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. 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 Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Participant contribution receivable EBP, Participant Contribution, Receivable 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, Description of Plan and Accounting Change [Abstract] Investment Type [Axis] Investment Type [Axis] Rollover contributions EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Rollover Number of Shares EBP, Investment, Number of Shares EBP, Tax Status [Text Block] EBP, Tax Status [Text Block] Total Liabilities EBP, Liability EBP, Description of Plan [Line Items] EBP, Description of Plan [Line Items] Global Equity Fund Global Equity Fund [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. EBP, Schedule of Asset Held for Investment [Table] EBP, Schedule of Asset Held for Investment [Table] Investments EBP, Investments [Text Block] The entire disclosure for fully benefit-responsive and nonparticipant-directed investments held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Notes Receivable from Participants EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution Net Assets Available for Benefits per the Form 5500 EBP, Form 5500 Caption, Net Assets EBP, Investment, Fair Value and NAV [Text Block] EBP, Investment, Fair Value and NAV [Text Block] Net appreciation in fair value of 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 Contribution, Total EBP, Change in Net Asset Available for Benefit, Increase from Contribution Subsequent Event Subsequent Event [Member] Administrative expenses payable EBP, Accrued Expense EBP, Party-in-Interest Transactions [Table] EBP, Related Party and Party-in-Interest Transactions [Table] Investments [Table] EBP, Fully Benefit-Responsive Investment Contract [Table] Equity Funds Equity Funds [Member] Distributions Dividend distribution to participants EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Employer contribution receivable EBP, Employer Contribution, Receivable Participant contributions EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover Participant-Directed EBP, Participant-Directed [Member] Changes in Net Assets: EBP, Change in Net Asset Available for Benefit, Increase (Decrease) [Abstract] Bond Index Fund Bond 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 fixed income securities included in the Barclays U.S. Government/Credit Bond Index. There are currently no redemption restrictions on this investment. 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 Net Assets Available for Benefits Net Assets Available for Benefits, December 31, 2024 Net Assets Available for Benefits, December 31, 2025 Net assets available for benefits EBP, Net Asset Available for Benefit 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] Total Investments EBP, Investment, Excluding Plan Interest in Master Trust, Fair and Contract Value Investments [Line Items] EBP, Fully Benefit-Responsive Investment Contract [Line Items] Total Assets 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] Interest Income Fund Fixed Income Funds [Member] EBP, Reconciliation of Financial Statement to Form 5500 [Table] EBP, Reconciliation of Financial Statement to Form 5500 [Table] 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 AT&T Inc, Common Stock EBP, Employer, Common Stock [Member] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] EBP, Tax Status [Abstract] EBP, Tax Status [Abstract] Net Increase EBP, Change in Net Asset Available for Benefit, Increase (Decrease) Cover [Abstract] Maximum Maximum [Member] ASSETS EBP, Asset [Abstract] Minimum Minimum [Member] Subsequent Event Type [Domain] Subsequent Event Type [Domain] EBP, Schedule of Asset Held for Investment [Abstract] EBP, Schedule of Asset Held for Investment [Abstract] Dividends EBP, Change in Net Asset Available for Benefit, Increase from Dividend Income on Investment EBP, Reconciliation of Financial Statement to Form 5500 [Text Block] EBP, Reconciliation of Financial Statement to Form 5500 [Text Block] Entity [Domain] Entity [Domain] Asset Held for Investment, Total EBP, Asset Held for Investment Investment, Identifier [Axis] Investment, Identifier [Axis] Maturity Date EBP, Investment, Maturity Date Transfer to (from) Plan EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan EBP, Investment, Fair Value and NAV [Abstract] EBP, Investment, Fair Value and NAV [Abstract] EBP-43-1301883-004 [ASSP] EBP-43-1301883-004 [Member] EBP-43-1301883-004 - AT&T Savings and Security Plan EBP, Subsequent Event [Line Items] EBP, Subsequent Event [Line Items] 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 Fund 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] EBP, Reconciliation of Financial Statement to Form 5500 [Abstract] Fully benefit-responsive investment contracts at contract value Investment, Contract Value EBP, Investment, Excluding Plan Interest in Master Trust, Contract Value Dividends and interest receivable EBP, Investment Income, Receivable EBP, Other Liability EBP, Other Liability Amendment Flag Amendment Flag Administrative Expenses EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense Common/collective trust funds Common Collective Trust [Member] Interest EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Investment EBP, Statement of Change in Net Asset Available for Benefit [Abstract] 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 [Abstract] EBP, Related Party and Party-in-Interest Transactions [Line Items] EBP, Related Party and Party-in-Interest Transactions [Line Items] EBP, Statement of Net Asset Available for Benefit [Abstract] EBP, Statement of Net Asset Available for Benefit [Abstract] Net Assets Available for Benefits per the Form 5500 EBP, Reconciliation to Form 5500, Net Asset Available for Benefit, Deemed Distribution EBP, Description of Plan [Text Block] EBP, Description of Plan [Text Block] 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 Notes Receivable from Participants, Interest Rate EBP, Asset Held for Investment, Participant Loan, Interest Rate Investment at fair value Current 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 Investment Income, Total EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] Interest Rate EBP, Investment, Interest Rate Plan Number EBP, Plan Number Contributions: EBP, Change in Net Asset Available for Benefit, Increase from Contribution [Abstract] 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] Subsequent Event Type [Axis] Subsequent Event Type [Axis] EBP, Fully Benefit-Responsive Investment Contract [Abstract] 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] Investment Type Category [Axis] Investment Type Category [Axis] Detail information of type of investments. Notes receivable from participants EBP, Note Receivable from Participant Fair Value, Inputs, Level 2 Fair Value, Inputs, Level 2 [Member] Investment Type Category [Domain] Investment Type Category [Domain] Detail information of investments. EBP, Schedule of Asset Held for Investment [Table Text Block] EBP, Schedule of Asset Held for Investment [Table Text Block] Adjustment From Fair Value To Contract Value For Fully Benefit-Responsive Investment Contracts Fair Value to Contract Value Adjustments Adjustments from fair value to contract value for investment contracts. 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. Investments [Domain] Investments [Domain] EBP, Subsequent Event [Abstract] EBP, Subsequent Event [Abstract] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] Fair Value, Inputs, Level 1 Fair Value, Inputs, Level 1 [Member] Entity Registrant Name Entity Registrant Name EBP, Subsequent Event [Text Block] EBP, Subsequent Event [Text Block] Investment Income: EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment [Abstract] 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] EBP, Interest Bearing Cash EBP, Interest Bearing Cash Unallocated interest bearing cash related to contributions, uncashed checks and fees pending allocation to participant accounts or clearance through the plan funds. LIABILITIES EBP, Liability [Abstract] 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