Broadcast Licenses, Goodwill and Other Intangible Assets (Schedule of certain key estimates and assumptions used in impairment test) (Details)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Measurement Input, Discount Rate [Member] | Minimum [Member]
Impairment measurement input	12.6	12.2	12.0
Measurement Input, Discount Rate [Member] | Maximum [Member]
Impairment measurement input	13.0	12.2	12.0
Measurement Input Operating Profit Margin [Member] | Minimum [Member]
Impairment measurement input	17.8	19.0	19.0
Measurement Input Operating Profit Margin [Member] | Maximum [Member]
Impairment measurement input	36.4	36.4	36.4
Measurement Input, Long-term Revenue Growth Rate [Member] | Minimum [Member]
Impairment measurement input	0.2	0.0	0.5
Measurement Input, Long-term Revenue Growth Rate [Member] | Maximum [Member]
Impairment measurement input	2.9	2.9	2.9