Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Total ViacomCBS Stockholders’ Equity [Member]	Noncontrolling Interest [Member]
Balance, beginning of year (shares) at Dec. 31, 2018		613.0
Balance, beginning of year at Dec. 31, 2018	$ 10,503	$ 1	$ 49,907	$ (43,420)	$ 5,569	$ (1,608)	$ 10,449	$ 54
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation activity (shares)		2.0
Stock-based compensation activity	132		115	21	(4)		132
Dividends	(450)				(450)		(450)
Noncontrolling interests	(35)		(10)		(8)		(18)	(17)
Net earnings	3,593				3,566		3,566	27
Reclassification of income tax effect of the Tax Reform Act	(230)				230	(230)
Other comprehensive income (loss)	(14)					(16)	(16)	2
Balance, end of year (shares) at Sep. 30, 2019		615.0
Balance, end of year at Sep. 30, 2019	13,729	$ 1	50,012	(43,399)	8,903	(1,854)	13,663	66
Balance, beginning of year (shares) at Jun. 30, 2019		615.0
Balance, beginning of year at Jun. 30, 2019	13,204	$ 1	49,944	(43,399)	8,418	(1,803)	13,161	43
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation activity (shares)		0.0
Stock-based compensation activity	68		68	0	0		68
Dividends	(151)				(151)		(151)
Noncontrolling interests	13		0		6		6	7
Net earnings	646				630		630	16
Other comprehensive income (loss)	(51)					(51)	(51)	0
Balance, end of year (shares) at Sep. 30, 2019		615.0
Balance, end of year at Sep. 30, 2019	13,729	$ 1	50,012	(43,399)	8,903	(1,854)	13,663	66
Balance, beginning of year (shares) at Dec. 31, 2019		615.0
Balance, beginning of year at Dec. 31, 2019	13,289	$ 1	29,590	(22,908)	8,494	(1,970)	13,207	82
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation activity (shares)		2.0
Stock-based compensation activity	$ 129		129	0			129
Class B Common Stock purchased (shares)	(1.3)	(1.0)
Class B Common Stock purchased	$ (50)			(50)			(50)
Dividends	(450)				(450)		(450)
Noncontrolling interests	398		0		48		48	350	[1]
Net earnings	1,872				1,612		1,612	260
Other comprehensive income (loss)	57					60	60	(3)
Balance, end of year (shares) at Sep. 30, 2020		616.0
Balance, end of year at Sep. 30, 2020	15,245	$ 1	29,719	(22,958)	9,704	(1,910)	14,556	689
Balance, beginning of year (shares) at Jun. 30, 2020		616.0
Balance, beginning of year at Jun. 30, 2020	14,550	$ 1	29,680	(22,958)	9,150	(1,999)	13,874	676
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation activity (shares)		0.0
Stock-based compensation activity	39		39	0			39
Dividends	(150)				(150)		(150)
Noncontrolling interests	90		0		89		89	1
Net earnings	627				615		615	12
Other comprehensive income (loss)	89					89	89	0
Balance, end of year (shares) at Sep. 30, 2020		616.0
Balance, end of year at Sep. 30, 2020	$ 15,245	$ 1	$ 29,719	$ (22,958)	$ 9,704	$ (1,910)	$ 14,556	$ 689

[1] Primarily reflects the acquisition of Miramax (see Note 2).