Note 11 - Business Segments (Details) - Operating Revenue and Operating Income by Segment (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Segment Reporting Information [Line Items]
Operating Revenue	$ 159,409		$ 164,474
Operating Income	8,640		12,538
Truckload Revenue, Net of Fuel Surcharge [Member]
Segment Reporting Information [Line Items]
Operating Revenue	97,530		94,965
Truckload Fuel Surcharge Revenue [Member]
Segment Reporting Information [Line Items]
Operating Revenue	26,534		26,769
Total Truckload Revenue [Member]
Segment Reporting Information [Line Items]
Operating Revenue	124,064		121,734
Logistics Revenue, Net of Intermodal Fuel Surcharge [Member]
Segment Reporting Information [Line Items]
Operating Revenue	30,009	[1]	37,760	[1]
Intermodal Fuel Surcharge Revenue [Member]
Segment Reporting Information [Line Items]
Operating Revenue	5,336		4,980
Total Logistics Revenue [Member]
Segment Reporting Information [Line Items]
Operating Revenue	35,345		42,740
Truckload [Member]
Segment Reporting Information [Line Items]
Operating Income	7,500		10,000
Logistics [Member]
Segment Reporting Information [Line Items]
Operating Income	$ 1,140		$ 2,538

[1] Logistics revenue is net of $2.1 million of inter-segment revenue in the three-month period ended March 31, 2013 for loads transported by our tractors and arranged by MWL prior to the deconsolidation of MWL effective March 28, 2013. Such revenue has been eliminated in consolidation.