Revenue (Disaggregation of Revenue by Revenue Source) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of revenue
Revenues	$ 618,264	$ 629,735	$ 1,841,914	$ 1,811,549
Truckload Transportation Services
Disaggregation of revenue
Revenues	480,351	484,782	1,423,201	1,386,615
Werner Logistics
Disaggregation of revenue
Revenues	121,331	129,422	369,584	380,854
Inter-segment eliminations
Disaggregation of revenue
Revenues	(1)	(208)	(240)	(878)
Transportation Services
Disaggregation of revenue
Revenues	601,681	613,996	1,792,545	1,766,591
Other revenues
Disaggregation of revenue
Revenues	$ 16,583	$ 15,739	$ 49,369	$ 44,958