Other Financial Information - Other Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Unrecognized tax benefits	$ 477	$ 453
Deferred revenue	103	97
Operating lease liability	51	49
Other	76	86
Total Other liabilities	707	$ 685
Held-for-sale \| Lumen Mass Markets fiber-to-the-home business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other non-current liabilities	$ 1

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Amount of deferred tax liability attributable to taxable temporary differences, after deferred tax asset, and other liabilities expected to be paid after one year or operating cycle, if longer.

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Amount of deferred income and obligation to transfer product and service to customer for which consideration has been received or is receivable.

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Amount classified as other liabilities attributable to disposal group held for sale or disposed of, expected to be disposed of beyond one year or the normal operating cycle, if longer.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount recognized for uncertainty in income taxes classified as noncurrent.

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Present value of lessee's discounted obligation for lease payments from operating lease, classified as noncurrent.

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