Note 4 - Related Party Transactions (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Oct. 31, 2019
Accounts Payable, Related Parties	$ 900	$ 19,000
M W L [Member]
Equity Method Investment, Ownership Percentage				45.00%
Construction Projects [Member] | Director [Member]
Related Party Transaction, Amounts of Transaction	154,000	0	$ 0
Accounts Payable, Related Parties	0	0
Purchase of Fuel, Tires and Related Services [Member]
Related Party Transaction, Amounts of Transaction	241,000	392,000	341,000
Tire Purchases [Member]
Related Party Transaction, Amounts of Transaction	$ 2,000,000.0	$ 1,700,000	$ 2,500,000