Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenue	$ 691,495	$ 561,441	$ 1,757,262	$ 1,653,300
Costs and expenses:
Transportation costs	591,048	464,460	1,478,864	1,356,949
Selling, general and administrative expenses	80,533	77,722	235,667	238,055
Depreciation and amortization	9,655	9,594	29,251	28,855
Income from operations	10,259	9,665	13,480	29,441
Interest expense	(1,014)	(2,821)	(5,200)	(9,789)
Income before provision for income taxes	9,245	6,844	8,280	19,652
Income tax expense	(2,427)	(2,001)	(3,444)	(6,245)
Net income	$ 6,818	$ 4,843	$ 4,836	$ 13,407
Earnings per common share:
Basic (in usd per share)	$ 0.26	$ 0.18	$ 0.19	$ 0.50
Diluted (in usd per share)	$ 0.26	$ 0.18	$ 0.18	$ 0.50