Investments - Components of EAM's investment management operations (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 30, 2013		Apr. 30, 2012		Apr. 30, 2011
Schedule of Investments [Line Items]
Value Line's non-voting revenues interest	$ 5,781		$ 5,684		$ 2,187
EAM's net income	6,619		6,925		37,782
EAM Trust
Schedule of Investments [Line Items]
Investment management fees earned from the Value Line Funds, net of waivers shown below	12,773		12,465		4,592	[1]
12b-1 fees and other fees, net of waivers shown below	3,905		3,466		1,293	[1]
Other income	14		12		3	[1]
Investment management fee waivers and reimbursements	379	[2]	806	[2]	303	[1],[2]
12b-1 fee waivers	2,156	[2]	2,257	[2]	855	[1],[2]
Value Line's non-voting revenues interest	5,781		5,684		2,187	[1]
EAM's net income	$ 945	[3]	$ 461	[3]	$ 336	[1],[3]

[1] Total results of EAM's investment management operations was for the period from December 23, 2010 through April 30, 2011.

[2] During fiscal 2013 investment management fee waivers and reimbursements primarily related to the Value Line Core Bond Fund and 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. The 12b-1 fee waivers related to nine of the Value Line Mutual Funds. In fiscal 2012, investment management fee waivers and reimbursements primarily related to the USGMMF and the 12b-1 fee waivers related to eleven of the Value Line Mutual Funds.

[3] 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.