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Long-Term Debt and Credit Facilities - Additional Information (Details) - USD ($) $ in Millions			9 Months Ended
	Jun. 15, 2021	Jan. 13, 2021	Sep. 30, 2021
Long-term Debt and Credit Facilities
Repayments of debt			$ 2,700
Gain on extinguishment of debt			8
Term loan
Long-term Debt and Credit Facilities
Repayments of debt			94
Qwest Capital Funding, Inc. \| Senior notes
Long-term Debt and Credit Facilities
Repayments of debt			97
Lumen Technologies, Inc. \| Senior notes \| 5.375% Senior Notes Due 2029
Long-term Debt and Credit Facilities
Face amount	$ 1,000
Stated interest rate	5.375%
Lumen Technologies, Inc. \| Senior notes
Long-term Debt and Credit Facilities
Repayments of debt			1,200
Lumen Technologies, Inc. \| Senior notes \| 6.450% Senior Notes, Series S, Due 2021
Long-term Debt and Credit Facilities
Stated interest rate	6.45%
Outstanding debt repaid	$ 1,200
Lumen Technologies, Inc. \| Credit facility \| Revolving Credit Facility
Long-term Debt and Credit Facilities
Repayments of debt			150
Level 3 Financing, Inc. \| Senior notes
Long-term Debt and Credit Facilities
Outstanding debt repaid		$ 900
Level 3 Financing, Inc. \| Senior notes \| 3.750% Sustainability-Linked Senior Notes 2029
Long-term Debt and Credit Facilities
Face amount		$ 900
Stated interest rate		3.75%
Level 3 Financing, Inc. \| Senior notes
Long-term Debt and Credit Facilities
Repayments of debt			900
Qwest Corporation \| Senior notes
Long-term Debt and Credit Facilities
Repayments of debt			$ 235