v3.26.1
Long-Term Debt and Credit Facilities - Long Term Debt (Details)
 3 Months Ended
Mar. 31, 2026
USD ($)
subsidiary
Dec. 31, 2025
USD ($)
Debt Disclosure [Abstract]    
Number of subsidiaries | subsidiary 3  
Long-term Debt and Credit Facilities    
Finance lease and other obligations $ 223,000,000 $ 220,000,000
Unamortized premiums (discounts), net 3,000,000 (223,000,000)
Unamortized debt issuance costs (134,000,000) (151,000,000)
Total long-term debt 12,960,000,000 17,441,000,000
Less current maturities (35,000,000) (88,000,000)
Long-term debt, excluding current maturities $ 12,925,000,000 17,353,000,000
Line of Credit | Series A Revolving Credit Facility    
Long-term Debt and Credit Facilities    
Basis spread (as a percent) 4.00%  
Long-term debt, gross $ 0 0
Line of Credit | Series B Revolving Credit Facility    
Long-term Debt and Credit Facilities    
Basis spread (as a percent) 6.00%  
Long-term debt, gross $ 0 0
Term Loan | Term Loan A    
Long-term Debt and Credit Facilities    
Long-term debt, gross 0 $ 338,000,000
Long-term debt, weighted average interest rate   9.916%
Term Loan | Term Loan B-1    
Long-term Debt and Credit Facilities    
Long-term debt, gross 0 $ 1,590,000,000
Long-term debt, weighted average interest rate   6.38%
Term Loan | Term Loan B-2    
Long-term Debt and Credit Facilities    
Long-term debt, gross $ 0 $ 1,590,000,000
Long-term debt, weighted average interest rate   6.38%
Term Loan | Term Loan B-4    
Long-term Debt and Credit Facilities    
Basis spread (as a percent) 3.25%  
Term Loan | Term Loan B-4 | Level 3 Financing, Inc.    
Long-term Debt and Credit Facilities    
Long-term debt, gross $ 2,400,000,000 $ 2,400,000,000
Long-term debt, weighted average interest rate 6.923% 7.166%
Senior Notes | Superpriority Notes    
Long-term Debt and Credit Facilities    
Long-term debt, gross $ 0 $ 1,247,000,000
Senior Notes | First Lien Notes | Level 3 Financing, Inc.    
Long-term Debt and Credit Facilities    
Long-term debt, gross $ 4,425,000,000 4,425,000,000
Senior Notes | First Lien Notes | Level 3 Financing, Inc. | Minimum    
Long-term Debt and Credit Facilities    
Stated interest rate (as a percent) 6.875%  
Senior Notes | First Lien Notes | Level 3 Financing, Inc. | Maximum    
Long-term Debt and Credit Facilities    
Stated interest rate (as a percent) 7.00%  
Senior Notes | Senior Notes Maturing 2028-2042    
Long-term Debt and Credit Facilities    
Long-term debt, gross $ 1,296,000,000 1,296,000,000
Senior Notes | Senior Notes Maturing 2028-2042 | Minimum    
Long-term Debt and Credit Facilities    
Stated interest rate (as a percent) 4.50%  
Senior Notes | Senior Notes Maturing 2028-2042 | Maximum    
Long-term Debt and Credit Facilities    
Stated interest rate (as a percent) 7.65%  
Senior Notes | Senior Notes Maturing 2028-2036 | Level 3 Financing, Inc.    
Long-term Debt and Credit Facilities    
Long-term debt, gross $ 2,794,000,000 2,144,000,000
Senior Notes | Senior Notes Maturing 2028-2036 | Level 3 Financing, Inc. | Minimum    
Long-term Debt and Credit Facilities    
Stated interest rate (as a percent) 3.625%  
Senior Notes | Senior Notes Maturing 2028-2036 | Level 3 Financing, Inc. | Maximum    
Long-term Debt and Credit Facilities    
Stated interest rate (as a percent) 8.50%  
Senior Notes | Second Lien Notes | Level 3 Financing, Inc.    
Long-term Debt and Credit Facilities    
Long-term debt, gross $ 52,000,000 660,000,000
Senior Notes | Second Lien Notes | Level 3 Financing, Inc. | Minimum    
Long-term Debt and Credit Facilities    
Stated interest rate (as a percent) 3.875%  
Senior Notes | Second Lien Notes | Level 3 Financing, Inc. | Maximum    
Long-term Debt and Credit Facilities    
Stated interest rate (as a percent) 4.875%  
Senior Notes | Senior Notes Maturing 2030-2057 | Qwest Corporation    
Long-term Debt and Credit Facilities    
Long-term debt, gross $ 1,736,000,000 1,736,000,000
Senior Notes | Senior Notes Maturing 2030-2057 | Qwest Corporation | Minimum    
Long-term Debt and Credit Facilities    
Stated interest rate (as a percent) 6.50%  
Senior Notes | Senior Notes Maturing 2030-2057 | Qwest Corporation | Maximum    
Long-term Debt and Credit Facilities    
Stated interest rate (as a percent) 7.75%  
Senior Notes | Senior Notes Maturing 2028-2031 | Qwest Capital Funding, Inc.    
Long-term Debt and Credit Facilities    
Long-term debt, gross $ 165,000,000 $ 169,000,000
Senior Notes | Senior Notes Maturing 2028-2031 | Qwest Capital Funding, Inc. | Minimum    
Long-term Debt and Credit Facilities    
Stated interest rate (as a percent) 6.875%  
Senior Notes | Senior Notes Maturing 2028-2031 | Qwest Capital Funding, Inc. | Maximum    
Long-term Debt and Credit Facilities    
Stated interest rate (as a percent) 7.75%