Segment Information - Schedule of Segment Revenues, Depreciation and Amortization, and Operating (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Segment Reporting Information [Line Items]
Total revenues	$ 187.9	$ 151.2	$ 348.3	$ 294.2
Depreciation & amortization:
Total depreciation and amortization			11.1	9.2
Operating income from continuing operations:
Total operating income from continuing operations	9.0	2.6	17.2	9.6
Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	145.4	115.6	270.9	230.8
Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	42.5	35.6	77.4	63.4
Reportable Segments
Depreciation & amortization:
Total depreciation and amortization	6.0	4.7	11.1	9.2
Reportable Segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	145.4	115.6	270.9	230.8
Depreciation & amortization:
Total depreciation and amortization	4.8	3.3	8.7	6.9
Operating income from continuing operations:
Total operating income from continuing operations	10.7	5.0	22.1	12.9
Reportable Segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	42.5	35.6	77.4	63.4
Depreciation & amortization:
Total depreciation and amortization	1.2	1.4	2.4	2.3
Operating income from continuing operations:
Total operating income from continuing operations	1.7	2.0	2.3	2.8
Corporate Activities
Operating income from continuing operations:
Total operating income from continuing operations	(3.4)	(4.4)	(7.2)	(6.1)
Service revenues
Segment Reporting Information [Line Items]
Total revenues	73.7	47.0	136.3	93.0
Service revenues | Reportable Segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	73.7	47.0	136.3	93.0
Service revenues | Reportable Segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	0.0	0.0	0.0	0.0
Product sales
Segment Reporting Information [Line Items]
Total revenues	114.2	104.2	212.0	201.2
Product sales | Reportable Segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	71.7	68.6	134.6	137.8
Product sales | Reportable Segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	$ 42.5	$ 35.6	$ 77.4	$ 63.4