Goodwill and Other Intangible Assets - Goodwill (Details) $ in Millions	3 Months Ended	12 Months Ended
Dec. 29, 2019 USD ($) contract	Dec. 29, 2019 USD ($) Segment	Dec. 31, 2017 USD ($)	Dec. 30, 2018 USD ($)
Goodwill [Line Items]
Number of operating segments \| Segment		5
Goodwill	$ 455.6	$ 455.6		$ 425.7
Number of lost contract opportunities \| contract	2
Lost contract opportunities period	5 years
Carrying amounts of goodwill by reportable segment
Gross value	$ 708.9	708.9		679.0
Less accumulated impairment	253.3	253.3		253.3
Net	455.6	455.6		425.7
Kratos Unmanned Systems (US)
Goodwill [Line Items]
Goodwill	97.3	97.3		97.3
Carrying amounts of goodwill by reportable segment
Gross value	111.1	111.1		111.1
Less accumulated impairment	13.8	13.8		13.8
Net	97.3	97.3		97.3
Kratos Government Solutions (KGS)
Goodwill [Line Items]
Goodwill	358.3	358.3		328.4
Impairment of goodwill			$ 24.2
Carrying amounts of goodwill by reportable segment
Gross value	597.8	597.8		567.9
Less accumulated impairment	239.5	239.5		239.5
Net	$ 358.3	$ 358.3		$ 328.4

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Number Of Lost Contract Opportunities

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