Note 1 - Summary of Significant Accounting Policies - Revenue by Operating Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Total revenues	$ 1,103,573	$ 1,216,858	$ 1,046,003
Highway Services [Member] | Expedited [Member]
Total revenues	423,820	452,713	337,063
Dedicated [Member]
Total revenues	320,287	362,997	324,541
Managed Freight [Member]
Total revenues	258,903	320,985	321,236
Managed Freight [Member] | Warehouse [Member]
Total revenues	$ 100,563	$ 80,163	$ 63,163