Large Cap U.S. Stock Index Fund Large Cap U.S. Stock Index Fund [Member] This category includes a common/collective trust fund with an objective of providing investment results that approximate the overall performance of the common stocks included in the Standard and Poor’s Composite Stock Price Index of 500 stocks (the S&P 500®). There are currently no redemption restrictions on this investment. EBP, Master Trust [Abstract] Statistical Measurement [Domain] Statistical Measurement [Domain] Party-in-Interest Transactions [Text Block] EBP, Related Party and Party-in-Interest Transactions [Text Block] Interest income on notes receivable from participants EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant EBP, Master Trust [Table Text Block] EBP, Master Trust [Table Text Block] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Participant contribution receivable EBP, Participant Contribution, Receivable EBP, Nonconsolidated, Master Trust [Member] EBP, Nonconsolidated, Master Trust [Member] Small and Mid-Sized U.S. Stock Index Fund Small and Mid-Sized U.S. Stock Index Fund [Member] This category includes a common/collective trust fund with an objective of providing investment results that approximate the overall performance of the common stocks included in the Dow Jones U.S. Completion Total Stock Market Index. There are currently no redemption restrictions on this investment. EBP, Description of Plan and Accounting Change [Abstract] EBP, Allocation Status [Domain] EBP, Allocation Status [Domain] Rollover contributions EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Rollover Investment Type [Axis] Investment Type [Axis] Number of Shares EBP, Investment, Number of Shares Investment Fund [Domain] Investment Fund [Domain] Investment Fund [Domain] AT&T Age-Based Asset Allocation 2015 Fund [Member] AT&T Age-Based Asset Allocation 2015 Fund [Member] AT&T Age-Based Asset Allocation 2015 Fund Liability at fair value Liability at fair value EBP, Investment Liability, Fair Value EBP, Tax Status [Text Block] EBP, Tax Status [Text Block] AT&T Age-Based Asset Allocation 2045 Fund [Member] AT&T Age-Based Asset Allocation 2045 Fund [Member] AT&T Age-Based Asset Allocation 2045 Fund AT&T Age-Based Asset Allocation 2000 Fund [Member] AT&T Age-Based Asset Allocation 2000 Fund [Member] AT&T Age-Based Asset Allocation 2000 Fund EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Domain] EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Domain] EBP, Liability EBP, Liability EBP, Description of Plan [Line Items] EBP, Description of Plan [Line Items] EBP, Nonconsolidated, Plan Interest in Master Trust EBP, Nonconsolidated, Plan Interest in Master Trust [Member] EBP, Master Trust [Text Block] EBP, Master Trust [Text Block] EBP, Schedule of Asset Held for Investment [Table] EBP, Schedule of Asset Held for Investment [Table] Fidelity BrokerageLink® Fidelity BrokerageLink® [Member] Fidelity BrokerageLink® Net Assets Available for Benefits per the Form 5500 EBP, Form 5500 Caption, Net Assets Foreign Exchange Future [Member] Foreign Exchange Future [Member] EBP, Investment, Fair Value and NAV [Text Block] EBP, Investment, Fair Value and NAV [Text Block] AT&T Age-Based Asset Allocation 2070 Fund [Member] AT&T Age-Based Asset Allocation 2070 Fund [Member] AT&T Age-Based Asset Allocation 2070 Fund Net appreciation in fair value of AT&T Master Trust Investments Net appreciation in fair value of Group Trust Investments EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Unrealized Gain (Loss) on Investment EBP, Investment, Fair Value and NAV [Table] EBP, Investment, Fair Value and NAV [Table] Allowance for Credit Loss EBP, Note Receivable from Participant, Allowance for Credit Loss Distributions payable to participants at December 31, 2024 EBP, Reconciliation to Form 5500, Payment to Participant, Prior Period, Decrease from Deemed Distribution AT&T International Stock Fund AT&T International Stock Fund [Member] AT&T International Stock Fund Contribution, Total EBP, Change in Net Asset Available for Benefit, Increase from Contribution EBP-43-1301883-011 [PRRSP] EBP-43-1301883-011 [Member] EBP-43-1301883-011 represents AT&T Inc. Puerto Rico Retirement Savings Plan Foreign Exchange Contract [Member] Foreign Exchange Contract [Member] EBP-43-1301883-009 [ARSP] EBP-43-1301883-009 [Member] EBP-43-1301883-009 represents AT&T Inc. Retirement Savings Plan Subsequent Event [Member] Subsequent Event [Member] AT&T Age-Based Asset Allocation 2060 Fund [Member] AT&T Age-Based Asset Allocation 2060 Fund [Member] AT&T Age-Based