Document and Entity Information Document - shares	6 Months Ended
	Jun. 30, 2017	Aug. 02, 2017
Entity Information [Line Items]
Entity Registrant Name	LEVEL 3 COMMUNICATIONS INC
Entity Central Index Key	0000794323
Document Type	10-Q
Document Period End Date	Jun. 30, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		362,691,792
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q2