Note 4 - Segment Reporting (Details) - Base Revenue and Fuel Surcharge Revenue by Segments (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Base revenue
Base Revenue	$ 113,856	$ 100,324	$ 330,206	$ 301,667
Fuel surcharge revenue
Fuel Surcharge Revenue	27,966	24,092	83,381	75,990
Total revenue	141,822	124,416	413,587	377,657
Operating Segments [Member] | Trucking [Member]
Base revenue
Base Revenue	81,804	71,951	243,005	219,733
Fuel surcharge revenue
Fuel Surcharge Revenue	23,140	20,204	68,756	62,198
Operating Segments [Member] | SCS [Member]
Base revenue
Base Revenue	33,416	34,509	91,638	99,207
Fuel surcharge revenue
Fuel Surcharge Revenue	5,234	5,907	15,872	18,157
Intersegment Eliminations [Member]
Base revenue
Base Revenue	(1,364)	(6,136)	(4,437)	(17,273)
Fuel surcharge revenue
Fuel Surcharge Revenue	$ (408)	$ (2,019)	$ (1,247)	$ (4,365)