Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2016
Property and equipment
Total property and equipment	$ 249,343	$ 225,874
Less: accumulated depreciation and amortization	85,761	71,409
Property, Plant and Equipment, Net, Total	163,582	154,465
Depreciation and amortization expense for property and equipment	24,100	25,600	$ 26,700
Land
Property and equipment
Total property and equipment	50,795	50,009
Buildings and leasehold improvements
Property and equipment
Total property and equipment	87,837	81,872
Machinery and equipment
Property and equipment
Total property and equipment	108,444	90,303
Construction in progress
Property and equipment
Total property and equipment	$ 2,267	$ 3,690