Segment Information - Segment Revenues, Depreciation and Amortization, and Operating (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 29, 2025	Jun. 30, 2024	Jun. 29, 2025	Jun. 30, 2024	Dec. 29, 2024
Segment Reporting Information [Line Items]
Total revenues	$ 351.5	$ 300.1	$ 654.1	$ 577.3
Total cost of sales	277.7	222.9	506.7	429.1
Selling, general and administrative expenses	59.9	54.5	116.9	108.9
Research and development expenses	10.2	10.2	20.2	19.8
Total segment operating income	3.7	12.5	10.3	19.5
Interest income (expense), net	(1.2)	0.1	(2.1)	(2.7)
Other income (expense), net	2.1	0.1	1.8	(0.1)
Income before income taxes	4.6	12.7	10.0	16.7
Total capital expenditures	20.5	12.7	43.1	29.3
Depreciation and amortization	11.8	10.4	22.2	19.7
Total assets	2,585.7		2,585.7		$ 1,950.9
Operating segments
Segment Reporting Information [Line Items]
Total revenues	351.5	300.1	654.1	577.3
Total cost of sales	277.7	222.9	506.7	429.1
Selling, general and administrative expenses	51.3	47.9	99.6	93.1
Research and development expenses	10.2	10.2	20.2	19.8
Total segment operating income	12.3	19.1	27.6	35.3
Total capital expenditures	20.4	12.5	43.0	29.1
Total assets	1,803.0		1,803.0		1,636.1
Unallocated amounts
Segment Reporting Information [Line Items]
Stock compensation expense	(8.6)	(6.6)	(17.3)	(15.8)
Interest income (expense), net	(1.2)	0.1	(2.1)	(2.7)
Other income (expense), net	2.1	0.1	1.8	(0.1)
Income before income taxes	4.6	12.7	10.0	16.7
Corporate capital expenditures
Segment Reporting Information [Line Items]
Total capital expenditures	0.1	0.2	0.1	0.2
Total assets	782.7		782.7		314.8
Service revenues
Segment Reporting Information [Line Items]
Total revenues	134.9	106.5	237.3	213.0
Total cost of sales	107.2	77.0	182.9	156.2
Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	134.9	106.5	237.3	213.0
Total cost of sales	107.2	77.0	182.9	156.2
Product sales
Segment Reporting Information [Line Items]
Total revenues	216.6	193.6	416.8	364.3
Total cost of sales	170.5	145.9	323.8	272.9
Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	216.6	193.6	416.8	364.3
Total cost of sales	170.5	145.9	323.8	272.9
Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	278.3	214.3	517.8	432.1
Kratos Government Solutions | Operating segments
Segment Reporting Information [Line Items]
Total revenues	278.3	214.3	517.8	432.1
Total cost of sales	216.1	152.9	392.0	311.3
Selling, general and administrative expenses	40.0	37.3	77.0	71.7
Research and development expenses	9.6	8.6	19.2	17.0
Total segment operating income	12.6	15.5	29.6	32.1
Total capital expenditures	12.6	5.4	26.2	14.9
Depreciation and amortization	8.2	6.9	15.3	13.0
Total assets	1,382.0		1,382.0		1,250.4
Kratos Government Solutions | Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	133.0	104.7	233.7	209.3
Total cost of sales	105.4	75.7	179.9	153.5
Kratos Government Solutions | Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	145.3	109.6	284.1	222.8
Total cost of sales	110.7	77.2	212.1	157.8
Unmanned Systems | Operating segments
Segment Reporting Information [Line Items]
Total revenues	73.2	85.8	136.3	145.2
Total cost of sales	61.6	70.0	114.7	117.8
Selling, general and administrative expenses	11.3	10.6	22.6	21.4
Research and development expenses	0.6	1.6	1.0	2.8
Total segment operating income	(0.3)	3.6	(2.0)	3.2
Total capital expenditures	7.8	7.1	16.8	14.2
Depreciation and amortization	3.6	3.5	6.9	6.7
Total assets	421.0		421.0		$ 385.7
Unmanned Systems | Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	1.9	1.8	3.6	3.7
Total cost of sales	1.8	1.3	3.0	2.7
Unmanned Systems | Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	71.3	84.0	132.7	141.5
Total cost of sales	$ 59.8	$ 68.7	$ 111.7	$ 115.1