Sales Of Receivables (Equipment Installment and AT&T Revolving Programs) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Asset Pledged as Collateral without Right
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, Fair Value Disclosure	$ 553
Equipment Installment Program | Guarantee Obligation
Accounts, Notes, Loans and Financing Receivable [Line Items]
Guarantee obligation	301	$ 385
Equipment Installment Program | Accounts payable and accrued liabilities | Guarantee Obligation
Accounts, Notes, Loans and Financing Receivable [Line Items]
Guarantee obligation	150	111
Equipment Installment Program | Deferred Purchase Price Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deferred purchase price receivable	3,185	2,270
Equipment Installment Program | Deferred Purchase Price Receivables | Prepaid Expenses and Other Current Assets
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deferred purchase price receivable	1,906	$ 1,296
Revolving Receivables Program | Maximum Amount
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving agreement, transfer amount	$ 2,770