Segment Information - Revenues, Operating Income (Loss) and Assets by Reportable Segments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 29, 2024	Dec. 31, 2023	Dec. 25, 2022
Segment Reporting Information [Line Items]
Total revenues	$ 1,136.3	$ 1,037.1	$ 898.3
Total costs	849.1	768.5	672.3
Selling, general and administrative expenses	214.0	197.8	182.8
Research and development expenses	40.3	38.4	38.6
Restructuring expenses and other	3.2	0.9	6.8
Total segment operating income	29.0	31.1	(2.9)
Merger and acquisition related items	(0.7)	(0.4)	(0.7)
Loss on extinguishment of debt	0.0	0.0	(13.0)
Other income (expense), net	0.5	0.5	0.6
Income before income taxes	26.5	11.1	(33.0)
Depreciation and amortization	40.3	33.2	30.5
Total capital expenditures	58.2	52.4	45.4
Total assets	1,950.9	1,632.5
Operating segments
Segment Reporting Information [Line Items]
Total revenues	1,136.3	1,037.1	898.3
Total costs	849.1	768.5	672.3
Selling, general and administrative expenses	184.2	172.4	162.1
Research and development expenses	40.3	38.4	38.6
Restructuring expenses and other	3.2	0.9	0.9
Total segment operating income	59.5	56.9	24.4
Total capital expenditures	57.8	51.8	45.2
Total assets	1,636.1	1,568.8
Unallocated amounts
Segment Reporting Information [Line Items]
Merger and acquisition related items	(0.7)	(0.4)	(0.7)
Stock compensation expense	(29.8)	(25.4)	(26.3)
Interest expense (net)	(3.0)	(20.5)	(17.7)
Loss on extinguishment of debt			(13.0)
Other income (expense), net	0.5	0.5	0.6
Income before income taxes	26.5	11.1	(32.7)
Corporate capital expenditures
Segment Reporting Information [Line Items]
Total capital expenditures	0.4	0.6	0.2
Total assets	314.8	63.7
Service revenues
Segment Reporting Information [Line Items]
Total revenues	423.4	402.6	325.2
Total costs	310.0	303.2	239.0
Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	423.4	402.6	325.2
Total costs	310.0	303.2	239.0
Product sales
Segment Reporting Information [Line Items]
Total revenues	712.9	634.5	573.1
Total costs	539.1	465.3	433.3
Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	712.9	634.5	573.1
Total costs	539.1	465.3	433.3
Kratos Government Solutions | Operating segments
Segment Reporting Information [Line Items]
Total revenues	865.8	824.9	676.6
Total costs	627.0	600.2	495.2
Selling, general and administrative expenses	142.9	135.8	121.1
Research and development expenses	36.1	35.3	32.2
Restructuring expenses and other	3.2	0.9	0.9
Total segment operating income	56.6	52.7	27.2
Depreciation and amortization	27.1	24.1	22.7
Total capital expenditures	30.5	26.9	21.0
Total assets	1,250.4	1,190.2
Kratos Government Solutions | Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	416.3	395.9	320.0
Total costs	304.7	298.3	235.2
Kratos Government Solutions | Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	449.5	429.0	356.6
Total costs	322.3	301.9	260.0
Unmanned Systems
Segment Reporting Information [Line Items]
Total revenues	270.5	212.2	221.7
Unmanned Systems | Operating segments
Segment Reporting Information [Line Items]
Total revenues	270.5	212.2	221.7
Total costs	222.1	168.3	177.1
Selling, general and administrative expenses	41.3	36.6	41.0
Research and development expenses	4.2	3.1	6.4
Restructuring expenses and other	0.0	0.0	0.0
Total segment operating income	2.9	4.2	(2.8)
Depreciation and amortization	13.2	9.1	7.8
Total capital expenditures	27.3	24.9	24.2
Total assets	385.7	378.6
Unmanned Systems | Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	7.1	6.7	5.2
Total costs	5.3	4.9	3.8
Unmanned Systems | Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	263.4	205.5	216.5
Total costs	$ 216.8	$ 163.4	$ 173.3