Segment Information - Schedule of Segment Revenues, Depreciation and Amortization, and Operating (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 25, 2022	Sep. 26, 2021	Sep. 25, 2022	Sep. 26, 2021
Segment Reporting Information [Line Items]
Total revenues	$ 228.6	$ 200.6	$ 649.0	$ 599.9
Depreciation and amortization:
Total depreciation and amortization	8.9	6.1	22.8	19.4
Operating income (loss) from continuing operations:
Total operating income (loss) from continuing operations	(3.6)	10.5	(6.7)	18.7
Corporate activities
Operating income (loss) from continuing operations:
Total operating income (loss) from continuing operations	(6.8)	(6.7)	(20.5)	(19.8)
Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	178.6	139.3	490.0	422.4
Depreciation and amortization:
Total depreciation and amortization	7.0	4.3	17.1	13.2
Kratos Government Solutions | Reportable Segments
Operating income (loss) from continuing operations:
Total operating income (loss) from continuing operations	3.3	14.6	18.4	27.6
Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	50.0	61.3	159.0	177.5
Depreciation and amortization:
Total depreciation and amortization	1.9	1.8	5.7	6.2
Unmanned Systems | Reportable Segments
Operating income (loss) from continuing operations:
Total operating income (loss) from continuing operations	(0.1)	2.6	(4.6)	10.9
Service revenues
Segment Reporting Information [Line Items]
Total revenues	88.6	51.6	235.3	166.9
Service revenues | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	87.3	50.5	231.3	163.3
Service revenues | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	1.3	1.1	4.0	3.6
Product sales
Segment Reporting Information [Line Items]
Total revenues	140.0	149.0	413.7	433.0
Product sales | Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	91.3	88.8	258.7	259.1
Product sales | Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	$ 48.7	$ 60.2	$ 155.0	$ 173.9