Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017
Disaggregation of Revenue [Line Items]
Total revenues	$ 159.4	$ 157.1	$ 453.6	$ 437.0
Kratos Government Solutions
Disaggregation of Revenue [Line Items]
Total revenues	126.1		356.9
Kratos Government Solutions | U.S. Government
Disaggregation of Revenue [Line Items]
Total revenues	90.8		245.3
Kratos Government Solutions | International
Disaggregation of Revenue [Line Items]
Total revenues	22.3		66.7
Kratos Government Solutions | U.S. Commercial and other customers
Disaggregation of Revenue [Line Items]
Total revenues	13.0		44.9
Kratos Government Solutions | Fixed price
Disaggregation of Revenue [Line Items]
Total revenues	108.5		311.8
Kratos Government Solutions | Cost plus fee
Disaggregation of Revenue [Line Items]
Total revenues	10.3		24.7
Kratos Government Solutions | Time and materials
Disaggregation of Revenue [Line Items]
Total revenues	7.3		20.4
Unmanned Systems
Disaggregation of Revenue [Line Items]
Total revenues	33.3		96.7
Unmanned Systems | U.S. Government
Disaggregation of Revenue [Line Items]
Total revenues	30.0		83.0
Unmanned Systems | International
Disaggregation of Revenue [Line Items]
Total revenues	2.7		13.0
Unmanned Systems | U.S. Commercial and other customers
Disaggregation of Revenue [Line Items]
Total revenues	0.6		0.7
Unmanned Systems | Fixed price
Disaggregation of Revenue [Line Items]
Total revenues	25.9		76.9
Unmanned Systems | Cost plus fee
Disaggregation of Revenue [Line Items]
Total revenues	7.1		18.5
Unmanned Systems | Time and materials
Disaggregation of Revenue [Line Items]
Total revenues	$ 0.3		$ 1.3