Asset Allocation 2060 Fund EBP, Party-in-Interest Transactions [Table] EBP, Related Party and Party-in-Interest Transactions [Table] Mortgage-backed securities Collateralized Mortgage Obligations [Member] Distributions Dividend distribution to participants Distributions EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Employer contribution receivable EBP, Employer Contribution, Receivable Assets at fair value EBP, Investment, Fair Value Participant contributions EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover EBP, Participant-Directed [Member] EBP, Participant-Directed [Member] U.S. Stock Market Index Fund Total U.S. Stock Market Index Fund U.S. Stock Market Index Fund [Member] This category includes a common/collective trust fund with an objective of providing investment results that approximate the overall performance of the common stocks included in the Dow Jones Total U.S. Stock Market Index. There are currently no redemption restrictions on this investment. Changes in Net Assets: EBP, Change in Net Asset Available for Benefit, Increase (Decrease) [Abstract] EBP, Other Investment [Member] Non-publicly traded registered investments companies EBP, Other Investment [Member] EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Axis] EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Axis] EBP, Participant-Directed and Nonparticipant-Directed Status [Domain] EBP, Participant-Directed and Nonparticipant-Directed Status [Domain] Employer contributions EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash and Noncash Other Investments [Member] Other Investments [Member] Non-US [Member] Non-US [Member] Investment in Group Trust Investments [Member] Net Assets Available for Benefits Net Assets Available for Benefits, December 31, 2024 Net Assets Available for Benefits, December 31, 2025 EBP, Net Asset Available for Benefit EBP, Net Asset Available for Benefit AT&T Age-Based Asset Allocation 2055 Fund [Member] AT&T Age-Based Asset Allocation 2055 Fund [Member] AT&T Age-Based Asset Allocation 2055 Fund Cash and Cash Equivalents [Member] Cash and Cash Equivalents [Member] EBP, Reconciliation of Financial Statement to Form 5500 [Line Items] EBP, Reconciliation of Financial Statement to Form 5500 [Line Items] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Asset EBP, Asset Interest-Bearing Cash Interest-Bearing Deposits [Member] EBP, Reconciliation of Financial Statement to Form 5500 [Table Text Block] EBP, Reconciliation of Financial Statement to Form 5500 [Table Text Block] Investment, Plan Interest in Master Trust, Fair Value EBP, Investment, Plan Interest in Master Trust, Fair Value EBP, Reconciliation of Financial Statement to Form 5500 [Table] EBP, Reconciliation of Financial Statement to Form 5500 [Table] US Treasury and Government [Member] US Treasury and Government [Member] Asset Allocation Funds Asset Allocation Funds [Member] This category includes 14 common/collective trust funds also known as Aged-Based Asset Allocation Funds which are well diversified portfolios that adjust the mix of the various underlying investments over time. The change in allocation of investments is designed to move from a more aggressive investment strategy to a more conservative strategy through the projected retirement date and for a number of years thereafter. The year associated with the fund identification denotes the projected year of retirement of the participant selecting the fund. There are currently no redemption restrictions on these investments. Distributions to participants per the Form 5500 EBP, Form 5500 Caption, Benefit Payment and Payments to Provide Benefits EBP, Employer, Common Stock [Member] EBP, Employer, Common Stock [Member] Net other assets and liabilities EBP, Net Other Assets And Liabilities Net amount of assets and liabilities held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), classified as other. Less: investment management expenses EBP, Change in Net Asset Available for Benefit, Decrease from Investment Expense Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] EBP, Tax Status [Abstract] Net Increase Before Transfers EBP, Change in Net Asset Available for Benefit, Increase (Decrease) Cover [Abstract] Maximum Maximum [Member] Minimum Minimum [Member] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Dividends EBP, Change in Net Asset Available for Benefit, Increase from Dividend Income on Investment EBP, Schedule of Asset Held for Investment [Abstract] EBP, Master Trust [Table] EBP, Master Trust [Table] EBP, Reconciliation of Financial Statement to Form 