Income Taxes Other (Details) - USD ($)	12 Months Ended
	Apr. 30, 2022	Apr. 30, 2021
Unrecognized tax benefits
Federal net operating loss carryforwards	$ 88,863,000
State net operating loss carryforwards	93,485,000
Foreign net operating loss carryforwards	64,000
Operating loss not subject to expiration	47,000
Operating losses subject to expiration	93,438,000
Unrecognized tax benefits which would impact the Company's effective tax rate if recognized	4,969,000
Increase in valuation allowance	7,387,000	$ 3,304,000
Activity related to gross unrecognized tax benefits
Beginning balance	17,556,000	14,347,000
Increases related to prior year tax positions	415,000	1,305,000
Decreases related to prior year tax positions	(239,000)	(116,000)
Increases related to current year tax positions	1,398,000	2,074,000
Decreases related to lapsing of statute of limitations	(1,324,000)	(54,000)
Ending balance	17,806,000	17,556,000
Accrued interest and penalties related to unrecognized tax positions	302,000	23,000
Statute of limitations expiration
Unrecognized tax benefits
Unrecognized tax benefits which would impact the Company's effective tax rate if recognized	17,806,000	$ 17,556,000
Increase in valuation allowance	9,956,000
Estimated decrease in unrecognized tax benefits in the next twelve months	$ (3,263,000)