Note F - Segment Information - Segment Revenue Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Operating revenues	$ 141,880	$ 155,342
Freight Transportation Service [Member]
Operating revenues	$ 122,662	$ 136,701
Freight Transportation Service [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	100.00%	100.00%
Truckload Services [Member] \| Freight Transportation Service [Member]
Operating revenues	$ 78,257	$ 92,429
Truckload Services [Member] \| Freight Transportation Service [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	63.80%	67.60%
Motor Carrier [Member] \| Revenue Benchmark [Member] \| Geographic Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	100.00%	100.00%
Motor Carrier [Member] \| UNITED STATES
Operating revenues	$ 79,448	$ 83,917
Motor Carrier [Member] \| UNITED STATES \| Revenue Benchmark [Member] \| Geographic Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	56.00%	54.00%
Motor Carrier [Member] \| MEXICO
Operating revenues	$ 62,110	$ 71,025
Motor Carrier [Member] \| MEXICO \| Revenue Benchmark [Member] \| Geographic Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	43.80%	45.70%
Motor Carrier [Member] \| CANADA
Operating revenues	$ 322	$ 400
Motor Carrier [Member] \| CANADA \| Revenue Benchmark [Member] \| Geographic Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	0.20%	0.30%
Brokerage and Logistics Services [Member] \| Freight Transportation Service [Member]
Operating revenues	$ 44,405	$ 44,272
Brokerage and Logistics Services [Member] \| Freight Transportation Service [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Revenue, before fuel surcharges, percentage	36.20%	32.40%