Segment Information - Revenues, Operating Income (Loss) and Assets by Reportable Segments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 25, 2022	Dec. 26, 2021
Segment Reporting Information [Line Items]
Total revenues	$ 1,037.1	$ 898.3	$ 811.5
Depreciation and amortization	33.2	30.5	25.7
Total operating income (loss)	31.1	(2.6)	27.9
Total assets	1,632.5	1,551.5	1,589.5
Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	824.9	676.6
Total operating income (loss)		6.4
Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	212.2	221.7
Operating segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	824.9	676.6	579.6
Depreciation and amortization	24.1	22.7	17.4
Total operating income (loss)	52.7	27.2	42.3
Total assets	1,190.2	1,105.1	907.6
Operating segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	212.2	221.7	231.9
Depreciation and amortization	9.1	7.8	8.3
Total operating income (loss)	4.2	(2.8)	13.2
Total assets	378.6	349.7	327.1
Corporate activities
Segment Reporting Information [Line Items]
Total operating income (loss)	(25.8)	(27.0)	(27.6)
Total assets	63.7	96.7	354.8
Service revenues
Segment Reporting Information [Line Items]
Total revenues	402.6	325.2	219.4
Service revenues | Operating segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	395.9	320.0	214.5
Service revenues | Operating segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	6.7	5.2	4.9
Product sales
Segment Reporting Information [Line Items]
Total revenues	634.5	573.1	592.1
Product sales | Operating segments | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	429.0	356.6	365.1
Product sales | Operating segments | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	$ 205.5	$ 216.5	$ 227.0