Goodwill and Other Intangible Assets - Goodwill (Details) - USD ($)	1 Months Ended	12 Months Ended
	Nov. 30, 2016	Dec. 25, 2016	Dec. 27, 2015
Goodwill [Line Items]
Intangible assets, net		$ 32,600,000	$ 36,500,000
Impairment of goodwill		0	0
Increase in goodwill	$ 2,000,000
Carrying amounts of goodwill by reportable segment [Abstract]
Gross value		732,800,000	730,800,000
Less accumulated impairment		247,400,000	247,400,000
Net		485,400,000	483,400,000
Public Safety & Security
Carrying amounts of goodwill by reportable segment [Abstract]
Gross value		53,900,000	53,900,000
Less accumulated impairment		18,300,000	18,300,000
Net		35,600,000	35,600,000
Kratos Unmanned Systems (US)
Carrying amounts of goodwill by reportable segment [Abstract]
Gross value		111,100,000	111,100,000
Less accumulated impairment		13,800,000	13,800,000
Net		97,300,000	97,300,000
Kratos Government Solutions (KGS)
Carrying amounts of goodwill by reportable segment [Abstract]
Gross value		567,800,000	565,800,000
Less accumulated impairment		215,300,000	215,300,000
Net		$ 352,500,000	$ 350,500,000