Long-Term Debt and Credit Facilities - Additional Information (Details) - USD ($)	3 Months Ended
Mar. 31, 2021	Jan. 13, 2021
Long-term Debt and Credit Facilities
Repayments of debt	$ 1,300,000,000
Gain on extinguishment of debt	8,000,000
Lumen Technologies, Inc. \| Credit facility \| Revolving Credit Facility
Long-term Debt and Credit Facilities
Repayments of debt	150,000,000
Level 3 Financing, Inc. \| Senior notes \| 3.750% Sustainability-Linked Senior Notes 2029
Long-term Debt and Credit Facilities
Face amount		$ 900,000,000
Stated interest rate		3.75%
Level 3 Financing, Inc. \| Senior notes
Long-term Debt and Credit Facilities
Repayments of debt	900,000,000
Qwest Corporation \| Senior notes
Long-term Debt and Credit Facilities
Repayments of debt	$ 235,000,000

Face (par) amount of debt instrument at time of issuance.

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