Income Taxes - Summary of Reconciliation of Provision from Income Taxes from Operations (Details) - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2022	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2018
Income Tax Disclosure [Abstract]
Federal income taxes expected at the statutory rate	$ (11,663)	$ 5,101	$ (22,649)
State income taxes, less federal income tax benefit	(633)	586	(1,117)
Stock compensation	(276)	(83)	86
Research and development tax credit	(291)	(288)	(199)
Goodwill impairment	7,633		11,741
Change in deferred tax valuation allowance	14,200	241
Other	374	330	485
Total income tax expense/(benefit)	$ 9,344	$ 5,887	$ (11,653)	$ (11,653)

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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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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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Amount of reported income tax expense (benefit) in excess of (less than) expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to nondeductible expense for award under share-based payment arrangement. Includes, but is not limited to, expense determined to be nondeductible upon grant or after for award under share-based payment arrangement.

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