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Recent Accounting Pronouncements (Narrative) (Details) - USD ($) $ in Millions | Dec. 31, 2019 | Jan. 01, 2019
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New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Operating lease liabilities | $ 4,606 |
Finance lease liabilities |  | $ 787
NBCUniversal Media LLC [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Operating lease liabilities | $ 1,670 |
Accounting Standards Update 2016-02 [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Operating lease assets |  | 4,200
Operating lease liabilities |  | 4,800
Accounting Standards Update 2016-02 [Member] | NBCUniversal Media LLC [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Operating lease assets |  | 1,700
Operating lease liabilities |  | 1,800
Finance lease liabilities |  | 332
Sky Limited [Member] | Accounting Standards Update 2016-02 [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Additional finance lease liability |  | $ 229

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