Long-Term Debt and Credit Facilities - Covenants and Guarantees (Details) $ in Millions	9 Months Ended
Sep. 30, 2026 USD ($) indenture	Apr. 14, 2026 USD ($)
Letter of Credit \| Uncommitted Letter of Credit Facility
Long-term Debt and Credit Facilities
Maximum borrowing capacity	$ 225
Line of Credit \| Minimum
Long-term Debt and Credit Facilities
Interest coverage ratio	2.00
Line of Credit \| Revolving Credit Facility
Long-term Debt and Credit Facilities
Maximum total net leverage ratio	5.25
Maximum borrowing capacity	$ 825	$ 825
Senior Notes
Long-term Debt and Credit Facilities
Number of indentures \| indenture	4
Redemption price (as a percent)	101.00%
Senior Notes \| Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Redemption price (as a percent)	101.00%

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