Note 2 - Summary of Significant Accounting Policies - Noncash Stock-based Compensation Expense (Details) - USD ($) |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
|
| Noncash stock compensation expense | $ 636,000 | $ 470,000 | $ 1,609,000 | $ 1,570,000 |
| Selling and Marketing Expense [Member] | ||||
| Noncash stock compensation expense | 289,000 | 272,000 | 708,000 | 668,000 |
| Research and Development Expense [Member] | ||||
| Noncash stock compensation expense | 41,000 | 51,000 | 98,000 | 199,000 |
| General and Administrative Expense [Member] | ||||
| Noncash stock compensation expense | $ 306,000 | $ 147,000 | $ 803,000 | $ 703,000 |
| X | ||||||||||
- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Details
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| X | ||||||||||
- Details
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| X | ||||||||||
- Details
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