Note 7 - Segment Information - Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Revenues from external customers	$ 1,864,286	$ 1,266,521	$ 5,218,729	$ 3,814,342
Segment operating income	127,037	90,169	369,559	219,185
Segment income before taxes	120,547	91,849	381,079	223,235
Segment assets	3,742,579	2,777,329	3,742,579	2,777,329	$ 3,119,977
Truck Segment [Member]
Revenues from external customers	1,859,823	1,261,885	5,205,802	3,801,675
Segment operating income	126,770	89,841	368,596	217,953
Segment income before taxes	120,373	91,595	380,397	222,218
Segment assets	3,688,151	2,722,614	3,688,151	2,722,614
Other Segments [Member]
Revenues from external customers	4,463	4,636	12,927	12,667
Segment operating income	267	328	963	1,232
Segment income before taxes	174	254	682	1,017
Segment assets	$ 54,428	$ 54,715	$ 54,428	$ 54,715