v3.26.1
Sales Of Receivables (Equipment Installment and AT&T Revolving Programs) (Narrative) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Mar. 31, 2026
Asset Pledged as Collateral without Right    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Receivables, Fair Value Disclosure   $ 377
Equipment Installment | Guarantee Obligation    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Guarantee obligation $ 410 447
Equipment Installment | Balance Sheet Location [Axis]: us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent | Guarantee Obligation    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Guarantee obligation 216 227
Equipment Installment | Deferred Purchase Price Receivable    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Deferred purchase price receivable 2,067 2,463
Equipment Installment | Deferred Purchase Price Receivable | Balance Sheet Location [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Deferred purchase price receivable 1,338 $ 1,737
Revolving Receivables Program | Maximum    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Revolving agreement, transfer amount (up to) $ 2,940