Business, Basis of Presentation and Summary of Significant Accounting Policies - Insurance Liabilities (Details) - USD ($) $ in Thousands	Apr. 30, 2021	Apr. 30, 2020
Other accrued expenses and current liabilities.
Loss Contingencies [Line Items]
Medical self-insurance	$ 3,852	$ 3,770
General liability
Loss Contingencies [Line Items]
Deductible amount	300
General liability | Minimum
Loss Contingencies [Line Items]
Primary layer of insurance coverage	300
Workers' compensation
Loss Contingencies [Line Items]
Deductible amount	500
Workers' compensation | Minimum
Loss Contingencies [Line Items]
Primary layer of insurance coverage	500
Automobile
Loss Contingencies [Line Items]
Deductible amount	1,000
Automobile | Minimum
Loss Contingencies [Line Items]
Primary layer of insurance coverage	1,000
General liability, workers' compensation and automobile | Other accrued expenses and current liabilities.
Loss Contingencies [Line Items]
General liability, automobile and workers’ compensation	19,807	19,410
General liability, workers' compensation and automobile | Prepaid expenses and other current assets
Loss Contingencies [Line Items]
Expected recoveries for insurance liabilities	(3,209)	$ (6,037)
General liability, workers' compensation and automobile | Minimum
Loss Contingencies [Line Items]
Buffer layer of insurance coverage	5,000
Excess layer of insurance coverage	10,000
General liability, workers' compensation and automobile | Maximum
Loss Contingencies [Line Items]
Primary layer of insurance coverage	5,000
Buffer layer of insurance coverage	10,000
Excess layer of insurance coverage	$ 100,000