Goodwill, Customer Relationships and Other Intangible Assets - Goodwill, Customer Relationships, and Other Intangible Assets (Details) - USD ($) $ in Millions	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Goodwill [Line Items]
Goodwill	$ 0		$ 1,964
Indefinite-lived intangible assets	0		9
Total other intangible assets, net	4,525		4,806
Held for sale | Mass Markets Fiber-to-the Home Business
Goodwill [Line Items]
Goodwill	(1,336)
Customer Relationships
Goodwill [Line Items]
Other intangible assets subject to amortization	2,899		3,196
Accumulated amortization	4,648		4,504
Capitalized Software
Goodwill [Line Items]
Other intangible assets subject to amortization	1,560		1,529
Accumulated amortization	3,789		4,067
Patents and Other
Goodwill [Line Items]
Other intangible assets subject to amortization	66		72
Accumulated amortization	$ 93		$ 86
Fully Amortized and Retired Customer Relationships
Goodwill [Line Items]
Gross carrying value		$ 161
Fully Amortized and Retired Capitalized Software
Goodwill [Line Items]
Gross carrying value		$ 211