Segment Information (Summary Of Segment Information) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Revenues	$ 627,533	$ 619,130	$ 1,223,650	$ 1,181,814
Operating Income	58,442	50,783	106,461	85,898
Truckload Transportation Services
Segment Reporting Information [Line Items]
Revenues	479,959	470,277	942,850	901,833
Operating Income	51,665	43,432	94,618	76,854
Werner Logistics
Segment Reporting Information [Line Items]
Revenues	130,883	134,012	248,253	251,432
Operating Income	5,182	5,602	9,893	8,359
Other
Segment Reporting Information [Line Items]
Revenues	16,096	14,422	31,568	27,681
Operating Income	2,293	243	3,472	(143)
Corporate
Segment Reporting Information [Line Items]
Revenues	629	631	1,218	1,538
Operating Income	(698)	1,506	(1,522)	828
Subtotal
Segment Reporting Information [Line Items]
Revenues	627,567	619,342	1,223,889	1,182,484
Inter-segment eliminations
Segment Reporting Information [Line Items]
Revenues	$ (34)	$ (212)	$ (239)	$ (670)