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Recent Accounting Pronouncements (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities	$ 4,707
NBCUniversal Media LLC [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities	$ 1,702
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
Finance lease liabilities		787
Accounting Standards Update 2016-02 [Member] | Sky Limited [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Additional finance lease liability		229
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

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- Definition

Present value of lessee's discounted obligation for lease payments from finance lease for additional contracts determined to be leases in connection with Sky transaction.

+ References

No definition available.

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- Definition

Present value of lessee's discounted obligation for lease payments from finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918701-209980

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
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Present value of lessee's discounted obligation for lease payments from 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 (b)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

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- Definition

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-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
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