Note 8 - Lease Obligations (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Impairment of Long-Lived Assets to be Disposed of	$ 0	$ 0	$ 26,569	$ 0
Revenue Equipment Rentals and Purchased Transportation	58,604	$ 50,428	151,677	$ 146,267
Operating Lease, Right-of-Use Asset	41,700		41,700		$ 58,800
Finance Lease, Right-of-Use Asset, after Accumulated Amortization, Total	50,600		50,600		$ 35,600
Leased Office Facility [Member]
Impairment of Long-Lived Assets to be Disposed of	0		2,200
Revenue Equipment Rentals and Purchased Transportation	$ 0		$ 800