Note 1 - Significant Accounting Policies (Details Textual) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2018	Sep. 30, 2017
Tractors [Member]
Property, Plant and Equipment, Useful Life		5 years
Property, Plant and Equipment, Salvage Value, Percentage		15.00%
Refrigerated Trailers [Member]
Property, Plant and Equipment, Useful Life		7 years
Dry Van Trailers [Member]
Property, Plant and Equipment, Useful Life		10 years
Property, Plant and Equipment, Salvage Value, Percentage		25.00%
Scenario, Forecast [Member] | Accounting Standards Update 2015-14 [Member]
Cumulative Effect on Retained Earnings, Net of Tax	$ 1