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Supplemental Financial Information (Summary of Operating Lease Assets and Liabilities Recorded in the Consolidated Balance Sheets) (Details) - Accounting Standards Update 2016-02 [Member] - USD ($) $ in Millions | Mar. 31, 2019 | Jan. 01, 2019
--- | --- | ---
Lessee, Lease, Description [Line Items] |  |
Operating lease assets |  | $ 4,200
Other Noncurrent Assets, Net [Member] |  |
Lessee, Lease, Description [Line Items] |  |
Operating lease assets | $ 4,100 |
Accrued Expenses and Other Current Liabilities [Member] |  |
Lessee, Lease, Description [Line Items] |  |
Operating lease liabilities, current | 693 |
Other Noncurrent Liabilities [Member] |  |
Lessee, Lease, Description [Line Items] |  |
Operating lease liabilities, noncurrent | 4,014 |
NBCUniversal Media LLC [Member] |  |
Lessee, Lease, Description [Line Items] |  |
Operating lease assets |  | $ 1,700
NBCUniversal Media LLC [Member] | Other Noncurrent Assets, Net [Member] |  |
Lessee, Lease, Description [Line Items] |  |
Operating lease assets | 1,599 |
NBCUniversal Media LLC [Member] | Accrued Expenses and Other Current Liabilities [Member] |  |
Lessee, Lease, Description [Line Items] |  |
Operating lease liabilities, current | 177 |
NBCUniversal Media LLC [Member] | Other Noncurrent Liabilities [Member] |  |
Lessee, Lease, Description [Line Items] |  |
Operating lease liabilities, noncurrent | $ 1,525 |

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Present value of lessee's discounted obligation for lease payments from operating lease, classified as current. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977 + Details
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- Definition Amount of lessee's right to use underlying asset under operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977 + Details
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