| COVER PAGE | Feb. 25, 2021 |
| Entity Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Feb. 25, 2021 |
| Entity Registrant Name | Kratos Defense & Security Solutions, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-34460 |
| Entity Tax Identification Number | 13-3818604 |
| Entity Address, Address Line One | 1 Chisholm Trail |
| Entity Address, Address Line Two | Suite 3200 |
| Entity Address, City or Town | Round Rock |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 78681 |
| City Area Code | 512 |
| Local Phone Number | 238-9840 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Title of 12(b) Security | Common Stock, $0.001 par value |
| Trading Symbol | KTOS |
| Security Exchange Name | NASDAQ |
| Entity Central Index Key | 0001069258 |
| Amendment Flag | false |
| Former Address | |
| Entity Information [Line Items] | |
| Entity Address, Address Line One | 10680 Treena St. |
| Entity Address, Address Line Two | Suite 600 |
| Entity Address, City or Town | San Diego |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 92131 |
