Condensed Consolidating Financial Information (Narrative) (Details) $ in Millions |
3 Months Ended |
|---|---|
|
Mar. 31, 2016
USD ($)
| |
| Comcast Holdings' ZONES due October2029 [Member] | |
| Debt Instrument, Maturity Date, Description | October 2029 |
| Principal amount of debt securities subject to guarantee | $ 185 |
| Comcast Holdings' ZONES due November 2029 [Member] | |
| Debt Instrument, Maturity Date, Description | November 2029 |
| Principal amount of debt securities not subject to guarantee | $ 62 |
| Comcast And Comcast Cable Communications, LLC Revolving Credit Facility [Member] | |
| Debt Instrument, Maturity Date, Description | 2017 |
| Principal amount of debt securities subject to guarantee | $ 6,250 |
| NBCUniversal Enterprise Senior Debt Securities [Member] | |
| Principal amount of debt securities subject to guarantee | 4,000 |
| Universal Studios Japan Term Loans [Member] | |
| Principal amount of debt securities not subject to guarantee | $ 3,500 |