Revenue (Revenue by Geographic Location) (Details) - USD ($) $ in Millions |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2019 |
Sep. 30, 2019 |
Jun. 30, 2019 |
Mar. 31, 2019 |
Dec. 31, 2018 |
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Disaggregation of Revenue [Line Items] | |||||||||||
| Revenue | $ 28,398 | $ 26,827 | $ 26,858 | $ 26,859 | $ 27,846 | $ 22,135 | $ 21,735 | $ 22,791 | $ 108,942 | $ 94,507 | $ 85,029 |
| United States [Member] | |||||||||||
| Disaggregation of Revenue [Line Items] | |||||||||||
| Revenue | 82,952 | 82,233 | 77,246 | ||||||||
| Europe [Member] | |||||||||||
| Disaggregation of Revenue [Line Items] | |||||||||||
| Revenue | 21,553 | 7,721 | 3,190 | ||||||||
| Other [Member] | |||||||||||
| Disaggregation of Revenue [Line Items] | |||||||||||
| Revenue | 4,437 | 4,553 | 4,593 | ||||||||
| NBCUniversal Media LLC [Member] | |||||||||||
| Disaggregation of Revenue [Line Items] | |||||||||||
| Revenue | 34,021 | 35,895 | 32,950 | ||||||||
| NBCUniversal Media LLC [Member] | United States [Member] | |||||||||||
| Disaggregation of Revenue [Line Items] | |||||||||||
| Revenue | 27,002 | 28,309 | 25,303 | ||||||||
| NBCUniversal Media LLC [Member] | Foreign [Member] | |||||||||||
| Disaggregation of Revenue [Line Items] | |||||||||||
| Revenue | $ 7,019 | $ 7,586 | $ 7,647 | ||||||||