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Note 11 - Stock-based Compensation (Details) - Fair Value of Employee Stock Purchase Plan (USD $)
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12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2014
|
Dec. 31, 2013
|
Dec. 31, 2012
|
|
| Note 11 - Stock-based Compensation (Details) - Fair Value of Employee Stock Purchase Plan [Line Items] | |||
| Risk-free interest rate | 1.41% | 1.32% | |
| Expected life (in years) | 6 years 3 months | 6 years 80 days | |
| Expected volatility | 50.00% | 50.00% | |
| Employee Stock Purchase Plan [Member] | |||
| Note 11 - Stock-based Compensation (Details) - Fair Value of Employee Stock Purchase Plan [Line Items] | |||
| Risk-free interest rate | 0.07% | 0.10% | 0.13% |
| Expected life (in years) | 6 months | 178 days | 6 months |
| Expected volatility | 40.00% | 45.00% | 81.00% |
| Estimated fair value (in Dollars per share) | $ 3.55 | $ 2.86 | $ 4.69 |