v3.6.0.2
Related Party Transactions (Narrative) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2016
Sep. 30, 2016
Dec. 31, 2015
Related Party Transaction [Line Items]      
Other noncurrent liabilities $ 10,925   $ 10,637
NBCUniversal Media LLC [Member]      
Related Party Transaction [Line Items]      
Other noncurrent liabilities 4,130   3,790
NBCUniversal Media LLC [Member] | Carrying Value Of Related Party Contractual Obligation [Member]      
Related Party Transaction [Line Items]      
Other noncurrent liabilities $ 383   $ 383
NBCUniversal Media LLC [Member] | NBCUniversal Holdings Preferred Stock [Member]      
Related Party Transaction [Line Items]      
Preferred stock, dividend rate 8.25%    
Preferred stock liquidation preference value $ 9,400    
NBCUniversal Media LLC [Member] | Former Comcast And NBCUniversal Revolving Credit Agreements [Member]      
Related Party Transaction [Line Items]      
Revolving credit agreement capacity   $ 3,000  
NBCUniversal Media LLC [Member] | Comcast and NBCUniversal Revolving Credit Agreements [Member]      
Related Party Transaction [Line Items]      
Revolving credit agreement capacity   $ 5,000  
Borrowing margin for LIBOR based borrowings 1.00%