Quarterly Financial Data (Unaudited) (Details) - USD ($) $ in Millions		3 Months Ended					12 Months Ended
	Sep. 22, 2015	Dec. 31, 2017	Dec. 25, 2016	Sep. 25, 2016	Jun. 26, 2016	Mar. 27, 2016	Dec. 31, 2017	Dec. 25, 2016	Dec. 27, 2015	May 31, 2014
Effect of Fourth Quarter Events [Line Items]
Loss (gain) on extinguishment of debt							$ 17.3	$ (0.2)	$ 3.4
Restructuring charges							0.0	$ 9.1	$ 0.0
Loss on contract				$ 18.7
Facility Closure
Effect of Fourth Quarter Events [Line Items]
Restructuring charges			$ 1.4	$ 0.1	$ 4.7	$ 3.0
Kratos Government Solutions (KGS)
Effect of Fourth Quarter Events [Line Items]
Impairment of goodwill		$ 24.2					24.2
Senior notes | 7% Senior Notes due 2019
Effect of Fourth Quarter Events [Line Items]
Loss (gain) on extinguishment of debt	$ 3.4	$ 15.2	$ (0.2)				$ 17.3
Stated interest rate		7.00%					7.00%			7.00%