v3.20.4

Sales Of Receivables (Finance Receivables Repurchased) (Details) - Equipment Installment - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value of repurchased receivables | $ 1,271 | $ 1,418 | $ 1,480
Carrying value of deferred purchase price | 1,235 | 1,350 | 1,393
Gain on repurchases | $ 36 | $ 68 | $ 87

X
- Definition Reflects the net positive or negative amount derived from subtracting from fair value the carrying amounts, of notes receivable repurchased and included in Selling, general and administrative in the consolidated statements of income. + References No definition available. + Details
Name: | t_GainLossOnSaleOfNotesReceivableRepurchased
Namespace Prefix: | t_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount, during period, representing an agreement for an unconditional promise by the maker to pay the entity (holder) a definite sum of money at a future date. Such amount may include accrued interest receivable in accordance with the terms of the note. The note also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among a myriad of other features and characteristics. Excludes amounts related to receivables held-for-sale. + References No definition available. + Details
Name: | t_NotesReceivableGrossDuringPeriod
Namespace Prefix: | t_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fair value portion of receivables during period, including, but not limited to, trade account receivables, note receivables, and loan receivables. + References No definition available. + Details
Name: | t_ReceivablesFairValueDisclosureDuringPeriod
Namespace Prefix: | t_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- 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_AccountsNotesAndLoansReceivableLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | t_FinanceReceivableProgramsAxis=t_EquipmentInstallmentProgramMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |