Description of Business and Summary of Significant Accounting Policies - Narrative (Detail) shares in Millions	12 Months Ended
	Dec. 31, 2024 state plan segment shares	Dec. 31, 2023 shares	Dec. 31, 2022 shares
Organization And Summary Of Significant Accounting Policies [Line Items]
Number of reportable segments | segment	2
Number of states in which wireline services are provided | state	9
Number of payment plans | plan	2
Restricted stock units outstanding to purchase shares included in diluted earnings per common share (in shares) | shares	4.7	4.2	1.9
Minimum threshold period for existing customers	210 days
Maximum threshold period for new customers	210 days
Wireless Licenses
Organization And Summary Of Significant Accounting Policies [Line Items]
Average remaining renewal period of wireless license portfolio (in years)	10 years	10 years
Wireless Licenses | Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Average remaining renewal period of wireless license portfolio (in years)	15 years
Wireless Licenses | Minimum
Organization And Summary Of Significant Accounting Policies [Line Items]
Average remaining renewal period of wireless license portfolio (in years)	10 years
Non-Network Internal-Use Software | Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Useful life for finite-lived intangible assets, years	7 years
Non-Network Internal-Use Software | Minimum
Organization And Summary Of Significant Accounting Policies [Line Items]
Useful life for finite-lived intangible assets, years	3 years
Fixed Term Plan
Organization And Summary Of Significant Accounting Policies [Line Items]
Contract term	36 months
Device Payment Plan
Organization And Summary Of Significant Accounting Policies [Line Items]
Contract term	36 months