Note 4 - Segment Reporting (Details) - Base Revenue and Fuel Surcharge Revenue by Segments (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Base revenue
Base Revenue	$ 111,462	$ 103,520	$ 216,350	$ 201,342
Fuel surcharge revenue
Fuel Surcharge Revenue	28,276	26,049	55,416	51,900
Total revenue	139,738	129,569	271,766	253,242
Operating Segments [Member] | Trucking [Member]
Base revenue
Base Revenue	81,441	71,846	161,244	147,782
Fuel surcharge revenue
Fuel Surcharge Revenue	23,392	20,964	45,615	41,995
Operating Segments [Member] | SCS and Intermodal [Member]
Base revenue
Base Revenue	31,434	37,974	58,222	64,698
Fuel surcharge revenue
Fuel Surcharge Revenue	5,260	6,921	10,638	12,250
Intersegment Eliminations [Member]
Base revenue
Base Revenue	(1,413)	(6,300)	(3,116)	(11,138)
Fuel surcharge revenue
Fuel Surcharge Revenue	$ (376)	$ (1,836)	$ (837)	$ (2,345)