Income Taxes (Schedule Of Reconciliation Between Income Tax Provision And Statutory Federal Tax Rate) (Details)	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Income Tax Disclosure [Abstract]
U.S. statutory tax rate	21.00%	21.00%	21.00%
State income taxes, net of federal income tax benefit	1.80%	20.40%	2.30%
Earnings taxed in foreign jurisdictions	(1.20%)	619.40%	(2.70%)
Permanent differences	0.50%	(257.50%)	0.30%
Impairment of goodwill	0.00%	(832.50%)	0.00%
Uncertain tax positions	7.50%	508.30%	(2.30%)
U.S. tax on income from foreign affiliates	1.00%	(247.40%)	0.00%
Remeasurement of deferred tax assets and liabilities	(0.10%)	117.60%	0.20%
Changes in prior year estimates	(0.50%)	55.50%	0.00%
Federal income tax credits	(0.90%)	216.30%	0.00%
Tax impacts of stock-based compensation vesting	0.00%	44.80%	0.00%
Tax benefit due to NOL carryback under CARES Act	(17.50%)	0.00%	0.00%
Tax deductible write-down of foreign investment	(1.70%)	0.00%	0.00%
Change in valuation allowance - domestic	(0.20%)	37.10%	0.40%
Change in valuation allowance - foreign	1.70%	20.60%	(0.80%)
Other	0.30%	(41.20%)	(0.10%)
Effective tax rate	11.70%	282.40%	18.30%