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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

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

+ References

+ Details

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

- Definition

Identification of the contractual issuer of the debt instrument (for example, a subsidiary of the reporting entity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

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

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

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

- Definition

Date the debt instrument was repurchased, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

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

- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

+ Details

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

- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

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

- Definition

Weighted average interest rate of long-term debt outstanding calculated at point in time.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585

+ Details

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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=t_AttInc4600GlobalNotesDue2045Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=t_AttInc4000GlobalNotesDue2049Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=t_DebtInstrumentIssuedWithVariousNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=t_WarnerMediaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
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Debt (Financing Activities) (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Feb. 29, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt			$ 17,039	$ 41,875	$ 48,793
Repayment of long-term debt			27,592	$ 52,643	$ 12,339
Debt Instrument - principal/face amount			$ 17,235
Debt Instrument Weighted Average Maturity Period			9 years
Debt Instrument Weighted Average Interest Rate			4.40%	4.40%
Debt Instrument - debt redeemed			$ 27,440
Debt Instrument, Repurchase Date			Dec. 19, 2019
Debt Instrument, Repurchased Face Amount			$ 1,409
Debt Instrument, Issuer			various subsidiaries
AT&T Inc. 4.600% Global Notes Due 2045 [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Dec. 31, 2045
Debt instument - stated percentage rate	4.60%
Debt Instrument - debt redeemed	$ 2,619
Debt Instrument, Repurchase Date	Feb. 29, 2020
AT&T Inc. 4.000% Global Notes Due 2049 [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Dec. 31, 2049
Proceeds from Issuance of Long-term Debt	$ 2,995
Debt instument - stated percentage rate	4.00%
Weighted Average [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Interest Rate			3.40%
Weighted Average [Member] \| Various Notes [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Interest Rate			3.50%
WarnerMedia [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt		$ 11,041
Repayment of long-term debt		$ 11,041
Debt Instrument, Repurchase Date		Jun. 30, 2019
Debt Instrument, Repurchased Face Amount		$ 590
Debt Instrument, Issuer		WarnerMedia subsidiaries
WarnerMedia [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Interest Rate		1.95%
WarnerMedia [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument Weighted Average Interest Rate		9.15%