Income Taxes - Effective Income Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Income Tax Disclosure [Abstract]
Computed “expected” income tax expense	$ 2,691	$ 2,905	$ 1,858
Increase (decrease) in income taxes resulting from:
State income taxes, net of federal income tax effect	601	396	323
Research and development credits	(586)	(522)	(640)
Excess tax benefits from stock option deductions	(70)	(1,737)	(641)
Foreign tax credits	(37)	(44)	(1)
Other, net, including permanent items	(134)	57	(140)
Income tax expense	$ 2,465	$ 1,055	$ 759

Amount of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to expense for award under share-based payment arrangement. Excludes expense determined to be nondeductible upon grant or after for award under share-based payment arrangement.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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