Segment Information (Summary Of Segment Information) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenues	$ 508,676	$ 534,448	$ 1,490,159	$ 1,564,746
Operating Income	29,074	52,800	91,114	143,195
Truckload Transportation Services
Segment Reporting Information [Line Items]
Revenues	384,312	417,861	1,136,478	1,225,439
Operating Income	19,846	48,747	74,971	131,901
Werner Logistics
Segment Reporting Information [Line Items]
Revenues	109,459	102,149	310,001	296,459
Operating Income	4,894	5,021	16,502	12,474
Other Segment
Segment Reporting Information [Line Items]
Revenues	14,804	14,087	43,148	41,996
Operating Income	(1,191)	(1,354)	(4,964)	(2,038)
Corporate Segment
Segment Reporting Information [Line Items]
Revenues	313	634	1,300	1,880
Operating Income	5,525	386	4,605	858
Subtotal
Segment Reporting Information [Line Items]
Revenues	508,888	534,731	1,490,927	1,565,774
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Revenues	$ (212)	$ (283)	$ (768)	$ (1,028)