Employee Benefits	12 Months Ended
Dec. 31, 2017
Retirement Benefits [Abstract]
Employee Benefits	Employee Benefits Pension and Post-Retirement Benefits QCII's post-retirement benefit plans were merged into CenturyLink's post-retirement benefit plans on January 1, 2012 and on December 31, 2014, QCII's qualified pension plan and a pension plan of an affiliate were merged into the CenturyLink Retirement Plan, which was renamed the CenturyLink Combined Pension Plan. Prior to the plan mergers, a substantial portion of our active and retired employees participated in QCII's pension and post-retirement plans. Based on current laws and circumstances, (i) CenturyLink was not required to make a cash contribution to the CenturyLink Combined Pension Plan in 2017 and (ii) CenturyLink does not expect it will be required to make a contribution in 2018. The amount of required contributions to the CenturyLink Combined Pension Plan in 2019 and beyond will depend on earnings on plan investments, prevailing discount rates, demographic experience, changes in plan benefits and changes in funding laws and regulations. CenturyLink occasionally makes voluntary contributions in addition to required contributions, and CenturyLink made such voluntary cash contributions of $100 million to the CenturyLink Combined Pension Plan during each of the third quarters of 2017 and 2016. CenturyLink currently expects to make a voluntary contribution of $100 million to the trust for its qualified pension plan in 2018. No contributions were made to the post-retirement occupational health care trust in 2017 or 2016 and CenturyLink does not expect to make a contribution in 2018. The unfunded status of CenturyLink's qualified pension plan for accounting purposes was $2.004 billion and $2.352 billion as of December 31, 2017 and 2016, respectively, which includes the merged QCII qualified pension plan. The unfunded status of CenturyLink's post-retirement benefit plans for accounting purposes was $3.352 billion and $3.360 billion as of December 31, 2017 and 2016, respectively. 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. The affiliate obligations, net in current and noncurrent liabilities on the consolidated balance sheets primarily represents the cumulative allocation of expense, net of payments, associated with QCII's pension plans and post-retirement benefits plans prior to the plan mergers. 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. For the years ended December 31, 2017 and 2016, we made settlement payments in the aggregate of $87 million and $97 million, respectively, to QCII under the plan. Changes in the affiliate obligations, net are reflected in operating activities on our consolidated statements of cash flows. We were allocated $44 million of pension service costs and $12 million of post-retirement service costs during the year ended December 31, 2017, which represented 70% of CenturyLink's total pension and post-retirement service costs for the year. The combined net pension and post-retirement service costs is included in cost of services and products and selling, general and administrative expenses on our consolidated statement of operations for the year ended December 31, 2017. We were allocated $45 million of pension service costs and $14 million of post-retirement service costs during the year ended December 31, 2016, which represented 70% of CenturyLink's total pension and post-retirement service costs for the year. The combined net pension and post-retirement service costs is included in cost of services and products and selling, general and administrative expenses on our consolidated statement of operations for the year ended December 31, 2016. We were allocated $57 million of pension service costs and $17 million of post-retirement service costs during the year ended December 31, 2015, which represented 69% of CenturyLink's total pension and post-retirement service costs for the year. The combined net pension and post-retirement service costs is included in cost of services and products and selling, general and administrative expenses on our consolidated statement of operations for the year ended December 31, 2015. CenturyLink sponsors a noncontributory qualified defined benefit pension plan that covers substantially all of our employees. As noted above, on December 31, 2014, QCII's pension plan was merged into the CenturyLink Retirement Plan, which was renamed the CenturyLink Combined Pension Plan. The plan also provides survivor and disability benefits to certain employees. In November 2009, and prior to the plan merger, the pension plan was amended to no longer provide pension benefit accruals for active non-represented employees after December 31, 2009. In addition, non-represented employees hired after January 1, 2009 are not eligible to participate in the plans. Active non-represented employees who participate in these plans retain their accrued pension benefit earned as of December 31, 2009 and certain participants will continue to earn interest credits on their benefit after December 31, 2009. Employees are eligible to receive their vested accrued benefit when they separate from CenturyLink. The plans also provided a death benefit for eligible beneficiaries of certain retirees; however, the plan was amended to eliminate this benefit effective March 1, 2010 for retirees who retired prior to January 1, 2004 and whose deaths occur after February 28, 2010 and eliminate the death benefit for eligible beneficiaries of certain retirees who retired after December 31, 2003. CenturyLink maintains post-retirement benefit plans that provide health care and life insurance benefits for certain eligible retirees. The QCII post-retirement benefit plans were merged into CenturyLink's post-retirement benefit plans on January 1, 2012. The benefit obligation for the occupational health care and life insurance post-retirement plans is estimated based on the terms of benefit plans. In calculating this obligation, CenturyLink considers numerous assumptions, estimates and judgments, including but not limited to, discount rates, health care cost trend rates and plan amendments. In June 2017, we renewed a collective bargaining agreement for three years which covers approximately 10,000 of our unionized employees. Effective with the renewal, there were no significant changes to the existing benefits for the approximately 10,000 active employees and eligible post-1990 retirees who are former represented employees. This agreement expires in March 2020. The terms of the post-retirement health care and life insurance plans between CenturyLink and its eligible non-represented employees and its eligible post-1990 non-represented retirees are established by CenturyLink and are subject to change at its discretion. CenturyLink has a practice of sharing some of the cost of providing health care benefits with its non-represented employees and post-1990 non-represented retirees. The benefit obligation for the non-represented post-retirement health care benefits is based on the terms of the current written plan documents and is adjusted for anticipated continued cost sharing with non-represented employees and post-1990 non-represented retirees. However, CenturyLink's contribution under its post-1990 non-represented retirees' health care plan is capped at a specific dollar amount. Medicare Prescription Drug, Improvement and Modernization Act of 2003 CenturyLink sponsors post-retirement health care plans with several benefit options that provide prescription drug benefits that CenturyLink deems actuarially equivalent to or exceeding Medicare Part D. CenturyLink recognizes the impact of the federal subsidy received under the Medicare Prescription Drug, Improvement and Modernization Act of 2003 in the calculation of its post-retirement benefit obligation and net periodic post-retirement benefit expense. Other Benefit Plans Health Care and Life Insurance We provide health care and life insurance benefits to essentially all of our active employees. We are largely self-funded for the cost of the health care plan. Our health care benefit expense for current employees was $204 million, $241 million and $217 million for the years ended December 31, 2017, 2016 and 2015, respectively. Union-represented employee benefits are based on negotiated collective bargaining agreements. Employees' group basic life insurance plans are fully insured and the premiums are paid by CenturyLink. 401(k) Plans CenturyLink sponsors qualified defined contribution plans covering substantially all of our employees. Under these plans, employees may contribute a percentage of their annual compensation up to certain maximums, as defined by the plans and by the Internal Revenue Service ("IRS"). Currently, we match a percentage of our employees' contributions in cash. We recognized $42 million, $42 million and $43 million in expense related to these plans for the years ended December 31, 2017, 2016 and 2015, respectively.

