v3.3.1.900
Long-Term Debt (Narrative) (Details)
$ in Millions, ¥ in Billions
12 Months Ended
Nov. 13, 2015
JPY (¥)
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Long-term Debt, Fair Value   $ 58,000 $ 55,300
Amounts available under revolving credit facilities   6,400  
Unused irrevocable standby letters of credit   464  
Revolver Line of credit amount outstanding   0 0
NBCUniversal Media LLC [Member]      
Long-term Debt, Fair Value   13,400 $ 11,500
NBCUniversal Enterprise [Member] | NBCUniversal Media LLC [Member]      
Related Party Aggregate Principal Amount Senior Notes Not Subject To Guarantee   4,000  
Related Party Credit Facility Not Subject To Guarantee   1,350  
Related Party Liquidation Preference Preferred Stock Not Subject To Guarantee   725  
Commercial Paper Program      
Commercial Paper Capacity   $ 6,250  
NBCUniversal Enterprise Credit Facility [Member]      
Debt Instrument, Maturity Date, Description   March 2018  
Borrowing margin for LIBOR based borrowings   1.00%  
Amounts available under revolving credit facilities   $ 775  
Credit facility borrowing capacity   1,350  
Comcast And Comcast Cable Debt Securities [Member] | NBCUniversal Media LLC [Member]      
Guarantee Obligations Current Principal Balance   $ 35,100  
Comcast And Comcast Cable Communications, LLC Revolving Credit Facility [Member]      
Debt Instrument, Maturity Date, Description   June 2017  
Borrowing margin for LIBOR based borrowings   1.00%  
Credit facility borrowing capacity   $ 6,250  
Comcast And Comcast Cable Communications, LLC Revolving Credit Facility [Member] | NBCUniversal Media LLC [Member]      
Revolver Line of credit amount outstanding   0  
NBCUniversal Enterprise Commercial Paper [Member]      
Commercial Paper Capacity   $ 1,350  
Universal Studios Japan Term Loans [Member]      
Debt Instrument, Maturity Date, Description November 2020    
Universal Studios Japan Long-term Debt | ¥ ¥ 400    
Universal Studios Japan Term Loans [Member] | NBCUniversal Media LLC [Member]      
Debt Instrument, Maturity Date, Description November 2020    
Universal Studios Japan Long-term Debt | ¥ ¥ 400