Sales Of Receivables (Equipment Installment and AT&T Revolving Programs) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Equipment Installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross receivables	$ 5,565	$ 4,576
Other Assets	2,295	1,632
Outstanding portfolio of receivables derecognized from our consolidated balance sheets	7,827	9,713
Cash proceeds received, net of remittances	5,646	7,211
Equipment Installment \| Notes receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	2,716	2,467
Equipment Installment \| Trade receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	554	477
Revolving
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross receivables	3,909	3,324
Other Assets	194	515
Outstanding portfolio of receivables derecognized from our consolidated balance sheets	5,300	4,300
Cash proceeds received, net of remittances	5,300	4,300
Revolving \| Notes receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	0	0
Revolving \| Trade receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 3,715	$ 2,809

The cummulative cash proceeds received, net of remittances (excluding amounts returned as deferred purchase price).

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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.

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No definition available.

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Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business.

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- Definition

Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as noncurrent.

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Amount of transferred financial assets in which the transferor has continuing involvement with the assets underlying the transaction that have been derecognized. Continuing involvement includes, but is not limited to, servicing, recourse, and restrictions on transferor's interests in transferred financial assets.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
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