Reportable Segments (Schedule of Total Assets by Segment) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total assets	$ 33,438	$ 33,735
Operating Segments | U.S. Networks
Segment Reporting Information [Line Items]
Total assets	17,505	18,156
Operating Segments | International Networks
Segment Reporting Information [Line Items]
Total assets	7,947	8,145
Operating Segments | Corporate, inter-segment eliminations and other
Segment Reporting Information [Line Items]
Total assets	$ 7,986	$ 7,434