Consolidated Condensed Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating revenue	$ 216,011	$ 214,973	$ 647,041	$ 626,086
Operating expenses (income):
Salaries, wages and benefits	74,797	69,312	221,034	201,449
Purchased transportation	37,066	40,435	113,676	117,352
Fuel and fuel taxes	24,268	31,275	73,433	89,904
Supplies and maintenance	12,440	12,116	36,501	34,739
Depreciation	25,580	24,290	76,979	70,295
Operating taxes and licenses	2,749	2,651	8,003	7,422
Insurance and claims	11,243	9,618	35,160	29,355
Communications and utilities	1,999	1,901	5,961	5,801
Other	5,315	5,900	16,223	17,395
Total operating expenses	191,611	194,939	579,353	568,375
Operating income	24,400	20,034	67,688	57,711
Other	(17)	(255)	(127)	(928)
Income before income taxes	24,417	20,289	67,815	58,639
Income taxes expense	6,373	3,702	17,919	13,316
Net income	$ 18,044	$ 16,587	$ 49,896	$ 45,323
Basic earnings per common share (in dollars per share)	$ 0.22	$ 0.20	$ 0.61	$ 0.55
Diluted earnings per common share (in dollars per share)	0.22	0.20	0.60	0.55
Dividends declared per common share (in dollars per share)	$ 0.04	$ 0.453	$ 0.093	$ 0.493
Revenue Equipment [Member]
Operating expenses (income):
Gain on disposition of property, plant and equipment	$ (2,128)	$ (2,559)	$ (5,899)	$ (5,337)
Facility [Member]
Operating expenses (income):
Gain on disposition of property, plant and equipment	$ (1,718)	$ 0	$ (1,718)	$ 0