Segment Information (Summary of Inter-Segment Eliminations) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Revenues, net	$ 646,291	$ 772,299	$ 1,380,666	$ 1,556,520
Inter-segment eliminations
Segment Reporting Information [Line Items]
Revenues, net	(10,539)	(11,966)	(13,596)	(14,953)
Inter-segment eliminations | National Networks
Segment Reporting Information [Line Items]
Revenues, net	(8,111)	(10,260)	(10,180)	(11,650)
Inter-segment eliminations | International and Other
Segment Reporting Information [Line Items]
Revenues, net	$ (2,428)	$ (1,706)	$ (3,416)	$ (3,303)