Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Operating Loss Carryforwards [Line Items]
Impairment of goodwill	$ 0	$ 106,000	$ 0
Effective tax rate	11.70%	282.40%	18.30%
Income (loss) from continuing operations before income taxes (benefit)	$ 668,736	$ (3,374)	$ 545,160
Net loss	6,421	13,682	22,747
Tax benefits from discontinued operations	3,883	4,085	6,788
Valuation allowance, decrease in deferred tax asset	10,300
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction	13,500
SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense	3,200
Net NOL DTAs	49,500
Net NOL DTAs subject to expiration	10,400
Net NOL DTAs not subject to expiration	39,100
Unrecognized tax benefits that would impact effective tax rate	214,900	132,300	122,500
Amount of unrecorded benefit	69,800
Total gross interest and penalties accrued	24,900	$ 22,000	$ 22,400
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, valuation allowance	21,300
Foreign
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, valuation allowance	$ 33,200