Employee Benefits

Pension and Post-Retirement Benefits

QCII's post-retirement benefit plans were merged into CenturyLink's post-retirement benefit plans on January 1, 2012 and on December 31, 2014, QCII's qualified pension plan and a pension plan of an affiliate were merged into the CenturyLink Retirement Plan, which was renamed the CenturyLink Combined Pension Plan. Prior to the plan mergers, a substantial portion of our active and retired employees participated in QCII's pension and post-retirement plans. Based on current laws and circumstances, (i) CenturyLink was not required to make a cash contribution to the CenturyLink Combined Pension Plan in 2017 and (ii) CenturyLink does not expect it will be required to make a contribution in 2018. The amount of required contributions to the CenturyLink Combined Pension Plan in 2019 and beyond will depend on earnings on plan investments, prevailing discount rates, demographic experience, changes in plan benefits and changes in funding laws and regulations. CenturyLink occasionally makes voluntary contributions in addition to required contributions, and CenturyLink made such voluntary cash contributions of $100 million to the CenturyLink Combined Pension Plan during each of the third quarters of 2017 and 2016. CenturyLink currently expects to make a voluntary contribution of $100 million to the trust for its qualified pension plan in 2018. No contributions were made to the post-retirement occupational health care trust in 2017 or 2016 and CenturyLink does not expect to make a contribution in 2018.

The unfunded status of CenturyLink's qualified pension plan for accounting purposes was $2.004 billion and $2.352 billion as of December 31, 2017 and 2016, respectively, which includes the merged QCII qualified pension plan. The unfunded status of CenturyLink's post-retirement benefit plans for accounting purposes was $3.352 billion and $3.360 billion as of December 31, 2017 and 2016, respectively.

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.

The affiliate obligations, net in current and noncurrent liabilities on the consolidated balance sheets primarily represents the cumulative allocation of expense, net of payments, associated with QCII's pension plans and post-retirement benefits plans prior to the plan mergers. 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. For the years ended December 31, 2017 and 2016, we made settlement payments in the aggregate of $87 million and $97 million, respectively, to QCII under the plan. Changes in the affiliate obligations, net are reflected in operating activities on our consolidated statements of cash flows.

