Segment Information - Schedule of Segment Revenues, Depreciation and Amortization, and Operating (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 01, 2023	Sep. 25, 2022	Oct. 01, 2023	Sep. 25, 2022
Segment Reporting Information [Line Items]
Total revenues	$ 274.6	$ 228.6	$ 763.3	$ 649.0
Depreciation and amortization:
Total depreciation and amortization	8.2	8.9	24.0	22.8
Operating income (loss):
Total operating income (loss)	12.2	(3.6)	19.4	(6.7)
Corporate activities
Operating income (loss):
Total operating income (loss)	(6.3)	(6.8)	(19.0)	(20.5)
Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	217.9	178.6	606.5	490.0
Depreciation and amortization:
Total depreciation and amortization	6.0	7.0	17.8	17.1
Kratos Government Solutions | Reportable Segments
Operating income (loss):
Total operating income (loss)	15.9	3.3	35.2	18.4
Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	56.7	50.0	156.8	159.0
Depreciation and amortization:
Total depreciation and amortization	2.2	1.9	6.2	5.7
Unmanned Systems | Reportable Segments
Operating income (loss):
Total operating income (loss)	2.6	(0.1)	3.2	(4.6)
Service revenues
Segment Reporting Information [Line Items]
Total revenues	106.5	88.6	301.8	235.3
Service revenues | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	104.4	87.3	296.8	231.3
Service revenues | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	2.1	1.3	5.0	4.0
Product sales
Segment Reporting Information [Line Items]
Total revenues	168.1	140.0	461.5	413.7
Product sales | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	113.5	91.3	309.7	258.7
Product sales | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	$ 54.6	$ 48.7	$ 151.8	$ 155.0