Long-Term Debt and Credit Facilities - Additional Information (Details) - USD ($)			6 Months Ended
	Jan. 31, 2020	Jan. 24, 2020	Jun. 30, 2020	Aug. 07, 2020	Jul. 15, 2020	Jun. 15, 2020
Derivative [Line Items]
Repayments of debt			$ 2,600,000,000
Loss on extinguishment of debt	$ (67,000,000)
Senior notes | Subsequent Event
Derivative [Line Items]
Repurchased face amount					$ 1,200,000,000
CenturyLink, Inc.
Derivative [Line Items]
Repayments of debt			1,250,000,000
Amended Credit Agreement
Derivative [Line Items]
Face amount	$ 8,699,000,000
Amended Credit Agreement | Base Rate | Minimum
Derivative [Line Items]
Basis spread (as a percent)	1.50%
Amended Credit Agreement | Base Rate | Maximum
Derivative [Line Items]
Basis spread (as a percent)	2.25%
Amended Credit Agreement | Eurodollar | Minimum
Derivative [Line Items]
Basis spread (as a percent)	0.50%
Amended Credit Agreement | Eurodollar | Maximum
Derivative [Line Items]
Basis spread (as a percent)	1.25%
6.875% Senior Notes Due 2054 | Qwest Corporation | Senior notes | Subsequent Event
Derivative [Line Items]
Stated interest rate				6.875%
Repurchased face amount				$ 300,000,000
5.625% Senior Notes Due 2023 | Level 3 Financing, Inc. | Senior notes | Subsequent Event
Derivative [Line Items]
Stated interest rate					5.625%
Repurchased face amount					$ 360,000,000
5.375% Senior Notes Due 2022 | Level 3 Financing, Inc. | Senior notes | Subsequent Event
Derivative [Line Items]
Stated interest rate					5.375%
Repurchased face amount					$ 840,000,000
Term loan | CenturyLink, Inc.
Derivative [Line Items]
Repayments of debt			62,000,000
Term loan | Term Loan B | CenturyLink, Inc.
Derivative [Line Items]
Repayments of debt		$ 1,250,000,000
Senior notes
Derivative [Line Items]
Loss on extinguishment of debt			(86,000,000)
Senior notes | CenturyLink, Inc.
Derivative [Line Items]
Repayments of debt			78,000,000
Payment of aggregate principal amount at maturity			$ 973,000,000
Senior notes | CenturyLink, Inc. | Minimum
Derivative [Line Items]
Stated interest rate			5.125%
Senior notes | CenturyLink, Inc. | Maximum
Derivative [Line Items]
Stated interest rate			7.65%
Senior notes | Qwest Corporation
Derivative [Line Items]
Repayments of debt			$ 1,300,000,000
Senior notes | Qwest Corporation | Minimum
Derivative [Line Items]
Stated interest rate			6.125%
Senior notes | Qwest Corporation | Maximum
Derivative [Line Items]
Stated interest rate			7.75%
Senior notes | Level 3 Financing, Inc. | Minimum
Derivative [Line Items]
Stated interest rate			4.25%
Senior notes | Level 3 Financing, Inc. | Maximum
Derivative [Line Items]
Stated interest rate			5.625%
Senior notes | Amended Credit Agreement, Term Loan A
Derivative [Line Items]
Face amount	$ 1,166,000,000
Senior notes | Amended Credit Agreement, Term Loan A-1
Derivative [Line Items]
Face amount	333,000,000
Senior notes | Amended Credit Agreement, Term Loan B
Derivative [Line Items]
Face amount	$ 5,000,000,000.0
Senior notes | Amended Credit Agreement, Term Loan B | Base Rate
Derivative [Line Items]
Basis spread (as a percent)	1.25%
Senior notes | Amended Credit Agreement, Term Loan B | Eurodollar
Derivative [Line Items]
Basis spread (as a percent)	2.25%
Senior notes | 4.250% Senior Secured Notes Due 2028 | Level 3 Financing, Inc.
Derivative [Line Items]
Face amount						$ 1,200,000,000
Stated interest rate						4.25%
Senior notes | 4.000% Senior Secured Notes Due 2027 | CenturyLink, Inc.
Derivative [Line Items]
Face amount		$ 1,250,000,000
Stated interest rate		4.00%	4.00%
Credit facility | Amended Credit Agreement | Revolving Credit Facility
Derivative [Line Items]
Maximum borrowing capacity	$ 2,200,000,000