6. STOCKHOLDERS' EQUITY (Details) - Series E Preferred Stock [Member] $ / shares in Units, $ in Thousands	9 Months Ended
	Jan. 31, 2019 USD ($) $ / shares
Qtr 1, FY 2019 [Member]
Declaration Date	Jun. 06, 2018
Record date	Jun. 18, 2018
Payment date	Jul. 02, 2018
Total dividends paid | $	$ 1,081
Dividend per share | $ / shares	$ 0.65625
Qtr 2, FY 2019 [Member]
Declaration Date	Sep. 05, 2018
Record date	Sep. 17, 2018
Payment date	Oct. 01, 2018
Total dividends paid | $	$ 1,081
Dividend per share | $ / shares	$ 0.65625
Qtr 3, FY 2019 [Member]
Declaration Date	Dec. 05, 2018
Record date	Dec. 17, 2018
Payment date	Jan. 02, 2019
Total dividends paid | $	$ 1,081
Dividend per share | $ / shares	$ 0.65625