| Cover Page | Nov. 29, 2019 |
| Entity Information [Line Items] | |
| Entity Registrant Name | CenturyLink, Inc. |
| Amendment Flag | false |
| Entity Central Index Key | 0000018926 |
| Document Type | 8-K |
| Document Period End Date | Nov. 29, 2019 |
| Entity Incorporation, State or Country Code | LA |
| Entity File Number | 001-7784 |
| Entity Tax Identification Number | 72-0651161 |
| Entity Address, Address Line One | 100 CenturyLink Drive |
| Entity Address, City or Town | Monroe |
| Entity Address, State or Province | LA |
| Entity Address, Postal Zip Code | 71203 |
| City Area Code | 318 |
| Local Phone Number | 388-1000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | CTL |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Level 3 Parent LLC [Member] | |
| Entity Information [Line Items] | |
| Entity Registrant Name | Level 3 Parent, LLC |
| Entity Central Index Key | 0000794323 |
| Document Type | 8-K |
| Document Period End Date | Nov. 29, 2019 |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-35134 |
| Entity Tax Identification Number | 47-0210602 |
| Entity Address, Address Line One | 1025 Eldorado Blvd. |
| Entity Address, City or Town | Broomfield |
| Entity Address, State or Province | CO |
| Entity Address, Postal Zip Code | 80021 |
| City Area Code | 720 |
| Local Phone Number | 888-1000 |
| Entity Emerging Growth Company | false |
