Segment Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments	2
Revenues
Total Operating Revenue	$ 450,760	$ 432,568
Operating Income
Total Operating Income (Loss)	7,998	(3,668)
Truckload Segment [Member]
Revenues
Total Operating Revenue	368,920	382,092
Operating Income
Total Operating Income (Loss)	6,728	1,200
Brokerage Segment [Member]
Revenues
Total Operating Revenue	81,840	50,476
Operating Income
Total Operating Income (Loss)	$ 1,270	$ (4,868)