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Schedule II Valuation and Qualifying Accounts | 12 Months Ended
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Dec. 31, 2015
Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] |
Comcast Corporation and Subsidiaries |  |  |  |  |  |  |  |
Schedule II — Valuation and Qualifying Accounts |  |  |  |  |  |  |  |
Year ended December 31, 2015, 2014 and 2013 |  |  |  |  |  |  |  |
Year Ended December 31 (in millions) |  | Balance at Beginning of Year |  | Additions Charged to Costs and Expenses(a) |  | Deductions from Reserves(a) |  | Balance at End of Year
2015 |  |  |  |  |  |  |  |
| Allowance for doubtful accounts | $ | 205 | $ | 166 | $ | 145 | $ | 226
| Allowance for returns and customer incentives |  | 359 |  | 1,236 |  | 1,122 |  | 473
| Valuation allowance on deferred tax assets |  | 375 |  | 4 |  | 37 |  | 342
2014 |  |  |  |  |  |  |  |
| Allowance for doubtful accounts | $ | 221 | $ | 162 | $ | 178 | $ | 205
| Allowance for returns and customer incentives |  | 375 |  | 932 |  | 948 |  | 359
| Valuation allowance on deferred tax assets |  | 405 |  | 33 |  | 63 |  | 375
2013 |  |  |  |  |  |  |  |
| Allowance for doubtful accounts | $ | 198 | $ | 317 | $ | 294 | $ | 221
| Allowance for returns and customer incentives |  | 307 |  | 811 |  | 743 |  | 375
| Valuation allowance on deferred tax assets |  | 355 |  | 71 |  | 21 |  | 405
(a) Additions and deductions related to allowance for returns and customer incentives include amounts for distribution on behalf of third parties. Additions and deductions related to allowance for returns and customer incentives for the year ended December 31, 2013 also reflec t corrections to change amounts that were previously recorded net.
NBCUniversal Media LLC [Member] |
Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] |
NBCUniversal Media, LLC |  |  |  |  |  |  |  |
Schedule II — Valuation and Qualifying Accounts |  |  |  |  |  |  |  |
Year ended December 31, 2015, 2014 and 2013 |  |  |  |  |  |  |  |
Year Ended December 31 (in millions) |  | Balance at Beginning of Year |  | Additions Charged to Costs and Expenses(a) |  | Deductions from Reserves(a) |  | Balance at End of Year
2015 |  |  |  |  |  |  |  |
| Allowance for doubtful accounts | $ | 60 | $ | 27 | $ | 18 | $ | 69
| Allowance for returns and customer incentives |  | 356 |  | 1,233 |  | 1,120 |  | 469
| Valuation allowance on deferred tax assets |  | 87 |  | 4 |  | 20 |  | 71
2014 |  |  |  |  |  |  |  |
| Allowance for doubtful accounts | $ | 65 | $ | 11 | $ | 16 | $ | 60
| Allowance for returns and customer incentives |  | 372 |  | 930 |  | 946 |  | 356
| Valuation allowance on deferred tax assets |  | 60 |  | 33 |  | 6 |  | 87
2013 |  |  |  |  |  |  |  |
| Allowance for doubtful accounts | $ | 46 | $ | 33 | $ | 14 | $ | 65
| Allowance for returns and customer incentives |  | 307 |  | 808 |  | 743 |  | 372
| Valuation allowance on deferred tax assets |  | 73 |  | 8 |  | 21 |  | 60
(a) Additions and deductions related to allowance for returns and customer incentives include amounts for distribution on behalf of third parties. Additions and deductions related to allowance for returns and customer incentives for the year ended December 31, 2013 also reflec t corrections to change amounts that were previously recorded net.

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- Definition The entire disclosure for any allowance and reserve accounts (their beginning and ending balances, as well as a reconciliation by type of activity during the period). Alternatively, disclosure of the required information may be within the footnotes to the financial statements or a supplemental schedule to the financial statements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 09 -Article 12 + Details
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