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Goodwill, Customer Relationships and Other Intangible Assets - Rollforward Goodwill (Details) - USD ($)			3 Months Ended		9 Months Ended
	Sep. 30, 2025	Apr. 30, 2025	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Goodwill [Line Items]
Accumulated impairment losses	$ 22,300,000,000		$ 22,300,000,000		$ 22,300,000,000		$ 21,700,000,000
Goodwill [Roll Forward]
Beginning balance					1,964,000,000
Impairment	0	$ 0	0	$ 0	(628,000,000)	$ 0
Reclassified as held for sale					(1,336,000,000)
Ending balance	0		0		0
Held for sale \| Mass Markets Fiber-to-the Home Business
Goodwill [Line Items]
Goodwill	1,336,000,000		1,336,000,000		1,336,000,000
Business
Goodwill [Roll Forward]
Beginning balance					0
Impairment					0
Reclassified as held for sale					0
Ending balance	0		0		0
Mass Markets
Goodwill [Roll Forward]
Beginning balance					1,964,000,000
Impairment					(628,000,000)
Reclassified as held for sale					(1,336,000,000)
Ending balance	$ 0		$ 0		$ 0