Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended								12 Months Ended
	Oct. 30, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effect of Fourth Quarter Events [Line Items]
Revenues		$ 6,874	$ 5,837	$ 6,075	$ 6,499	$ 6,656	$ 6,481	$ 6,925	$ 6,936	$ 25,285	$ 26,998	$ 26,425
Operating income (loss)		1,083	903	1,251	902	(44)	984	1,414	1,792	4,139	4,146	5,062
Net earnings from continuing operations (ViacomCBS and noncontrolling interests)		802	580	698	504	(298)	600	953	1,944	2,584	3,199	3,357
Net earnings (ViacomCBS and noncontrolling interests)		829	627	726	519	(254)	646	983	1,964	2,701	3,339	3,492
Net earnings from continuing operations attributable to ViacomCBS		783	568	453	501	(302)	584	947	1,939	2,305	3,168	3,320
Net earnings attributable to ViacomCBS		$ 810	$ 615	$ 481	$ 516	$ (258)	$ 630	$ 977	$ 1,959	$ 2,422	$ 3,308	$ 3,455
Basic net earnings per common share attributable to ViacomCBS:
Net earnings from continuing operations (in dollars per share)		$ 1.27	$ 0.92	$ 0.74	$ 0.82	$ (0.49)	$ 0.95	$ 1.54	$ 3.16	$ 3.74	$ 5.15	$ 5.38
Net earnings (loss) (in dollars per share)		1.31	1.00	0.78	0.84	(0.42)	1.02	1.59	3.20	3.93	5.38	5.60
Diluted net earnings per common share attributable to ViacomCBS:
Net earnings from continuing operations (in dollars per share)		1.26	0.92	0.73	0.81	(0.49)	0.95	1.53	3.14	3.73	5.13	5.35
Net earnings (loss) (in dollars per share)		$ 1.31	$ 1.00	$ 0.78	$ 0.84	$ (0.42)	$ 1.02	$ 1.58	$ 3.18	$ 3.92	$ 5.36	$ 5.56
Weighted average number of common shares outstanding:
Basic weighted average number of common shares outstanding (in shares)		617	616	615	614	615	615	615	613	616	615	617
Diluted weighted average number of common shares outstanding (in shares)		620	618	617	616	615	617	617	617	618	617	621
Restructuring and other corporate matters		$ 177	$ 52	$ 158	$ 231	$ 467	$ 122	$ 7	$ 173	$ 618	$ 769	$ 489
Programming charges		38		121		$ 589				159	589	162
(Gain) loss on extinguishment of debt			23	103						126	0	$ (18)
Discrete tax provision (benefit)			$ (117)						(768)
fuboTV [Member]
Weighted average number of common shares outstanding:
Equity securities, gain		174		$ 32						$ 213
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | CNET Media Group [Member]
Weighted average number of common shares outstanding:
Gain on disposition	$ 214	214
Gain on disposition, net	$ 183	$ 183
CBS Television City [Member]
Weighted average number of common shares outstanding:
Gain on sale of property and sound stage operation									549
Gain on sale of property and sound stage operation, net									$ 386		$ 386