Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Disaggregation of Revenue [Line Items]
Total Revenues	$ 202.0	$ 184.1	$ 541.3	$ 532.4
Kratos Government Solutions
Disaggregation of Revenue [Line Items]
Total Revenues	148.5	138.4	403.8	409.3
Kratos Government Solutions | U.S. Government
Disaggregation of Revenue [Line Items]
Total Revenues	98.7	89.1	273.4	272.2
Kratos Government Solutions | International
Disaggregation of Revenue [Line Items]
Total Revenues	34.5	29.6	87.4	82.9
Kratos Government Solutions | U.S. Commercial and other customers
Disaggregation of Revenue [Line Items]
Total Revenues	15.3	19.7	43.0	54.2
Kratos Government Solutions | Fixed price
Disaggregation of Revenue [Line Items]
Total Revenues	113.3	114.6	315.9	346.2
Kratos Government Solutions | Cost plus fee
Disaggregation of Revenue [Line Items]
Total Revenues	27.7	15.6	62.9	39.1
Kratos Government Solutions | Time and materials
Disaggregation of Revenue [Line Items]
Total Revenues	7.5	8.2	25.0	24.0
Unmanned Systems
Disaggregation of Revenue [Line Items]
Total Revenues	53.5	45.7	137.5	123.1
Unmanned Systems | U.S. Government
Disaggregation of Revenue [Line Items]
Total Revenues	46.6	37.1	125.4	104.8
Unmanned Systems | International
Disaggregation of Revenue [Line Items]
Total Revenues	6.5	8.3	11.4	17.3
Unmanned Systems | U.S. Commercial and other customers
Disaggregation of Revenue [Line Items]
Total Revenues	0.4	0.3	0.7	1.0
Unmanned Systems | Fixed price
Disaggregation of Revenue [Line Items]
Total Revenues	39.6	38.9	95.5	100.1
Unmanned Systems | Cost plus fee
Disaggregation of Revenue [Line Items]
Total Revenues	12.9	6.6	39.8	22.1
Unmanned Systems | Time and materials
Disaggregation of Revenue [Line Items]
Total Revenues	$ 1.0	$ 0.2	$ 2.2	$ 0.9