Note 2 - Summary of Significant Accounting Policies - Stock-based Compensation Expense (Details) - USD ($) |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2021 |
Jun. 30, 2020 |
Jun. 30, 2021 |
Jun. 30, 2020 |
|
| General and Administrative Expense [Member] | ||||
| Share-based Payment Arrangement, Expense | $ 1,774,800 | $ 1,790,106 | $ 4,180,236 | $ 2,072,058 |
| Selling and Marketing Expense [Member] | ||||
| Share-based Payment Arrangement, Expense | 252,318 | 218,793 | 916,781 | 260,075 |
| Research and Development Expense [Member] | ||||
| Share-based Payment Arrangement, Expense | $ 166,751 | $ 42,242 | $ 864,526 | $ 134,179 |