Income Taxes Reconciliation (Details) - USD ($)	12 Months Ended
	Apr. 30, 2022	Apr. 30, 2021	Apr. 30, 2020
Income Taxes
U.S. federal statutory income tax rate (as a percent)	21.00%	21.00%	21.00%
Foreign rate differential (as a percent)	4.90%
State and local income taxes, net of federal benefit (as a percent)	40.80%	(1.40%)	(2.10%)
R&D and other tax credits (as a percent)	23.00%
R&D and other tax credits		(11.50%)	(6.80%)
Valuation allowance (as a percent)	(37.40%)	3.20%	3.40%
Return to provision adjustments (as a percent)	(0.90%)	(0.30%)	0.10%
Permanent items (as a percent)	(3.30%)	3.60%	0.70%
Foreign derived intangible income (as a percent)		(7.60%)	(3.90%)
Excess benefit of equity awards (as a percent)	5.20%	(5.70%)	(1.50%)
Other (as a percent)	0.90%	0.30%	0.20%
Effective income tax rate (as a percent)	54.20%	1.60%	11.10%
Current:
Federal	$ (3,025,000)	$ 3,094,000	$ 3,005,000
State	165,000	448,000	390,000
Foreign	279,000
Current	(2,581,000)	3,542,000	3,395,000
Deferred:
Federal	(5,764,000)	(3,247,000)	2,063,000
State	483,000	244,000	421,000
Foreign	(2,507,000)		(31,000)
Deferred	(7,788,000)	(3,003,000)	2,453,000
Total income tax expense	(10,369,000)	539,000	$ 5,848,000
Deferred income tax assets:
Accrued expenses	3,399,000	4,422,000
Stock based compensation	1,892,000	2,492,000
Allowances, reserves, and other	4,455,000	1,482,000
Outside basis difference	89,000	4,617,000
Unrealized loss on securities	3,229,000	110,000
Net operating loss and credit carry-forwards	41,931,000	33,155,000
Lease liability	6,303,000	5,645,000
Total deferred income tax assets	61,298,000	51,923,000
Deferred income tax liabilities:
Fixed asset basis	(10,413,000)	(10,286,000)
Right of use assets	(5,878,000)	(5,119,000)
Intangible basis	(15,503,000)	(17,004,000)
Total deferred income tax liabilities	(31,794,000)	(32,409,000)
Valuation allowance	(24,840,000)	(17,453,000)
Net deferred tax assets	$ 4,664,000	$ 2,061,000