Common Stock - Narrative (Details) - USD ($)						12 Months Ended
	Apr. 27, 2017	Feb. 22, 2017	Jan. 24, 2017	Jul. 06, 2016	Jun. 15, 2016	Apr. 30, 2017	Apr. 30, 2016
Class of Stock [Line Items]
Proceeds from June 2016 Public Offering					$ 4,300,000	$ 4,340,000	$ 0
Payments of issuance costs					$ 742,000	0	18,000
Issuance of common stock (in shares)	3,807	7,614	3,247	3,896
Issuance of common stock for services	$ 7,500	$ 15,000	$ 11,852	$ 8,688		$ 44,000	$ 44,000
Common Stock
Class of Stock [Line Items]
Issuance of registered shares (in shares)					2,000,000
Share Price					$ 2.25
Over-Allotment Option | Common Stock
Class of Stock [Line Items]
Issuance of registered shares (in shares)					258,749