Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Jun. 30, 2014	Feb. 10, 2015
Document And Entity Information [Abstract]
Entity Registrant Name	CBS Corporation
Entity Central Index Key	0000813828
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Amendment Flag	false
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Document Type	10-K
Document Period End Date	Dec. 31, 2014
Class of Stock [Line Items]
Entity Public Float		$ 32,764,308,589
Common Class A [Member]
Class of Stock [Line Items]
Common Stock Outstanding			37,826,904
Entity Public Float		489,547,031
Common Class B [Member]
Class of Stock [Line Items]
Common Stock Outstanding			459,445,346
Entity Public Float		$ 32,274,761,558