v3.20.4

Fair Value Measurements And Disclosure (Narrative) (Details)	1 Months Ended	12 Months Ended
	May 31, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 EUR (€)	Dec. 31, 2019 USD ($)
Fair Value Disclosures [Abstract]
Available-for-sale debt securities		$ 1,479,000,000		$ 1,444,000,000
Available-for-sale debt securities - maturities less than 1 year		29,000,000
Available-for-sale debt securities - maturities within 1 to 3 years		159,000,000
Available-for-sale debt securities - maturities within 3 to 5 years		179,000,000
Available-for-sale debt securities - maturities for 5 or more years		1,112,000,000
Fair Value, Option, Quantitative Disclosures [Line Items]
Anticipated reclassification of holding losses during the next 12 months - cash flow hedges		92,000,000
Aggregate principal amount of debt		32,241,000,000
Net losses on net investment hedges recognized in accumulated OCI		147,000,000
Collateral submitted to counterparty		53,000,000		204,000,000
Collateral received from counterparty		694,000,000		44,000,000
Collateral contingently payable to the counterparty		33,000,000
Nonrecurring Fair Value Measurements
Fair Value, Option, Quantitative Disclosures [Line Items]
Nonrecurring fair value measurements				$ 0
Communications | Video | Nonrecurring Fair Value Measurements
Fair Value, Option, Quantitative Disclosures [Line Items]
Nonrecurring fair value measurements		9,744,000,000
Property, plant, and equipment, fair value measurements		2,258,000,000
Communications | Video | Nonrecurring Fair Value Measurements | Orbital slots
Fair Value, Option, Quantitative Disclosures [Line Items]
Finite-lived intangible assets, fair value measurements		5,873,000,000
Communications | Video | Nonrecurring Fair Value Measurements | Customer lists
Fair Value, Option, Quantitative Disclosures [Line Items]
Finite-lived intangible assets, fair value measurements		1,613,000,000
WarnerMedia | Warner Bros. | Nonrecurring Fair Value Measurements
Fair Value, Option, Quantitative Disclosures [Line Items]
Film costs, fair value measurements		844,000,000
Measurement Input, Entity Credit Risk
Fair Value, Option, Quantitative Disclosures [Line Items]
Collateral contingently payable to the counterparty		676,000,000
Measurement Input, Entity Credit Risk | Communications | DirecTV
Fair Value, Option, Quantitative Disclosures [Line Items]
Collateral contingently payable to the counterparty		$ 134,000,000
Net Investment Hedging
Fair Value, Option, Quantitative Disclosures [Line Items]
Aggregate principal amount of debt | €			€ 1,450,000,000
Interest rate locks | Cash Flow Hedging
Fair Value, Option, Quantitative Disclosures [Line Items]
Payment for hedge	$ 731,000,000

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- Definition

This item represents the fair value of debt securities which are expected to mature more than fourth calendar years after the current calendar year and which are categorized neither as held-to-maturity nor trading securities. This item also includes debt securities, at cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, which are expected to mature more than fourth calendar years after the current calendar year and which are categorized as held-to-maturity.

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This item represents the fair value of debt securities which are expected to mature over the next two calendar years after the current calendar years and which are categorized neither as held-to-maturity nor trading securities. This item also includes debt securities, at cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, which are expected to mature over the next two calendar years after the current calendar year and which are categorized as held-to-maturity.

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This item represents the fair value of debt securities which are expected to mature over the third and fourth calendar years after the current calendar year and which are categorized neither as held-to-maturity nor trading securities. This item also includes debt securities, at cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, which are expected to mature over the third and fourth calendar years after the current calendar year and which are categorized as held-to-maturity.

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), maturing in next fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

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Face (par) amount of debt instrument at time of issuance.

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Fair value, after offset of derivative liability, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, before offset against an obligation to return collateral under a master netting arrangement. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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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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Fair value portion of assets, excluding financial assets, that lack physical substance, having a limited useful life.

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The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

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The cash outflow for a financial contract that meets the hedge criteria as either cash flow hedge, fair value hedge or hedge of net investment in foreign operations.

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Fair value portion of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Amount, before tax, of increase (decrease) in the cumulative translation adjustment from gain (loss) on foreign currency derivatives that are designated as, and are effective as, economic hedges of a net investment in a foreign entity.

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