Note 3 - Short Term Investments Available for Sale - Short-term Investment by Bond Maturities (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Short-term investments, fair value	$ 12,724,020
Total short-term investments	12,734,184	$ 1,680,000
Total short-term investments	12,724,020	1,680,000
Certificate of Deposit [Member]
Short-term investments, cost		1,680,000
Short-term investments, fair value		1,680,000
Investment Maturing Within Three Months [Member]
Total short-term investments		1,680,000
Total short-term investments		1,680,000
Corporate Debt Securities [Member]
Short-term investments, cost	12,734,184
Short-term investments, fair value	12,724,020
Investment Maturing Between 3 and 12 Months [Member]
Total short-term investments	12,734,184
Total short-term investments	$ 12,724,020