Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 25, 2016	Feb. 24, 2017	Jun. 26, 2016
Document And Entity Information
Entity Registrant Name	KRATOS DEFENSE & SECURITY SOLUTIONS, INC.
Entity Central Index Key	0001069258
Current Fiscal Year End Date	--12-25
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 25, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		74,533,342
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 182.6