Note 6 - Additional Cash Flow Disclosures (Details Textual) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Statement Line Items [Line Items] | |||
| Interest paid | $ 0 | $ 0 | $ 21 |
| Accretion Expense | $ 13 | ||
| X | ||||||||||
- Definition The amount of accretion expense incurred during the period. No definition available.
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| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition The cash outflow for interest paid, classified as financing activities. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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