Note 6 - Short-term Investment by Bond Maturities (Details)	Dec. 31, 2015 USD ($)
Certificate of Deposit [Member]
Short-term investments	$ 4,800,000
Short-term investments available for sale	4,798,810
Investment Maturing Within Three Months [Member]
Short-term investments maturities	10,803,748
Short-term investments maturities	10,799,890
Corporate Debt Securities [Member]
Short-term investments	6,003,748
Short-term investments available for sale	$ 6,001,080
Investment Maturing Between 3 and 12 Months [Member]
Short-term investments maturities
Short-term investments maturities
Short-term investments	$ 10,803,748
Short-term investments available for sale	10,799,890
Short-term investments maturities	10,803,748
Short-term investments maturities	$ 10,799,890

This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 2
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-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
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