Consolidated Balance Sheets (Parentheticals) - $ / shares |
Dec. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Statement of Financial Position [Abstract] | ||
| Preferred stock, par value (in dollars per share) | $ 0.001 | $ 0.001 |
| Preferred stock, shares authorized | 5,000,000 | 5,000,000 |
| Preferred stock, shares issued | 0.000 | 0.000 |
| Common stock, par value (in dollars per share) | $ 0.001 | $ 0.001 |
| Common stock, shares authorized | 50,000,000 | 50,000,000 |
| Common stock, shares issued | 12,979,414 | 12,979,414 |
| Treasury stock, shares | 1,692,218 | 840,202 |