v3.26.3
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, 2026
Sep. 30, 2025
Financing Receivable, Allowance for Credit Loss [Roll Forward]    
Allowance for credit losses and unamortized discount, beginning of period $ 1,172 $ 990
Bad debt expense 1,261 925
Write-offs (1,246) (930)
Allowance for credit losses for acquired credit deteriorated receivables 0 88
Change in unamortized discount on short-term and long-term EIP receivables 127 100
Impact on the unamortized discount from sales of EIP receivables (141) (135)
Allowance for credit losses and unamortized discount, end of period 1,173 1,038
Accounts Receivable Allowance    
Financing Receivable, Allowance for Credit Loss [Roll Forward]    
Allowance for credit losses and unamortized discount, beginning of period 226 176
Bad debt expense 615 478
Write-offs (590) (458)
Allowance for credit losses for acquired credit deteriorated receivables 0 10
Allowance for credit losses and unamortized discount, end of period 251 206
EIP Receivables Allowance    
Financing Receivable, Allowance for Credit Loss [Roll Forward]    
Allowance for credit losses and unamortized discount, beginning of period 946 814
Bad debt expense 646 447
Write-offs (656) (472)
Allowance for credit losses for acquired credit deteriorated receivables 0 78
Change in unamortized discount on short-term and long-term EIP receivables 127 100
Impact on the unamortized discount from sales of EIP receivables (141) (135)
Allowance for credit losses and unamortized discount, end of period $ 922 $ 832