Device Payment Plan Agreement and Wireless Service Receivables - Schedule of Credit Quality Indicators (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Device payment plan agreement receivables, at amortized cost
Device payment plan agreement receivables, at amortized cost	$ 31,308	$ 29,206
Wireless service
Gross write-offs
Gross write-offs	557
Device payment plan agreement
Device payment plan agreement receivables, at amortized cost
2024	17,413
2023	9,617
Prior to 2021	3,303
Device payment plan agreement receivables, at amortized cost	30,333
Gross write-offs
2024	428
2023	764
2022 and prior	266
Gross write-offs	1,458
Wireless service
Device payment plan agreement receivables, at amortized cost
2024	5,760
2023	49
Device payment plan agreement receivables, at amortized cost	5,809
Gross write-offs
2024	374
2023 and prior	183
Gross write-offs	557
New customers | Device payment plan agreement
Device payment plan agreement receivables, at amortized cost
2024	3,277
2023	1,542
Prior to 2021	397
Device payment plan agreement receivables, at amortized cost	5,216
Gross write-offs
2024	376
2023	563
2022 and prior	111
Gross write-offs	1,050
Existing customers | Device payment plan agreement
Device payment plan agreement receivables, at amortized cost
2024	14,136
2023	8,075
Prior to 2021	2,906
Device payment plan agreement receivables, at amortized cost	25,117
Gross write-offs
2024	52
2023	201
2022 and prior	155
Gross write-offs	$ 408