Segment Information (Summary Of Segment Information) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Revenues	$ 498,681	$ 534,644	$ 981,483	$ 1,030,298
Operating Income	29,553	52,210	62,040	90,395
Truckload Transportation Services
Segment Reporting Information [Line Items]
Revenues	379,249	417,015	752,166	807,578
Operating Income	22,766	47,312	55,125	83,154
Werner Logistics
Segment Reporting Information [Line Items]
Revenues	103,965	103,450	200,542	194,310
Operating Income	6,573	5,004	11,608	7,453
Other Segment
Segment Reporting Information [Line Items]
Revenues	15,166	13,924	28,344	27,909
Operating Income	(1,839)	(239)	(3,773)	(684)
Corporate Segment
Segment Reporting Information [Line Items]
Revenues	614	725	987	1,246
Operating Income	2,053	133	(920)	472
Subtotal
Segment Reporting Information [Line Items]
Revenues	498,994	535,114	982,039	1,031,043
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Revenues	$ (313)	$ (470)	$ (556)	$ (745)