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Goodwill and Intangible Assets (Intangible Assets) (Details) - USD ($) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Jun. 30, 2017
Schedule of Indefinite and Finite-Lived Intangible Assets [Line Items] |  |  |
Total | $ 112,710 | $ 111,917 |
Finite-Lived Intangible Assets [Line Items] |  |  |
Accumulated Amortization | (17,217) | (14,194) |
Franchise Rights [Member] |  |  |
Indefinite-lived Intangible Assets [Line Items] |  |  |
Gross Carrying Amount | 59,365 | 59,365 |
Trade Names [Member] |  |  |
Indefinite-lived Intangible Assets [Line Items] |  |  |
Gross Carrying Amount | 8,809 | 9,633 |
FCC Licenses [Member] |  |  |
Indefinite-lived Intangible Assets [Line Items] |  |  |
Gross Carrying Amount | $ 2,337 | 2,333 | $ 1,700
Customer Relationships [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Weighted-Average Original Useful Life | 14 years |  |
Gross Carrying Amount | $ 22,884 | 25,046 |
Accumulated Amortization | $ (8,295) | (6,682) |
Software [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Weighted-Average Original Useful Life | 5 years |  |
Gross Carrying Amount | $ 15,357 | 11,395 |
Accumulated Amortization | $ (7,287) | (5,990) |
Other Agreements and Rights [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Weighted-Average Original Useful Life | 23 years |  |
Gross Carrying Amount | $ 3,958 | 4,145 |
Accumulated Amortization | (1,635) | (1,522) |
NBCUniversal Media LLC [Member] |  |  |
Schedule of Indefinite and Finite-Lived Intangible Assets [Line Items] |  |  |
Total | 22,599 | 22,256 |
Finite-Lived Intangible Assets [Line Items] |  |  |
Accumulated Amortization | (9,659) | (8,590) |
NBCUniversal Media LLC [Member] | Trade Names [Member] |  |  |
Indefinite-lived Intangible Assets [Line Items] |  |  |
Gross Carrying Amount | 2,927 | 2,981 |
NBCUniversal Media LLC [Member] | FCC Licenses [Member] |  |  |
Indefinite-lived Intangible Assets [Line Items] |  |  |
Gross Carrying Amount | $ 612 | 608 |
NBCUniversal Media LLC [Member] | Customer Relationships [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Weighted-Average Original Useful Life | 19 years |  |
Gross Carrying Amount | $ 13,261 | 13,269 |
Accumulated Amortization | $ (6,929) | (6,283) |
NBCUniversal Media LLC [Member] | Software [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Weighted-Average Original Useful Life | 5 years |  |
Gross Carrying Amount | $ 2,088 | 1,779 |
Accumulated Amortization | $ (1,205) | (932) |
NBCUniversal Media LLC [Member] | Other Agreements and Rights [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Weighted-Average Original Useful Life | 19 years |  |
Gross Carrying Amount | $ 3,711 | 3,619 |
Accumulated Amortization | $ (1,525) | $ (1,375) |

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