Segment Information - Revenues, Operating Income (Loss) and Assets by Reportable Segments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 25, 2022	Dec. 26, 2021	Dec. 27, 2020
Segment Reporting Information [Line Items]
Total revenues	$ 898.3	$ 811.5	$ 747.7
Depreciation and amortization	30.5	25.7	24.6
Total operating income (loss)	(2.6)	27.9	29.3
Total assets	1,551.5	1,589.5	1,562.8
Discontinued operations
Segment Reporting Information [Line Items]
Total assets	0.0	0.0	0.0
Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	676.6	579.6
Total operating income (loss)	6.4
Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	221.7	231.9
Operating segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	676.6	579.6	560.7
Depreciation and amortization	22.7	17.4	17.9
Total operating income (loss)	27.2	42.3	43.6
Total assets	1,105.1	907.6	877.2
Operating segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	221.7	231.9	187.0
Depreciation and amortization	7.8	8.3	6.7
Total operating income (loss)	(2.8)	13.2	8.7
Total assets	349.7	327.1	292.4
Corporate activities
Segment Reporting Information [Line Items]
Total operating income (loss)	(27.0)	(27.6)	(23.0)
Total assets	96.7	354.8	393.2
Service revenues
Segment Reporting Information [Line Items]
Total revenues	325.2	219.4	248.7
Service revenues | Operating segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	320.0	214.5	248.7
Service revenues | Operating segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	5.2	4.9	0.0
Product sales
Segment Reporting Information [Line Items]
Total revenues	573.1	592.1	499.0
Product sales | Operating segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	356.6	365.1	312.0
Product sales | Operating segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	$ 216.5	$ 227.0	$ 187.0