accrued other	5,383	3,947
Total accrued expenses and deferred revenue	$ 42,545	$ 39,322