Preparation Of Interim Financial Statements (Policies)	9 Months Ended
	Sep. 30, 2022
Accounting Policies [Abstract]
Principles of Consolidation [Policy Text Block]	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 in our results on a one quarter lag. We also record our proportionate share of our equity method investees’ other comprehensive income (OCI) items, including translation adjustments.
Basis of Accounting [Policy Text Block]	The preparation of financial statements in conformity with U.S. generally accepted accounting principles (GAAP) requires management to make estimates and assumptions, including estimates of fair value, probable losses and expenses, that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Moreover, unfavorable changes in market conditions, including interest rates, could adversely impact those estimates and result in asset impairments. Certain prior period amounts have been conformed to the current period’s presentation. Unless otherwise noted, the information in Notes 1 through 12 refer only to our continuing operations and do not include discussion of balances or activity of WarnerMedia, Vrio, Xandr and Playdemic, which are part of discontinued operations.
Customer Acquisition and Fulfillment Costs [Policy Text Block]	Customer Acquisition and Fulfillment Costs During the first quarter of 2022, we updated our analysis of expected economic lives of customer relationships. As of January 1, 2022, we extended the amortization period for deferred acquisition and fulfillment contract costs within Mobility and broadband/fiber in Consumer Wireline and Business Wireline to better reflect the estimated economic lives of the relationships. These changes in accounting estimate decreased other cost of revenues approximately $80, or $0.01 per diluted share from continuing operations in the third quarter and $335, or $0.03 per diluted share from continuing operations for the first nine months of 2022.
Fiber Network Assets, Policy [Policy Text Block]	Fiber Network Assets During the first quarter of 2022, we updated our analysis of economic lives of AT&T owned fiber network assets. As of January 1, 2022, we extended the estimated economic life and depreciation period of such costs to better reflect the physical life of the assets that we had been experiencing and absence of technological changes that would replace fiber as the best broadband technology in the industry. The change in accounting estimate decreased depreciation expense $70, or $0.01 per diluted share from continuing operations in the third quarter and $210, or $0.02 per diluted share from continuing operations for the first nine months of 2022.
Convertible Instruments, Policy [Policy Text Block]	Convertible Instruments As of January 1, 2022, we adopted, through retrospective application, Accounting Standards Update (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). ASU 2020-06 requires that instruments which may be settled in cash or stock are presumed settled in stock in calculating diluted earnings per share. While our intent is to settle the Series A Cumulative Perpetual Membership Interests in AT&T Mobility II LLC (Mobility preferred interests) in cash, the ability to settle this instrument in AT&T shares will result in additional dilutive impact, the magnitude of which is influenced by the fair value of the Mobility II preferred interests and the average AT&T common stock price during the reporting period, which could vary from period-to-period.
Government Assistance [Policy Text Block]	Government Assistance The Financial Accounting Standards Board (FASB) issued ASU No, 2021-10, “Government Assistance (Topic 832): Disclosures by Business Entities about Government Assistance” (ASU 2021-10), which requires annual disclosures, beginning with the 2022 Annual Report on Form 10-K, in the notes to the financial statements, about transactions with a government that are accounted for by applying a grant or contribution accounting model by analogy to other guidance. The annual disclosures include terms and conditions, accounting treatment and impacted financial statement lines reflecting the impact of the transactions. ASU 2021-10 will be effective for annual reporting periods beginning after December 15, 2021, which we plan to adopt under prospective application for all in scope government transactions in the financial statements as of our adoption date or thereafter.
New Accounting Pronouncement, Policy [Policy Text Block]	Supplier Finance Obligations In September 2022, the FASB issued ASU No. 2022-04, “Liabilities – Supplier Finance Programs (Subtopic 405-50): Disclosure of Supplier Finance Program Obligations” (ASU 2022-04), which establishes interim and annual reporting disclosure requirements about a company’s supplier finance programs for its purchase of goods and services. Interim and annual requirements include disclosure of outstanding amounts under the obligations as of the end of the reporting period, and annual requirements include a rollforward of those obligations for the annual reporting period, as well as a description of payment and other key terms of the programs. ASU 2022-04 will be effective for interim and annual periods beginning after December 15, 2022, with retrospective application, except for the annual rollforward requirement, which becomes effective for annual periods beginning after December 15, 2023, with prospective application. The standard allows early adoption of all requirements. In the year of adoption, the disclosure of payment and other key terms under the programs and outstanding balances under the obligations will also apply to interim reporting dates. We are in the process of evaluating the impact of our adoption of ASU 2022-04.