Segment Information (Summary Of Segment Information) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Revenues	$ 618,264	$ 629,735	$ 1,841,914	$ 1,811,549
Operating Income	53,357	63,386	159,818	149,284
Truckload Transportation Services
Segment Reporting Information [Line Items]
Revenues	480,351	484,782	1,423,201	1,386,615
Operating Income	48,870	58,894	143,488	135,748
Werner Logistics
Segment Reporting Information [Line Items]
Revenues	121,331	129,422	369,584	380,854
Operating Income	3,028	4,776	12,921	13,135
Other
Segment Reporting Information [Line Items]
Revenues	15,896	15,107	47,464	42,788
Operating Income	1,709	576	5,181	433
Corporate
Segment Reporting Information [Line Items]
Revenues	687	632	1,905	2,170
Operating Income	(250)	(860)	(1,772)	(32)
Subtotal
Segment Reporting Information [Line Items]
Revenues	618,265	629,943	1,842,154	1,812,427
Inter-segment eliminations
Segment Reporting Information [Line Items]
Revenues	$ (1)	$ (208)	$ (240)	$ (878)