Long-Term Debt and Credit Facilities - Level 3 Financing Credit Agreement (Details) - Term Loan - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Dec. 31, 2025
Term Loan B-4
Long-term Debt and Credit Facilities
Basis spread (as a percent)	3.25%
Term Loan B-4 \| Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 2,400	$ 2,400
Term Loan B-3 \| Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Debt instrument, floor interest rate (as a percent)	0.00%
Prepayment from net cash proceeds of certain asset sales (as a percent)	100.00%
Prepayment from net cash proceeds of certain debt issuances (as a percent)	100.00%
Term Loan B-3 \| Level 3 Financing, Inc. \| Federal Funds Rate
Long-term Debt and Credit Facilities
Basis spread (as a percent)	0.50%
Term Loan B-3 \| Level 3 Financing, Inc. \| One Month SOFR Rate
Long-term Debt and Credit Facilities
Basis spread (as a percent)	1.00%
Term Loan B-3 \| Level 3 Financing, Inc. \| SOFR
Long-term Debt and Credit Facilities
Basis spread (as a percent)	3.25%

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