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Note 5 - Related Party Transactions (Details Textual) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Oct. 31, 2019
Accounts Payable, Related Parties | $ 19,000 | $ 0 |  |
M W L [Member] |  |  |  |
Equity Method Investment, Ownership Percentage |  |  |  | 45.00%
Purchase of Fuel, Tires and Related Services [Member] |  |  |  |
Related Party Transaction, Amounts of Transaction | 392,000 | 341,000 | $ 328,000 |
Tire Purchases [Member] |  |  |  |
Related Party Transaction, Amounts of Transaction | $ 1,700,000 | $ 2,500,000 | $ 2,500,000 |

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