| Cover | Nov. 03, 2020 |
| Cover [Abstract] | |
| Document Period End Date | Nov. 3, 2020 |
| Entity Registrant Name | Mercury Systems, Inc. |
| Entity Address, Address Line One | 50 Minuteman Road, |
| Entity Address, City or Town | Andover, |
| Entity Address, State or Province | MA |
| City Area Code | 978 |
| Local Phone Number | 256-1300 |
| Entity Emerging Growth Company | false |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Document Type | 8-K |
| Title of 12(b) Security | Common Stock, par value $0.01 |
| Security Exchange Name | NASDAQ |
| Entity Tax Identification Number | 04-2741391 |
| Entity Incorporation, State or Country Code | MA |
| Entity Address, Postal Zip Code | 01810 |
| Entity File Number | 000-23599 |
| Trading Symbol | MRCY |
| Amendment Flag | false |
| Entity Central Index Key | 0001049521 |
