Note 2 - Summary of Significant Accounting Policies - Other Comprehensive Income (Loss) (Details)	3 Months Ended
	Mar. 31, 2020 USD ($)
Beginning balance	$ 984,286
Ending balance	779,364
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Beginning balance	(568,030)
Other comprehensive income (loss) before reclassifications	(74,477)
Amounts reclassified from accumulated other comprehensive loss
Ending balance	$ (642,507)