Note 4 - Property and Equipment - Property and Equipment, at Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property, plant, and equipment, gross	$ 725,383	$ 638,770
Revenue Equipment [Member]
Property, plant, and equipment, gross	$ 588,828	504,192
Revenue Equipment [Member] | Minimum [Member]
Estimated useful lives (Year)	3 years
Revenue Equipment [Member] | Maximum [Member]
Estimated useful lives (Year)	10 years
Office Equipment [Member]
Property, plant, and equipment, gross	$ 6,189	3,850
Office Equipment [Member] | Minimum [Member]
Estimated useful lives (Year)	5 years
Office Equipment [Member] | Maximum [Member]
Estimated useful lives (Year)	1 year
Land and Land Improvements [Member]
Property, plant, and equipment, gross	$ 23,398	25,240
Land and Land Improvements [Member] | Minimum [Member]
Estimated useful lives (Year)	0 years
Land and Land Improvements [Member] | Maximum [Member]
Estimated useful lives (Year)	15 years
Building and Building Improvements [Member]
Property, plant, and equipment, gross	$ 75,471	75,134
Building and Building Improvements [Member] | Minimum [Member]
Estimated useful lives (Year)	7 years
Building and Building Improvements [Member] | Maximum [Member]
Estimated useful lives (Year)	40 years
Construction in Progress [Member]
Property, plant, and equipment, gross	$ 400	3,121
Property, Plant and Equipment, Other Types [Member]
Property, plant, and equipment, gross	$ 31,097	$ 27,233
Property, Plant and Equipment, Other Types [Member] | Minimum [Member]
Estimated useful lives (Year)	2 years
Property, Plant and Equipment, Other Types [Member] | Maximum [Member]
Estimated useful lives (Year)	10 years