Investments - Components of EAM's investment management operations (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Oct. 31, 2013		Oct. 31, 2012		Oct. 31, 2013		Oct. 31, 2012
Schedule of Investments [Line Items]
Value Line's non-voting revenues interest	$ 1,663		$ 1,414		$ 3,261		$ 2,808
EAM's net income	1,616		1,572		3,061		3,348
EAM Trust
Schedule of Investments [Line Items]
Investment management fees earned from the Value Line Funds, net of waivers shown below	3,580		3,149		7,065		6,229
12b-1 fees and other fees, net of waivers shown below	1,294		985		2,413		1,876
Other income	8				10
Investment management fee waivers	23	[1]	167	[1]	47	[1]	348	[1]
12b-1 fee waivers	379	[1]	547	[1]	902	[1]	1,090	[1]
Value Line's non-voting revenues interest	1,663		1,414		3,261		2,808
EAM's net income	$ 382	[2]	$ 230	[2]	$ 724	[2]	$ 388	[2]

[1] During fiscal 2013, investment management fee waivers primarily related to the U.S. Government Money Market Fund ("USGMMF") which was merged into a third party fund, the Daily Income Fund, managed by Reich & Tang, effective October 19, 2012. During fiscal 2014 and 2013, the 12b-1 fee waivers related to seven and nine of the Value Line Mutual Funds, respectively.

[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.