Long-Term Debt and Credit Facilities - Additional Information (Details)				12 Months Ended
	Nov. 02, 2017	Jun. 19, 2017 USD ($) lender	May 05, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2015 USD ($)	Feb. 15, 2019 USD ($) bank	Dec. 31, 2017 USD ($)	Nov. 01, 2017 USD ($)	Jul. 19, 2017	Apr. 27, 2017 USD ($)
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 35,854,000,000
Coverage ratio				2.00
Subsequent event | Interest Rate Swap
Long-term Debt and Credit Facilities
Derivative, notional amount						$ 2,500,000,000
Number of banks involved | bank						5
Derivative, fixed interest rate						2.47926%
Debt Covenant, Period One
Long-term Debt and Credit Facilities
Leverage ratio				5.00
Debt Covenant, Period Two
Long-term Debt and Credit Facilities
Leverage ratio				4.75
Qwest Corporation
Long-term Debt and Credit Facilities
EBITDA ratio				2.85
Embarq Corporation
Long-term Debt and Credit Facilities
Maximum indebtedness, as a percent of tangible assets				15.00%
Medium-term Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 100,000,000			$ 100,000,000
Interest rate, stated percentage				4.53%
Medium-term Notes | Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 4,611,000,000			$ 4,611,000,000
Interest rate, stated percentage				4.754%			3.557%
Medium-term Notes | Level 3 Financing, Inc. | London Interbank Offered Rate (LIBOR)
Long-term Debt and Credit Facilities
Interest rate margin					1.00%
Medium-term Notes | Level 3 Financing, Inc. | Federal Funds Effective Swap Rate
Long-term Debt and Credit Facilities
Interest rate margin					0.50%
Medium-term Notes | Level 3 Financing, Inc. | Eurodollar
Long-term Debt and Credit Facilities
Interest rate margin					2.25%
Letter of Credit | Level 3 Parent, LLC | Letter of Credit
Long-term Debt and Credit Facilities
Letters of credit outstanding				$ 30,000,000			$ 36,000,000
Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 5,956,000,000			7,294,000,000
Senior Notes | Qwest Corporation | Minimum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				6.125%
Senior Notes | Qwest Corporation | Maximum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				7.75%
Senior Notes | Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 5,315,000,000			5,315,000,000
Senior Notes | Level 3 Financing, Inc. | Minimum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				5.125%
Senior Notes | Level 3 Financing, Inc. | Maximum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				6.125%
Senior Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 8,036,000,000			8,125,000,000
Redemption price, percentage				101.00%
Senior Notes | CenturyLink, Inc. | Minimum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				5.625%
Senior Notes | CenturyLink, Inc. | Maximum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				7.65%
Senior Notes | Level 3 Parent, LLC
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 600,000,000			600,000,000
Interest rate, stated percentage				5.75%
Senior Notes | Qwest Capital Funding, Inc
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 697,000,000			981,000,000
Senior Notes | Qwest Capital Funding, Inc | Minimum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				6.875%
Senior Notes | Qwest Capital Funding, Inc | Maximum
Long-term Debt and Credit Facilities
Interest rate, stated percentage				7.75%
Senior Notes | Embarq Corporation
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 1,485,000,000			1,485,000,000
Interest rate, stated percentage				7.995%
New Senior Secured Credit Facilities
Long-term Debt and Credit Facilities
Long-term debt, gross		$ 10,245,000,000
2017 Revolving Credit Facility | Revolving Credit Facility | CenturyLink Escrow, LLC
Long-term Debt and Credit Facilities
Maximum borrowing capacity		$ 2,168,000,000
Lenders of credit facility | lender		18
2017 Revolving Credit Facility | Revolving Credit Facility | CenturyLink Escrow, LLC | Swingline Loan
Long-term Debt and Credit Facilities
Maximum borrowing capacity		$ 100,000,000
2017 Revolving Credit Facility | Revolving Credit Facility | CenturyLink Escrow, LLC | Letter of Credit
Long-term Debt and Credit Facilities
Maximum borrowing capacity		400,000,000
2017 Revolving Credit Facility | Revolving Credit Facility | CenturyLink Escrow, LLC | Minimum
Long-term Debt and Credit Facilities
Lending commitment per lender		36,400,000
2017 Revolving Credit Facility | Revolving Credit Facility | CenturyLink Escrow, LLC | Maximum
Long-term Debt and Credit Facilities
Lending commitment per lender		$ 167,800,000
2017 Revolving Credit Facility | Senior Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Repurchased face amount of Senior Notes								$ 319,000,000
Term Loan A | Medium-term Notes | CenturyLink Escrow, LLC
Long-term Debt and Credit Facilities
Lenders of credit facility | lender		18
Aggregate principal amount of debt issuance		$ 1,707,000,000
Term Loan A | Medium-term Notes | CenturyLink Escrow, LLC | Minimum
Long-term Debt and Credit Facilities
Lending commitment per lender		$ 28,600,000
