Note 3 - Short-term Investments Available for Sale (Details) - Short-Term Investment by Bond Maturities - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Short-term investments
Short-term investments	$ 10,803,748	$ 24,189,438
Short-term investments	10,799,890	24,173,406
Short-term investment maturities
Short-term investments maturities	10,803,748	24,189,438
Short-term investments maturities	10,799,890	24,173,406
Certificate of Deposit [Member]
Short-term investments
Short-term investments	4,800,000	5,000,000
Short-term investments	4,798,810	4,996,568
Corporate Debt Securities [Member]
Short-term investments
Short-term investments	6,003,748	19,189,438
Short-term investments	6,001,080	19,176,838
Investment Maturing Within 3 Months [Member]
Short-term investment maturities
Short-term investments maturities	10,803,748	16,881,490
Short-term investments maturities	$ 10,799,890	16,872,158
Investment Maturing Between 3 and 12 Months [Member]
Short-term investment maturities
Short-term investments maturities		7,307,948
Short-term investments maturities		$ 7,301,248