Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 27, 2021	Jun. 28, 2020	Jun. 27, 2021	Jun. 28, 2020
Disaggregation of Revenue [Line Items]
Total Revenues	$ 205.1	$ 170.4	$ 399.3	$ 339.3
Kratos Government Solutions
Disaggregation of Revenue [Line Items]
Total Revenues	144.8	128.4	283.1	255.3
Kratos Government Solutions | U.S. Government
Disaggregation of Revenue [Line Items]
Total Revenues	91.8	90.0	184.4	174.7
Kratos Government Solutions | International
Disaggregation of Revenue [Line Items]
Total Revenues	35.8	24.9	67.5	52.9
Kratos Government Solutions | U.S. Commercial and other customers
Disaggregation of Revenue [Line Items]
Total Revenues	17.2	13.5	31.2	27.7
Kratos Government Solutions | Fixed price
Disaggregation of Revenue [Line Items]
Total Revenues	107.1	98.2	206.6	202.6
Kratos Government Solutions | Cost plus fee
Disaggregation of Revenue [Line Items]
Total Revenues	28.0	20.8	56.6	35.2
Kratos Government Solutions | Time and materials
Disaggregation of Revenue [Line Items]
Total Revenues	9.7	9.4	19.9	17.5
Unmanned Systems
Disaggregation of Revenue [Line Items]
Total Revenues	60.3	42.0	116.2	84.0
Unmanned Systems | U.S. Government
Disaggregation of Revenue [Line Items]
Total Revenues	54.4	39.4	104.0	78.8
Unmanned Systems | International
Disaggregation of Revenue [Line Items]
Total Revenues	5.5	2.5	11.8	4.9
Unmanned Systems | U.S. Commercial and other customers
Disaggregation of Revenue [Line Items]
Total Revenues	0.4	0.1	0.4	0.3
Unmanned Systems | Fixed price
Disaggregation of Revenue [Line Items]
Total Revenues	36.4	28.6	73.6	55.9
Unmanned Systems | Cost plus fee
Disaggregation of Revenue [Line Items]
Total Revenues	23.4	12.8	41.3	26.9
Unmanned Systems | Time and materials
Disaggregation of Revenue [Line Items]
Total Revenues	$ 0.5	$ 0.6	$ 1.3	$ 1.2