Concentration of Risk (Details) - Customer Concentration Risk	3 Months Ended		6 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
Customer receivables | Customer A
Concentration Risk [Line Items]
Concentration risk (as a percent)			33.10%	31.50%
Customer receivables | Customer B
Concentration Risk [Line Items]
Concentration risk (as a percent)			18.40%	25.50%
Sales revenue, gross | Customer A
Concentration Risk [Line Items]
Concentration risk (as a percent)	31.70%	30.50%	31.80%	29.20%
Sales revenue, gross | Customer B
Concentration Risk [Line Items]
Concentration risk (as a percent)	15.80%	19.20%	15.60%	18.10%