4. Stockholders' Equity (Details Narrative) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jul. 31, 2019	Jul. 31, 2018
Dividends paid	$ 1,081	$ 1,081
Series E Preferred Stock [Member]
Dividend declared per share	$ 0.65625
Liquidation preference	$ 25.00
Dividends paid	$ 1,081
Dividend declared date	Jun. 05, 2019
Dividend record date	Jun. 17, 2019
Common stock to be issued if Series E stock is converted	6,826,435
Each outstanding share that could be converted into common shares	4