Note 1 - Organization and Summary of Significant Accounting Policies (Details Textual) - USD ($)	9 Months Ended	12 Months Ended
	Jan. 31, 2019	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Net Cash Provided by (Used in) Operating Activities, Total		$ 11,831,000	$ 9,857,000	$ 4,036,000
Money Market Funds, at Carrying Value		5,617,000	4,982,000
Net Cash Provided by (Used in) Investing Activities, Total		(3,309,000)	(1,190,000)	$ (2,775,000)
Accounting Standards Update 2016-15 [Member]
Net Cash Provided by (Used in) Operating Activities, Total		9,300,000	8,800,000
Net Cash Provided by (Used in) Investing Activities, Total		$ (9,300,000)	$ (8,800,000)
EAM Trust [Member]
Non Voting Profits Interest Percent	50.00%	50.00%
EAM Trust [Member] | Minimum [Member]
Non Voting Revenues Interest Percent	41.00%	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%	55.00%