Segment Information - Revenues, Operating Income (Loss) and Assets by Reportable Segments (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 29, 2019	Sep. 29, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 30, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 29, 2019	Dec. 30, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 185.1	$ 184.1	$ 187.9	$ 160.4	$ 164.4	$ 159.4	$ 151.2	$ 143.0	$ 717.5	$ 618.0	$ 603.3
Depreciation and amortization									23.4	17.9	22.2
Total operating income (loss)	9.3	$ 11.5	$ 9.0	$ 8.2	10.8	$ 10.1	$ 2.6	$ 7.0	38.0	30.5	(12.0)
Total assets	1,186.0				1,010.1				1,186.0	1,010.1	1,024.0
Discontinued operations
Segment Reporting Information [Line Items]
Total assets	3.3				8.3				3.3	8.3	97.4
Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues									556.1	485.1
Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues									161.4	132.9
Operating Segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues									556.1	485.1	481.6
Depreciation and amortization									18.2	13.2	14.4
Total operating income (loss)									45.2	35.5	(0.1)
Total assets	777.6				602.8				777.6	602.8	597.9
Operating Segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues									161.4	132.9	121.7
Depreciation and amortization									5.2	4.7	7.8
Total operating income (loss)									6.1	5.1	(3.6)
Total assets	246.3				220.9				246.3	220.9	201.9
Corporate activities
Segment Reporting Information [Line Items]
Total operating income (loss)									(13.3)	(10.1)	(8.3)
Total assets	$ 158.8				$ 178.1				158.8	178.1	126.8
Service revenues
Segment Reporting Information [Line Items]
Total revenues									272.6	200.7	197.8
Service revenues | Operating Segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues									272.6	200.7	197.8
Service revenues | Operating Segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues									0.0	0.0	0.0
Product sales
Segment Reporting Information [Line Items]
Total revenues									444.9	417.3	405.5
Product sales | Operating Segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues									283.5	284.4	283.8
Product sales | Operating Segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues									$ 161.4	$ 132.9	$ 121.7