Cover - shares	9 Months Ended
	Sep. 27, 2024	Oct. 22, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 27, 2024
Document Transition Report	false
Entity File Number	001-33072
Entity Registrant Name	Leidos Holdings, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-3562868
Entity Address, Address Line One	1750 Presidents Street,
Entity Address, City or Town	Reston,
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	20190
City Area Code	571
Local Phone Number	526-6000
Title of 12(b) Security	Common stock, par value $.0001 per share
Trading Symbol	LDOS
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		133,433,109
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001336920
Current Fiscal Year End Date	--01-03