v3.19.3
Document and Entity Information
Nov. 05, 2019
Document And Entity Information [Line Items]  
Entity Registrant Name COMCAST CORP
Amendment Flag false
Entity Central Index Key 0001166691
Document Type 8-K
Document Period End Date Nov. 05, 2019
Entity Incorporation State Country Code PA
Entity File Number 001-32871
Entity Tax Identification Number 27-0000798
Entity Address, Address Line One One Comcast Center
Entity Address, City or Town Philadelphia
Entity Address, State or Province PA
Entity Address, Postal Zip Code 19103-2838
City Area Code (215)
Local Phone Number 286-1700
Written Communications false
Soliciting Material false
Pre Commencement Tender Offer false
Pre Commencement Issuer Tender Offer false
Entity Emerging Growth Company false
Common Class B [Member]  
Document And Entity Information [Line Items]  
Security 12b Title Class A Common Stock, $0.01 par value
Trading Symbol CMCSA
Security Exchange Name NASDAQ
Exchangeable Subordinated Debentures 2.0 Percent Due 2029 [Member]  
Document And Entity Information [Line Items]  
Security 12b Title 2.0% Exchangeable Subordinated Debentures due 2029
Trading Symbol CCZ
Security Exchange Name NYSE
Notes 5.50 Percent Due 2029 [Member]  
Document And Entity Information [Line Items]  
Security 12b Title 5.50% Notes due 2029
Trading Symbol CCGBP29
Security Exchange Name NYSE
Guaranteed Notes 9.455 Percent Due 2022 [Member]  
Document And Entity Information [Line Items]  
Security 12b Title 9.455% Guaranteed Notes due 2022
Trading Symbol CMCSA/22
Security Exchange Name NYSE