Segment Information (Summary Of Segment Information) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Revenues	$ 616,446	$ 592,703
Operating Income	62,471	31,066
Truckload Transportation Services
Segment Reporting Information [Line Items]
Revenues	462,949	464,863
Operating Income	57,628	29,089
Werner Logistics
Segment Reporting Information [Line Items]
Revenues	137,853	112,164
Operating Income	4,574	1,085
Other
Segment Reporting Information [Line Items]
Revenues	15,399	15,068
Operating Income	866	2,900
Corporate
Segment Reporting Information [Line Items]
Revenues	379	619
Operating Income	(597)	(2,008)
Subtotal
Segment Reporting Information [Line Items]
Revenues	616,580	592,714
Inter-segment eliminations
Segment Reporting Information [Line Items]
Revenues	$ (134)	$ (11)