Long-Term Debt and Credit Facilities - Schedule of Long Term Debt (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Long-term Debt and Credit Facilities
Finance lease and other obligations	$ 214	$ 801
Unamortized discounts and other, net	(30)	(8)
Unamortized debt issuance costs	(266)	(283)
Total long-term debt	35,125	36,061
Less current maturities	(1,744)	(652)
Long-term debt, excluding current maturities	33,381	35,409
CenturyLink, Inc. \| Line of credit \| 2017 Revolving Credit Facility
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 700	$ 550
CenturyLink, Inc. \| Line of credit \| 2017 Revolving Credit Facility \| Minimum
Long-term Debt and Credit Facilities
Stated interest rate	4.786%
CenturyLink, Inc. \| Medium-term notes
Long-term Debt and Credit Facilities
Long-term debt, weighted average interest rate	4.794%	5.272%
CenturyLink, Inc. \| Medium-term notes \| Term Loan A
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 1,558	$ 1,622
CenturyLink, Inc. \| Medium-term notes \| Term Loan A-1
Long-term Debt and Credit Facilities
Long-term debt, gross	338	351
CenturyLink, Inc. \| Medium-term notes \| Term Loan B
Long-term Debt and Credit Facilities
Long-term debt, gross	5,895	5,940
CenturyLink, Inc. \| Senior notes
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 7,446	8,036
CenturyLink, Inc. \| Senior notes \| Minimum
Long-term Debt and Credit Facilities
Stated interest rate	5.625%
CenturyLink, Inc. \| Senior notes \| Maximum
Long-term Debt and Credit Facilities
Stated interest rate	7.65%
Level 3 Financing, Inc. \| Medium-term notes
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 4,611	$ 4,611
Long-term debt, weighted average interest rate	4.294%	4.754%
Level 3 Financing, Inc. \| Senior notes
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 5,915	$ 5,315
Level 3 Financing, Inc. \| Senior notes \| Minimum
Long-term Debt and Credit Facilities
Stated interest rate	4.625%
Level 3 Financing, Inc. \| Senior notes \| Maximum
Long-term Debt and Credit Facilities
Stated interest rate	6.125%
Embarq Corporation \| First mortgage bonds
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 138	138
Embarq Corporation \| First mortgage bonds \| Minimum
Long-term Debt and Credit Facilities
Stated interest rate	7.125%
Embarq Corporation \| First mortgage bonds \| Maximum
Long-term Debt and Credit Facilities
Stated interest rate	8.375%
Embarq Corporation \| Senior notes
Long-term Debt and Credit Facilities
Stated interest rate	7.995%
Long-term debt, gross	$ 1,450	1,485
Embarq Corporation \| Other
Long-term Debt and Credit Facilities
Stated interest rate	9.00%
Long-term debt, gross	$ 148	150
Level 3 Parent, LLC \| Senior notes
Long-term Debt and Credit Facilities
Stated interest rate	5.75%
Long-term debt, gross	$ 600	600
Qwest Corporation \| Medium-term notes
Long-term Debt and Credit Facilities
Stated interest rate	4.05%
Long-term debt, gross	$ 100	100
Qwest Corporation \| Senior notes
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 5,956	5,956
Qwest Corporation \| Senior notes \| Minimum
Long-term Debt and Credit Facilities
Stated interest rate	6.125%
Qwest Corporation \| Senior notes \| Maximum
Long-term Debt and Credit Facilities
Stated interest rate	7.75%
Qwest Capital Funding, Inc. \| Senior notes
Long-term Debt and Credit Facilities
Long-term debt, gross	$ 352	$ 697
Qwest Capital Funding, Inc. \| Senior notes \| Minimum
Long-term Debt and Credit Facilities
Stated interest rate	6.875%
Qwest Capital Funding, Inc. \| Senior notes \| Maximum
Long-term Debt and Credit Facilities
Stated interest rate	7.75%
London Interbank Offered Rate (LIBOR) \| CenturyLink, Inc. \| Medium-term notes \| Term Loan A
Long-term Debt and Credit Facilities
Basis spread	2.75%
London Interbank Offered Rate (LIBOR) \| CenturyLink, Inc. \| Medium-term notes \| Term Loan A-1
Long-term Debt and Credit Facilities
Basis spread	2.75%
London Interbank Offered Rate (LIBOR) \| CenturyLink, Inc. \| Medium-term notes \| Term Loan B
Long-term Debt and Credit Facilities
Basis spread	2.75%
London Interbank Offered Rate (LIBOR) \| Level 3 Financing, Inc. \| Medium-term notes
Long-term Debt and Credit Facilities
Basis spread	2.25%

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