Revenue and Contract Costs - Narrative (Details)	12 Months Ended
	Dec. 31, 2024 USD ($) segment	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Disaggregation of Revenue [Line Items]
Number of reportable segments | segment	2
Revenue from arrangements not accounted for under Topic 606	$ 3,100,000,000	$ 2,900,000,000	$ 3,200,000,000
Contract with customer asset period increase	128,000,000
Contract with customer, asset, credit loss expense (reversal)	53,000,000
Contract with customer liability period increase	776,000,000
Revenue recognized from previously recognized contract liability	5,000,000,000.0	4,900,000,000
Amortization of deferred contract costs	3,400,000,000	3,200,000,000
Deferred contract costs, impairment charges	$ 0	$ 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, remaining performance obligation	$ 28,500,000,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, remaining performance obligation	$ 17,500,000,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period
Revenue, remaining performance obligation	$ 7,200,000,000
Minimum
Disaggregation of Revenue [Line Items]
Deferred contract cost, amortization period	2 years
Minimum | Consumer
Disaggregation of Revenue [Line Items]
Contract term	12 months
Maximum
Disaggregation of Revenue [Line Items]
Deferred contract cost, amortization period	7 years
Maximum | Consumer
Disaggregation of Revenue [Line Items]
Contract term	2 years
Maximum | Business
Disaggregation of Revenue [Line Items]
Contract term	12 months
Wireless postpaid contracts
Disaggregation of Revenue [Line Items]
Percentage of month-to-month contracts of total service contracts	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	95.00%	94.00%
Wireless Service, Device Payment Plans | Minimum
Disaggregation of Revenue [Line Items]
Contract term	1 month
Wireless Service, Device Payment Plans | Maximum
Disaggregation of Revenue [Line Items]
Contract term	36 months
Reseller Arrangements | Minimum | Consumer
Disaggregation of Revenue [Line Items]
Contract term	2 years
Customer Contracts that Have Contract Minimum over Total Contract Term | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	29 years
Revenue, remaining performance obligation	$ 1,800,000,000