Long-Term Debt and Credit Facilities - Exchange Offers and Repurchases (Details) - USD ($)		12 Months Ended
	Apr. 17, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Mar. 31, 2023
Long-term Debt and Credit Facilities
Aggregate principal amount	$ 630,000,000
Gain (loss) on extinguishment of debt		$ 618,000,000	$ 214,000,000	$ 8,000,000
Level 3 Financing, Inc. | Senior Notes | 10.500% Senior Secured Notes Due 2030
Long-term Debt and Credit Facilities
Debt instrument, face amount	$ 9,000,000				$ 915,000,000
Stated interest rate (as a percent)	10.50%				10.50%
Lumen Technologies Incorporated | Senior Notes
Long-term Debt and Credit Facilities
Debt instrument, face amount	$ 19,000,000				$ 1,535,000,000
Repurchased face amount					$ 24,000,000