Note 4 - Related Party Transactions (Details Textual) - USD ($)	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Oct. 31, 2019
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	$ 124,000	$ 201,000
Tire Purchases [Member]
Related Party Transaction, Amounts of Transaction	$ 1,200,000	$ 571,000