Note 4 - Stockholders' Equity (Details Textual) - Stifel ATM Program [Member]	3 Months Ended	9 Months Ended
	Sep. 30, 2016 USD ($) shares	Sep. 30, 2016 USD ($) shares
Maximum Potential Common Stock Available for Issue, Value	$ 25,000,000	$ 25,000,000
Stock Issued During Period, Shares, New Issues | shares	159,051	187,022
Stock Issued During Period, Value, New Issues	$ 432,000	$ 503,000
Proceeds from Issuance of Common Stock	402,000	471,000
Common Stock, Remaining Shares Available under Program, Value	$ 22,500,000	$ 22,500,000