Segment Information (Summary Of Inter-Segment Eliminations) (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, net	$ 684,832	$ 601,138	$ 1,391,411	$ 1,269,820
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues, net	(6,081)	(353)	(7,186)	(874)
Intersegment Eliminations [Member] | National Networks [Member]
Segment Reporting Information [Line Items]
Revenues, net	(5,991)	(336)	(6,936)	(788)
Intersegment Eliminations [Member] | International And Other [Member]
Segment Reporting Information [Line Items]
Revenues, net	$ (90)	$ (17)	$ (250)	$ (86)