Note 11 - Business Segments (Details Textual)	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)
Dedicated [Member] | Minimum [Member]
Customer Contract Term			3 years
Dedicated [Member] | Maximum [Member]
Customer Contract Term			5 years
Dedicated [Member]
Depreciation, Depletion and Amortization	$ 5,200,000	$ 4,300,000	$ 15,300,000	$ 10,400,000
Truckload [Member]
Depreciation, Depletion and Amortization	14,100,000	13,300,000	41,700,000	40,000,000
Intermodal [Member]
Depreciation, Depletion and Amortization	995,000	1,400,000	2,900,000	4,300,000
Brokerage [Member]
Depreciation, Depletion and Amortization	$ 400,000	$ 295,000	$ 1,300,000	$ 854,000
Number of Operating Segments			5
Number of Reportable Segments			4