Note 3 - Related Party Transactions (Details Textual) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Apr. 30, 2019	Jan. 31, 2019	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Revenue from Related Parties			$ 384,000	$ 362,000
Federal Income Tax Payments to Parent			$ 2,700,000	3,975,000	$ 6,824,000
Ownership Percentage By Parent	89.34%		89.34%
Value Line Inc [Member]
Accounts Receivable, Related Parties	$ 0		$ 0	0
EAM Trust [Member]
Assets under Management, Carrying Amount	$ 3,090,000,000		3,090,000,000	2,480,000,000
Increase (Decrease) in Assets under Management			$ 610,000,000
Percentage of Assets Increased (Decreased) in Unconsolidated Entities			24.60%
Non Voting Profits Interest Percent		50.00%	50.00%
Percentage of Non Voting Revenues Interest in Unconsolidated Entity	50.31%
Non Voting Profits Interest in Variable Entity Not yet Paid	$ 2,420,000		$ 2,420,000	$ 2,113,000
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%