Note 10 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Stock Issued During Period, Shares, Employee Stock Purchase Plans | 26,474 | 17,775 |
| Stock Issued During Period, Value, Employee Stock Purchase Plan | $ 221,000 | $ 106,000 |
| Common Stock, Par or Stated Value Per Share | $ 0 | $ 0 |