Term Loan A | Medium-term Notes | CenturyLink Escrow, LLC | Minimum | London Interbank Offered Rate (LIBOR)
Long-term Debt and Credit Facilities
Interest rate margin		2.25%
Term Loan A | Medium-term Notes | CenturyLink Escrow, LLC | Minimum | Base Rate
Long-term Debt and Credit Facilities
Interest rate margin		1.25%
Term Loan A | Medium-term Notes | CenturyLink Escrow, LLC | Maximum
Long-term Debt and Credit Facilities
Lending commitment per lender		$ 132,200,000
Term Loan A | Medium-term Notes | CenturyLink Escrow, LLC | Maximum | London Interbank Offered Rate (LIBOR)
Long-term Debt and Credit Facilities
Interest rate margin		3.00%
Term Loan A | Medium-term Notes | CenturyLink Escrow, LLC | Maximum | Base Rate
Long-term Debt and Credit Facilities
Interest rate margin		2.00%
Term Loan A | Medium-term Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 1,622,000,000			1,575,000,000
Interest rate, stated percentage				5.272%
Term Loan A-1 | Medium-term Notes | CenturyLink Escrow, LLC
Long-term Debt and Credit Facilities
Aggregate principal amount of debt issuance		$ 370,000,000
Term Loan A-1 | Medium-term Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 351,000,000			370,000,000
Interest rate, stated percentage				5.272%
Term Loan B | Medium-term Notes | CenturyLink Escrow, LLC
Long-term Debt and Credit Facilities
Aggregate principal amount of debt issuance		$ 6,000,000,000
Interest rate, stated percentage		1.375%							2.75%
Term Loan B | Medium-term Notes | CenturyLink Escrow, LLC | London Interbank Offered Rate (LIBOR)
Long-term Debt and Credit Facilities
Interest rate margin	2.75%
Term Loan B | Medium-term Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 5,940,000,000			6,000,000,000
Interest rate, stated percentage				5.272%
Term Loan | Medium-term Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Long-term debt, gross				$ 100,000,000			100,000,000
Aggregate principal amount of debt issuance					$ 100,000,000
Term Loan | Medium-term Notes | Qwest Corporation | Minimum | London Interbank Offered Rate (LIBOR)
Long-term Debt and Credit Facilities
Interest rate margin					1.50%
Term Loan | Medium-term Notes | Qwest Corporation | Minimum | Base Rate
Long-term Debt and Credit Facilities
Interest rate margin					0.50%
Term Loan | Medium-term Notes | Qwest Corporation | Maximum | London Interbank Offered Rate (LIBOR)
Long-term Debt and Credit Facilities
Interest rate margin					2.50%
Term Loan | Medium-term Notes | Qwest Corporation | Maximum | Base Rate
Long-term Debt and Credit Facilities
Interest rate margin					1.50%
Term Loan | Medium-term Notes | Level 3 Financing, Inc.
Long-term Debt and Credit Facilities
Interest rate, stated percentage				1.25%
Uncommitted Revolving Letter of Credit Facility | Letter of Credit | CenturyLink, Inc. | Letter of Credit
Long-term Debt and Credit Facilities
Maximum borrowing capacity				$ 225,000,000
Letters of credit outstanding				97,000,000			104,000,000
Collateralized Debt Obligations | Letter of Credit | Level 3 Parent, LLC | Letter of Credit
Long-term Debt and Credit Facilities
Letters of credit outstanding				$ 24,000,000			$ 30,000,000
6.75% Notes due 2057 | Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Aggregate principal amount of debt issuance										$ 575,000,000
Interest rate, stated percentage										6.75%
Redemption price, percentage				100.00%
Principal amount of over-allotment										$ 85,000,000
Net proceeds from issuance of debt			$ 638,000,000
Qwest Notes due 2018 | Senior Notes | Qwest Capital Funding, Inc
Long-term Debt and Credit Facilities
Interest rate, stated percentage				6.50%
Repayments of debt				$ 174,000,000
Qwest Notes Due 2051 | Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Interest rate, stated percentage				7.50%
Repayments of debt				$ 164,000,000
Qwest Notes due 2052 | Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Interest rate, stated percentage				7.00%
Repayments of debt				$ 925,000,000
Qwest Notes 2035 | Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Interest rate, stated percentage				7.25%
Repayments of debt				$ 250,000,000
8.77% Notes due 2017 | Senior Notes | Embarq Corporation
Long-term Debt and Credit Facilities
Interest rate, stated percentage							8.77%
Repurchased face amount of Senior Notes							$ 72,000,000
5.15% Notes due 2017 | Senior Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Interest rate, stated percentage							5.15%
Repurchased face amount of Senior Notes							$ 350,000,000
7.5% Notes due 2051 | Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Aggregate principal amount of debt issuance							$ 288,000,000
Interest rate, stated percentage							7.50%
Repurchased face amount of Senior Notes							$ 125,000,000
6.5% Notes due 2017 | Senior Notes | Qwest Corporation
Long-term Debt and Credit Facilities
Interest rate, stated percentage							6.50%
Repurchased face amount of Senior Notes							$ 500,000,000
6.00% Noted due 2017 | Senior Notes | CenturyLink, Inc.
Long-term Debt and Credit Facilities
Interest rate, stated percentage							6.00%
Repurchased face amount of Senior Notes							$ 500,000,000