Redeemable Noncontrolling Interests (Narrative) (Details)	Dec. 31, 2018	Apr. 20, 2018
Levity [Member]
Noncontrolling Interest [Line Items]
Noncontrolling Interest, Right to Put	50.00%
Business Acquisition, Percentage of Voting Interests Acquired		57.00%
New Video (BBC AMERICA) [Member]
Noncontrolling Interest [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired	50.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	50.10%