Consolidated Condensed Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating revenue	$ 212,384	$ 212,090	$ 431,030	$ 411,113
Operating expenses (income):
Salaries, wages and benefits	73,476	68,613	146,237	132,137
Purchased transportation	36,165	38,668	76,610	76,917
Fuel and fuel taxes	20,868	30,952	49,165	58,629
Supplies and maintenance	11,833	11,502	24,061	22,623
Depreciation	25,972	23,462	51,399	46,005
Operating taxes and licenses	2,615	2,438	5,254	4,771
Insurance and claims	11,633	9,862	23,917	19,737
Communications and utilities	1,977	1,950	3,962	3,900
Gain on disposition of revenue equipment	(2,216)	(1,230)	(3,771)	(2,778)
Other	4,805	5,929	10,908	11,495
Total operating expenses	187,128	192,146	387,742	373,436
Operating income	25,256	19,944	43,288	37,677
Other	(13)	(395)	(110)	(673)
Income before income taxes	25,269	20,339	43,398	38,350
Income taxes expense	7,135	5,149	11,546	9,614
Net income	$ 18,134	$ 15,190	$ 31,852	$ 28,736
Basic earnings per common share (in dollars per share)	$ 0.33	$ 0.28	$ 0.58	$ 0.53
Diluted earnings per common share (in dollars per share)	0.33	0.28	0.58	0.52
Dividends declared per common share (in dollars per share)	$ 0.04	$ 0.03	$ 0.08	$ 0.06
Pro Forma [Member]
Operating expenses (income):
Net income	$ 18,134	$ 15,190	$ 31,852	$ 28,736
Basic earnings per common share (in dollars per share)	$ 0.22	$ 0.19	$ 0.39	$ 0.35
Diluted earnings per common share (in dollars per share)	0.22	0.18	0.38	0.35
Dividends declared per common share (in dollars per share)	$ 0.027	$ 0.02	$ 0.053	$ 0.04