5. Stockholders' Equity (Details Narrative) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Dec. 31, 2020	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020	Apr. 30, 2020
Preferred stock par value (in Dollars per share)		$ 0.001		$ 0.001		$ 0.001
Preferred stock, shares authorized		5,000,000		5,000,000		5,000,000
Preferred stock, shares issued		1,648,000		1,648,000		1,648,000
Preferred stock, shares outstanding		1,648,000		1,648,000		1,648,000
Dividends paid		$ 1,081	$ 1,081	$ 3,244	$ 3,244
Proceeds from sale of common stock				$ 32,141	$ 0
Underwritten Public Offering [Member]
Stock issued new, shares	3,833,335
Proceeds from sale of common stock	$ 345,000
Share price	$ 9.00
Payment of stock issuance costs	$ 24,000
Series E Preferred Stock [Member]
Preferred stock, shares authorized		2,000,000		2,000,000
Preferred stock, shares issued		1,647,760		1,647,760
Preferred stock, shares outstanding		1,647,760		1,647,760
Conversion price per share		$ 21.00		$ 21.00
Redemption price		25.00		25.00
Liquidation preference price per share		$ 2.625		$ 2.625
Dividends paid		$ 1,100		$ 3,200
Series E Preferred Stock [Member] | Change of Control [Member]
Conversion price per share		$ 5.985		$ 5.985
Common stock to be issued if Series E stock is converted				6,826,435
Series E Preferred Stock [Member] | If Converted [Member]
Common stock to be issued if Series E stock is converted				1,978,783