Segment Information - Segment Revenues, Depreciation and Amortization, and Operating (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2026	Mar. 30, 2025	Dec. 28, 2025
Segment Reporting Information [Line Items]
Total revenues	$ 371.0	$ 302.6
Total cost of sales	281.4	229.0
Selling, general and administrative expenses	72.3	57.0
Research and development expenses	10.7	10.0
Total segment operating income (loss)	4.7	6.6
Merger and acquisition related expenses	(1.9)	0.0
Interest income (expense), net	4.5	(0.9)
Other income (expense), net	0.6	(0.3)
Income before income taxes	9.8	5.4
Total capital expenditures	19.9	22.6
Depreciation and amortization	16.8	10.4
Total assets	4,042.7		$ 2,467.2
Operating segments
Segment Reporting Information [Line Items]
Total revenues	371.0	302.6
Total cost of sales	281.4	229.0
Selling, general and administrative expenses	57.3	48.3
Research and development expenses	10.7	10.0
Total segment operating income (loss)	21.6	15.3
Total capital expenditures	19.2	22.6
Total assets	2,617.1		1,911.6
Unallocated amounts
Segment Reporting Information [Line Items]
Merger and acquisition related expenses	(1.9)	0.0
Stock compensation expense	(15.0)	(8.7)
Interest income (expense), net	4.5	(0.9)
Other income (expense), net	0.6	(0.3)
Income before income taxes	9.8	5.4
Corporate capital expenditures
Segment Reporting Information [Line Items]
Total capital expenditures	0.7	0.0
Total assets	1,425.6		555.6
Service revenues
Segment Reporting Information [Line Items]
Total revenues	134.0	102.4
Total cost of sales	99.3	75.7
Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	134.0	102.4
Total cost of sales	99.3	75.7
Product sales
Segment Reporting Information [Line Items]
Total revenues	237.0	200.2
Total cost of sales	182.1	153.3
Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	237.0	200.2
Total cost of sales	182.1	153.3
Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	288.4	239.5
Kratos Government Solutions | Operating segments
Segment Reporting Information [Line Items]
Total revenues	288.4	239.5
Total cost of sales	212.9	175.9
Selling, general and administrative expenses	45.3	37.0
Research and development expenses	9.9	9.6
Total segment operating income (loss)	20.3	17.0
Total capital expenditures	12.5	13.6
Depreciation and amortization	13.0	7.1
Total assets	2,162.1		1,472.9
Kratos Government Solutions | Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	131.3	100.7
Total cost of sales	97.2	74.5
Kratos Government Solutions | Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	157.1	138.8
Total cost of sales	115.7	101.4
US | Operating segments
Segment Reporting Information [Line Items]
Total revenues	82.6	63.1
Total cost of sales	68.5	53.1
Selling, general and administrative expenses	12.0	11.3
Research and development expenses	0.8	0.4
Total segment operating income (loss)	1.3	(1.7)
Total capital expenditures	6.7	9.0
Depreciation and amortization	3.8	3.3
Total assets	455.0		$ 438.7
US | Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	2.7	1.7
Total cost of sales	2.1	1.2
US | Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	79.9	61.4
Total cost of sales	$ 66.4	$ 51.9