Consolidated Statements of Comprehensive Income (Loss) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues
Revenue	$ 450,760	$ 432,568
Operating expenses
Salaries, wages, and benefits	142,003	135,378
Fuel and fuel taxes	40,404	40,207
Vehicle rents	21,463	21,877
Depreciation and amortization, net of (gain) loss on sale of property	22,382	25,803
Operating expenses and supplies	32,515	35,730
Insurance premiums and claims	21,777	26,023
Operating taxes and licenses	3,269	3,677
Communications and utilities	2,388	2,452
General and other operating expenses	14,900	15,335
Total operating expenses	442,762	436,236
Operating income	7,998	(3,668)
Other expense (income)
Interest expense, net	3,687	5,421
Other, net		2,000
Nonoperating Income (Expense), Total	(3,687)	(7,421)
Income (loss) before income tax provision	4,311	(11,089)
Income tax provision	1,650	(1,857)
Net total and comprehensive income (loss)	2,661	(9,232)
Net total and comprehensive income (loss) attributable to noncontrolling interest	123	(16)
Net total and comprehensive income (loss) attributable to controlling interest	$ 2,538	$ (9,216)
Earnings (loss) per share
Basic earnings (loss) per share (in dollars per share)	$ 0.05	$ (0.19)
Basic weighted average shares outstanding (in shares)	49,975	49,217
Diluted earnings (loss) per share (in dollars per share)	$ 0.05	$ (0.19)
Diluted weighted average shares outstanding (in shares)	51,524	49,217
Cargo and Freight [Member]
Revenues
Revenue	$ 417,641	$ 392,820
Fuel Surcharge [Member]
Revenues
Revenue	33,119	39,748
Shipping and Handling [Member]
Operating expenses
Purchased transportation	$ 141,661	$ 129,754