v2.4.0.8

Business and Basis of Presentation (Details) | Mar. 19, 2013 | Mar. 19, 2013 NBCUniversal Media, LLC [Member] | Dec. 31, 2013 Video Customers [Member] numberofcustomers | Dec. 31, 2013 High-speed Internet Customers [Member] numberofcustomers | Dec. 31, 2013 Phone Customers [Member] numberofcustomers
--- | --- | --- | --- | --- | ---
Number of customers |  |  | 21,700,000 | 20,700,000 | 10,700,000
Remaining equity interest acquired | 49.00% | 49.00% |  |  |

X
- Definition Represents the percentage of voting interest acquired at the acquisition date from a noncontrolling interest. + References No definition available. + Details
Name: | cmcsa_NoncontrollingInterestAcquired
Namespace Prefix: | cmcsa_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of customers + References No definition available. + Details
Name: | cmcsa_NumberOfCustomers
Namespace Prefix: | cmcsa_
Data Type: | xbrli:positiveIntegerItemType
Balance Type: | na
Period Type: | instant