Employee Benefits (Details)	1 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Employee Benefits
Collective bargaining agreements term	3 years
Collective bargaining arrangement, number of participating unionized employees			10,000
Collective bargaining arrangement, number of participating active employees and retirees			10,000
Qwest Communications International, Inc.
Employee Benefits
Description of related party transaction					In 2015, we agreed to a plan to settle the outstanding affiliate obligations, net balance with QCII over a 30 year term. Under the plan, payments are scheduled to be made on a monthly basis.
CenturyLink, Inc.
Employee Benefits
Allocated expenses by parent entities (as a percent)			70.00%	70.00%	69.00%
Pension Plan
Employee Benefits
Defined benefit plan, service cost			$ 44,000,000	$ 45,000,000	$ 57,000,000
Pension Plan | CenturyLink, Inc.
Employee Benefits
Employer contributions to benefit plan			100,000,000	100,000,000
Unfunded status			(2,004,000,000)	(2,352,000,000)
Post-Retirement Benefit Plan
Employee Benefits
Defined benefit plan, service cost			12,000,000	14,000,000	$ 17,000,000
Post-Retirement Benefit Plan | CenturyLink, Inc.
Employee Benefits
Employer contributions to benefit plan			0	0
Unfunded status			(3,352,000,000)	(3,360,000,000)
Pension, Supplemental and Other Postretirement Benefit Plans | Qwest Communications International, Inc.
Employee Benefits
Description of related party transaction					In 2015, we agreed to a plan to settle the outstanding pension and post-retirement affiliate obligations, net balance with QCII over a 30 year term. Under the plan, payments are scheduled to be made on a monthly basis.
Repayments on affiliate obligation			$ 87,000,000	$ 97,000,000
Change in accounting method accounted for as change in estimate | Pension, Supplemental and Other Postretirement Benefit Plans
Employee Benefits
Change in allocation of pension and post-retirement service costs					In 2015, our ultimate parent company, CenturyLink, changed their allocation methodology with respect to their now centrally managed pension and post-retirement plans. Specifically, under this new methodology, CenturyLink will allocate current service costs to subsidiaries relative to employees who are currently earning benefits under the pension and post-retirement benefit plans. The net periodic benefit cost allocated to us is now paid on a monthly basis through CenturyLink’s intercompany cash management process.
Forecast | Pension Plan | CenturyLink, Inc.
Employee Benefits
Employer contributions to benefit plan		$ 100,000,000