Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues
Revenue	$ 222,914	$ 243,303	$ 661,393	$ 613,187
Operating expenses:
Salaries, wages, and related expenses	84,093	86,249	239,376	211,621
Fuel expense	28,812	33,428	85,859	89,817
Operations and maintenance	14,742	16,457	44,814	40,783
Revenue equipment rentals and purchased transportation	50,428	47,445	146,267	115,525
Operating taxes and licenses	3,170	3,377	9,719	8,649
Insurance and claims	14,051	12,675	35,758	31,269
Communications and utilities	1,791	1,810	5,269	5,216
General supplies and expenses	7,685	6,391	21,701	16,833
Depreciation and amortization, including gains and losses on disposition of property and equipment	20,073	19,290	60,291	56,803
Total operating expenses	224,845	227,122	649,054	576,516
Operating (loss) income	(1,931)	16,181	12,339	36,671
Interest expense, net	2,992	2,460	8,121	6,360
Income from equity method investment	(2,138)	(2,142)	(7,548)	(5,407)
(Loss) income before income taxes	(2,785)	15,863	11,766	35,718
Income tax expense	404	4,249	4,451	9,716
Net (loss) income	$ (3,189)	$ 11,614	$ 7,315	$ 26,002
Net (loss) income per share:
Basic net (loss) income per share (in dollars per share)	$ (0.17)	$ 0.63	$ 0.40	$ 1.42
Diluted net (loss) income per share (in dollars per share)	$ (0.17)	$ 0.63	$ 0.39	$ 1.41
Basic weighted average shares outstanding (in shares)	18,458	18,343	18,426	18,337
Diluted weighted average shares outstanding (in shares)	18,719	18,497	18,620	18,448
Cargo and Freight [Member]
Revenues
Revenue	$ 199,832	$ 214,623	$ 590,511	$ 535,721
Fuel Surcharge [Member]
Revenues
Revenue	$ 23,082	$ 28,680	$ 70,882	$ 77,466