Note 5 - Segment Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenue	$ 291,585	$ 220,889
Operating income	23,847	10,509
Operating Segments [Member]
Revenue	291,585	220,889
Operating income	23,847	10,509
Intersegment Eliminations [Member]
Revenue	891	446
Consolidation, Eliminations [Member]
Revenue	(891)	(446)
Highway Services [Member] | Operating Segments [Member]
Revenue	98,797	78,481
Operating income	9,331	6,237
Highway Services [Member] | Intersegment Eliminations [Member]
Revenue	891	446
Dedicated [Member] | Operating Segments [Member]
Revenue	88,947	75,446
Operating income	2,641	(1,770)
Dedicated [Member] | Intersegment Eliminations [Member]
Revenue	0	0
Managed Freight [Member] | Operating Segments [Member]
Revenue	86,151	51,397
Operating income	10,831	4,887
Managed Freight [Member] | Intersegment Eliminations [Member]
Revenue	0	0
Factoring [Member] | Operating Segments [Member]
Revenue	17,690	15,565
Operating income	1,044	1,155
Factoring [Member] | Intersegment Eliminations [Member]
Revenue	$ 0	$ 0