Segment Information - Revenues, Operating Income (Loss) and Assets by Reportable Segments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 26, 2021	Dec. 27, 2020	Dec. 29, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 811.5	$ 747.7	$ 717.5
Depreciation and amortization	25.7	24.6	23.4
Total operating income	27.9	29.3	38.0
Total assets	1,589.5	1,562.8	1,186.0
Discontinued operations
Segment Reporting Information [Line Items]
Total assets	0.0	0.0	3.3
Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	579.6	560.7
Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	231.9	187.0
Operating Segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	579.6	560.7	556.1
Depreciation and amortization	17.4	17.9	18.2
Total operating income	42.3	43.6	45.2
Total assets	907.6	877.2	777.6
Operating Segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	231.9	187.0	161.4
Depreciation and amortization	8.3	6.7	5.2
Total operating income	13.2	8.7	6.1
Total assets	327.1	292.4	246.3
Corporate activities
Segment Reporting Information [Line Items]
Total operating income	(27.6)	(23.0)	(13.3)
Total assets	354.8	393.2	158.8
Service revenues
Segment Reporting Information [Line Items]
Total revenues	219.4	248.7	272.6
Service revenues | Operating Segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	214.5	248.7	272.6
Service revenues | Operating Segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	4.9	0.0	0.0
Product sales
Segment Reporting Information [Line Items]
Total revenues	592.1	499.0	444.9
Product sales | Operating Segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	365.1	312.0	283.5
Product sales | Operating Segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	$ 227.0	$ 187.0	$ 161.4