Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Jun. 30, 2018
Document and Entity Information
Entity Registrant Name	LEVEL 3 PARENT, LLC
Entity Central Index Key	0000794323
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Public Float		$ 0
Entity Common Stock, Shares Outstanding	0
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY