Note 1 - Organization and Summary of Significant Accounting Policies (Details Textual) - USD ($)	3 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Apr. 30, 2018
Net Cash Provided by (Used in) Operating Activities, Total	$ 1,512,000	$ 2,978,000
Money Market Funds, at Carrying Value	4,084,000		$ 4,982,000
Net Cash Provided by (Used in) Investing Activities, Total	(574,000)	(1,438,000)
Accounting Standards Update 2016-15 [Member]
Net Cash Provided by (Used in) Operating Activities, Total	2,300,000	$ 2,100,000
Net Cash Provided by (Used in) Investing Activities, Total	$ (2,300,000)
EAM Trust [Member]
Non Voting Profits Interest Percent	50.00%
EAM Trust [Member] | Minimum [Member]
Non Voting Revenues Interest Percent	41.00%
Percentage of Non Voting Profits Interests Due from Ex Subsidiary Payable to Parent under Agreement	90.00%
EAM Trust [Member] | Maximum [Member]
Non Voting Revenues Interest Percent	55.00%