Reportable Segments (Operating Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Stock-based compensation	$ (49)	$ (56)	$ (101)	$ (143)
Depreciation and amortization	(95)	(122)	(194)	(234)
Restructuring and other corporate matters	(35)	(158)	(35)	(389)
Programming charges		(121)		(121)
Net gain on sales	116	0	116	0
Operating income	1,226	1,251	2,754	2,153
Interest expense	(243)	(263)	(502)	(504)
Interest income	13	11	26	25
Net gains from investments	32	32	52	32
Loss on extinguishment of debt	0	(103)	(128)	(103)
Other items, net	(10)	(26)	(29)	(54)
Earnings from continuing operations before income taxes and equity in loss of investee companies	1,018	902	2,173	1,549
(Provision) benefit for income taxes	34	(192)	(192)	(326)
Equity in loss of investee companies, net of tax	(44)	(12)	(62)	(21)
Net earnings from continuing operations	1,008	698	1,919	1,202
Net earnings from discontinued operations, net of tax	41	28	53	43
Net earnings (ViacomCBS and noncontrolling interests)	1,049	726	1,972	1,245
Net earnings attributable to noncontrolling interests	(13)	(245)	(25)	(248)
Net earnings attributable to ViacomCBS	1,036	481	1,947	997
TV Entertainment [Member]
Segment Reporting Information [Line Items]
Programming charges		(66)		(66)
Cable Networks [Member]
Segment Reporting Information [Line Items]
Programming charges		(50)		(50)
Filmed Entertainment [Member]
Segment Reporting Information [Line Items]
Programming charges		(5)		(5)
Operating Segments [Member] | TV Entertainment [Member]
Segment Reporting Information [Line Items]
Adjusted OIBDA	216	392	665	965
Operating Segments [Member] | Cable Networks [Member]
Segment Reporting Information [Line Items]
Adjusted OIBDA	1,125	1,285	2,309	2,079
Operating Segments [Member] | Filmed Entertainment [Member]
Segment Reporting Information [Line Items]
Adjusted OIBDA	72	116	276	143
Corporate and Eliminations [Member]
Segment Reporting Information [Line Items]
Adjusted OIBDA	(124)	(97)	(282)	(193)
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Stock-based compensation	(49)	(44)	(101)	(97)
Depreciation and amortization	(95)	(122)	(194)	(234)
Restructuring and other corporate matters	(35)	(158)	(35)	(389)
Programming charges	0	(121)	0	(121)
Net gain on sales	$ 116	$ 0	$ 116	$ 0