Revenue - Customer Concentration and Accounts Receivable (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2022	Jan. 31, 2021	Apr. 30, 2021
Disaggregation of Revenue [Line Items]
Unbilled receivables	$ 5.1		$ 5.1		$ 3.8
Customer Concentration Risk | Revenue | Customer One
Disaggregation of Revenue [Line Items]
Customer concentration risk, percentage	36.00%	16.00%	30.00%	16.00%
Customer Concentration Risk | Revenue | Customer Two
Disaggregation of Revenue [Line Items]
Customer concentration risk, percentage	10.00%	12.00%	10.00%	12.00%
Customer Concentration Risk | Accounts Receivable | Customer One
Disaggregation of Revenue [Line Items]
Customer concentration risk, percentage			21.00%		18.00%
Customer Concentration Risk | Accounts Receivable | Customer Two
Disaggregation of Revenue [Line Items]
Customer concentration risk, percentage			19.00%		14.00%
Customer Concentration Risk | Accounts Receivable | Customer Three
Disaggregation of Revenue [Line Items]
Customer concentration risk, percentage			14.00%		14.00%
Customer Concentration Risk | Accounts Receivable | Customer Four
Disaggregation of Revenue [Line Items]
Customer concentration risk, percentage			12.00%		11.00%