Note 2 - Investments - Schedule of Components of EAM's Investment Management Operations (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Value Line’s non-voting revenues interest		$ 1,803	$ 1,825	$ 5,389	$ 5,546
EAM's net income (2)		1,445	1,913	9,283	6,024
EAM Trust [Member]
Investment management fees earned from the Value Line Funds, net of fee waivers		3,674	3,656	10,991	11,147
12b-1 fees and other fees, net of fee waivers		1,438	1,440	4,357	4,278
Other income (loss)		57	(57)	136	(84)
Investment management fee waivers (1)	[1]	132	48	308	143
12b-1 fee waivers (1)	[1]	235	235	700	848
Value Line’s non-voting revenues interest		1,803	1,825	5,389	5,546
EAM's net income (2)	[2]	$ 262	$ 188	$ 786	$ 710

[1] During fiscal 2017 and 2016 investment management fee waivers primarily related to the Value Line Core Bond Fund and the 12b-1 fee waivers related to four of the Value Line Mutual Funds.

[2] Represents EAM's net income, after giving effect to Value Line's non-voting revenues interest, but before distributions to voting profits interest holders and to the Company in respect of its 50% non-voting profits interest.