Debt (Credit Facility Narrative) (Details) - Revolving Credit Facility [Member]	1 Months Ended	9 Months Ended
	Jan. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)
Line of Credit Facility [Line Items]
Period for Consolidated EBITDA		12 months
CBS Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under credit facility	$ 2,500,000,000
Viacom Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under credit facility	2,500,000,000
ViacomCBS Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under credit facility	$ 3,500,000,000
Maximum consolidated leverage ratio	4.5
Maximum Consolidated Leverage Ratio, potential increase	5.0
Amount borrowed under credit facility		$ 0
Availability under credit facility		$ 3,500,000,000