CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME
Operating revenue	$ 710,387	$ 551,138
Operating expenses:
Salaries, wages and employee benefits	155,352	141,590
Fuel and fuel taxes	50,244	38,804
Depreciation and amortization	35,865	41,359
Insurance and claims	21,704	19,855
Equipment rent	7,891	7,349
Operations and maintenance	33,491	37,234
Purchased transportation	343,989	226,716
Operating taxes and licenses	4,833	4,795
Communications and utilities	2,984	3,470
(Gain) loss on disposal of assets, net	(811)	427
Other	17,526	16,681
Total operating expenses	673,068	538,280
Operating income	37,319	12,858
Other expenses:
Interest expense, net	3,929	5,605
Other, net	334	298
Total other expenses, net	4,263	5,903
Income before income taxes	33,056	6,955
Income tax expense	8,288	2,209
Consolidated net income and comprehensive income	$ 24,768	$ 4,746
Net earnings per share:
Average shares outstanding (basic) (in shares)	8,815	8,775
Basic earnings per share (in dollars per share)	$ 2.81	$ 0.54
Average shares outstanding (diluted) (in shares)	8,973	8,874
Diluted earnings per share (in dollars per share)	$ 2.76	$ 0.53