Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 47	$ 47
Unrecognized tax benefits	8,907	7,287	$ 6,421
Unrecognized tax benefits that would impact effective tax rate	7,059
Increase (decrease) in unrecognized tax benefits	1,620
Accrued interest and penalties	354	242
Increase in tax expense	112	$ 51
Decrease in unrecognized tax benefits is reasonable possible	1,800
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 97,144