Note 11 - Equity Method Investment - TEL's Summarized Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Total Assets	$ 703,954		$ 703,954		$ 676,716
Total Liabilities	374,059		374,059		386,074
Other Assets [Member]
Investment in TEL	41,924		41,924		34,365
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] | Transport Enterprise Leasing LLC [Member]
Total Assets	350,253		350,253		374,591
Total Liabilities	273,870		273,870		318,743
Total Equity	76,383		76,383		55,848
Revenue	27,626	$ 22,984	76,063	$ 72,202
Cost of Sales	3,030	2,748	6,263	10,332
Operating Expenses	16,214	15,184	45,156	51,708
Operating Income	8,382	5,052	24,644	10,162
Net Income	6,572	$ 2,729	19,191	$ 2,308
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] | Transport Enterprise Leasing LLC [Member] | Driver Advances and Other Receivable [Member]
Accounts receivable from TEL	$ 830		$ 830		$ 661