Revenue (Disaggregation of Revenue by Revenue Source) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of revenue
Revenues	$ 590,214	$ 618,264	$ 1,751,876	$ 1,841,914
Truckload Transportation Services
Disaggregation of revenue
Revenues	458,256	480,351	1,368,172	1,423,201
Werner Logistics
Disaggregation of revenue
Revenues	117,351	121,331	339,678	369,584
Inter-segment eliminations
Disaggregation of revenue
Revenues	(30)	(1)	(55)	(240)
Transportation Services
Disaggregation of revenue
Revenues	575,577	601,681	1,707,795	1,792,545
Other revenues
Disaggregation of revenue
Revenues	$ 14,637	$ 16,583	$ 44,081	$ 49,369