Supplemental Financial Information (Noncash Activities) (Details) $ / shares in Units, $ in Millions	9 Months Ended
Sep. 30, 2019 USD ($) $ / shares
Supplemental Financial Information [Line Items]
Property and equipment and intangible assets accrued but not yet paid	$ 2,000
Dividends payable	$ 955
Dividends payable (in dollars per share) \| $ / shares	$ 0.21
NBCUniversal Media LLC [Member]
Supplemental Financial Information [Line Items]
Property and equipment and intangible assets accrued but not yet paid	$ 755

Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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