Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2016 |
Sep. 30, 2016 |
Jun. 30, 2016 |
Mar. 31, 2016 |
Dec. 31, 2015 |
Sep. 30, 2015 |
Jun. 30, 2015 |
Mar. 31, 2015 |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Quarterly Financial Information [Line Items] | |||||||||||
| Revenue | $ 21,025 | $ 21,319 | $ 19,269 | $ 18,790 | $ 19,245 | $ 18,669 | $ 18,743 | $ 17,853 | $ 80,403 | $ 74,510 | $ 68,775 |
| Operating income | 4,264 | 4,440 | 4,066 | 4,089 | 4,002 | 4,001 | 4,105 | 3,890 | 16,859 | 15,998 | 14,904 |
| Net Income (Loss) Attributable to Parent | $ 2,296 | $ 2,237 | $ 2,028 | $ 2,134 | $ 1,971 | $ 1,996 | $ 2,137 | $ 2,059 | $ 8,695 | $ 8,163 | $ 8,380 |
| Basic earnings per common share attributable to Comcast Corporation shareholders (in dollars per share) | $ 0.96 | $ 0.93 | $ 0.84 | $ 0.88 | $ 0.80 | $ 0.81 | $ 0.85 | $ 0.82 | $ 3.61 | $ 3.28 | $ 3.24 |
| Diluted earnings per common share attributable to Comcast Corporation shareholders (in dollars per share) | 0.95 | 0.92 | 0.83 | 0.87 | 0.79 | 0.80 | 0.84 | 0.81 | 3.57 | 3.24 | 3.20 |
| Dividends declared per common share (in dollars per share) | $ 0.275 | $ 0.275 | $ 0.275 | $ 0.275 | $ 0.25 | $ 0.25 | $ 0.25 | $ 0.25 | $ 1.10 | $ 1.00 | $ 0.90 |
| Verizon Wireless [Member] | |||||||||||
| Quarterly Financial Information [Line Items] | |||||||||||
| Income resulting from an agency agreement | $ 225 | ||||||||||
| Income Resulting From An Agency Agreement, Net of Tax | $ 143 | ||||||||||