Segment Information - Narrative (Details) $ in Millions	12 Months Ended
Dec. 31, 2023 USD ($) segment	Dec. 25, 2022 USD ($)	Dec. 26, 2021 USD ($)
Segment Reporting Information [Line Items]
Number of reportable (in segments) \| segment	2
Litigation settlement charges	$ 0.0	$ 5.5	$ 0.0
Operating income	31.1	(2.6)	27.9
Total revenues	$ 1,037.1	$ 898.3	$ 811.5
Percentage of foreign revenue to total revenue (percent)	19.00%	19.00%	21.00%
Company's C5ISR
Segment Reporting Information [Line Items]
Litigation settlement charges	$ 3.4
Company's Training Solutions
Segment Reporting Information [Line Items]
Litigation settlement charges	3.0
Kratos Government Solutions
Segment Reporting Information [Line Items]
Litigation settlement charges		$ 5.5
Operating income		6.4
Total revenues	824.9	676.6
Assets of foreign subsidiaries	204.6	178.3	$ 166.2
Non-US
Segment Reporting Information [Line Items]
Total revenues	$ 202.0	$ 173.1	$ 169.8

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