v3.10.0.1
Revenue (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Disaggregation of Revenue [Line Items]                      
Revenue $ 27,846 $ 22,135 $ 21,735 $ 22,791 $ 22,075 $ 21,081 $ 21,286 $ 20,587 $ 94,507 $ 85,029 $ 80,736
Cable Communications [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 55,143 53,070 50,577
Cable Communications [Member] | Residential, High-Speed Internet [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 17,144 15,681 14,421
Cable Communications [Member] | Residential, Video [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 22,455 22,874 22,204
Cable Communications [Member] | Residential, Voice [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 3,960 4,090 4,159
Cable Communications [Member] | Business Services [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 7,129 6,437 5,705
Cable Communications [Member] | Advertising [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 2,795 2,450 2,626
Cable Communications [Member] | Other [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 $ 1,660 $ 1,538 $ 1,462
Cable Communications [Member] | Franchise And Other Regulatory Fees [Member]                      
Disaggregation of Revenue [Line Items]                      
Cable segment revenue types as percentage of total cable revenue                 2.70% 2.80% 2.90%
Cable Networks [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 $ 11,773 $ 10,497 $ 10,324
Cable Networks [Member] | Distribution [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 6,826 6,081 5,978
Cable Networks [Member] | Advertising [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 3,587 3,359 3,530
Cable Networks [Member] | Content Licensing And Other [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,360 1,057 816
Broadcast Television [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 11,439 9,563 10,085
Broadcast Television [Member] | Advertising [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 7,010 5,654 6,834
Broadcast Television [Member] | Content Licensing [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 2,182 2,114 1,837
Broadcast Television [Member] | Distribution And Other [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 2,247 1,795 1,414
Filmed Entertainment [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 7,152 7,595 6,229
Filmed Entertainment [Member] | Content Licensing [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 2,899 2,956 2,518
Filmed Entertainment [Member] | Theatrical [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 2,111 2,192 1,560
Filmed Entertainment [Member] | Home Entertainment [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,048 1,287 1,182
Filmed Entertainment [Member] | Other [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,094 1,160 969
Theme Parks [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 5,683 5,443 4,946
NBCUniversal Segments [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 35,761 32,836 31,276
Sky Limited [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 4,587 0 0
Sky Limited [Member] | Advertising [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 651 0 0
Sky Limited [Member] | Direct To Consumer [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 3,632 0 0
Sky Limited [Member] | Content [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 304 0 0
Corporate, Non-Segment [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,403 1,193 886
Corporate, Non-Segment [Member] | NBCUniversal Segments [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 63 45 20
Eliminations [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 (2,387) (2,070) (2,003)
Eliminations [Member] | NBCUniversal Segments [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 (349) (307) (328)
NBCUniversal Media LLC [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 35,895 32,950 31,398
NBCUniversal Media LLC [Member] | Cable Networks [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 11,773 10,497 10,324
NBCUniversal Media LLC [Member] | Cable Networks [Member] | Distribution [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 6,826 6,081 5,978
NBCUniversal Media LLC [Member] | Cable Networks [Member] | Advertising [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 3,587 3,359 3,530
NBCUniversal Media LLC [Member] | Cable Networks [Member] | Content Licensing And Other [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,360 1,057 816
NBCUniversal Media LLC [Member] | Broadcast Television [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 11,439 9,563 10,085
NBCUniversal Media LLC [Member] | Broadcast Television [Member] | Advertising [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 7,010 5,654 6,834
NBCUniversal Media LLC [Member] | Broadcast Television [Member] | Content Licensing [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 2,182 2,114 1,837
NBCUniversal Media LLC [Member] | Broadcast Television [Member] | Distribution And Other [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 2,247 1,795 1,414
NBCUniversal Media LLC [Member] | Filmed Entertainment [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 7,152 7,595 6,229
NBCUniversal Media LLC [Member] | Filmed Entertainment [Member] | Content Licensing [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 2,899 2,956 2,518
NBCUniversal Media LLC [Member] | Filmed Entertainment [Member] | Theatrical [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 2,111 2,192 1,560
NBCUniversal Media LLC [Member] | Filmed Entertainment [Member] | Home Entertainment [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,048 1,287 1,182
NBCUniversal Media LLC [Member] | Filmed Entertainment [Member] | Other [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 1,094 1,160 969
NBCUniversal Media LLC [Member] | Theme Parks [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 5,683 5,443 4,946
NBCUniversal Media LLC [Member] | Corporate, Non-Segment [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 212 179 157
NBCUniversal Media LLC [Member] | Eliminations [Member]                      
Disaggregation of Revenue [Line Items]                      
Revenue                 $ (364) $ (327) $ (343)