Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jun. 25, 2017	Jul. 01, 2018	Jun. 25, 2017
Disaggregation of Revenue [Line Items]
Total revenues	$ 151.2	$ 147.9	$ 294.2	$ 279.9
Kratos Government Solutions
Disaggregation of Revenue [Line Items]
Total revenues	115.6		230.8
Kratos Government Solutions | U.S. Government
Disaggregation of Revenue [Line Items]
Total revenues	72.1		143.0
Kratos Government Solutions | International
Disaggregation of Revenue [Line Items]
Total revenues	29.0		55.9
Kratos Government Solutions | U.S. Commercial and other customers
Disaggregation of Revenue [Line Items]
Total revenues	14.5		31.9
Kratos Government Solutions | Fixed price
Disaggregation of Revenue [Line Items]
Total revenues	101.5		203.3
Kratos Government Solutions | Cost plus fee
Disaggregation of Revenue [Line Items]
Total revenues	7.2		14.4
Kratos Government Solutions | Time and materials
Disaggregation of Revenue [Line Items]
Total revenues	6.9		13.1
Unmanned Systems
Disaggregation of Revenue [Line Items]
Total revenues	35.6		63.4
Unmanned Systems | U.S. Government
Disaggregation of Revenue [Line Items]
Total revenues	28.9		53.0
Unmanned Systems | International
Disaggregation of Revenue [Line Items]
Total revenues	6.6		10.3
Unmanned Systems | U.S. Commercial and other customers
Disaggregation of Revenue [Line Items]
Total revenues	0.1		0.1
Unmanned Systems | Fixed price
Disaggregation of Revenue [Line Items]
Total revenues	29.1		51.0
Unmanned Systems | Cost plus fee
Disaggregation of Revenue [Line Items]
Total revenues	5.9		11.4
Unmanned Systems | Time and materials
Disaggregation of Revenue [Line Items]
Total revenues	$ 0.6		$ 1.0