Note 3 - Revenue Recognition - Disaggregation of Revenue by Type (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues	$ 135,381	$ 107,358	$ 260,394	$ 209,028
Trucking [Member]
Revenues	85,569	71,545	164,302	141,825
USAT Logistics [Member]
Revenues	49,812	35,813	96,092	67,203
Freight [Member]
Revenues	117,549	94,409	224,831	182,360
Freight [Member] | Trucking [Member]
Revenues	72,925	61,667	139,729	121,516
Freight [Member] | USAT Logistics [Member]
Revenues	44,624	32,742	85,102	60,844
Fuel Surcharge [Member]
Revenues	16,274	11,320	31,008	23,162
Fuel Surcharge [Member] | Trucking [Member]
Revenues	12,123	8,828	23,298	18,015
Fuel Surcharge [Member] | USAT Logistics [Member]
Revenues	4,151	2,492	7,710	5,147
Accessorial [Member]
Revenues	1,558	1,629	4,555	3,506
Accessorial [Member] | Trucking [Member]
Revenues	521	1,050	1,275	2,294
Accessorial [Member] | USAT Logistics [Member]
Revenues	$ 1,037	$ 579	$ 3,280	$ 1,212