Device Payment Plan Agreement and Wireless Service Receivables - Schedule of Credit Quality Indicators (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2025	Dec. 31, 2024
Device payment plan agreement receivables, at amortized cost
Device payment plan agreement receivables, at amortized cost	$ 31,491	$ 31,308
Device payment plan agreement
Device payment plan agreement receivables, at amortized cost
2025	9,932
2024	13,476
2023 and prior	7,070
Device payment plan agreement receivables, at amortized cost	30,478
Gross write-offs
2025	73
2024	404
2023 and prior	195
Gross write-offs	672
Wireless Service Plan Receivables
Device payment plan agreement receivables, at amortized cost
2025	6,237
2024	120
Device payment plan agreement receivables, at amortized cost	6,357
Gross write-offs
2025	98
2024 and prior	179
Gross write-offs	277
New customers | Device payment plan agreement
Device payment plan agreement receivables, at amortized cost
2025	1,948
2024	2,335
2023 and prior	1,067
Device payment plan agreement receivables, at amortized cost	5,350
Gross write-offs
2025	70
2024	314
2023 and prior	93
Gross write-offs	477
Existing customers | Device payment plan agreement
Device payment plan agreement receivables, at amortized cost
2025	7,984
2024	11,141
2023 and prior	6,003
Device payment plan agreement receivables, at amortized cost	25,128
Gross write-offs
2025	3
2024	90
2023 and prior	102
Gross write-offs	$ 195