Long-Term Debt and Credit Facilities - Schedule of Long Term Debt (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2021	Dec. 31, 2020
Long-term Debt and Credit Facilities
Finance lease and other obligations	$ 352	$ 295
Unamortized premiums (discounts), net	23	(78)
Unamortized debt issuance costs	(228)	(237)
Total long-term debt	29,761	31,837
Less current maturities	(2,501)	(2,427)
Long-term debt, excluding current maturities	27,260	29,410
Lumen Technologies, Inc. \| Credit facility \| Revolving Credit Facility
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 0	150
Lumen Technologies, Inc. \| Credit facility \| Revolving Credit Facility \| LIBOR
Long-term Debt and Credit Facilities
Basis spread (as a percent)	2.00%
Lumen Technologies, Inc. \| Term loan \| Term Loan A
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 1,064	$ 1,108
Long-term debt, weighted average interest rate	2.085%	2.147%
Lumen Technologies, Inc. \| Term loan \| Term Loan A \| LIBOR
Long-term Debt and Credit Facilities
Basis spread (as a percent)	2.00%
Lumen Technologies, Inc. \| Term loan \| Term Loan A-1
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 304	$ 316
Long-term debt, weighted average interest rate	2.085%	2.147%
Lumen Technologies, Inc. \| Term loan \| Term Loan A-1 \| LIBOR
Long-term Debt and Credit Facilities
Basis spread (as a percent)	2.00%
Lumen Technologies, Inc. \| Term loan \| Term Loan B
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 4,913	$ 4,950
Long-term debt, weighted average interest rate	2.335%	2.397%
Lumen Technologies, Inc. \| Term loan \| Term Loan B \| LIBOR
Long-term Debt and Credit Facilities
Basis spread (as a percent)	2.25%
Lumen Technologies, Inc. \| Senior notes \| 4.000% Senior Secured Notes Due 2027
Long-term Debt and Credit Facilities
Stated interest rate	4.00%
Long-term debt, gross	$ 1,250	$ 1,250
Lumen Technologies, Inc. \| Senior notes \| Senior Notes Maturing 2022-2042
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 8,414	8,645
Lumen Technologies, Inc. \| Senior notes \| Senior Notes Maturing 2022-2042 \| Minimum
Long-term Debt and Credit Facilities
Stated interest rate	4.50%
Lumen Technologies, Inc. \| Senior notes \| Senior Notes Maturing 2022-2042 \| Maximum
Long-term Debt and Credit Facilities
Stated interest rate	7.65%
Level 3 Financing, Inc. \| Term loan \| Tranche B 2027 Term Loan
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 3,111	$ 3,111
Long-term debt, weighted average interest rate	1.835%	1.897%
Level 3 Financing, Inc. \| Term loan \| Tranche B 2027 Term Loan \| LIBOR
Long-term Debt and Credit Facilities
Basis spread (as a percent)	1.75%
Level 3 Financing, Inc. \| Senior notes \| Senior Notes, Maturing 2027-2029
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 1,500	$ 1,500
Level 3 Financing, Inc. \| Senior notes \| Senior Notes, Maturing 2027-2029 \| Minimum
Long-term Debt and Credit Facilities
Stated interest rate	3.40%
Level 3 Financing, Inc. \| Senior notes \| Senior Notes, Maturing 2027-2029 \| Maximum
Long-term Debt and Credit Facilities
Stated interest rate	3.875%
Level 3 Financing, Inc. \| Senior notes \| Senior Notes Maturing 2025-2029
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 5,515	5,515
Level 3 Financing, Inc. \| Senior notes \| Senior Notes Maturing 2025-2029 \| Minimum
Long-term Debt and Credit Facilities
Stated interest rate	3.625%
Level 3 Financing, Inc. \| Senior notes \| Senior Notes Maturing 2025-2029 \| Maximum
Long-term Debt and Credit Facilities
Stated interest rate	5.375%
Embarq Corporation and subsidiary \| Senior notes
Long-term Debt and Credit Facilities
Stated interest rate	7.995%
Long-term debt, gross	$ 0	1,437
Embarq Corporation and subsidiary \| First mortgage bonds
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 138	138
Embarq Corporation and subsidiary \| First mortgage bonds \| Minimum
Long-term Debt and Credit Facilities
Stated interest rate	7.125%
Embarq Corporation and subsidiary \| First mortgage bonds \| Maximum
Long-term Debt and Credit Facilities
Stated interest rate	8.375%
Qwest Corporation \| Term loan
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 215	$ 215
Long-term debt, weighted average interest rate	2.09%	2.15%
Qwest Corporation \| Term loan \| LIBOR
Long-term Debt and Credit Facilities
Basis spread (as a percent)	2.00%
Qwest Corporation \| Senior notes
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 2,935	$ 3,170
Qwest Corporation \| Senior notes \| Minimum
Long-term Debt and Credit Facilities
Stated interest rate	6.50%
Qwest Corporation \| Senior notes \| Maximum
Long-term Debt and Credit Facilities
Stated interest rate	7.75%
Qwest Capital Funding, Inc. \| Senior notes
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 255	$ 352
Qwest Capital Funding, Inc. \| Senior notes \| Minimum
Long-term Debt and Credit Facilities
Stated interest rate	6.875%
Qwest Capital Funding, Inc. \| Senior notes \| Maximum
Long-term Debt and Credit Facilities
Stated interest rate	7.75%

Finance Lease And Other Obligations

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Amount of short-term and long-term debt and lease obligation.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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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, after accumulated amortization, of debt discount (premium).

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount of long-term debt and lease obligation, classified as noncurrent.

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Weighted average interest rate of long-term debt outstanding calculated at point in time.

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