Other Accrued Expenses and Current Liabilities (Details) - USD ($) $ in Thousands	Apr. 30, 2018	Apr. 30, 2017
Other Accrued Expenses and Current Liabilities
Insurance related liabilities	$ 11,432	$ 11,027
Sales taxes payable	9,864	8,920
Derivative liability	5,108
Accrued rebates	3,640	3,041
Contingent consideration	1,917	5,708
Real estate and personal property taxes	1,823	1,686
Deferred revenue	1,402	573
Other	9,960	6,936
Other accrued expenses and current liabilities	$ 45,146	$ 37,891