5500 [Text Block] EBP, Reconciliation of Financial Statement to Form 5500 [Text Block] Entity [Domain] Entity [Domain] AT&T Age-Based Asset Allocation 2065 Fund [Member] AT&T Age-Based Asset Allocation 2065 Fund [Member] AT&T Age-Based Asset Allocation 2065 Fund Asset Held for Investment, Total EBP, Asset Held for Investment EBP-43-1301883-021 [Group Trust] EBP-43-1301883-021 [Member] EBP-43-1301883-021 represents AT&T Inc. Group Trust AT&T Shares Fund [Member] AT&T Shares Fund [Member] AT&T Shares Fund EBP, Allocation Status [Axis] EBP, Allocation Status [Axis] Transfer to (from) Plan EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan EBP, Investment, Fair Value and NAV [Abstract] AT&T Stable Value Fund AT&T Stable Value Fund [Member] AT&T Stable Value Fund EBP, Subsequent Event [Line Items] EBP, Subsequent Event [Line Items] Investment Fund [Axis] Investment Fund [Axis] Information by investment fund options EBP, Accounting Standard Update and Change in Accounting Principle [Table] EBP, Accounting Standard Update and Change in Accounting Principle [Table] EBP, Tax Status [Line Items] EBP, Tax Status [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Table] EBP, Statement of Change in Net Asset Available for Benefit [Table] Mutual funds Mutual Fund [Member] Mutual Fund [Member] EBP, Description of Plan [Table] EBP, Description of Plan [Table] Asset Held for Investment, Party-in-Interest [true false] EBP, Asset Held for Investment, Party-in-Interest [true false] EBP, Reconciliation of Financial Statement to Form 5500 [Abstract] AT&T Age-Based Asset Allocation 2050 Fund [Member] AT&T Age-Based Asset Allocation 2050 Fund [Member] AT&T Age-Based Asset Allocation 2050 Fund EBP, Other Liability EBP, Other Liability Amendment Flag Amendment Flag Administrative expenses EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense Interest EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Investment Common/collective trust funds Common Collective Trust [Member] Fair Value Measured at Net Asset Value Per Share [Member] Fair Value Measured at Net Asset Value Per Share [Member] Net Increase After Transfers EBP, Change in Net Asset Available for Benefit, Increase (Decrease) After Transfers Amount of increase (decrease) in net asset available for benefit to participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) after transfers to (from) plan. EBP, Statement of Change in Net Asset Available for Benefit [Abstract] EBP, Subsequent Event [Table] EBP, Subsequent Event [Table] EBP, Related Party and Party-in-Interest Transactions [Abstract] EBP, Related Party and Party-in-Interest Transactions [Line Items] EBP, Related Party and Party-in-Interest Transactions [Line Items] Income from investment in Group Trust Net investment income of Group Trust Investments EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Other Investment Income (Loss) EBP, Statement of Net Asset Available for Benefit [Abstract] Distributions payable to participants EBP, Reconciliation to Form 5500, Net Asset Available for Benefit, Deemed Distribution Assets at contract value EBP, Investment, Contract Value EBP, Description of Plan [Text Block] EBP, Description of Plan [Text Block] Investment income: EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment [Abstract] EBP, Summary of Accounting Policy [Text Block] EBP, Summary of Accounting Policy [Text Block] EBP, Participant-Directed and Nonparticipant-Directed Status [Axis] EBP, Participant-Directed and Nonparticipant-Directed Status [Axis] EBP, Statement of Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Line Items] Entity Central Index Key Entity Central Index Key EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value Legal Entity [Axis] Legal Entity [Axis] Entity Tax Identification Number Entity Tax Identification Number Net income from investment in AT&T Savings Plan Master Trust EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment EBP, Pooled Separate Account EBP, Pooled Separate Account [Member] EBP-43-1301883-022 [Master Trust] EBP-43-1301883-022 [Member] EBP-43-1301883-022 represents AT&T Inc. Master Trust Foreign cash Currency Swap [Member] EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] AT&T Age-Based Asset Allocation 2035 Fund [Member] AT&T Age-Based Asset Allocation 2035 Fund [Member] AT&T Age-Based Asset Allocation 2035 Fund Notes receivable from participants, interest rate EBP, Investment, Interest Rate Derivative [Member] Derivative [Member] EBP, Plan Number EBP, Plan Number Geographical [Domain] Geographical [Domain] Contributions: