Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Statement [Abstract]
Operating Revenue	$ 151,275	$ 152,402
Operating Expenses
Salaries, wages, and benefits	58,638	64,782
Rent and purchased transportation	748	964
Fuel	29,711	24,157
Operating Costs and Expenses	5,079	5,688
Cost, Direct Tax and License	3,209	3,621
Insurance and claims	5,566	5,439
Communications and utilities	1,078	1,226
Depreciation and amortization	23,311	26,926
Other operating expenses	5,798	5,552
Gain on disposal of property and equipment	(4,258)	(4,232)
Total operating expenses	128,880	134,123
Operating income	22,395	18,279
Interest income	146	138
Income before income taxes	22,541	18,417
Federal and state income taxes	5,766	4,683
Net Income	16,775	13,734
Other comprehensive income, net of tax	0	0
Comprehensive income	$ 16,775	$ 13,734
Net income per share
Basic	$ 0.21	$ 0.17
Diluted	$ 0.21	$ 0.17
Weighted average shares outstanding
Basic	78,929	80,152
Diluted	78,953	80,206
Dividends declared per share	$ 0.02	$ 0.02