Document and Entity Information - shares	9 Months Ended
	Sep. 27, 2015	Oct. 30, 2015
Document And Entity Information
Entity Registrant Name	KRATOS DEFENSE & SECURITY SOLUTIONS, INC.
Entity Central Index Key	0001069258
Current Fiscal Year End Date	--12-27
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 27, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		59,088,317