Note 10 - Goodwill and Other Intangible Assets (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Feb. 28, 2022	Dec. 31, 2021
Goodwill, Gross	$ 120,600		$ 120,600			$ 100,500
Acquired Finite-Lived Intangible Asset, Residual Value	0		0
Amortization of Intangible Assets	4,800	$ 3,500	13,400	$ 10,700
Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year	18,200		18,200
Finite-Lived Intangible Asset, Expected Amortization, Year One	19,500		19,500
Finite-Lived Intangible Asset, Expected Amortization, Year Two	18,300		18,300
Finite-Lived Intangible Asset, Expected Amortization, Year Three	18,000		18,000
Finite-Lived Intangible Asset, Expected Amortization, Year Four	17,200		17,200
Final Mile Services [Member]
Goodwill, Gross	111,900		111,900
Intermodal Business Segments [Member]
Goodwill, Gross	8,700		8,700
Zenith Freight Lines, LLC [Member]
Goodwill, Gross	20,100		20,100
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 43,600		$ 43,600		$ 42,700