Long-Term Debt and Credit Facilities - Redemptions (Details) - Senior Notes $ in Millions	Feb. 15, 2025 USD ($)
Long-term Debt and Credit Facilities
Aggregate principal amount	$ 202
5.625% unsecured Senior Notes due 2025
Long-term Debt and Credit Facilities
Stated interest rate	5.625%
Aggregate principal amount	$ 55
7.200% unsecured Senior Notes due 2025
Long-term Debt and Credit Facilities
Stated interest rate	7.20%
Aggregate principal amount	$ 29
5.125% unsecured Senior Notes due 2026
Long-term Debt and Credit Facilities
Stated interest rate	5.125%
Aggregate principal amount	$ 7
4.000% unsecured Senior Notes due 2027
Long-term Debt and Credit Facilities
Stated interest rate	4.00%
Aggregate principal amount	$ 41
3.400% unsecured Senior Notes due 2027 | Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Stated interest rate	3.40%
Aggregate principal amount	$ 5
4.625% unsecured Senior Notes due 2027 | Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Stated interest rate	4.625%
Aggregate principal amount	$ 65