Property and Equipment, net Other (Details) - USD ($)	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Depreciation expense	$ 6,913,000	$ 5,993,000	$ 8,116,000
Computer equipment and software
Depreciation expense	375,000	455,000
Property and equipment under capital lease, cost	1,836,000	1,836,000
Accumulated depreciation of asset under capital lease	$ 1,433,000	$ 1,058,000