Organization, Use of Estimates and Basis of Presentation - Calculation of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			6 Months Ended
	Oct. 31, 2018	Jul. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Basic loss per share computation
Net income (loss) attributable to common stockholders	$ 267	$ 483	$ (94)	$ 750	$ (768)
Weighted Average common shares - basic (in shares)	11,278,312		10,988,321	11,135,358	10,984,703
Basic net income (loss) per share (in dollars per share)	$ 0.02		$ (0.01)	$ 0.07	$ (0.07)
Income (loss) available to common stockholders	$ 267		$ (94)	$ 750	$ (768)
Incremental shares from assumed exercise of warrants and stock options (in shares)	2,758,778		0	2,356,144	0
Adjusted weighted average share - diluted (in shares)	14,037,090		10,988,321	13,491,502	10,984,703
Diluted net income (loss) per share (in usd per share)	$ 0.02		$ (0.01)	$ 0.06	$ (0.07)