Segment Information - Segment Revenues, Depreciation and Amortization, and Operating (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2025	Sep. 29, 2024	Sep. 28, 2025	Sep. 29, 2024	Dec. 29, 2024
Segment Reporting Information [Line Items]
Total revenues	$ 347.6	$ 275.9	$ 1,001.7	$ 853.2
Total cost of sales	270.5	206.7	777.2	635.8
Selling, general and administrative expenses	59.8	52.6	176.7	161.5
Research and development expenses	10.0	9.9	30.2	29.7
Total segment operating income	7.1	6.5	17.4	26.0
Merger and acquisition related expenses	(0.2)	(0.2)	(0.2)	(0.2)
Interest income (expense), net	4.6	0.0	2.5	(2.7)
Other income (expense), net	0.2	(0.7)	2.0	(0.8)
Income before income taxes	11.9	5.8	21.9	22.5
Total capital expenditures	28.1	15.3	71.1	44.6
Depreciation and amortization	11.9	10.3	34.1	30.0
Total assets	2,423.3		2,423.3		$ 1,950.9
Operating segments
Segment Reporting Information [Line Items]
Total revenues	347.6	275.9	1,001.7	853.2
Total cost of sales	270.5	206.7	777.2	635.8
Selling, general and administrative expenses	50.7	45.4	150.3	138.5
Research and development expenses	10.0	9.9	30.2	29.7
Total segment operating income	16.4	13.9	44.0	49.2
Total capital expenditures	28.1	15.1	71.1	44.2
Total assets	1,849.8		1,849.8		1,636.1
Unallocated amounts
Segment Reporting Information [Line Items]
Merger and acquisition related expenses	(0.2)	(0.2)	(0.2)	(0.2)
Stock compensation expense	(9.1)	(7.2)	(26.4)	(23.0)
Interest income (expense), net	4.6	0.0	2.5	(2.7)
Other income (expense), net	0.2	(0.7)	2.0	(0.8)
Income before income taxes	11.9	5.8	21.9	22.5
Corporate capital expenditures
Segment Reporting Information [Line Items]
Total capital expenditures	0.0	0.2	0.0	0.4
Total assets	573.5		573.5		314.8
Service revenues
Segment Reporting Information [Line Items]
Total revenues	117.4	103.9	354.7	316.9
Total cost of sales	91.2	76.7	274.1	232.9
Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	117.4	103.9	354.7	316.9
Total cost of sales	91.2	76.7	274.1	232.9
Product sales
Segment Reporting Information [Line Items]
Total revenues	230.2	172.0	647.0	536.3
Total cost of sales	179.3	130.0	503.1	402.9
Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	230.2	172.0	647.0	536.3
Total cost of sales	179.3	130.0	503.1	402.9
Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	260.3	211.7	778.1	643.8
Kratos Government Solutions | Operating segments
Segment Reporting Information [Line Items]
Total revenues	260.4	211.7	778.2	643.8
Total cost of sales	198.1	153.8	590.1	465.1
Selling, general and administrative expenses	39.2	35.2	116.2	106.9
Research and development expenses	9.4	9.2	28.6	26.2
Total segment operating income	13.7	13.5	43.3	45.6
Total capital expenditures	18.5	8.6	44.7	23.5
Depreciation and amortization	8.4	7.1	23.7	20.1
Total assets	1,415.5		1,415.5		1,250.4
Kratos Government Solutions | Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	114.7	102.0	348.4	311.3
Total cost of sales	89.1	75.3	269.0	228.8
Kratos Government Solutions | Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	145.7	109.7	429.8	332.5
Total cost of sales	109.0	78.5	321.1	236.3
Unmanned Systems | Operating segments
Segment Reporting Information [Line Items]
Total revenues	87.2	64.2	223.5	209.4
Total cost of sales	72.4	52.9	187.1	170.7
Selling, general and administrative expenses	11.5	10.2	34.1	31.6
Research and development expenses	0.6	0.7	1.6	3.5
Total segment operating income	2.7	0.4	0.7	3.6
Total capital expenditures	9.6	6.5	26.4	20.7
Depreciation and amortization	3.5	3.2	10.4	9.9
Total assets	434.3		434.3		$ 385.7
Unmanned Systems | Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	2.7	1.9	6.3	5.6
Total cost of sales	2.1	1.4	5.1	4.1
Unmanned Systems | Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	84.5	62.3	217.2	203.8
Total cost of sales	$ 70.3	$ 51.5	$ 182.0	$ 166.6