Significant Accounting Policies - Calculation of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jul. 31, 2020	Jul. 31, 2019
Basic loss per share computation
Net income (loss) attributable to common stockholders	$ 75	$ (641)
Weighted Average common shares - basic (in shares)	12,727,275	11,619,538
Basic net income (loss) per share (in dollars per share)	$ 0.01	$ (0.06)
Income (loss) available to common stockholders	$ 75	$ (641)
Incremental shares from assumed exercise of warrants and stock options (in shares)	1,504,366	0
Adjusted weighted average share - diluted (in shares)	14,231,641	11,619,538
Diluted net income (loss) per share (in usd per share)	$ 0.01	$ (0.06)