Note 6 - Commitments and Contingencies (Details Textual) - USD ($) |
3 Months Ended | 6 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|---|
Jun. 30, 2019 |
Jun. 30, 2019 |
Jun. 30, 2018 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Note To Financial Statement Details Textual | |||||
| Operating Lease, Expense | $ 98,000 | $ 165,000 | $ 115,000 | $ 232,000 | $ 225,000 |