Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
OPERATING REVENUE	$ 607,284	$ 645,262	$ 596,815
Operating Expenses
Salaries, wages and benefits	250,035	269,482	240,139
Rent and purchased transportation	3,810	4,643	7,984
Fuel	99,597	86,094	101,871
Operations and maintenance	21,522	27,647	24,479
Operating taxes and licenses	13,595	14,962	14,459
Insurance and claims	20,826	22,229	17,003
Communications and utilities	4,447	5,281	4,953
Depreciation and amortization	104,083	109,937	100,212
Other operating expenses	21,400	26,398	22,781
Gain on disposal of property and equipment	(37,438)	(14,830)	(31,341)
Total operating expenses	501,877	551,843	502,540
Operating income	105,407	93,419	94,275
Interest income	640	842	3,955
Interest expense	0	0	(1,052)
Income before income taxes	106,047	94,261	97,178
Federal and state income tax expense	26,770	23,455	24,211
Net Income	79,277	70,806	72,967
Other comprehensive income, net of tax	0	0	0
Comprehensive income	$ 79,277	$ 70,806	$ 72,967
Net income per share
Basic	$ 1.00	$ 0.87	$ 0.89
Diluted	$ 1.00	$ 0.87	$ 0.89
Weighted average shares outstanding
Basic	79,573	81,388	81,980
Diluted	79,612	81,444	82,024
Dividends declared per share	$ 0.58	$ 0.08	$ 0.08