Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2015	Jul. 31, 2015	Dec. 31, 2014
Document Documentand Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Trading Symbol	MRCY
Entity Registrant Name	MERCURY SYSTEMS INC
Entity Central Index Key	0001049521
Current Fiscal Year End Date	--06-30
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		34,430,270
Entity Public Float			$ 475.4