Note F - Segment Information - Segment Revenue Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Operating revenues	$ 164,652	$ 151,134	$ 306,532	$ 306,475
Freight Transportation Service [Member]
Operating revenues	$ 136,894	$ 133,806	$ 259,556	$ 270,506
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]
Operating revenues	$ 86,074	$ 92,824	$ 164,331	$ 185,253
Truckload Services [Member] \| Freight Transportation Service [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	62.90%	69.40%	63.30%	68.50%
Motor Carrier [Member] \| Revenue Benchmark [Member] \| Geographic Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	100.00%	100.00%	100.00%	100.00%
Motor Carrier [Member] \| UNITED STATES
Operating revenues	$ 93,570	$ 84,304	$ 172,954	$ 168,148
Motor Carrier [Member] \| UNITED STATES \| Revenue Benchmark [Member] \| Geographic Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	56.80%	55.80%	56.40%	54.90%
Motor Carrier [Member] \| MEXICO
Operating revenues	$ 70,843	$ 66,537	$ 133,017	$ 137,634
Motor Carrier [Member] \| MEXICO \| Revenue Benchmark [Member] \| Geographic Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	43.00%	44.00%	43.40%	44.90%
Motor Carrier [Member] \| CANADA
Operating revenues	$ 239	$ 293	$ 561	$ 693
Motor Carrier [Member] \| CANADA \| Revenue Benchmark [Member] \| Geographic Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	0.20%	0.20%	0.20%	0.20%
Brokerage and Logistics Services [Member] \| Freight Transportation Service [Member]
Operating revenues	$ 50,820	$ 40,982	$ 95,225	$ 85,253
Brokerage and Logistics Services [Member] \| Freight Transportation Service [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	37.10%	30.60%	36.70%	31.50%