Name:	t_CreditFacilitiesAbstract
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Period Type:	duration

The stated amount payable to holders if debt instrument is held to maturity debt security.

No definition available.

Name:	t_DebtInstrumentRedemptionAmount
Namespace Prefix:	t_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

Weighted average date of a group of debt instruments scheduled for full repayment, in 'PnYnMnDTnHnMnS' format.

No definition available.

Name:	t_DebtInstrumentWeightedAverageMaturityPeriod
Namespace Prefix:	t_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Date of amendment of credit agreement.

No definition available.

Name:	t_LineOfCreditAmendmentDate
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Period Type:	duration

Amount of additional borrowing capacity under the long-term credit facility over its term, absent events of default or other defined conditions.

No definition available.

Name:	t_LineOfCreditFacilityAdditionalBorrowingCapacity
Namespace Prefix:	t_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Line Of Credit Facility Covenant Debt Ratio

No definition available.

Name:	t_LineOfCreditFacilityCovenantDebtRatio
Namespace Prefix:	t_
Data Type:	xbrli:stringItemType
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Period Type:	duration

Minimum amount of borrowing capacity at the discretion of the company as debtor.

No definition available.

Name:	t_LineOfCreditFacilityMinimumBorrowingCapacity
Namespace Prefix:	t_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Potential extension of term of long-term credit agreement (in years).

No definition available.

Name:	t_LineOfCreditFacilityPotentialExtensionOfTermYears
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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Minimum lender approval level for an extension of the term of a credit agreement.

No definition available.

Name:	t_LineOfCreditMinimumLenderApprovalPercentageForTermExtension
Namespace Prefix:	t_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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Period Type:	duration

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

No definition available.

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Period Type:	duration

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

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-Name Accounting Standards Codification
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Name:	us-gaap_DebtInstrumentFaceAmount
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Period Type:	instant

Contractual interest rate for funds borrowed, under the debt agreement.

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Maximum contractual interest rate for funds borrowed, under the debt agreement.

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMaximum
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Minimum contractual interest rate for funds borrowed, under the debt agreement.

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Data Type:	num:percentItemType
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Period Type:	duration

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.

No definition available.

Name:	us-gaap_DebtInstrumentLineItems
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Period Type:	duration

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

Name:	us-gaap_DebtInstrumentMaturityDate
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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

Latest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

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Period Type:	duration

Earliest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

Name:	us-gaap_DebtInstrumentMaturityDateRangeStart1
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Balance Type:	na
Period Type:	duration

The amount of debt discount (net of debt premium) that was originally recognized at the issuance of the instrument that has yet to be amortized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Name:	us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Section 02
-Paragraph 19, 20, 22
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Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

No definition available.

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Description of the terms of a credit facility arrangement. Terms typically include interest rate, collateral required, guarantees required, repayment requirements, and restrictions on use of assets and activities of the entity.

Name:	us-gaap_LineOfCreditFacilityDescription
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Date the credit facility first became available, in CCYY-MM-DD format.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

Description of the interest rate for the amounts borrowed under the credit facility, including the terms and the method for determining the interest rate (for example, fixed or variable, LIBOR plus a percentage, increasing rate, timing of interest rate resets, remarketing provisions).

Name:	us-gaap_LineOfCreditFacilityInterestRateDescription
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

No definition available.

Name:	us-gaap_LongTermDebtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Weighted average interest rate of long-term debt outstanding.

No definition available.

Name:	us-gaap_LongtermDebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Including both current and noncurrent portions, carrying amount as of the balance sheet date of other forms of debt not elsewhere specified in the taxonomy with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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Name:	us-gaap_OtherLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

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Name:	us-gaap_ProceedsFromIssuanceOfLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

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Name:	us-gaap_RepaymentsOfLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Name:	us-gaap_StatementBusinessSegmentsAxis=t_DirectvMember
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Data Type:	na
Balance Type:
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Name:	us-gaap_DebtInstrumentAxis=t_DecemberTwoZeroOneEightFacilityMember
Namespace Prefix:
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Name:	us-gaap_DebtInstrumentAxis=t_DecemberTwoZeroOneSevenFacilityMember
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Name:	us-gaap_DebtInstrumentAxis=t_DebtIssueInForeignMarketsMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_DebtInstrumentAxis=t_EighteenmonthcreditagreementMember
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Data Type:	na
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Data Type:	na
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Name:	us-gaap_ExternalCreditRatingByGroupingAxis=t_HighCreditRatingMember
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Name:	us-gaap_ExternalCreditRatingByGroupingAxis=t_ModerateCreditRatingMember
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Name:	us-gaap_ExternalCreditRatingByGroupingAxis=t_LowCreditRatingMember
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Data Type:	na
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Namespace Prefix:
Data Type:	na
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Name:	us-gaap_ExternalCreditRatingByGroupingAxis=t_VeryLowCreditRatingMember
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Data Type:	na
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Data Type:	na
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Name:	us-gaap_DebtInstrumentAxis=t_SyndicatedCreditAgreementMember
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Name:	t_DebtExchangeAxis=t_AdditionalMarginUponDefaultMember
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Data Type:	na
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Name:	us-gaap_DebtInstrumentAxis=t_TrancheaFacilityMember
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Data Type:	na
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Name:	us-gaap_DebtInstrumentAxis=t_TranchebFacilityMember
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Name:	us-gaap_DebtInstrumentAxis=t_AnnualPutResetSecuritiesMember
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Data Type:	na
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Name:	us-gaap_DebtInstrumentAxis=t_ZeroCouponMember
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Data Type:	na
Balance Type:
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Name:	us-gaap_DebtInstrumentAxis=t_NotesAndDebenturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_DebtInstrumentAxis=t_GlobalNotesDue2020Member
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