Note 2 - Significant Accounting Policies (Details Textual) - USD ($)		Dec. 31, 2018	Dec. 31, 2017
Deposits with Clearing Organizations and Others, Securities	[1]	$ 64,242,167	$ 40,347,527

[1] Cost of short-term investments held at broker (restricted): $64,238,656 and $40,346,355, respectively.