Note 7 - Related Party Transactions (Details Textual) - USD ($)	2 Months Ended	3 Months Ended
	Oct. 31, 2016	Jul. 31, 2016	Jul. 31, 2015	Apr. 30, 2016
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%
EAM Trust [Member]
Assets under Management, Carrying Amount		$ 2,320,000,000	$ 2,350,000,000
Percentage of Assets Increased (Decreased) in Unconsolidated Entities		1.40%
Non Voting Profits Interest Percent		50.00%
NonVotingProfitsInterest, Remaining Percentage	50.00%
Percentage of Non Voting Profits Interests Due from Ex Subsidiary Payable to Parent under Agreement		90.00%
Percentage of Non Voting Revenues Interest in Unconsolidated Entity		49.45%	50.05%
Accrued Non Voting Revenues and Non Voting Profits Interests Payable		$ 1,903,000		$ 1,750,000
Percent of Revenue Interest		100.00%
Ownership Percentage By Parent		88.80%
Value Line Inc [Member]
Reimbursement Revenue		$ 84,000	$ 31,000
Federal Income Tax Payments to Parent		$ 268,000	$ 0
Percentage of Non Voting Profits Interests Due from Ex Subsidiary Payable to Parent under Agreement		90.00%
Accrued Non Voting Revenues and Non Voting Profits Interests Payable		$ 1,903,000
Percent of Revenue Interest		100.00%