Provision for Income Taxes - Components of Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Federal Income Tax Expense (Benefit), Continuing Operations [Abstract]
Provision for Income Taxes, Current, Federal	$ (14)	$ 0
Provision for Income Taxes, Total, Federal	(14)	0
State and Local Income Tax Expense (Benefit), Continuing Operations [Abstract]
Provision for Income Taxes, Current, State	0	0
Provision for Income Taxes, Total, State	0	0
Foreign Income Tax Expense (Benefit), Continuing Operations [Abstract]
Provision for Income Taxes, Current, Foreign	33	92
Provision for Income Taxes, Total, Foreign	33	92
Provision for Income Taxes, Current, Total	19	92
Provision for Income Taxes, Total	$ 19	$ 92