CONDENSED CONSOLIDATED STATEMENTS OF INCOME (LOSS) AND COMPREHENSIVE INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
CONDENSED CONSOLIDATED STATEMENTS OF INCOME (LOSS) AND COMPREHENSIVE INCOME (LOSS)
Operating revenue	$ 201,063	$ 158,505
Operating expenses:
Salaries, wages and employee benefits	41,887	36,555
Fuel and fuel taxes	17,037	11,444
Depreciation and amortization	8,024	9,570
Insurance and claims	6,623	5,809
Equipment rent	1,834	1,949
Operations and maintenance	8,515	7,066
Purchased transportation	98,319	74,103
Operating taxes and licenses	1,260	1,272
Communications and utilities	1,006	804
(Gain) loss on disposal of assets, net	(6,401)	(177)
Other	4,276	4,064
Total operating expenses	182,380	152,459
Operating income	18,683	6,046
Other expenses:
Interest expense, net	1,417	1,025
Other, net	68	61
Total other expenses, net	1,485	1,086
Income before income taxes	17,198	4,960
Income tax expense	4,087	1,363
Consolidated net income and comprehensive income	$ 13,111	$ 3,597
Net earnings per share:
Average shares outstanding (basic) (in shares)	8,831	8,841
Basic earnings per share (in dollars per share)	$ 1.48	$ 0.41
Average shares outstanding (diluted) (in shares)	9,043	9,007
Diluted earnings per share (in dollars per share)	$ 1.45	$ 0.40