Note 2 - Significant Accounting Policies (Details Textual) - USD ($)		Dec. 31, 2019	Dec. 31, 2018
Deposits with Clearing Organizations and Others, Securities	[1]	$ 29,438,936	$ 64,242,167

[1] Cost of short-term investments held at broker (restricted): $29,427,850 and $64,238,656, respectively.