We were allocated $44 million of pension service costs and $12 million of post-retirement service costs during the year ended December 31, 2017, which represented 70% of CenturyLink's total pension and post-retirement service costs for the year. The combined net pension and post-retirement service costs is included in cost of services and products and selling, general and administrative expenses on our consolidated statement of operations for the year ended December 31, 2017.

We were allocated $45 million of pension service costs and $14 million of post-retirement service costs during the year ended December 31, 2016, which represented 70% of CenturyLink's total pension and post-retirement service costs for the year. The combined net pension and post-retirement service costs is included in cost of services and products and selling, general and administrative expenses on our consolidated statement of operations for the year ended December 31, 2016.

We were allocated $57 million of pension service costs and $17 million of post-retirement service costs during the year ended December 31, 2015, which represented 69% of CenturyLink's total pension and post-retirement service costs for the year. The combined net pension and post-retirement service costs is included in cost of services and products and selling, general and administrative expenses on our consolidated statement of operations for the year ended December 31, 2015.

CenturyLink sponsors a noncontributory qualified defined benefit pension plan that covers substantially all of our employees. As noted above, on December 31, 2014, QCII's pension plan was merged into the CenturyLink Retirement Plan, which was renamed the CenturyLink Combined Pension Plan. The plan also provides survivor and disability benefits to certain employees. In November 2009, and prior to the plan merger, the pension plan was amended to no longer provide pension benefit accruals for active non-represented employees after December 31, 2009. In addition, non-represented employees hired after January 1, 2009 are not eligible to participate in the plans. Active non-represented employees who participate in these plans retain their accrued pension benefit earned as of December 31, 2009 and certain participants will continue to earn interest credits on their benefit after December 31, 2009. Employees are eligible to receive their vested accrued benefit when they separate from CenturyLink. The plans also provided a death benefit for eligible beneficiaries of certain retirees; however, the plan was amended to eliminate this benefit effective March 1, 2010 for retirees who retired prior to January 1, 2004 and whose deaths occur after February 28, 2010 and eliminate the death benefit for eligible beneficiaries of certain retirees who retired after December 31, 2003.

CenturyLink maintains post-retirement benefit plans that provide health care and life insurance benefits for certain eligible retirees. The QCII post-retirement benefit plans were merged into CenturyLink's post-retirement benefit plans on January 1, 2012. The benefit obligation for the occupational health care and life insurance post-retirement plans is estimated based on the terms of benefit plans. In calculating this obligation, CenturyLink considers numerous assumptions, estimates and judgments, including but not limited to, discount rates, health care cost trend rates and plan amendments. In June 2017, we renewed a collective bargaining agreement for three years which covers approximately 10,000 of our unionized employees. Effective with the renewal, there were no significant changes to the existing benefits for the approximately 10,000 active employees and eligible post-1990 retirees who are former represented employees. This agreement expires in March 2020.

The terms of the post-retirement health care and life insurance plans between CenturyLink and its eligible non-represented employees and its eligible post-1990 non-represented retirees are established by CenturyLink and are subject to change at its discretion. CenturyLink has a practice of sharing some of the cost of providing health care benefits with its non-represented employees and post-1990 non-represented retirees. The benefit obligation for the non-represented post-retirement health care benefits is based on the terms of the current written plan documents and is adjusted for anticipated continued cost sharing with non-represented employees and post-1990 non-represented retirees. However, CenturyLink's contribution under its post-1990 non-represented retirees' health care plan is capped at a specific dollar amount.

Medicare Prescription Drug, Improvement and Modernization Act of 2003

CenturyLink sponsors post-retirement health care plans with several benefit options that provide prescription drug benefits that CenturyLink deems actuarially equivalent to or exceeding Medicare Part D. CenturyLink recognizes the impact of the federal subsidy received under the Medicare Prescription Drug, Improvement and Modernization Act of 2003 in the calculation of its post-retirement benefit obligation and net periodic post-retirement benefit expense.

Other Benefit Plans

Health Care and Life Insurance

We provide health care and life insurance benefits to essentially all of our active employees. We are largely self-funded for the cost of the health care plan. Our health care benefit expense for current employees was $204 million, $241 million and $217 million for the years ended December 31, 2017, 2016 and 2015, respectively. Union-represented employee benefits are based on negotiated collective bargaining agreements. Employees' group basic life insurance plans are fully insured and the premiums are paid by CenturyLink.

401(k) Plans

CenturyLink sponsors qualified defined contribution plans covering substantially all of our employees. Under these plans, employees may contribute a percentage of their annual compensation up to certain maximums, as defined by the plans and by the Internal Revenue Service ("IRS"). Currently, we match a percentage of our employees' contributions in cash. We recognized $42 million, $42 million and $43 million in expense related to these plans for the years ended December 31, 2017, 2016 and 2015, respectively.