Note 1 - Accounting Policies (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Bank Overdrafts	$ 2,572,000	$ 3,669,000
Due from Employees, Current	211,000	220,000
Other Receivables, Net, Current, Total	3,769,000	3,814,000
Impairment of Long-Lived Assets Held-for-use		$ 0
Period for Amortizing Prepaid Tires		2 years
Advertising Expense	1,269,000	$ 1,234,000	$ 1,087,000
AOCI Attributable to Parent [Member]
Reclassification of Gain (Loss) Unrealized on Equity Securities from AOCI to Retained Earnings		(7,444,000)
Accounting Standards Update 2016-01 [Member] | AOCI Attributable to Parent [Member]
Reclassification of Gain (Loss) Unrealized on Equity Securities from AOCI to Retained Earnings		$ (7,400,000)
Settlement Of Collective And Class Action Lawsuit [Member]
Loss Contingency Accrual, Ending Balance	$ 16,500,000
Truckload Services [Member] | Sales [Member] | Product Concentration Risk [Member]
Concentration Risk, Percentage	82.70%	80.00%	86.30%
Independent Contractors [Member]
Other Receivables, Net, Current, Total	$ 1,381,000	$ 1,724,000