Segment Information - Segment Revenues, Depreciation and Amortization, and Operating (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 30, 2025	Mar. 31, 2024	Dec. 29, 2024
Segment Reporting Information [Line Items]
Total revenues	$ 302.6	$ 277.2
Total cost of sales	229.0	206.2
Selling, general and administrative expenses	57.0	54.4
Research and development expenses	10.0	9.6
Total segment operating income	6.6	7.0
Other expense, net	(0.3)	(0.2)
Income before income taxes	5.4	4.0
Total capital expenditures	22.6	16.6
Depreciation and amortization	10.4	9.3
Total assets	2,004.9	1,950.9	$ 1,950.9
Operating segments
Segment Reporting Information [Line Items]
Total revenues	302.6	277.2
Total cost of sales	229.0	206.2
Selling, general and administrative expenses	48.3	45.2
Research and development expenses	10.0	9.6
Restructuring expenses and other		0.0
Total segment operating income	15.3	16.2
Total capital expenditures	22.6	16.6
Total assets	1,747.8	1,636.1
Unallocated amounts
Segment Reporting Information [Line Items]
Stock compensation expense	(8.7)	(9.2)
Interest expense, (net)	(0.9)	(2.8)
Other expense, net	(0.3)	(0.2)
Income before income taxes	5.4	4.0
Corporate capital expenditures
Segment Reporting Information [Line Items]
Total capital expenditures	0.0	0.0
Total assets	257.1	314.8
Service revenues
Segment Reporting Information [Line Items]
Total revenues	102.4	106.5
Total cost of sales	75.7	79.2
Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	102.4	106.5
Total cost of sales	75.7	79.2
Product sales
Segment Reporting Information [Line Items]
Total revenues	200.2	170.7
Total cost of sales	153.3	127.0
Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	200.2	170.7
Total cost of sales	153.3	127.0
Kratos Government Solutions
Segment Reporting Information [Line Items]
Total revenues	239.5	217.8
Kratos Government Solutions | Operating segments
Segment Reporting Information [Line Items]
Total revenues	239.5	217.8
Total cost of sales	175.9	158.4
Selling, general and administrative expenses	37.0	34.5
Research and development expenses	9.6	8.3
Restructuring expenses and other		0.0
Total segment operating income	17.0	16.6
Total capital expenditures	13.6	9.5
Depreciation and amortization	7.1	6.1
Total assets	1,348.0	1,250.4
Kratos Government Solutions | Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	100.7	104.6
Total cost of sales	74.5	77.8
Kratos Government Solutions | Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	138.8	113.2
Total cost of sales	101.4	80.6
Unmanned Systems | Operating segments
Segment Reporting Information [Line Items]
Total revenues	63.1	59.4
Total cost of sales	53.1	47.8
Selling, general and administrative expenses	11.3	10.7
Research and development expenses	0.4	1.3
Restructuring expenses and other		0.0
Total segment operating income	(1.7)	(0.4)
Total capital expenditures	9.0	7.1
Depreciation and amortization	3.3	3.2
Total assets	399.8	385.7
Unmanned Systems | Service revenues | Operating segments
Segment Reporting Information [Line Items]
Total revenues	1.7	1.9
Total cost of sales	1.2	1.4
Unmanned Systems | Product sales | Operating segments
Segment Reporting Information [Line Items]
Total revenues	61.4	57.5
Total cost of sales	$ 51.9	$ 46.4