Segment Information (Summary Of Inter-Segment Eliminations) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Revenues, net	$ 632,165	$ 519,550	$ 1,901,985	$ 1,566,197
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues, net	(3,578)	(577)	(4,452)	(1,792)
Intersegment Eliminations [Member] | National Networks [Member]
Segment Reporting Information [Line Items]
Revenues, net	(3,563)	(407)	(4,351)	(1,397)
Intersegment Eliminations [Member] | International And Other [Member]
Segment Reporting Information [Line Items]
Revenues, net	$ (15)	$ (170)	$ (101)	$ (395)