Document and Entity Information |
3 Months Ended |
|---|---|
|
Mar. 31, 2017
shares
| |
| Document And Entity Information [Line Items] | |
| Document Type | 10-Q |
| Amendment Flag | false |
| Document Period End Date | Mar. 31, 2017 |
| Document Fiscal Year Focus | 2017 |
| Document Fiscal Period Focus | Q1 |
| Trading Symbol | cmcsa |
| Entity Registrant Name | COMCAST CORP |
| Entity Central Index Key | 0001166691 |
| Current Fiscal Year End Date | --12-31 |
| Entity Filer Category | Large Accelerated Filer |
| NBCUniversal Media LLC [Member] | |
| Document And Entity Information [Line Items] | |
| Entity Registrant Name | NBCUniversal Media, LLC |
| Entity Central Index Key | 0000902739 |
| Entity Filer Category | Non-accelerated Filer |
| Class A Common Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Entity Common Stock, Shares Outstanding | 4,733,512,494 |
| Class B Common Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Entity Common Stock, Shares Outstanding | 9,444,375 |