Employee Benefits - Pension and Post-Retirement Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CenturyLink, Inc.
Employee Benefits
Allocated expenses by parent entities (as a percent)	87.00%	72.00%	69.00%
Pension Plan
Employee Benefits
Defined benefit plan, service cost	$ 22,000,000	$ 31,000,000	$ 38,000,000
Pension Plan | CenturyLink, Inc.
Employee Benefits
Employer contributions to benefit plan	0	0
Pension Plan | CenturyLink, Inc.
Employee Benefits
Unfunded status	769,000,000	615,000,000
Post-Retirement Benefit Plan
Employee Benefits
Defined benefit plan, service cost	4,000,000	7,000,000	$ 10,000,000
Post-Retirement Benefit Plan | CenturyLink, Inc.
Employee Benefits
Unfunded status	$ 1,900,000,000	2,000,000,000
Pension, Supplemental and Other Postretirement Benefit Plans | Affiliated Entity
Employee Benefits
Pension settlement term	30 years
Revenue from affiliate	$ 57,000,000	$ 61,000,000