Long-Term Debt and Credit Facilities - Senior Notes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Jun. 30, 2024
Long-term Debt and Credit Facilities
Face amount		$ 11,970
First Lien Notes | Senior Notes | Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Face amount	$ 1,575
Proceeds from debt issuance	1,325
Non-cash fee	$ 50
4.000% Senior Secured Notes Due 2027 | Senior Notes
Long-term Debt and Credit Facilities
Stated interest rate	4.00%	4.00%
4.000% Senior Secured Notes Due 2027 | Senior Notes | Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Face amount	$ 200