v3.25.3
Receivables and Related Allowance for Credit Losses - Schedule of Unamortized Imputed Discount and Allowance for Credit Losses for Equipment Installment Plan Receivables (Details) - USD ($)
$ in Millions
 9 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]    
Allowance for credit losses and imputed discount, beginning of period $ 990 $ 934
Bad debt expense 925 836
Write-offs (930) (835)
Allowance for credit losses for acquired credit deteriorated receivables 88 0
Change in imputed discount on short-term and long-term EIP receivables 100 87
Impact on the imputed discount from sales of EIP receivables (135) (155)
Allowance for credit losses and imputed discount, end of period 1,038 867
Accounts Receivable Allowance    
Financing Receivable, Allowance for Credit Loss [Roll Forward]    
Allowance for credit losses and imputed discount, beginning of period 176 161
Bad debt expense 478 409
Write-offs (458) (408)
Allowance for credit losses for acquired credit deteriorated receivables 10 0
Allowance for credit losses and imputed discount, end of period 206 162
EIP Receivables Allowance    
Financing Receivable, Allowance for Credit Loss [Roll Forward]    
Allowance for credit losses and imputed discount, beginning of period 814 773
Bad debt expense 447 427
Write-offs (472) (427)
Allowance for credit losses for acquired credit deteriorated receivables 78 0
Change in imputed discount on short-term and long-term EIP receivables 100 87
Impact on the imputed discount from sales of EIP receivables (135) (155)
Allowance for credit losses and imputed discount, end of period $ 832 $ 705