Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Property and equipment
Total property and equipment	$ 225,874	$ 207,637
Less: accumulated depreciation and amortization	71,409	54,377
Property, Plant and Equipment, Net, Total	154,465	153,260
Depreciation and amortization expense for property and equipment	25,565	26,667	$ 32,208
Land
Property and equipment
Total property and equipment	50,009	50,001
Buildings and leasehold improvements
Property and equipment
Total property and equipment	81,872	77,049
Machinery and equipment
Property and equipment
Total property and equipment	90,303	78,142
Construction in progress
Property and equipment
Total property and equipment	$ 3,690	$ 2,445