Note 11 - Business Segments (Details Textual)	3 Months Ended
	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)
Number of Operating Segments	5
Number of Reportable Segments	4
Dedicated [Member]
Depreciation, Depletion and Amortization	$ 5,300,000	$ 5,000,000
Dedicated [Member] | Minimum [Member]
Customer Contract Term	3 years
Dedicated [Member] | Maximum [Member]
Customer Contract Term	5 years
Truckload [Member]
Depreciation, Depletion and Amortization	$ 14,600,000	13,700,000
Intermodal [Member]
Depreciation, Depletion and Amortization	1,100,000	941,000
Brokerage [Member]
Depreciation, Depletion and Amortization	$ 334,000	$ 481,000