Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments			2
Revenues
Total Operating Revenue	$ 491,140	$ 431,469	$ 1,416,921	$ 1,286,514
Operating Income
Total Operating Income (Loss)	6,635	15,891	23,539	28,500
Truckload Segment [Member]
Revenues
Total Operating Revenue	400,320	375,499	1,147,773	1,134,039
Operating Income
Total Operating Income (Loss)	8,081	20,407	23,553	42,035
Brokerage Segment [Member]
Revenues
Total Operating Revenue	90,820	55,970	269,148	152,475
Operating Income
Total Operating Income (Loss)	$ (1,446)	$ (4,516)	$ (14)	$ (13,535)