Note 7 - Segment Information (Details) - Segment Reporting Information (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenues from external customers, by segment	$ 1,182,461	$ 789,674	$ 2,141,128	$ 1,546,462
Segment income (loss) from continuing operations before taxes, by segment	32,389	9,309	52,004	31,409
Segment assets, by segment	2,353,564	1,972,240	2,353,564	1,972,240	2,167,798
Truck Segment [Member]
Segment Reporting Information [Line Items]
Revenues from external customers, by segment	1,177,306	784,573	2,131,936	1,536,803
Segment income (loss) from continuing operations before taxes, by segment	32,112	8,943	52,093	31,091
Segment assets, by segment	2,321,639	1,945,552	2,321,639	1,945,552
Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers, by segment	5,155	5,101	9,192	9,659
Segment income (loss) from continuing operations before taxes, by segment	277	366	(89)	318
Segment assets, by segment	$ 31,925	$ 26,688	$ 31,925	$ 26,688