Note 9 - Asset Retirement Obligation (Details Textual) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
Mar. 31, 2017 |
|
| Asset Retirement Obligations, Noncurrent, Total | $ 0 | $ 790,000 | $ 700,000 |
| Asset Retirement Obligation, Accretion Expense | $ 45,000 | $ 46,000 | |
| X | ||||||||||
- Definition Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Noncurrent portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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