Restructuring and Other Related Charges (Summary of Restructuring and Other Related Charges by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Restructuring Cost and Reserve [Line Items]
Total restructuring and other related charges	$ 17,162	$ 0	$ 19,804	$ 0
Operating segments | National Networks
Restructuring Cost and Reserve [Line Items]
Total restructuring and other related charges	274	0	576
Operating segments | International and Other
Restructuring Cost and Reserve [Line Items]
Total restructuring and other related charges	16,888	0	19,923
Inter-segment eliminations
Restructuring Cost and Reserve [Line Items]
Total restructuring and other related charges	$ 0	$ 0	$ (695)