Revenue (Disaggregation of Revenue by Revenue Source) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of revenue
Revenues	$ 568,959	$ 627,533	$ 1,161,662	$ 1,223,650
Truckload Transportation Services
Disaggregation of revenue
Revenues	445,053	479,959	909,916	942,850
Werner Logistics
Disaggregation of revenue
Revenues	110,163	130,883	222,327	248,253
Inter-segment eliminations
Disaggregation of revenue
Revenues	(14)	(34)	(25)	(239)
Transportation Services
Disaggregation of revenue
Revenues	555,202	610,808	1,132,218	1,190,864
Other revenues
Disaggregation of revenue
Revenues	$ 13,757	$ 16,725	$ 29,444	$ 32,786