Revenue (Disaggregation of Revenue by Revenue Source) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of revenue
Revenues	$ 702,891	$ 590,214	$ 1,969,151	$ 1,751,876
Truckload Transportation Services
Disaggregation of revenue
Revenues	527,697	458,256	1,481,846	1,368,172
Werner Logistics
Disaggregation of revenue
Revenues	157,968	117,351	437,494	339,678
Inter-segment eliminations
Disaggregation of revenue
Revenues	(212)	(30)	(539)	(55)
Transportation Services
Disaggregation of revenue
Revenues	685,453	575,577	1,918,801	1,707,795
Other revenues
Disaggregation of revenue
Revenues	$ 17,438	$ 14,637	$ 50,350	$ 44,081