Income Taxes Other (Details) - USD ($)	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Unrecognized tax benefits
State net operating loss carryforwards	$ 10,000
Foreign net operating loss carryforwards	205,000
Foreign net operating losses subject to expiration	73,000
Activity related to gross unrecognized tax benefits
Beginning balance	11,170,000	$ 9,856,000
Increases related to prior year tax positions	216,000	228,000
Increases related to current year tax positions	1,756,000	1,347,000
Decreases related to lapsing of statute of limitations	(549,000)	(261,000)
Ending balance	12,593,000	11,170,000
Reversal of uncertain tax position reserve, including interest	549,000
Accrued interest and penalties related to unrecognized tax positions	18,000	$ 16,000
Statute of limitations expiration
Unrecognized tax benefits
Estimated decrease in unrecognized tax benefits in the next twelve months	$ (224,000)