Revenues and Contract Costs - Additional Information (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) segment	Jun. 30, 2024 USD ($)
Disaggregation of Revenue [Line Items]
Number of reportable segments | segment			2
Revenue recognized related to contract liabilities existing	$ 275,000,000	$ 262,000,000	$ 4,900,000,000	$ 4,700,000,000
Amortization of deferred contract costs	892,000,000	829,000,000	1,800,000,000	1,700,000,000
Contract assets impairment charge	$ 0	$ 0	$ 0	$ 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-07-01
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	36 months		36 months
Revenue, remaining performance obligation	$ 53,500,000,000		$ 53,500,000,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-07-01
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period
Wireless postpaid contracts
Disaggregation of Revenue [Line Items]
Percentage of month-to-month contracts of total service contracts	95.00%	95.00%	95.00%	95.00%
Wireline Consumer And Business Markets And Other Contracts
Disaggregation of Revenue [Line Items]
Percentage of month-to-month contracts of total service contracts	94.00%	95.00%	94.00%	95.00%
Customer Contracts that Have Contract Minimum over Total Contract Term | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-07-01
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	28 years		28 years
Revenue, remaining performance obligation	$ 1,500,000,000		$ 1,500,000,000
Minimum
Disaggregation of Revenue [Line Items]
Deferred contract cost, amortization period	1 year		1 year
Minimum | Wireless Service, Device Payment Plan and Fixed-Term Plan
Disaggregation of Revenue [Line Items]
Customer contracts service term			1 month
Minimum | Consumer
Disaggregation of Revenue [Line Items]
Customer contracts service term			12 months
Minimum | Consumer | Reseller Arrangements
Disaggregation of Revenue [Line Items]
Customer contracts service term			2 years
Maximum
Disaggregation of Revenue [Line Items]
Deferred contract cost, amortization period	7 years		7 years
Maximum | Wireless Service, Device Payment Plan and Fixed-Term Plan
Disaggregation of Revenue [Line Items]
Customer contracts service term			36 months
Maximum | Consumer
Disaggregation of Revenue [Line Items]
Customer contracts service term			2 years
Maximum | Business
Disaggregation of Revenue [Line Items]
Customer contracts service term			12 months