Earnings Per Share - Calculations of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019
Basic and diluted net loss per share computation (dollars in thousands):
Net income (loss) attributable to common stockholders	$ (1,975)	$ 128
Weighted Average common shares - basic (in shares)	11,843,463	11,340,184
Basic net income (loss) per share (in usd per share)	$ (0.17)	$ 0.01
Diluted income (loss) per share computation
Net income (loss) attributable to common stockholders	$ (1,975)	$ 128
Weighted Average common shares (in shares)	11,843,463	11,340,184
Incremental shares from assumed exercise of warrants and stock options (in shares)	0	2,755,933
Adjusted weighted average share - diluted (in shares)	11,843,463	14,096,117
Diluted net income (loss) per share (in usd per share)	$ (0.17)	$ 0.01