Income Taxes - Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2022	Apr. 30, 2021	Apr. 30, 2020
Current:
Federal	$ 1,294	$ 693	$ 295
State	615	386	370
Total current income tax expense	1,909	1,079	665
Deferred:
Federal	(712)	(238)	(513)
State	(142)	(82)	(96)
Total deferred income tax expense	(854)	(320)	(609)
Income tax expense	$ 1,055	$ 759	$ 56