Investments - Components of EAM's investment management operations (Details 2) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015
Schedule of Investments [Line Items]
Value Line's non-voting revenues interest		$ 1,825	$ 1,862	$ 5,546	$ 5,498
EAM's net income		1,913	2,177	6,024	6,195
EAM Trust
Schedule of Investments [Line Items]
Investment management fees earned from the Value Line Funds, net of fee waivers		3,656	3,792	11,147	11,269
12b-1 fees and other fees, net of fee waivers		1,440	1,385	4,278	4,094
Other income (loss)		(57)	4	(84)	13
Investment management fee waivers	[1]	48	57	143	147
12b-1 fee waivers	[1]	235	378	848	1,147
Value Line's non-voting revenues interest		1,825	1,862	5,546	5,498
EAM's net income	[2]	$ 188	$ 324	$ 710	$ 994

[1] During fiscal 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. During fiscal 2015 investment management fee waivers primarily related to the Value Line Core Bond Fund and the 12b-1 fee waivers related to six 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.