Note 3 - Related Party Transactions (Details Textual) - USD ($)	3 Months Ended	12 Months Ended
	Apr. 30, 2018	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2016
Federal Income Tax Payments to Parent		$ 3,975,000	$ 6,824,000	$ 3,545,000
Ownership Percentage By Parent	89.08%	89.08%
Value Line Inc [Member]
Revenue from Related Parties		$ 362,000	383,000
Accounts Receivable, Related Parties	$ 0	0	0
EAM Trust [Member]
Assets under Management, Carrying Amount	$ 2,480,000,000	2,480,000,000	2,410,000,000
Increase (Decrease) in Assets under Management		$ 70,000,000
Percentage of Assets Increased (Decreased) in Unconsolidated Entities		2.80%
Non Voting Profits Interest Percent		50.00%
Percentage of Non Voting Revenues Interest in Unconsolidated Entity	51.44%
Non Voting Profits Interest in Variable Entity Not yet Paid	$ 2,113,000	$ 2,113,000	$ 1,919,000
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%