Document and Entity Information - USD ($)	11 Months Ended
	Jan. 01, 2016	Feb. 17, 2016	Jul. 03, 2015
Document Information [Line Items]
Document Type	10-KT
Amendment Flag	false
Document Period End Date	Jan. 01, 2016
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Trading Symbol	LDOS
Entity Registrant Name	Leidos Holdings, Inc.
Entity Central Index Key	0001336920
Current Fiscal Year End Date	--01-01
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		72,164,921
Entity Public Float			$ 2,892,032,677
Leidos, Inc.
Document Information [Line Items]
Document Type	10-KT
Amendment Flag	false
Document Period End Date	Jan. 01, 2016
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Entity Registrant Name	LEIDOS, INC.
Entity Central Index Key	0000353394
Current Fiscal Year End Date	--01-01
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		5,000