Note 2 - Certificates of Deposit (Details Textual) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2019
Certificates Of Deposit Maximum Value Per Deposit				$ 250,000
Certificates of Deposit, at Carrying Value, Current and Noncurrent		$ 2,697,000	$ 4,095,000
Payments to Acquire Investments, Total		255,578	$ 244,825
Certificates of Deposit [Member]
Payments to Acquire Investments, Total	$ 3,145,000	2,456,000
Proceeds from Sale, Maturity and Collection of Investments, Total	$ 2,662,890	$ 3,854,000