Segment Information (Reconciliation of Adjusted EBITDA from Segment to Consolidated Statements) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Adjusted EBITDA	$ 34,258	$ 30,165	$ 27,956
Adjustment for legal settlement	0	(125)	(250)
Adjustment for Sky transaction-related costs	(180)	(355)	0
Depreciation	(8,663)	(8,281)	(7,914)
Amortization	(4,290)	(2,736)	(2,216)
Other operating gains	0	341	442
Interest expense	(4,567)	(3,542)	(3,086)
Investment and other income (loss), net	438	(225)	421
Income (loss) before income taxes	16,996	15,242	15,353
NBCUniversal Media LLC [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Adjusted EBITDA	8,755	8,633	8,181
Depreciation	(1,023)	(1,001)	(994)
Amortization	(1,106)	(1,107)	(1,047)
Other operating gains	0	141	337
Interest expense	(738)	(489)	(727)
Investment and other income (loss), net	396	(521)	(144)
Income (loss) before income taxes	$ 6,284	$ 5,656	$ 5,606

The measure used to evaluate the profitability of operating segments.

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Acquisition related and integration costs which have been expensed during the period. Such costs could include costs directly related to the transaction, including the U.K. share acquisition tax and success-based investment banker fees, and legal, accounting and valuation services, and costs incurred to effect a business combination, such as business integration costs, systems integration and conversion costs, and severance and other employee-related costs.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.

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Amount of gain (loss) recognized in settlement of litigation and insurance claims. Excludes claims within an insurance entity's normal claims settlement process.

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Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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Amount of the cost of borrowed funds accounted for as interest expense.

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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.

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