Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2021	Mar. 29, 2020
Disaggregation of Revenue [Line Items]
Total Revenues	$ 194.2	$ 168.9
Kratos Government Solutions
Disaggregation of Revenue [Line Items]
Total Revenues	138.3	126.9
Kratos Government Solutions | U.S. Government
Disaggregation of Revenue [Line Items]
Total Revenues	92.6	84.7
Kratos Government Solutions | International
Disaggregation of Revenue [Line Items]
Total Revenues	31.7	28.0
Kratos Government Solutions | U.S. Commercial and other customers
Disaggregation of Revenue [Line Items]
Total Revenues	14.0	14.2
Kratos Government Solutions | Fixed price
Disaggregation of Revenue [Line Items]
Total Revenues	99.5	104.4
Kratos Government Solutions | Cost plus fee
Disaggregation of Revenue [Line Items]
Total Revenues	28.6	14.4
Kratos Government Solutions | Time and materials
Disaggregation of Revenue [Line Items]
Total Revenues	10.2	8.1
Unmanned Systems
Disaggregation of Revenue [Line Items]
Total Revenues	55.9	42.0
Unmanned Systems | U.S. Government
Disaggregation of Revenue [Line Items]
Total Revenues	49.6	39.4
Unmanned Systems | International
Disaggregation of Revenue [Line Items]
Total Revenues	6.3	2.4
Unmanned Systems | U.S. Commercial and other customers
Disaggregation of Revenue [Line Items]
Total Revenues	0.0	0.2
Unmanned Systems | Fixed price
Disaggregation of Revenue [Line Items]
Total Revenues	37.2	27.3
Unmanned Systems | Cost plus fee
Disaggregation of Revenue [Line Items]
Total Revenues	17.9	14.1
Unmanned Systems | Time and materials
Disaggregation of Revenue [Line Items]
Total Revenues	$ 0.8	$ 0.6