Restructuring Charges, Net - Additional Information (Detail) - USD ($)	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Restructuring Cost And Reserve [Line Items]
Restructuring charges, net	$ 0	$ 78,000	$ 34,600,000
Facilities
Restructuring Cost And Reserve [Line Items]
Restructuring charges, net		$ 100,000	18,600,000
Severance
Restructuring Cost And Reserve [Line Items]
Restructuring charges, net			$ 16,000,000