Note 11 - Equity Method Investment - TEL's Summarized Financial Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable, after Allowance for Credit Loss, Total	$ 91,300	$ 81,200	$ 97,500
Investment in TEL	34,365	31,906
Current Assets	147,796	254,385
Current Liabilities	133,381	161,257
Other Assets [Member]
Investment in TEL	34,365	31,906
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] | Transport Enterprise Leasing LLC [Member]
Current Assets	27,167	28,577
Non-current Assets	283,913	346,014
Current Liabilities	66,495	85,751
Non-current Liabilities	183,393	232,992
Total Equity	61,192	55,848
Revenue	95,016	110,298	108,801
Cost of Sales	11,617	20,404	37,307
Operating Expenses	64,581	65,058	47,281
Operating Income	18,818	24,836	24,213
Net Income	8,344	13,403	$ 16,496
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] | Transport Enterprise Leasing LLC [Member] | Driver Advances and Other Receivable [Member]
Accounts Receivable, after Allowance for Credit Loss, Total	$ 661	$ 1,251