Note F - Segment Information - Segment Revenue Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue, before fuel surcharges	$ 121,942	$ 128,994	$ 344,075	$ 390,680
Freight Transportation Service [Member]
Revenue, before fuel surcharges	$ 109,854	$ 110,149	$ 307,441	$ 332,846
Freight Transportation Service [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	100.00%	100.00%	100.00%	100.00%
Truckload Services [Member] \| Freight Transportation Service [Member]
Revenue, before fuel surcharges	$ 82,949	$ 92,443	$ 244,217	$ 275,323
Truckload Services [Member] \| Freight Transportation Service [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	75.50%	83.90%	79.40%	82.70%
Brokerage and Logistics Services [Member] \| Freight Transportation Service [Member]
Revenue, before fuel surcharges	$ 26,905	$ 17,706	$ 63,224	$ 57,523
Brokerage and Logistics Services [Member] \| Freight Transportation Service [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	24.50%	16.10%	20.60%	17.30%

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

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+ Details