Note 6 - Equity Incentive Plan - Granted and Exercised Stock-based Compensation Awards (Details) - shares |
3 Months Ended | 6 Months Ended | ||
---|---|---|---|---|
Jun. 30, 2018 |
Jun. 30, 2017 |
Jun. 30, 2018 |
Jun. 30, 2017 |
|
Employee Stock Option [Member] | ||||
Grants: | ||||
Stock options (in shares) | 17,500 | 5,500 | 209,800 | 410,135 |
Exercises: | ||||
Stock options (in shares) | 273,123 | 3,850 | 284,548 | 9,437 |
Restricted Stock [Member] | ||||
Grants: | ||||
Restricted stock grants (in shares) | 64,578 | |||
Restricted Stock Units (RSUs) [Member] | ||||
Grants: | ||||
Restricted stock grants (in shares) | 8,130 | 9,970 | ||
Stock Appreciation Rights (SARs) [Member] | ||||
Exercises: | ||||
SARs (in shares) | 5,000 |