Supplemental Financial Information (Receivables)(Details) - USD ($) $ in Millions |
Mar. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Supplemental Financial Information [Line Items] | ||
| Receivables, gross | $ 8,111 | $ 8,622 |
| Less: Allowance for returns and customer incentives | 347 | 417 |
| Less: Allowance for doubtful accounts | 239 | 250 |
| Receivables, net | 7,525 | 7,955 |
| NBCUniversal Media LLC [Member] | ||
| Supplemental Financial Information [Line Items] | ||
| Receivables, gross | 6,647 | 6,799 |
| Less: Allowance for returns and customer incentives | 343 | 413 |
| Less: Allowance for doubtful accounts | 77 | 84 |
| Receivables, net | $ 6,227 | $ 6,302 |