Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details) (Maximum)	12 Months Ended
Jun. 30, 2013
Maximum
Restricted Cash and Cash Equivalents Items [Line Items]
Maturity of cash and cash equivalents	90 days

Represents the maximum original maturity period of investments classified as cash and cash equivalents at the date of acquisition.

No definition available.

Name:	mrcy_CashAndCashEquivalentMaturityPeriod
Namespace Prefix:	mrcy_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration