Preparation Of Interim Financial Statements (Policies)	9 Months Ended
Sep. 30, 2020
Accounting Policies [Abstract]
Principles of Consolidation	All significant intercompany transactions are eliminated in the consolidation process. Investments in subsidiaries and partnerships which we do not control but have significant influence are accounted for under the equity method. Earnings from certain investments accounted for using the equity method are included for periods ended within up to one quarter of our period end. We also record our proportionate share of our equity method investees’ other comprehensive income (OCI) items.
Basis of Accounting	The preparation of financial statements in conformity with U.S. generally accepted accounting principles (GAAP) requires management to make estimates and assumptions, including potential impacts arising from the COVID-19 pandemic, that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Certain prior period amounts have been conformed to the current period’s presentation, including the combination of our prior Xandr segment with the WarnerMedia segment.
Credit Losses	Credit Losses As of January 1, 2020, we adopted, through modified retrospective application, the Financial Accounting Standards Board’s (FASB) Accounting Standards Update (ASU) No. 2016-13, “Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” (ASU 2016-13, as amended), which replaces the incurred loss impairment methodology under prior GAAP with an expected credit loss model. ASU 2016-13 affects trade receivables, loans, contract assets, certain beneficial interests, off-balance-sheet credit exposures not accounted for as insurance and other financial assets that are not subject to fair value through net income, as defined by the standard. Under the expected credit loss model, we are required to consider future economic trends to estimate expected credit losses over the lifetime of the asset. Upon adoption, we recorded a $293 reduction to “Retained earnings,” $395 increase to “allowances for doubtful accounts” applicable to our trade and loan receivables, $10 reduction of contract assets, $105 reduction of net deferred income tax liability and $7 reduction of “Noncontrolling interest” as an opening adjustment. Our adoption of ASU 2016-13 did not have a material impact on our financial statements.
Reference Rate Reform and Convertible Instruments	Reference Rate Reform In March 2020, the FASB issued ASU No. 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting” (ASU 2020-04), which provides optional expedients, and allows for certain exceptions to existing GAAP, for contract modifications triggered by the expected market transition of certain benchmark interest rates to alternative reference rates. ASU 2020-04 applies to contracts, hedging relationships and other arrangements that reference the London Interbank Offering Rate (LIBOR) or any other rates ending after December 31, 2022. We are evaluating the impact of our adoption of ASU 2020-04, including optional expedients, to our financial statements. Convertible Instruments In August 2020, the FASB issued ASU No. 2020-06, “Debt—Debt With Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity” (ASU 2020-06), which eliminated certain separation models regarding cash conversion and beneficial conversion features to simplify reporting for convertible instruments as a single liability or equity, with no separate accounting for embedded conversion features. ASU 2020-06 will be effective for fiscal years beginning after December 31, 2021, under modified retrospective or full retrospective application, subject to early adoption in 2021. We are evaluating the impact of our adoption of ASU 2020-06 on our financial statements.
Intangible Assets	Intangible Assets In the second quarter, driven by significant and adverse economic and political environments in Latin America, including the impact of the COVID-19 pandemic, we experienced accelerated subscriber losses and revenue decline in the region, as well as closure of our operations in Venezuela. When combining these business trends and higher weighted-average cost of capital resulting from the increase in country-risk premiums in the region, we concluded that it is more likely than not that the fair value of the Vrio reporting unit, estimated using discounted cash flow and market multiple approaches, is less than its carrying amount. We recorded a $2,212 goodwill impairment in the reporting unit in the second quarter, with $105 attributable to noncontrolling interest. The impairment is not deductible for tax purposes and resulted in an increase in our effective tax rate. During the first quarter of 2020, we reassessed and changed the estimated economic lives of certain trade names in our Latin America business from indefinite to finite-lived and began amortizing them using the straight-line method over their average remaining economic life of 15 years. This change had an insignificant impact on our financial statements. Also during the first quarter of 2020, in conjunction with the nationwide launch of AT&T TV and our customers’ continued shift from linear to streaming video services, we reassessed the estimated economic lives and renewal assumptions for our orbital slot licenses. As a result, we have changed the estimated lives of these licenses from indefinite to finite-lived, effective January 1, 2020, and began amortizing our orbital slot licenses using the sum-of-months-digits method over their average remaining economic life of 15 years. This change in accounting increased amortization expense $373, or $0.04 per diluted share available to common stock during the third quarter and $1,138, or $0.12, per diluted share available to common stock for the first nine months of 2020.
Recognition of Actuarial Gains and Losses	We recognize actuarial gains and losses on pension and postretirement plan assets in our consolidated results as a component of “Other income (expense) – net” at our annual measurement date of December 31, unless earlier remeasurements are required.
Derivatives, Offsetting Fair Value Amounts	We do not offset the fair value of collateral, whether the right to reclaim cash collateral (a receivable) or the obligation to return cash collateral (a payable) exists, against the fair value of the derivative instruments.

Preparation Of Interim Financial Statements (Policies)

9 Months Ended

Sep. 30, 2020

All significant intercompany transactions are eliminated in the consolidation process. Investments in subsidiaries and partnerships which we do not control but have significant influence are accounted for under the equity method. Earnings from certain investments accounted for using the equity method are included for periods ended within up to one quarter of our period end. We also record our proportionate share of our equity method investees’ other comprehensive income (OCI) items.

Basis of Accounting

The preparation of financial statements in conformity with U.S. generally accepted accounting principles (GAAP) requires management to make estimates and assumptions, including potential impacts arising from the COVID-19 pandemic, that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Certain prior period amounts have been conformed to the current period’s presentation, including the combination of our prior Xandr segment with the WarnerMedia segment.

Credit Losses

Credit Losses As of January 1, 2020, we adopted, through modified retrospective application, the Financial Accounting Standards Board’s (FASB) Accounting Standards Update (ASU) No. 2016-13, “Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” (ASU 2016-13, as amended), which replaces the incurred loss impairment methodology under prior GAAP with an expected credit loss model. ASU 2016-13 affects trade receivables, loans, contract assets, certain beneficial interests, off-balance-sheet credit exposures not accounted for as insurance and other financial assets that are not subject to fair value through net income, as defined by the standard. Under the expected credit loss model, we are required to consider future economic trends to estimate expected credit losses over the lifetime of the asset. Upon adoption, we recorded a $293 reduction to “Retained earnings,” $395 increase to “allowances for doubtful accounts” applicable to our trade and loan receivables, $10 reduction of contract assets, $105 reduction of net deferred income tax liability and $7 reduction of “Noncontrolling interest” as an opening adjustment. Our adoption of ASU 2016-13 did not have a material impact on our financial statements.

Reference Rate Reform and Convertible Instruments

Reference Rate Reform In March 2020, the FASB issued ASU No. 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting” (ASU 2020-04), which provides optional expedients, and allows for certain exceptions to existing GAAP, for contract modifications triggered by the expected market transition of certain benchmark interest rates to alternative reference rates. ASU 2020-04 applies to contracts, hedging relationships and other arrangements that reference the London Interbank Offering Rate (LIBOR) or any other rates ending after December 31, 2022. We are evaluating the impact of our adoption of ASU 2020-04, including optional expedients, to our financial statements.

Convertible Instruments In August 2020, the FASB issued ASU No. 2020-06, “Debt—Debt With Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity” (ASU 2020-06), which eliminated certain separation models regarding cash conversion and beneficial conversion features to simplify reporting for convertible instruments as a single liability or equity, with no separate accounting for embedded conversion features. ASU 2020-06 will be effective for fiscal years beginning after December 31, 2021, under modified retrospective or full retrospective application, subject to early adoption in 2021. We are evaluating the impact of our adoption of ASU 2020-06 on our financial statements.

Intangible Assets

Intangible Assets In the second quarter, driven by significant and adverse economic and political environments in Latin America, including the impact of the COVID-19 pandemic, we experienced accelerated subscriber losses and revenue decline in the region, as well as closure of our operations in Venezuela. When combining these business trends and higher weighted-average cost of capital resulting from the increase in country-risk premiums in the region, we concluded that it is more likely than not that the fair value of the Vrio reporting unit, estimated using discounted cash flow and market multiple approaches, is less than its carrying amount. We recorded a $2,212 goodwill impairment in the reporting unit in the second quarter, with $105 attributable to noncontrolling interest. The impairment is not deductible for tax purposes and resulted in an increase in our effective tax rate.

During the first quarter of 2020, we reassessed and changed the estimated economic lives of certain trade names in our Latin America business from indefinite to finite-lived and began amortizing them using the straight-line method over their average remaining economic life of 15 years. This change had an insignificant impact on our financial statements.

Also during the first quarter of 2020, in conjunction with the nationwide launch of AT&T TV and our customers’ continued shift from linear to streaming video services, we reassessed the estimated economic lives and renewal assumptions for our orbital slot licenses. As a result, we have changed the estimated lives of these licenses from indefinite to finite-lived, effective January 1, 2020, and began amortizing our orbital slot licenses using the sum-of-months-digits method over their average remaining economic life of 15 years. This change in accounting increased amortization expense $373, or $0.04 per diluted share available to common stock during the third quarter and $1,138, or $0.12, per diluted share available to common stock for the first nine months of 2020.

Recognition of Actuarial Gains and Losses

We recognize actuarial gains and losses on pension and postretirement plan assets in our consolidated results as a component of “Other income (expense) – net” at our annual measurement date of December 31, unless earlier remeasurements are required.

Derivatives, Offsetting Fair Value Amounts

We do not offset the fair value of collateral, whether the right to reclaim cash collateral (a receivable) or the obligation to return cash collateral (a payable) exists, against the fair value of the derivative instruments.