Note 2 - Investments - Income From Securities Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Dividend income	$ 66	$ 74	$ 170	$ 147
Interest income	25	4	75	6
Capital gain distributions	152	39	152	39
Other	15	15	48	34
Total income from securities transactions, net	$ 258	$ 132	$ 445	$ 226