Revenue (Disaggregation of Revenue by Revenue Source) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of revenue
Revenues	$ 616,446	$ 592,703
Truckload Transportation Services
Disaggregation of revenue
Revenues	462,949	464,863
Werner Logistics
Disaggregation of revenue
Revenues	137,853	112,164
Inter-segment eliminations
Disaggregation of revenue
Revenues	(134)	(11)
Transportation Services
Disaggregation of revenue
Revenues	600,668	577,016
Other revenues
Disaggregation of revenue
Revenues	$ 15,778	$ 15,687