Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Income Tax Disclosure [Abstract]
U.S. statutory tax rate	21.00%	21.00%	35.00%
Net income(loss) from discontinued operations	$ (22,747)	$ (13,760)	$ (11,972)
Tax benefits from discontinued operations	6,788	7,016	6,986
Net deferred tax assets	95,100
Operating Loss Carryforwards [Line Items]
Valuation on deferred tax assets increase	2,100
Net NOL DTAs	25,500
Net NOL DTAs subject to expiration	3,200
Net NOL DTAs not subject to expiration	22,300
Unrecognized tax benefits that would impact effective tax rate	122,500	132,400	118,200
Amount of unrecorded benefit	27,000
Total gross interest and penalties accrued	22,400	$ 18,700	$ 21,000
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, valuation allowance	24,200
Foreign
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, valuation allowance	22,900
Write-off of certain NOL DTAs
Operating Loss Carryforwards [Line Items]
Valuation on deferred tax assets increase	(4,400)
Expiration of certain state NOL's
Operating Loss Carryforwards [Line Items]
Valuation on deferred tax assets increase	$ (2,300)