Redeemable Noncontrolling Interests (Narrative) (Details)	Dec. 31, 2017
New Video (BBC AMERICA) [Member]
Noncontrolling Interest [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	50.10%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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