Reportable Segments (Operating Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Stock-based compensation	$ (46)	$ (65)	$ (191)	$ (171)
Depreciation and amortization	(98)	(108)	(335)	(323)
Restructuring and other corporate matters	(52)	(122)	(443)	(307)
Gain on sale of assets	0	0	0	549
Operating income	959	1,036	3,162	4,286
Interest expense	(259)	(246)	(763)	(723)
Interest income	14	19	39	53
Loss on extinguishment of debt	(23)	0	(126)	0
Other items, net	(20)	(27)	(47)	(2)
Earnings from continuing operations before income taxes and equity in loss of investee companies	671	782	2,265	3,614
(Provision) benefit for income taxes	(38)	(126)	(377)	9
Equity in loss of investee companies, net of tax	(9)	(14)	(30)	(53)
Net earnings from continuing operations	624	642	1,858	3,570
Net earnings from discontinued operations, net of tax	3	4	14	23
Net earnings (ViacomCBS and noncontrolling interests)	627	646	1,872	3,593
Net earnings attributable to noncontrolling interests	(12)	(16)	(260)	(27)
Net earnings attributable to ViacomCBS	615	630	1,612	3,566
Operating Segments [Member] | TV Entertainment [Member]
Segment Reporting Information [Line Items]
Adjusted OIBDA	343	463	1,308	1,818
Operating Segments [Member] | Cable Networks [Member]
Segment Reporting Information [Line Items]
Adjusted OIBDA	866	841	2,945	2,723
Operating Segments [Member] | Filmed Entertainment [Member]
Segment Reporting Information [Line Items]
Adjusted OIBDA	54	66	197	199
Operating Segments [Member] | Publishing [Member]
Segment Reporting Information [Line Items]
Adjusted OIBDA	58	55	115	109
Corporate [Member]
Segment Reporting Information [Line Items]
Adjusted OIBDA	(171)	(112)	(364)	(334)
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Stock-based compensation	(41)	(47)	(140)	(148)
Depreciation and amortization	(98)	(108)	(335)	(323)
Restructuring and other corporate matters	(52)	(122)	(443)	(307)
Programming charges	0	0	(121)	0
Gain on sale of assets	$ 0	$ 0	$ 0	$ 549