Note 3 - Revenue From Contracts With Customers - Changes in Contract Liabilities (Details) - USD ($) |
3 Months Ended | |
|---|---|---|
Mar. 31, 2022 |
Mar. 31, 2021 |
|
| Total deferred revenue, beginning of period | $ 700,000 | $ 700,000 |
| Deferred revenue related to milestones achieved | 100,000 | 0 |
| Total deferred revenue, end of period | $ 800,000 | $ 700,000 |
| X | ||||||||||
- Definition Amount of revenue deferred for which consideration to customer has not been performed related to milestone achieved. No definition available.
|
| X | ||||||||||
- Definition Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|