Segment Information (Summary of Inter-Segment Eliminations) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Revenues, net	$ 654,015	$ 718,597	$ 2,034,681	$ 2,275,117
Inter-segment eliminations
Segment Reporting Information [Line Items]
Revenues, net	(7,426)	(23,234)	(21,022)	(38,187)
Inter-segment eliminations | National Networks
Segment Reporting Information [Line Items]
Revenues, net	(7,166)	(18,140)	(17,346)	(29,790)
Inter-segment eliminations | International and Other
Segment Reporting Information [Line Items]
Revenues, net	$ (260)	$ (5,094)	$ (3,676)	$ (8,397)