Note 7 - Share-based Compensation - Stock Compensation Expense (Details) - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 31, 2020 |
Mar. 31, 2019 |
|
| Stock compensation expense | $ 1,113 | $ 531 |
| Research and Development Expense [Member] | ||
| Stock compensation expense | 174 | 67 |
| Selling and Marketing Expense [Member] | ||
| Stock compensation expense | 229 | 154 |
| General and Administrative Expense [Member] | ||
| Stock compensation expense | 577 | 278 |
| Cost of Sales [Member] | ||
| Stock compensation expense | $ 133 | $ 32 |