Provision for Income Taxes - Reconciliation of Effective Tax Rate (Details)	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Income Tax Disclosure [Abstract]
Federal income tax at statutory rate	34.00%	34.00%
State income tax, net of federal benefit	3.90%	3.10%
Permanent differences	(0.20%)	(0.20%)
Increase in uncertain tax position	1.60%	(0.60%)
Other	(0.30%)	(2.20%)
Change in valuation allowance	(39.80%)	(37.20%)
Changes in tax rates	0.50%	2.20%
Income tax expense	(0.30%)	(0.90%)