Name:	t_FixedIncomeInvestmentSecuritiesDebtMaturitiesAfterFourCalendarYearsAvailableForSaleFairValueHeldToMaturityNetCarryingAmount
Namespace Prefix:	t_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

This item represents the fair value of debt securities which are expected to mature over the next two calendar years after the current calendar years and which are categorized neither as held-to-maturity nor trading securities. This item also includes debt securities, at cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, which are expected to mature over the next two calendar years after the current calendar year and which are categorized as held-to-maturity.

No definition available.

Name:	t_FixedIncomeInvestmentSecuritiesDebtMaturitiesNextTwoCalendarYearsAvailableForSaleFairValueHeldToMaturityNetCarryingAmount
Namespace Prefix:	t_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

This item represents the fair value of debt securities which are expected to mature over the third and fourth calendar years after the current calendar year and which are categorized neither as held-to-maturity nor trading securities. This item also includes debt securities, at cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, which are expected to mature over the third and fourth calendar years after the current calendar year and which are categorized as held-to-maturity.

No definition available.

Name:	t_FixedIncomeInvestmentSecuritiesDebtMaturitiesThirdAndFourthCalendarYearsAvailableForSaleFairValueHeldToMaturityNetCarryingAmount
Namespace Prefix:	t_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

This item represents the fair value of debt securities which are expected to mature within the current calendar year and which are categorized neither as held-to-maturity nor trading securities. This item also includes debt securities, at cost, net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any, which are expected to mature within the current calendar year and which are categorized as held-to-maturity.

No definition available.

Name:	t_FixedIncomeInvestmentSecuritiesDebtMaturitiesWithinOneYearAvailableForSaleFairValueHeldToMaturityNetCarryingAmount
Namespace Prefix:	t_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The change in the aggregate notional amount of interest rate locks designated as cash flow hedging instruments during the period. The notional amount relates to a number of currency units, shares, bushels, pounds, or other units specified in a derivative instrument.

No definition available.

Name:	t_NotionalAmountOfCashFlowHedgeInstrumentsInterestRateLocksChangeDuringPeriod
Namespace Prefix:	t_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Accumulated change, net of tax, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 130

-Paragraph 26

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 10A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 14

-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e681-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 30

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=7668309&loc=d3e80784-113994

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e637-108580

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 14A

-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669686-108580

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

The aggregate fair value of additional assets that would be required to be posted as collateral for derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4H

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44D

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_AdditionalCollateralAggregateFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44D

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4H

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624258-113959

Name:	us-gaap_CollateralAlreadyPostedAggregateFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount as of the balance sheet date of the fair value of derivative assets that in accordance with the entity's accounting policy was not offset against an obligation to return cash collateral under a master netting arrangement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=d3e41678-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FIN39-1

-Paragraph 10B

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7668309&loc=d3e80748-113994

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 45

-Subparagraph b(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.