EBP, Change in Net Asset Available for Benefit, Increase from Contribution [Abstract] EBP-58-1533433-004 [BSSP] EBP-58-1533433-004 [Member] EBP-58-1533433-004 - BellSouth Savings and Security Plan Document Type Document Type Fair Value, Inputs, Level 3 Fair Value, Inputs, Level 3 [Member] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Investment, Fair Value and NAV [Line Items] EBP, Investment, Fair Value and NAV [Line Items] EBP, Form 5500 Caption, Net Assets [Abstract] EBP, Form 5500 Caption, Net Assets [Abstract] AT&T Age-Based Asset Allocation 2010 Fund [Member] AT&T Age-Based Asset Allocation 2010 Fund [Member] AT&T Age-Based Asset Allocation 2010 Fund AT&T Age-Based Asset Allocation 2025 Fund [Member] AT&T Age-Based Asset Allocation 2025 Fund [Member] AT&T Age-Based Asset Allocation 2025 Fund EBP, Interest in Master Trust, Percentage EBP, Interest in Master Trust, Percentage Subsequent Event Type [Axis] Subsequent Event Type [Axis] Statistical Measurement [Axis] Statistical Measurement [Axis] EBP, Form 5500 Caption, Benefit Payment and Payments to Provide Benefits [Abstract] EBP, Form 5500 Caption, Benefit Payment and Payments to Provide Benefits [Abstract] EBP, Master Trust [Line Items] EBP, Master Trust [Line Items] Notes receivable from participants EBP, Note Receivable from Participant Equity Securities [Member] Equity Securities [Member] Fair Value, Inputs, Level 2 Fair Value, Inputs, Level 2 [Member] EBP, Schedule of Asset Held for Investment [Table Text Block] EBP, Schedule of Asset Held for Investment [Table Text Block] 103-12 investments Commingled Funds [Member] The objective of these equity commingled funds is to provide diversified exposure to international markets as represented by the All Country World Index ex U.S. that invest in both developed and emerging countries. AT&T Age-Based Asset Allocation 2040 Fund [Member] AT&T Age-Based Asset Allocation 2040 Fund [Member] AT&T Age-Based Asset Allocation 2040 Fund EBP, Other Liability (Asset) at Fair Value EBP, Other Liability (Asset) at Fair Value Amount of liability (asset) held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), classified as other. Distributions payable to participants at December 31, 2025 EBP, Reconciliation to Form 5500, Payment to Participant, Current Period, Increase from Deemed Distribution International Stock Index Fund International Stock Index Fund [Member] This category includes a common/collective trust fund with an objective of providing investment results that approximate the overall performance of the common stocks included in the All Country World Index ex U.S. Index. Except for a short-term trading fee applicable to certain participant transactions, there are currently no redemption restrictions on this investment. AT&T U.S. Stock Fund AT&T U.S. Stock Fund [Member] AT&T U.S. Stock Fund AT&T Age-Based Asset Allocation 2030 Fund [Member] AT&T Age-Based Asset Allocation 2030 Fund [Member] AT&T Age-Based Asset Allocation 2030 Fund EBP, Subsequent Event [Abstract] Investments [Domain] Investments [Domain] AT&T Age-Based Asset Allocation 2005 Fund [Member] AT&T Age-Based Asset Allocation 2005 Fund [Member] AT&T Age-Based Asset Allocation 2005 Fund Self-directed brokerage accounts EBP, Self-Directed Brokerage Account [Member] Geographical [Axis] Geographical [Axis] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] Net Asset Available for Benefit [Abstract] EBP, Net Asset Available for Benefit [Abstract] EBP, Unallocated [Member] EBP, Unallocated [Member] Fair Value, Inputs, Level 1 Fair Value, Inputs, Level 1 [Member] Entity Registrant Name Entity Registrant Name UNITED STATES UNITED STATES AT&T Age-Based Asset Allocation 2020 Fund [Member] AT&T Age-Based Asset Allocation 2020 Fund [Member] AT&T Age-Based Asset Allocation 2020 Fund EBP, Subsequent Event [Text Block] EBP, Subsequent Event [Text Block] AT&T common stock Common Stock [Member] EBP, Tax Status [Table] EBP, Tax Status [Table] EBP, Accounting Standard Update and Change in Accounting Principle [Line Items] EBP, Accounting Standard Update and Change in Accounting Principle [Line Items] AT&T Total Return Bond Fund AT&T Total Return Bond Fund [Member] AT&T Total Return Bond Fund EBP, Investment, Excluding Plan Interest in Master Trust, Cost EBP, Investment, Excluding Plan Interest in Master Trust, Cost Receivable [Abstract] EBP, Receivable [Abstract] Corporate debt Corporate Debt Securities [Member] Fair Value, Inputs, Level 1, Level 2, and Level 3 Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] Total Receivables EBP, Receivable