Related Party Transactions (Detail Textuals 1) (USD $) In Millions, unless otherwise specified	Dec. 16, 2011 Value Line Convertible Fund	May 18, 2012 Value Line New York Tax Exempt Trust	May 18, 2012 Value Line Tax Exempt Fund	Mar. 31, 2013 Value Line Core Bond Fund Subsequent Event
Related Party Transaction [Line Items]
Assets under management	$ 20	$ 15	$ 90
Minimum expected asset under management carrying value				$ 100