Stockholders' Equity (Preferred Stock, Common Stock, Treasury Stock and Warrants Narrative) (Details) - USD ($)	3 Months Ended
	Jul. 31, 2018	Jul. 19, 2018	Apr. 30, 2018
Stockholders Equity [Line Items]
Preferred stock, shares authorized	10,000,000		10,000,000
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0		0
Per share price	$ 0.001		$ 0.001
Stock issuance costs paid by third parties	$ 30,000
Preferred Stock [Member]
Stockholders Equity [Line Items]
Preferred stock, shares authorized	10,000,000		10,000,000
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0		0
Common Stock [Member]
Stockholders Equity [Line Items]
Share issued in exercise of stock options	2,689
Proceeds from stock options exercised	$ 7,817
Treasury stock repurchased		1,000,000
Per share price		$ 7.40
Sale of common stock per share price		$ 7.40
Common Stock [Member] | Cashless Exercise of Stock Options [Member]
Stockholders Equity [Line Items]
Share issued in exercise of stock options	5,230