Segment Information (Summary Of Segment Information) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 501,221	$ 482,802
Operating Income	25,972	32,487
Truckload Transportation Services
Segment Reporting Information [Line Items]
Revenues	385,003	372,917
Operating Income	23,466	32,359
Werner Logistics
Segment Reporting Information [Line Items]
Revenues	99,853	96,577
Operating Income	3,049	5,035
Other Segment
Segment Reporting Information [Line Items]
Revenues	16,110	13,178
Operating Income	145	(1,934)
Corporate Segment
Segment Reporting Information [Line Items]
Revenues	422	373
Operating Income	(688)	(2,973)
Subtotal
Segment Reporting Information [Line Items]
Revenues	501,388	483,045
Intersegment Elimination
Segment Reporting Information [Line Items]
Revenues	$ (167)	$ (243)